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From: Jakub Jelinek <jakub@gcc.gnu.org>
To: gcc-cvs@gcc.gnu.org
Subject: [gcc r13-3108] libgcc: Decrease size of _Unwind_FrameState and even more size of cleared area in uw_frame_state_for
Date: Thu,  6 Oct 2022 09:06:18 +0000 (GMT)	[thread overview]
Message-ID: <20221006090618.381CB3857BA6@sourceware.org> (raw)

https://gcc.gnu.org/g:146e4591403239d662f36cab2d8b78a47cd01bd2

commit r13-3108-g146e4591403239d662f36cab2d8b78a47cd01bd2
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Oct 6 11:04:52 2022 +0200

    libgcc: Decrease size of _Unwind_FrameState and even more size of cleared area in uw_frame_state_for
    
    The following patch implements something that has Florian found as
    low hanging fruit in our unwinder and has been discussed in the
    https://gcc.gnu.org/wiki/cauldron2022#cauldron2022talks.inprocess_unwinding_bof
    talk.
    _Unwind_FrameState type seems to be (unlike the pre-GCC 3 frame_state
    which has been part of ABI) private to unwind-dw2.c + unwind.inc it
    includes, it is always defined on the stack of some entrypoints, initialized
    by static uw_frame_state_for and the address of it is also passed to other
    static functions or the static inlines handling machine dependent unwinding,
    but it isn't fortunately passed to any callbacks or public functions, so I
    think we can safely change it any time we want.
    Florian mentioned that the structure is large even on x86_64, 384 bytes
    there, starts with 328 bytes long element with frame_state_reg_info type
    which then starts with an array with __LIBGCC_DWARF_FRAME_REGISTERS__ + 1
    elements, each of them is 16 bytes long, on x86_64
    __LIBGCC_DWARF_FRAME_REGISTERS__ is just 17 but even that is big, on say
    riscv __LIBGCC_DWARF_FRAME_REGISTERS__ is I think 128, on powerpc 111,
    on sh 153 etc.  And, we memset to zero the whole fs variable with the
    _Unwind_FrameState type at the start of the unwinding.
    The reason why each element is 16 byte (on 64-bit arches) is that it
    contains some pointer or pointer sized integer and then an enum (with just
    7 different enumerators) + padding.
    
    The following patch decreases it by moving the enum into a separate
    array and using just one byte for each register in that second array.
    We could compress it even more, say 4 bits per register, but I don't
    want to uglify the code for it too much and make the accesses slower.
    Furthermore, the clearing of the object can clear only thos how array
    and members after it, because REG_UNSAVED enumerator (0) doesn't actually
    need any pointer or pointer sized integer, it is just the other kinds
    that need to have there something.
    By doing this, on x86_64 the above numbers change to _Unwind_FrameState
    type being now 264 bytes long, frame_state_reg_info 208 bytes and we
    don't clear the first 144 bytes of the object, so the memset is 120 bytes,
    so ~ 31% of the old clearing size.  On riscv 64-bit assuming it has same
    structure layout rules for the few types used there that would be
    ~ 2160 bytes of _Unwind_FrameState type before and ~ 1264 bytes after,
    with the memset previously ~ 2160 bytes and after ~ 232 bytes after.
    
    We've also talked about possibly adding a number of initially initialized
    regs and initializing the rest lazily, but at least for x86_64 with
    18 elements in the array that doesn't seem to be worth it anymore,
    especially because return address column is 16 there and that is usually the
    first thing to be touched.  It might theory help with lots of registers if
    they are usually untouched, but would uglify and complicate any stores to
    how by having to check there for the not initialized yet cases and lazy
    initialization, and similarly for all reads of how to do there if below
    last initialized one, use how, otherwise imply REG_UNSAVED.
    
    The disadvantage of the patch is that touching reg[x].loc and how[x]
    now means 2 cachelines rather than one as before, and I admit beyond
    bootstrap/regtest I haven't benchmarked it in any way.
    
    2022-10-06  Jakub Jelinek  <jakub@redhat.com>
    
            * unwind-dw2.h (REG_UNSAVED, REG_SAVED_OFFSET, REG_SAVED_REG,
            REG_SAVED_EXP, REG_SAVED_VAL_OFFSET, REG_SAVED_VAL_EXP,
            REG_UNDEFINED): New anonymous enum, moved from inside of
            struct frame_state_reg_info.
            (struct frame_state_reg_info): Remove reg[].how element and the
            anonymous enum there.  Add how element.
            * unwind-dw2.c: Include stddef.h.
            (uw_frame_state_for): Don't clear first
            offsetof (_Unwind_FrameState, regs.how[0]) bytes of *fs.
            (execute_cfa_program, __frame_state_for, uw_update_context_1,
            uw_update_context): Use fs->regs.how[X] instead of fs->regs.reg[X].how
            or fs.regs.how[X] instead of fs.regs.reg[X].how.
            * config/sh/linux-unwind.h (sh_fallback_frame_state): Likewise.
            * config/bfin/linux-unwind.h (bfin_fallback_frame_state): Likewise.
            * config/pa/linux-unwind.h (pa32_fallback_frame_state): Likewise.
            * config/pa/hpux-unwind.h (UPDATE_FS_FOR_SAR, UPDATE_FS_FOR_GR,
            UPDATE_FS_FOR_FR, UPDATE_FS_FOR_PC, pa_fallback_frame_state):
            Likewise.
            * config/alpha/vms-unwind.h (alpha_vms_fallback_frame_state):
            Likewise.
            * config/alpha/linux-unwind.h (alpha_fallback_frame_state): Likewise.
            * config/arc/linux-unwind.h (arc_fallback_frame_state,
            arc_frob_update_context): Likewise.
            * config/riscv/linux-unwind.h (riscv_fallback_frame_state): Likewise.
            * config/nios2/linux-unwind.h (NIOS2_REG): Likewise.
            * config/nds32/linux-unwind.h (NDS32_PUT_FS_REG): Likewise.
            * config/s390/tpf-unwind.h (s390_fallback_frame_state): Likewise.
            * config/s390/linux-unwind.h (s390_fallback_frame_state): Likewise.
            * config/sparc/sol2-unwind.h (sparc64_frob_update_context,
            MD_FALLBACK_FRAME_STATE_FOR): Likewise.
            * config/sparc/linux-unwind.h (sparc64_fallback_frame_state,
            sparc64_frob_update_context, sparc_fallback_frame_state): Likewise.
            * config/i386/sol2-unwind.h (x86_64_fallback_frame_state,
            x86_fallback_frame_state): Likewise.
            * config/i386/w32-unwind.h (i386_w32_fallback_frame_state): Likewise.
            * config/i386/linux-unwind.h (x86_64_fallback_frame_state,
            x86_fallback_frame_state): Likewise.
            * config/i386/freebsd-unwind.h (x86_64_freebsd_fallback_frame_state):
            Likewise.
            * config/i386/dragonfly-unwind.h
            (x86_64_dragonfly_fallback_frame_state): Likewise.
            * config/i386/gnu-unwind.h (x86_gnu_fallback_frame_state): Likewise.
            * config/csky/linux-unwind.h (csky_fallback_frame_state): Likewise.
            * config/aarch64/linux-unwind.h (aarch64_fallback_frame_state):
            Likewise.
            * config/aarch64/freebsd-unwind.h
            (aarch64_freebsd_fallback_frame_state): Likewise.
            * config/aarch64/aarch64-unwind.h (aarch64_frob_update_context):
            Likewise.
            * config/or1k/linux-unwind.h (or1k_fallback_frame_state): Likewise.
            * config/mips/linux-unwind.h (mips_fallback_frame_state): Likewise.
            * config/loongarch/linux-unwind.h (loongarch_fallback_frame_state):
            Likewise.
            * config/m68k/linux-unwind.h (m68k_fallback_frame_state): Likewise.
            * config/xtensa/linux-unwind.h (xtensa_fallback_frame_state):
            Likewise.
            * config/rs6000/darwin-fallback.c (set_offset): Likewise.
            * config/rs6000/aix-unwind.h (MD_FROB_UPDATE_CONTEXT): Likewise.
            * config/rs6000/linux-unwind.h (ppc_fallback_frame_state): Likewise.
            * config/rs6000/freebsd-unwind.h (frob_update_context): Likewise.

Diff:
---
 libgcc/config/aarch64/aarch64-unwind.h |  2 +-
 libgcc/config/aarch64/freebsd-unwind.h |  4 +-
 libgcc/config/aarch64/linux-unwind.h   |  8 ++--
 libgcc/config/alpha/linux-unwind.h     |  6 +--
 libgcc/config/alpha/vms-unwind.h       |  6 +--
 libgcc/config/arc/linux-unwind.h       |  4 +-
 libgcc/config/bfin/linux-unwind.h      | 84 +++++++++++++++++-----------------
 libgcc/config/csky/linux-unwind.h      | 16 +++----
 libgcc/config/i386/dragonfly-unwind.h  | 48 +++++++++----------
 libgcc/config/i386/freebsd-unwind.h    | 48 +++++++++----------
 libgcc/config/i386/gnu-unwind.h        | 16 +++----
 libgcc/config/i386/linux-unwind.h      | 48 +++++++++----------
 libgcc/config/i386/sol2-unwind.h       | 48 +++++++++----------
 libgcc/config/i386/w32-unwind.h        | 20 ++++----
 libgcc/config/loongarch/linux-unwind.h |  4 +-
 libgcc/config/m68k/linux-unwind.h      | 22 ++++-----
 libgcc/config/mips/linux-unwind.h      |  4 +-
 libgcc/config/nds32/linux-unwind.h     |  2 +-
 libgcc/config/nios2/linux-unwind.h     |  2 +-
 libgcc/config/or1k/linux-unwind.h      |  4 +-
 libgcc/config/pa/hpux-unwind.h         | 12 ++---
 libgcc/config/pa/linux-unwind.h        | 10 ++--
 libgcc/config/riscv/linux-unwind.h     |  4 +-
 libgcc/config/rs6000/aix-unwind.h      |  6 +--
 libgcc/config/rs6000/darwin-fallback.c |  2 +-
 libgcc/config/rs6000/freebsd-unwind.h  |  2 +-
 libgcc/config/rs6000/linux-unwind.h    | 24 +++++-----
 libgcc/config/s390/linux-unwind.h      |  6 +--
 libgcc/config/s390/tpf-unwind.h        | 10 ++--
 libgcc/config/sh/linux-unwind.h        | 22 ++++-----
 libgcc/config/sparc/linux-unwind.h     | 18 ++++----
 libgcc/config/sparc/sol2-unwind.h      | 12 ++---
 libgcc/config/xtensa/linux-unwind.h    |  4 +-
 libgcc/unwind-dw2.c                    | 40 ++++++++--------
 libgcc/unwind-dw2.h                    | 20 ++++----
 35 files changed, 296 insertions(+), 292 deletions(-)

diff --git a/libgcc/config/aarch64/aarch64-unwind.h b/libgcc/config/aarch64/aarch64-unwind.h
index e082e957821..26db9cbd9e5 100644
--- a/libgcc/config/aarch64/aarch64-unwind.h
+++ b/libgcc/config/aarch64/aarch64-unwind.h
@@ -80,7 +80,7 @@ aarch64_frob_update_context (struct _Unwind_Context *context,
 {
   const int reg = DWARF_REGNUM_AARCH64_RA_STATE;
   int ra_signed;
-  if (fs->regs.reg[reg].how == REG_UNSAVED)
+  if (fs->regs.how[reg] == REG_UNSAVED)
     ra_signed = fs->regs.reg[reg].loc.offset & 0x1;
   else
     ra_signed = _Unwind_GetGR (context, reg) & 0x1;
diff --git a/libgcc/config/aarch64/freebsd-unwind.h b/libgcc/config/aarch64/freebsd-unwind.h
index 8d64680b72a..2f795fb8234 100644
--- a/libgcc/config/aarch64/freebsd-unwind.h
+++ b/libgcc/config/aarch64/freebsd-unwind.h
@@ -90,7 +90,7 @@ aarch64_freebsd_fallback_frame_state
   fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
 
   for (n = 0; n < 32; n++)
-    fs->regs.reg[n].how = REG_SAVED_OFFSET;
+    fs->regs.how[n] = REG_SAVED_OFFSET;
 
   for (n = 0; n < 30; n++)
     fs->regs.reg[n].loc.offset = (_Unwind_Ptr) &(sc->XREG(n)) - new_cfa;
@@ -98,7 +98,7 @@ aarch64_freebsd_fallback_frame_state
   fs->regs.reg[30].loc.offset = (_Unwind_Ptr) &(sc->REG_NAME(lr)) - new_cfa;
   fs->regs.reg[31].loc.offset = (_Unwind_Ptr) &(sc->REG_NAME(sp)) - new_cfa;
 
-  fs->regs.reg[DARC].how = REG_SAVED_OFFSET;
+  fs->regs.how[DARC] = REG_SAVED_OFFSET;
   fs->regs.reg[DARC].loc.offset = (_Unwind_Ptr) &(sc->REG_NAME(elr)) - new_cfa;
 
   fs->retaddr_column = DARC;
diff --git a/libgcc/config/aarch64/linux-unwind.h b/libgcc/config/aarch64/linux-unwind.h
index 551b48923c6..bce3f3c9d93 100644
--- a/libgcc/config/aarch64/linux-unwind.h
+++ b/libgcc/config/aarch64/linux-unwind.h
@@ -89,7 +89,7 @@ aarch64_fallback_frame_state (struct _Unwind_Context *context,
 
   for (i = 0; i < AARCH64_DWARF_NUMBER_R; i++)
     {
-      fs->regs.reg[AARCH64_DWARF_R0 + i].how = REG_SAVED_OFFSET;
+      fs->regs.how[AARCH64_DWARF_R0 + i] = REG_SAVED_OFFSET;
       fs->regs.reg[AARCH64_DWARF_R0 + i].loc.offset =
 	(_Unwind_Ptr) & (sc->regs[i]) - new_cfa;
     }
@@ -115,7 +115,7 @@ aarch64_fallback_frame_state (struct _Unwind_Context *context,
 	    {
 	      _Unwind_Sword offset;
 
-	      fs->regs.reg[AARCH64_DWARF_V0 + i].how = REG_SAVED_OFFSET;
+	      fs->regs.how[AARCH64_DWARF_V0 + i] = REG_SAVED_OFFSET;
 
 	      /* sigcontext contains 32 128bit registers for V0 to
 		 V31.  The kernel will have saved the contents of the
@@ -142,12 +142,12 @@ aarch64_fallback_frame_state (struct _Unwind_Context *context,
 	}
     }
 
-  fs->regs.reg[31].how = REG_SAVED_OFFSET;
+  fs->regs.how[31] = REG_SAVED_OFFSET;
   fs->regs.reg[31].loc.offset = (_Unwind_Ptr) & (sc->sp) - new_cfa;
 
   fs->signal_frame = 1;
 
-  fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how =
+  fs->regs.how[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__] =
     REG_SAVED_VAL_OFFSET;
   fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset =
     (_Unwind_Ptr) (sc->pc) - new_cfa;
diff --git a/libgcc/config/alpha/linux-unwind.h b/libgcc/config/alpha/linux-unwind.h
index 1f7f95e8cee..1a3a69df92b 100644
--- a/libgcc/config/alpha/linux-unwind.h
+++ b/libgcc/config/alpha/linux-unwind.h
@@ -67,17 +67,17 @@ alpha_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
   for (i = 0; i < 30; ++i)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset
 	= (long) &sc->sc_regs[i] - new_cfa;
     }
   for (i = 0; i < 31; ++i)
     {
-      fs->regs.reg[i+32].how = REG_SAVED_OFFSET;
+      fs->regs.how[i+32] = REG_SAVED_OFFSET;
       fs->regs.reg[i+32].loc.offset
 	= (long) &sc->sc_fpregs[i] - new_cfa;
     }
-  fs->regs.reg[64].how = REG_SAVED_OFFSET;
+  fs->regs.how[64] = REG_SAVED_OFFSET;
   fs->regs.reg[64].loc.offset = (long)&sc->sc_pc - new_cfa;
   fs->retaddr_column = 64;
   fs->signal_frame = 1;
diff --git a/libgcc/config/alpha/vms-unwind.h b/libgcc/config/alpha/vms-unwind.h
index 5219d8e1a17..71b59a668ab 100644
--- a/libgcc/config/alpha/vms-unwind.h
+++ b/libgcc/config/alpha/vms-unwind.h
@@ -50,7 +50,7 @@ extern int SYS$GL_CALL_HANDL;
 
 #define UPDATE_FS_FOR_CFA_GR(FS, GRN, LOC, CFA) \
 do { \
-(FS)->regs.reg[GRN].how = REG_SAVED_OFFSET;      \
+(FS)->regs.how[GRN] = REG_SAVED_OFFSET;      \
 (FS)->regs.reg[GRN].loc.offset = (_Unwind_Sword) ((REG) (LOC) - (REG) (CFA)); \
 } while (0);
 
@@ -212,10 +212,10 @@ alpha_vms_fallback_frame_state (struct _Unwind_Context *context,
 	if (eh_debug)
 	  printf ("FALLBACK: REGISTER frame procedure\n");
 
-	fs->regs.reg[RA_COLUMN].how = REG_SAVED_REG;
+	fs->regs.how[RA_COLUMN] = REG_SAVED_REG;
 	fs->regs.reg[RA_COLUMN].loc.reg = pv->pdsc$b_save_ra;
 	
-	fs->regs.reg[29].how = REG_SAVED_REG;
+	fs->regs.how[29] = REG_SAVED_REG;
 	fs->regs.reg[29].loc.reg = pv->pdsc$b_save_fp;
 	
 	break;
diff --git a/libgcc/config/arc/linux-unwind.h b/libgcc/config/arc/linux-unwind.h
index be42a3163b2..231971a7ccc 100644
--- a/libgcc/config/arc/linux-unwind.h
+++ b/libgcc/config/arc/linux-unwind.h
@@ -122,7 +122,7 @@ arc_fallback_frame_state (struct _Unwind_Context *context,
 
   fs->signal_frame = 1;
   fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__;
-  fs->regs.reg[fs->retaddr_column].how = REG_SAVED_VAL_OFFSET;
+  fs->regs.how[fs->retaddr_column] = REG_SAVED_VAL_OFFSET;
   fs->regs.reg[fs->retaddr_column].loc.offset =
     ((_Unwind_Ptr) (regs[ret])) - new_cfa;
 
@@ -140,7 +140,7 @@ arc_frob_update_context (struct _Unwind_Context *context,
   _Unwind_Word fp_val;
   asm ("mov %0,fp" : "=r" (fp_val));
 
-  switch (fs->regs.reg[27].how)
+  switch (fs->regs.how[27])
     {
     case REG_UNSAVED:
     case REG_UNDEFINED:
diff --git a/libgcc/config/bfin/linux-unwind.h b/libgcc/config/bfin/linux-unwind.h
index 34ab7da5317..de7e321e709 100644
--- a/libgcc/config/bfin/linux-unwind.h
+++ b/libgcc/config/bfin/linux-unwind.h
@@ -68,93 +68,93 @@ bfin_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_reg = 14;
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (long)&sc->sc_r0 - new_cfa;
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
   fs->regs.reg[1].loc.offset = (long)&sc->sc_r1 - new_cfa;
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long)&sc->sc_r2 - new_cfa;
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
   fs->regs.reg[3].loc.offset = (long)&sc->sc_r3 - new_cfa;
-  fs->regs.reg[4].how = REG_SAVED_OFFSET;
+  fs->regs.how[4] = REG_SAVED_OFFSET;
   fs->regs.reg[4].loc.offset = (long)&sc->sc_r4 - new_cfa;
-  fs->regs.reg[5].how = REG_SAVED_OFFSET;
+  fs->regs.how[5] = REG_SAVED_OFFSET;
   fs->regs.reg[5].loc.offset = (long)&sc->sc_r5 - new_cfa;
-  fs->regs.reg[6].how = REG_SAVED_OFFSET;
+  fs->regs.how[6] = REG_SAVED_OFFSET;
   fs->regs.reg[6].loc.offset = (long)&sc->sc_r6 - new_cfa;
-  fs->regs.reg[7].how = REG_SAVED_OFFSET;
+  fs->regs.how[7] = REG_SAVED_OFFSET;
   fs->regs.reg[7].loc.offset = (long)&sc->sc_r7 - new_cfa;
-  fs->regs.reg[8].how = REG_SAVED_OFFSET;
+  fs->regs.how[8] = REG_SAVED_OFFSET;
   fs->regs.reg[8].loc.offset = (long)&sc->sc_p0 - new_cfa;
-  fs->regs.reg[9].how = REG_SAVED_OFFSET;
+  fs->regs.how[9] = REG_SAVED_OFFSET;
   fs->regs.reg[9].loc.offset = (long)&sc->sc_p1 - new_cfa;
-  fs->regs.reg[10].how = REG_SAVED_OFFSET;
+  fs->regs.how[10] = REG_SAVED_OFFSET;
   fs->regs.reg[10].loc.offset = (long)&sc->sc_p2 - new_cfa;
-  fs->regs.reg[11].how = REG_SAVED_OFFSET;
+  fs->regs.how[11] = REG_SAVED_OFFSET;
   fs->regs.reg[11].loc.offset = (long)&sc->sc_p3 - new_cfa;
-  fs->regs.reg[12].how = REG_SAVED_OFFSET;
+  fs->regs.how[12] = REG_SAVED_OFFSET;
   fs->regs.reg[12].loc.offset = (long)&sc->sc_p4 - new_cfa;
-  fs->regs.reg[13].how = REG_SAVED_OFFSET;
+  fs->regs.how[13] = REG_SAVED_OFFSET;
   fs->regs.reg[13].loc.offset = (long)&sc->sc_p5 - new_cfa;
 
-  fs->regs.reg[15].how = REG_SAVED_OFFSET;
+  fs->regs.how[15] = REG_SAVED_OFFSET;
   fs->regs.reg[15].loc.offset = (long)&sc->sc_fp - new_cfa;
-  fs->regs.reg[16].how = REG_SAVED_OFFSET;
+  fs->regs.how[16] = REG_SAVED_OFFSET;
   fs->regs.reg[16].loc.offset = (long)&sc->sc_i0 - new_cfa;
-  fs->regs.reg[17].how = REG_SAVED_OFFSET;
+  fs->regs.how[17] = REG_SAVED_OFFSET;
   fs->regs.reg[17].loc.offset = (long)&sc->sc_i1 - new_cfa;
-  fs->regs.reg[18].how = REG_SAVED_OFFSET;
+  fs->regs.how[18] = REG_SAVED_OFFSET;
   fs->regs.reg[18].loc.offset = (long)&sc->sc_i2 - new_cfa;
-  fs->regs.reg[19].how = REG_SAVED_OFFSET;
+  fs->regs.how[19] = REG_SAVED_OFFSET;
   fs->regs.reg[19].loc.offset = (long)&sc->sc_i3 - new_cfa;
-  fs->regs.reg[20].how = REG_SAVED_OFFSET;
+  fs->regs.how[20] = REG_SAVED_OFFSET;
   fs->regs.reg[20].loc.offset = (long)&sc->sc_b0 - new_cfa;
-  fs->regs.reg[21].how = REG_SAVED_OFFSET;
+  fs->regs.how[21] = REG_SAVED_OFFSET;
   fs->regs.reg[21].loc.offset = (long)&sc->sc_b1 - new_cfa;
-  fs->regs.reg[22].how = REG_SAVED_OFFSET;
+  fs->regs.how[22] = REG_SAVED_OFFSET;
   fs->regs.reg[22].loc.offset = (long)&sc->sc_b2 - new_cfa;
-  fs->regs.reg[23].how = REG_SAVED_OFFSET;
+  fs->regs.how[23] = REG_SAVED_OFFSET;
   fs->regs.reg[23].loc.offset = (long)&sc->sc_b3 - new_cfa;
-  fs->regs.reg[24].how = REG_SAVED_OFFSET;
+  fs->regs.how[24] = REG_SAVED_OFFSET;
   fs->regs.reg[24].loc.offset = (long)&sc->sc_l0 - new_cfa;
-  fs->regs.reg[25].how = REG_SAVED_OFFSET;
+  fs->regs.how[25] = REG_SAVED_OFFSET;
   fs->regs.reg[25].loc.offset = (long)&sc->sc_l1 - new_cfa;
-  fs->regs.reg[26].how = REG_SAVED_OFFSET;
+  fs->regs.how[26] = REG_SAVED_OFFSET;
   fs->regs.reg[26].loc.offset = (long)&sc->sc_l2 - new_cfa;
-  fs->regs.reg[27].how = REG_SAVED_OFFSET;
+  fs->regs.how[27] = REG_SAVED_OFFSET;
   fs->regs.reg[27].loc.offset = (long)&sc->sc_l3 - new_cfa;
-  fs->regs.reg[28].how = REG_SAVED_OFFSET;
+  fs->regs.how[28] = REG_SAVED_OFFSET;
   fs->regs.reg[28].loc.offset = (long)&sc->sc_m0 - new_cfa;
-  fs->regs.reg[29].how = REG_SAVED_OFFSET;
+  fs->regs.how[29] = REG_SAVED_OFFSET;
   fs->regs.reg[29].loc.offset = (long)&sc->sc_m1 - new_cfa;
-  fs->regs.reg[30].how = REG_SAVED_OFFSET;
+  fs->regs.how[30] = REG_SAVED_OFFSET;
   fs->regs.reg[30].loc.offset = (long)&sc->sc_m2 - new_cfa;
-  fs->regs.reg[31].how = REG_SAVED_OFFSET;
+  fs->regs.how[31] = REG_SAVED_OFFSET;
   fs->regs.reg[31].loc.offset = (long)&sc->sc_m3 - new_cfa;
   /* FIXME: Handle A0, A1, CC.  */
-  fs->regs.reg[35].how = REG_SAVED_OFFSET;
+  fs->regs.how[35] = REG_SAVED_OFFSET;
   fs->regs.reg[35].loc.offset = (long)&sc->sc_rets - new_cfa;
-  fs->regs.reg[36].how = REG_SAVED_OFFSET;
+  fs->regs.how[36] = REG_SAVED_OFFSET;
   fs->regs.reg[36].loc.offset = (long)&sc->sc_pc - new_cfa;
-  fs->regs.reg[37].how = REG_SAVED_OFFSET;
+  fs->regs.how[37] = REG_SAVED_OFFSET;
   fs->regs.reg[37].loc.offset = (long)&sc->sc_retx - new_cfa;
 
-  fs->regs.reg[40].how = REG_SAVED_OFFSET;
+  fs->regs.how[40] = REG_SAVED_OFFSET;
   fs->regs.reg[40].loc.offset = (long)&sc->sc_astat - new_cfa;
-  fs->regs.reg[41].how = REG_SAVED_OFFSET;
+  fs->regs.how[41] = REG_SAVED_OFFSET;
   fs->regs.reg[41].loc.offset = (long)&sc->sc_seqstat - new_cfa;
 
-  fs->regs.reg[44].how = REG_SAVED_OFFSET;
+  fs->regs.how[44] = REG_SAVED_OFFSET;
   fs->regs.reg[44].loc.offset = (long)&sc->sc_lt0 - new_cfa;
-  fs->regs.reg[45].how = REG_SAVED_OFFSET;
+  fs->regs.how[45] = REG_SAVED_OFFSET;
   fs->regs.reg[45].loc.offset = (long)&sc->sc_lt1 - new_cfa;
-  fs->regs.reg[46].how = REG_SAVED_OFFSET;
+  fs->regs.how[46] = REG_SAVED_OFFSET;
   fs->regs.reg[46].loc.offset = (long)&sc->sc_lc0 - new_cfa;
-  fs->regs.reg[47].how = REG_SAVED_OFFSET;
+  fs->regs.how[47] = REG_SAVED_OFFSET;
   fs->regs.reg[47].loc.offset = (long)&sc->sc_lc1 - new_cfa;
-  fs->regs.reg[48].how = REG_SAVED_OFFSET;
+  fs->regs.how[48] = REG_SAVED_OFFSET;
   fs->regs.reg[48].loc.offset = (long)&sc->sc_lb0 - new_cfa;
-  fs->regs.reg[49].how = REG_SAVED_OFFSET;
+  fs->regs.how[49] = REG_SAVED_OFFSET;
   fs->regs.reg[49].loc.offset = (long)&sc->sc_lb1 - new_cfa;
   fs->retaddr_column = 35;
 
diff --git a/libgcc/config/csky/linux-unwind.h b/libgcc/config/csky/linux-unwind.h
index a2e4a6d341c..bdc8f2e11bd 100644
--- a/libgcc/config/csky/linux-unwind.h
+++ b/libgcc/config/csky/linux-unwind.h
@@ -85,28 +85,28 @@ csky_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_reg = STACK_POINTER_REGNUM;
   fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
 
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (_Unwind_Ptr) & sc_pt_regs (a0) - new_cfa;
 
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
   fs->regs.reg[1].loc.offset = (_Unwind_Ptr) & sc_pt_regs (a1) - new_cfa;
 
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (_Unwind_Ptr) & sc_pt_regs (a2) - new_cfa;
 
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
   fs->regs.reg[3].loc.offset = (_Unwind_Ptr) & sc_pt_regs (a3) - new_cfa;
 
   for (i = 4; i < 14; i++)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset =
 	(_Unwind_Ptr) & sc_pt_regs (regs[i - 4]) - new_cfa;
     }
 
   for (i = 16; i < 31; i++)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset =
 	(_Unwind_Ptr) & sc_pt_regs (exregs[i - 16]) - new_cfa;
     }
@@ -114,10 +114,10 @@ csky_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.reg[31].loc.offset =
     (_Unwind_Ptr) & sc_pt_regs_tls (tls) - new_cfa;
   /* FIXME : hi lo ? */
-  fs->regs.reg[15].how = REG_SAVED_OFFSET;
+  fs->regs.how[15] = REG_SAVED_OFFSET;
   fs->regs.reg[15].loc.offset = (_Unwind_Ptr) & sc_pt_regs_lr - new_cfa;
 
-  fs->regs.reg[32].how = REG_SAVED_OFFSET;
+  fs->regs.how[32] = REG_SAVED_OFFSET;
   fs->regs.reg[32].loc.offset = (_Unwind_Ptr) & sc_pt_regs (pc) - new_cfa;
   fs->retaddr_column = 32;
   fs->signal_frame = 1;
diff --git a/libgcc/config/i386/dragonfly-unwind.h b/libgcc/config/i386/dragonfly-unwind.h
index de3e2307674..4cafc5c023b 100644
--- a/libgcc/config/i386/dragonfly-unwind.h
+++ b/libgcc/config/i386/dragonfly-unwind.h
@@ -102,37 +102,37 @@ x86_64_dragonfly_fallback_frame_state
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 
   /* The SVR4 register numbering macros aren't usable in libgcc.  */
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (long)&sf->REG_NAME(rax) - new_cfa;
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
   fs->regs.reg[1].loc.offset = (long)&sf->REG_NAME(rdx) - new_cfa;
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long)&sf->REG_NAME(rcx) - new_cfa;
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
   fs->regs.reg[3].loc.offset = (long)&sf->REG_NAME(rbx) - new_cfa;
-  fs->regs.reg[4].how = REG_SAVED_OFFSET;
+  fs->regs.how[4] = REG_SAVED_OFFSET;
   fs->regs.reg[4].loc.offset = (long)&sf->REG_NAME(rsi) - new_cfa;
-  fs->regs.reg[5].how = REG_SAVED_OFFSET;
+  fs->regs.how[5] = REG_SAVED_OFFSET;
   fs->regs.reg[5].loc.offset = (long)&sf->REG_NAME(rdi) - new_cfa;
-  fs->regs.reg[6].how = REG_SAVED_OFFSET;
+  fs->regs.how[6] = REG_SAVED_OFFSET;
   fs->regs.reg[6].loc.offset = (long)&sf->REG_NAME(rbp) - new_cfa;
-  fs->regs.reg[8].how = REG_SAVED_OFFSET;
+  fs->regs.how[8] = REG_SAVED_OFFSET;
   fs->regs.reg[8].loc.offset = (long)&sf->REG_NAME(r8) - new_cfa;
-  fs->regs.reg[9].how = REG_SAVED_OFFSET;
+  fs->regs.how[9] = REG_SAVED_OFFSET;
   fs->regs.reg[9].loc.offset = (long)&sf->REG_NAME(r9) - new_cfa;
-  fs->regs.reg[10].how = REG_SAVED_OFFSET;
+  fs->regs.how[10] = REG_SAVED_OFFSET;
   fs->regs.reg[10].loc.offset = (long)&sf->REG_NAME(r10) - new_cfa;
-  fs->regs.reg[11].how = REG_SAVED_OFFSET;
+  fs->regs.how[11] = REG_SAVED_OFFSET;
   fs->regs.reg[11].loc.offset = (long)&sf->REG_NAME(r11) - new_cfa;
-  fs->regs.reg[12].how = REG_SAVED_OFFSET;
+  fs->regs.how[12] = REG_SAVED_OFFSET;
   fs->regs.reg[12].loc.offset = (long)&sf->REG_NAME(r12) - new_cfa;
-  fs->regs.reg[13].how = REG_SAVED_OFFSET;
+  fs->regs.how[13] = REG_SAVED_OFFSET;
   fs->regs.reg[13].loc.offset = (long)&sf->REG_NAME(r13) - new_cfa;
-  fs->regs.reg[14].how = REG_SAVED_OFFSET;
+  fs->regs.how[14] = REG_SAVED_OFFSET;
   fs->regs.reg[14].loc.offset = (long)&sf->REG_NAME(r14) - new_cfa;
-  fs->regs.reg[15].how = REG_SAVED_OFFSET;
+  fs->regs.how[15] = REG_SAVED_OFFSET;
   fs->regs.reg[15].loc.offset = (long)&sf->REG_NAME(r15) - new_cfa;
-  fs->regs.reg[16].how = REG_SAVED_OFFSET;
+  fs->regs.how[16] = REG_SAVED_OFFSET;
   fs->regs.reg[16].loc.offset = (long)&sf->REG_NAME(rip) - new_cfa;
   fs->retaddr_column = 16;
   fs->signal_frame = 1;
@@ -182,21 +182,21 @@ x86_dragonfly_fallback_frame_state
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 
   /* The SVR4 register numbering macros aren't usable in libgcc.  */
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (long)&sf->REG_NAME(eax) - new_cfa;
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
   fs->regs.reg[3].loc.offset = (long)&sf->REG_NAME(ebx) - new_cfa;
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
   fs->regs.reg[1].loc.offset = (long)&sf->REG_NAME(ecx) - new_cfa;
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long)&sf->REG_NAME(edx) - new_cfa;
-  fs->regs.reg[6].how = REG_SAVED_OFFSET;
+  fs->regs.how[6] = REG_SAVED_OFFSET;
   fs->regs.reg[6].loc.offset = (long)&sf->REG_NAME(esi) - new_cfa;
-  fs->regs.reg[7].how = REG_SAVED_OFFSET;
+  fs->regs.how[7] = REG_SAVED_OFFSET;
   fs->regs.reg[7].loc.offset = (long)&sf->REG_NAME(edi) - new_cfa;
-  fs->regs.reg[5].how = REG_SAVED_OFFSET;
+  fs->regs.how[5] = REG_SAVED_OFFSET;
   fs->regs.reg[5].loc.offset = (long)&sf->REG_NAME(ebp) - new_cfa;
-  fs->regs.reg[8].how = REG_SAVED_OFFSET;
+  fs->regs.how[8] = REG_SAVED_OFFSET;
   fs->regs.reg[8].loc.offset = (long)&sf->REG_NAME(eip) - new_cfa;
   fs->retaddr_column = 8;
   fs->signal_frame = 1;
diff --git a/libgcc/config/i386/freebsd-unwind.h b/libgcc/config/i386/freebsd-unwind.h
index 777fda86f44..dcbd8cdf287 100644
--- a/libgcc/config/i386/freebsd-unwind.h
+++ b/libgcc/config/i386/freebsd-unwind.h
@@ -110,37 +110,37 @@ x86_64_freebsd_fallback_frame_state
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 
   /* The SVR4 register numbering macros aren't usable in libgcc.  */
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (long)&sf->REG_NAME(rax) - new_cfa;
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
   fs->regs.reg[1].loc.offset = (long)&sf->REG_NAME(rdx) - new_cfa;
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long)&sf->REG_NAME(rcx) - new_cfa;
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
   fs->regs.reg[3].loc.offset = (long)&sf->REG_NAME(rbx) - new_cfa;
-  fs->regs.reg[4].how = REG_SAVED_OFFSET;
+  fs->regs.how[4] = REG_SAVED_OFFSET;
   fs->regs.reg[4].loc.offset = (long)&sf->REG_NAME(rsi) - new_cfa;
-  fs->regs.reg[5].how = REG_SAVED_OFFSET;
+  fs->regs.how[5] = REG_SAVED_OFFSET;
   fs->regs.reg[5].loc.offset = (long)&sf->REG_NAME(rdi) - new_cfa;
-  fs->regs.reg[6].how = REG_SAVED_OFFSET;
+  fs->regs.how[6] = REG_SAVED_OFFSET;
   fs->regs.reg[6].loc.offset = (long)&sf->REG_NAME(rbp) - new_cfa;
-  fs->regs.reg[8].how = REG_SAVED_OFFSET;
+  fs->regs.how[8] = REG_SAVED_OFFSET;
   fs->regs.reg[8].loc.offset = (long)&sf->REG_NAME(r8) - new_cfa;
-  fs->regs.reg[9].how = REG_SAVED_OFFSET;
+  fs->regs.how[9] = REG_SAVED_OFFSET;
   fs->regs.reg[9].loc.offset = (long)&sf->REG_NAME(r9) - new_cfa;
-  fs->regs.reg[10].how = REG_SAVED_OFFSET;
+  fs->regs.how[10] = REG_SAVED_OFFSET;
   fs->regs.reg[10].loc.offset = (long)&sf->REG_NAME(r10) - new_cfa;
-  fs->regs.reg[11].how = REG_SAVED_OFFSET;
+  fs->regs.how[11] = REG_SAVED_OFFSET;
   fs->regs.reg[11].loc.offset = (long)&sf->REG_NAME(r11) - new_cfa;
-  fs->regs.reg[12].how = REG_SAVED_OFFSET;
+  fs->regs.how[12] = REG_SAVED_OFFSET;
   fs->regs.reg[12].loc.offset = (long)&sf->REG_NAME(r12) - new_cfa;
-  fs->regs.reg[13].how = REG_SAVED_OFFSET;
+  fs->regs.how[13] = REG_SAVED_OFFSET;
   fs->regs.reg[13].loc.offset = (long)&sf->REG_NAME(r13) - new_cfa;
-  fs->regs.reg[14].how = REG_SAVED_OFFSET;
+  fs->regs.how[14] = REG_SAVED_OFFSET;
   fs->regs.reg[14].loc.offset = (long)&sf->REG_NAME(r14) - new_cfa;
-  fs->regs.reg[15].how = REG_SAVED_OFFSET;
+  fs->regs.how[15] = REG_SAVED_OFFSET;
   fs->regs.reg[15].loc.offset = (long)&sf->REG_NAME(r15) - new_cfa;
-  fs->regs.reg[16].how = REG_SAVED_OFFSET;
+  fs->regs.how[16] = REG_SAVED_OFFSET;
   fs->regs.reg[16].loc.offset = (long)&sf->REG_NAME(rip) - new_cfa;
   fs->retaddr_column = 16;
   fs->signal_frame = 1;
@@ -189,21 +189,21 @@ x86_freebsd_fallback_frame_state
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 
   /* The SVR4 register numbering macros aren't usable in libgcc.  */
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (long)&sf->REG_NAME(eax) - new_cfa;
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
   fs->regs.reg[3].loc.offset = (long)&sf->REG_NAME(ebx) - new_cfa;
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
   fs->regs.reg[1].loc.offset = (long)&sf->REG_NAME(ecx) - new_cfa;
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long)&sf->REG_NAME(edx) - new_cfa;
-  fs->regs.reg[6].how = REG_SAVED_OFFSET;
+  fs->regs.how[6] = REG_SAVED_OFFSET;
   fs->regs.reg[6].loc.offset = (long)&sf->REG_NAME(esi) - new_cfa;
-  fs->regs.reg[7].how = REG_SAVED_OFFSET;
+  fs->regs.how[7] = REG_SAVED_OFFSET;
   fs->regs.reg[7].loc.offset = (long)&sf->REG_NAME(edi) - new_cfa;
-  fs->regs.reg[5].how = REG_SAVED_OFFSET;
+  fs->regs.how[5] = REG_SAVED_OFFSET;
   fs->regs.reg[5].loc.offset = (long)&sf->REG_NAME(ebp) - new_cfa;
-  fs->regs.reg[8].how = REG_SAVED_OFFSET;
+  fs->regs.how[8] = REG_SAVED_OFFSET;
   fs->regs.reg[8].loc.offset = (long)&sf->REG_NAME(eip) - new_cfa;
   fs->retaddr_column = 8;
   fs->signal_frame = 1;
diff --git a/libgcc/config/i386/gnu-unwind.h b/libgcc/config/i386/gnu-unwind.h
index 48fbff8f6e6..25eb690e370 100644
--- a/libgcc/config/i386/gnu-unwind.h
+++ b/libgcc/config/i386/gnu-unwind.h
@@ -123,14 +123,14 @@ x86_gnu_fallback_frame_state
   fs->regs.cfa_reg = 4;
   fs->regs.cfa_offset = usp - (unsigned long) context->cfa;
 
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
-  fs->regs.reg[5].how = REG_SAVED_OFFSET;
-  fs->regs.reg[6].how = REG_SAVED_OFFSET;
-  fs->regs.reg[7].how = REG_SAVED_OFFSET;
-  fs->regs.reg[8].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
+  fs->regs.how[5] = REG_SAVED_OFFSET;
+  fs->regs.how[6] = REG_SAVED_OFFSET;
+  fs->regs.how[7] = REG_SAVED_OFFSET;
+  fs->regs.how[8] = REG_SAVED_OFFSET;
 
   fs->retaddr_column = 8;
   fs->signal_frame = 1;
diff --git a/libgcc/config/i386/linux-unwind.h b/libgcc/config/i386/linux-unwind.h
index 7a9e4dcbcfd..48262b068ed 100644
--- a/libgcc/config/i386/linux-unwind.h
+++ b/libgcc/config/i386/linux-unwind.h
@@ -79,37 +79,37 @@ x86_64_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 
   /* The SVR4 register numbering macros aren't usable in libgcc.  */
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (long)&sc->rax - new_cfa;
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
   fs->regs.reg[1].loc.offset = (long)&sc->rdx - new_cfa;
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long)&sc->rcx - new_cfa;
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
   fs->regs.reg[3].loc.offset = (long)&sc->rbx - new_cfa;
-  fs->regs.reg[4].how = REG_SAVED_OFFSET;
+  fs->regs.how[4] = REG_SAVED_OFFSET;
   fs->regs.reg[4].loc.offset = (long)&sc->rsi - new_cfa;
-  fs->regs.reg[5].how = REG_SAVED_OFFSET;
+  fs->regs.how[5] = REG_SAVED_OFFSET;
   fs->regs.reg[5].loc.offset = (long)&sc->rdi - new_cfa;
-  fs->regs.reg[6].how = REG_SAVED_OFFSET;
+  fs->regs.how[6] = REG_SAVED_OFFSET;
   fs->regs.reg[6].loc.offset = (long)&sc->rbp - new_cfa;
-  fs->regs.reg[8].how = REG_SAVED_OFFSET;
+  fs->regs.how[8] = REG_SAVED_OFFSET;
   fs->regs.reg[8].loc.offset = (long)&sc->r8 - new_cfa;
-  fs->regs.reg[9].how = REG_SAVED_OFFSET;
+  fs->regs.how[9] = REG_SAVED_OFFSET;
   fs->regs.reg[9].loc.offset = (long)&sc->r9 - new_cfa;
-  fs->regs.reg[10].how = REG_SAVED_OFFSET;
+  fs->regs.how[10] = REG_SAVED_OFFSET;
   fs->regs.reg[10].loc.offset = (long)&sc->r10 - new_cfa;
-  fs->regs.reg[11].how = REG_SAVED_OFFSET;
+  fs->regs.how[11] = REG_SAVED_OFFSET;
   fs->regs.reg[11].loc.offset = (long)&sc->r11 - new_cfa;
-  fs->regs.reg[12].how = REG_SAVED_OFFSET;
+  fs->regs.how[12] = REG_SAVED_OFFSET;
   fs->regs.reg[12].loc.offset = (long)&sc->r12 - new_cfa;
-  fs->regs.reg[13].how = REG_SAVED_OFFSET;
+  fs->regs.how[13] = REG_SAVED_OFFSET;
   fs->regs.reg[13].loc.offset = (long)&sc->r13 - new_cfa;
-  fs->regs.reg[14].how = REG_SAVED_OFFSET;
+  fs->regs.how[14] = REG_SAVED_OFFSET;
   fs->regs.reg[14].loc.offset = (long)&sc->r14 - new_cfa;
-  fs->regs.reg[15].how = REG_SAVED_OFFSET;
+  fs->regs.how[15] = REG_SAVED_OFFSET;
   fs->regs.reg[15].loc.offset = (long)&sc->r15 - new_cfa;
-  fs->regs.reg[16].how = REG_SAVED_OFFSET;
+  fs->regs.how[16] = REG_SAVED_OFFSET;
   fs->regs.reg[16].loc.offset = (long)&sc->rip - new_cfa;
   fs->retaddr_column = 16;
   fs->signal_frame = 1;
@@ -159,21 +159,21 @@ x86_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 
   /* The SVR4 register numbering macros aren't usable in libgcc.  */
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (long)&sc->eax - new_cfa;
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
   fs->regs.reg[3].loc.offset = (long)&sc->ebx - new_cfa;
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
   fs->regs.reg[1].loc.offset = (long)&sc->ecx - new_cfa;
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long)&sc->edx - new_cfa;
-  fs->regs.reg[6].how = REG_SAVED_OFFSET;
+  fs->regs.how[6] = REG_SAVED_OFFSET;
   fs->regs.reg[6].loc.offset = (long)&sc->esi - new_cfa;
-  fs->regs.reg[7].how = REG_SAVED_OFFSET;
+  fs->regs.how[7] = REG_SAVED_OFFSET;
   fs->regs.reg[7].loc.offset = (long)&sc->edi - new_cfa;
-  fs->regs.reg[5].how = REG_SAVED_OFFSET;
+  fs->regs.how[5] = REG_SAVED_OFFSET;
   fs->regs.reg[5].loc.offset = (long)&sc->ebp - new_cfa;
-  fs->regs.reg[8].how = REG_SAVED_OFFSET;
+  fs->regs.how[8] = REG_SAVED_OFFSET;
   fs->regs.reg[8].loc.offset = (long)&sc->eip - new_cfa;
   fs->retaddr_column = 8;
   fs->signal_frame = 1;
diff --git a/libgcc/config/i386/sol2-unwind.h b/libgcc/config/i386/sol2-unwind.h
index 08c9cd5412b..718dc35ee0a 100644
--- a/libgcc/config/i386/sol2-unwind.h
+++ b/libgcc/config/i386/sol2-unwind.h
@@ -94,37 +94,37 @@ x86_64_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 
   /* The SVR4 register numbering macros aren't usable in libgcc.  */
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (long)&mctx->gregs[REG_RAX] - new_cfa;
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
   fs->regs.reg[1].loc.offset = (long)&mctx->gregs[REG_RDX] - new_cfa;
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long)&mctx->gregs[REG_RCX] - new_cfa;
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
   fs->regs.reg[3].loc.offset = (long)&mctx->gregs[REG_RBX] - new_cfa;
-  fs->regs.reg[4].how = REG_SAVED_OFFSET;
+  fs->regs.how[4] = REG_SAVED_OFFSET;
   fs->regs.reg[4].loc.offset = (long)&mctx->gregs[REG_RSI] - new_cfa;
-  fs->regs.reg[5].how = REG_SAVED_OFFSET;
+  fs->regs.how[5] = REG_SAVED_OFFSET;
   fs->regs.reg[5].loc.offset = (long)&mctx->gregs[REG_RDI] - new_cfa;
-  fs->regs.reg[6].how = REG_SAVED_OFFSET;
+  fs->regs.how[6] = REG_SAVED_OFFSET;
   fs->regs.reg[6].loc.offset = (long)&mctx->gregs[REG_RBP] - new_cfa;
-  fs->regs.reg[8].how = REG_SAVED_OFFSET;
+  fs->regs.how[8] = REG_SAVED_OFFSET;
   fs->regs.reg[8].loc.offset = (long)&mctx->gregs[REG_R8] - new_cfa;
-  fs->regs.reg[9].how = REG_SAVED_OFFSET;
+  fs->regs.how[9] = REG_SAVED_OFFSET;
   fs->regs.reg[9].loc.offset = (long)&mctx->gregs[REG_R9] - new_cfa;
-  fs->regs.reg[10].how = REG_SAVED_OFFSET;
+  fs->regs.how[10] = REG_SAVED_OFFSET;
   fs->regs.reg[10].loc.offset = (long)&mctx->gregs[REG_R10] - new_cfa;
-  fs->regs.reg[11].how = REG_SAVED_OFFSET;
+  fs->regs.how[11] = REG_SAVED_OFFSET;
   fs->regs.reg[11].loc.offset = (long)&mctx->gregs[REG_R11] - new_cfa;
-  fs->regs.reg[12].how = REG_SAVED_OFFSET;
+  fs->regs.how[12] = REG_SAVED_OFFSET;
   fs->regs.reg[12].loc.offset = (long)&mctx->gregs[REG_R12] - new_cfa;
-  fs->regs.reg[13].how = REG_SAVED_OFFSET;
+  fs->regs.how[13] = REG_SAVED_OFFSET;
   fs->regs.reg[13].loc.offset = (long)&mctx->gregs[REG_R13] - new_cfa;
-  fs->regs.reg[14].how = REG_SAVED_OFFSET;
+  fs->regs.how[14] = REG_SAVED_OFFSET;
   fs->regs.reg[14].loc.offset = (long)&mctx->gregs[REG_R14] - new_cfa;
-  fs->regs.reg[15].how = REG_SAVED_OFFSET;
+  fs->regs.how[15] = REG_SAVED_OFFSET;
   fs->regs.reg[15].loc.offset = (long)&mctx->gregs[REG_R15] - new_cfa;
-  fs->regs.reg[16].how = REG_SAVED_OFFSET;
+  fs->regs.how[16] = REG_SAVED_OFFSET;
   fs->regs.reg[16].loc.offset = (long)&mctx->gregs[REG_RIP] - new_cfa;
   fs->retaddr_column = 16;
   fs->signal_frame = 1;
@@ -180,21 +180,21 @@ x86_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 
   /* The SVR4 register numbering macros aren't usable in libgcc.  */
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (long)&mctx->gregs[EAX] - new_cfa;
-  fs->regs.reg[3].how = REG_SAVED_OFFSET;
+  fs->regs.how[3] = REG_SAVED_OFFSET;
   fs->regs.reg[3].loc.offset = (long)&mctx->gregs[EBX] - new_cfa;
-  fs->regs.reg[1].how = REG_SAVED_OFFSET;
+  fs->regs.how[1] = REG_SAVED_OFFSET;
   fs->regs.reg[1].loc.offset = (long)&mctx->gregs[ECX] - new_cfa;
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long)&mctx->gregs[EDX] - new_cfa;
-  fs->regs.reg[6].how = REG_SAVED_OFFSET;
+  fs->regs.how[6] = REG_SAVED_OFFSET;
   fs->regs.reg[6].loc.offset = (long)&mctx->gregs[ESI] - new_cfa;
-  fs->regs.reg[7].how = REG_SAVED_OFFSET;
+  fs->regs.how[7] = REG_SAVED_OFFSET;
   fs->regs.reg[7].loc.offset = (long)&mctx->gregs[EDI] - new_cfa;
-  fs->regs.reg[5].how = REG_SAVED_OFFSET;
+  fs->regs.how[5] = REG_SAVED_OFFSET;
   fs->regs.reg[5].loc.offset = (long)&mctx->gregs[EBP] - new_cfa;
-  fs->regs.reg[8].how = REG_SAVED_OFFSET;
+  fs->regs.how[8] = REG_SAVED_OFFSET;
   fs->regs.reg[8].loc.offset = (long)&mctx->gregs[EIP] - new_cfa;
   fs->retaddr_column = 8;
 
diff --git a/libgcc/config/i386/w32-unwind.h b/libgcc/config/i386/w32-unwind.h
index 7c5980f4516..096e314ccfb 100644
--- a/libgcc/config/i386/w32-unwind.h
+++ b/libgcc/config/i386/w32-unwind.h
@@ -153,21 +153,21 @@ i386_w32_fallback_frame_state (struct _Unwind_Context *context,
       fs->regs.cfa_offset = new_cfa_ - (long) ctx_cfa_;
 
       /* Restore registers.  */
-      fs->regs.reg[0].how = REG_SAVED_OFFSET;
+      fs->regs.how[0] = REG_SAVED_OFFSET;
       fs->regs.reg[0].loc.offset = (long)&proc_ctx_->Eax - new_cfa_;
-      fs->regs.reg[3].how = REG_SAVED_OFFSET;
+      fs->regs.how[3] = REG_SAVED_OFFSET;
       fs->regs.reg[3].loc.offset = (long)&proc_ctx_->Ebx - new_cfa_;
-      fs->regs.reg[1].how = REG_SAVED_OFFSET;
+      fs->regs.how[1] = REG_SAVED_OFFSET;
       fs->regs.reg[1].loc.offset = (long)&proc_ctx_->Ecx - new_cfa_;
-      fs->regs.reg[2].how = REG_SAVED_OFFSET;
+      fs->regs.how[2] = REG_SAVED_OFFSET;
       fs->regs.reg[2].loc.offset = (long)&proc_ctx_->Edx - new_cfa_;
-      fs->regs.reg[6].how = REG_SAVED_OFFSET;
+      fs->regs.how[6] = REG_SAVED_OFFSET;
       fs->regs.reg[6].loc.offset = (long)&proc_ctx_->Esi - new_cfa_;
-      fs->regs.reg[7].how = REG_SAVED_OFFSET;
+      fs->regs.how[7] = REG_SAVED_OFFSET;
       fs->regs.reg[7].loc.offset = (long)&proc_ctx_->Edi - new_cfa_;
-      fs->regs.reg[5].how = REG_SAVED_OFFSET;
+      fs->regs.how[5] = REG_SAVED_OFFSET;
       fs->regs.reg[5].loc.offset = (long)&proc_ctx_->Ebp - new_cfa_;
-      fs->regs.reg[8].how = REG_SAVED_OFFSET;
+      fs->regs.how[8] = REG_SAVED_OFFSET;
       fs->regs.reg[8].loc.offset = (long)&proc_ctx_->Eip - new_cfa_;
       fs->retaddr_column = 8;
       fs->signal_frame = 1;
@@ -189,12 +189,12 @@ i386_w32_fallback_frame_state (struct _Unwind_Context *context,
       fs->regs.cfa_offset = new_cfa_ - (long) ctx_cfa_;
 
       /* The saved value of %ecx is at CFA - 4 */
-      fs->regs.reg[1].how = REG_SAVED_OFFSET;
+      fs->regs.how[1] = REG_SAVED_OFFSET;
       fs->regs.reg[1].loc.offset = -4;
 
       /* and what is stored at the CFA is the return address.  */
       fs->retaddr_column = 8;
-      fs->regs.reg[8].how = REG_SAVED_OFFSET;
+      fs->regs.how[8] = REG_SAVED_OFFSET;
       fs->regs.reg[8].loc.offset = 0;
       fs->signal_frame = 1;
 
diff --git a/libgcc/config/loongarch/linux-unwind.h b/libgcc/config/loongarch/linux-unwind.h
index 89c168c8272..f6c782f8426 100644
--- a/libgcc/config/loongarch/linux-unwind.h
+++ b/libgcc/config/loongarch/linux-unwind.h
@@ -64,12 +64,12 @@ loongarch_fallback_frame_state (struct _Unwind_Context *context,
 
   for (i = 0; i < 32; i++)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset = (_Unwind_Ptr) & (sc->sc_regs[i]) - new_cfa;
     }
 
   fs->signal_frame = 1;
-  fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how
+  fs->regs.how[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__]
     = REG_SAVED_VAL_OFFSET;
   fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset
     = (_Unwind_Ptr) (sc->sc_pc) - new_cfa;
diff --git a/libgcc/config/m68k/linux-unwind.h b/libgcc/config/m68k/linux-unwind.h
index 1502ad1c9e5..ad0da69375e 100644
--- a/libgcc/config/m68k/linux-unwind.h
+++ b/libgcc/config/m68k/linux-unwind.h
@@ -68,21 +68,21 @@ m68k_fallback_frame_state (struct _Unwind_Context *context,
       fs->regs.cfa_reg = 15;
       fs->regs.cfa_offset = cfa - (long) context->cfa;
 
-      fs->regs.reg[0].how = REG_SAVED_OFFSET;
+      fs->regs.how[0] = REG_SAVED_OFFSET;
       fs->regs.reg[0].loc.offset = (long) &sc->sc_d0 - cfa;
-      fs->regs.reg[1].how = REG_SAVED_OFFSET;
+      fs->regs.how[1] = REG_SAVED_OFFSET;
       fs->regs.reg[1].loc.offset = (long) &sc->sc_d1 - cfa;
-      fs->regs.reg[8].how = REG_SAVED_OFFSET;
+      fs->regs.how[8] = REG_SAVED_OFFSET;
       fs->regs.reg[8].loc.offset = (long) &sc->sc_a0 - cfa;
-      fs->regs.reg[9].how = REG_SAVED_OFFSET;
+      fs->regs.how[9] = REG_SAVED_OFFSET;
       fs->regs.reg[9].loc.offset = (long) &sc->sc_a1 - cfa;
 
 #ifdef __uClinux__
-      fs->regs.reg[13].how = REG_SAVED_OFFSET;
+      fs->regs.how[13] = REG_SAVED_OFFSET;
       fs->regs.reg[13].loc.offset = (long) &sc->sc_a5 - cfa;
 #endif
 
-      fs->regs.reg[24].how = REG_SAVED_OFFSET;
+      fs->regs.how[24] = REG_SAVED_OFFSET;
       fs->regs.reg[24].loc.offset = (long) &sc->sc_pc - cfa;
 
 #ifndef __uClinux__
@@ -90,9 +90,9 @@ m68k_fallback_frame_state (struct _Unwind_Context *context,
 	{
 	  int *fpregs = (int *) sc->sc_fpregs;
 
-	  fs->regs.reg[16].how = REG_SAVED_OFFSET;
+	  fs->regs.how[16] = REG_SAVED_OFFSET;
 	  fs->regs.reg[16].loc.offset = (long) &fpregs[0] - cfa;
-	  fs->regs.reg[17].how = REG_SAVED_OFFSET;
+	  fs->regs.how[17] = REG_SAVED_OFFSET;
 	  fs->regs.reg[17].loc.offset = (long) &fpregs[M68K_FP_SIZE/4] - cfa;
 	}
 #elif defined __mcffpu__
@@ -124,12 +124,12 @@ m68k_fallback_frame_state (struct _Unwind_Context *context,
       /* register %d0-%d7/%a0-%a6  */
       for (i = 0; i <= 14; i++)
 	{
-	  fs->regs.reg[i].how = REG_SAVED_OFFSET;
+	  fs->regs.how[i] = REG_SAVED_OFFSET;
 	  fs->regs.reg[i].loc.offset = (long) &gregs[i] - cfa;
 	}
 
       /* return address  */
-      fs->regs.reg[24].how = REG_SAVED_OFFSET;
+      fs->regs.how[24] = REG_SAVED_OFFSET;
       fs->regs.reg[24].loc.offset = (long) &gregs[16] - cfa;
 
 #define uc_fpstate      uc_filler[0]
@@ -141,7 +141,7 @@ m68k_fallback_frame_state (struct _Unwind_Context *context,
 	  /* register %fp0-%fp7  */
 	  for (i = 16; i <= 23; i++)
 	    {
-	      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+	      fs->regs.how[i] = REG_SAVED_OFFSET;
 	      fs->regs.reg[i].loc.offset = fpregs - cfa;
 	      fpregs += M68K_FP_SIZE;
 	    }
diff --git a/libgcc/config/mips/linux-unwind.h b/libgcc/config/mips/linux-unwind.h
index e113f52aee9..80e6e77952e 100644
--- a/libgcc/config/mips/linux-unwind.h
+++ b/libgcc/config/mips/linux-unwind.h
@@ -103,7 +103,7 @@ mips_fallback_frame_state (struct _Unwind_Context *context,
 #endif
 
   for (i = 0; i < 32; i++) {
-    fs->regs.reg[i].how = REG_SAVED_OFFSET;
+    fs->regs.how[i] = REG_SAVED_OFFSET;
     fs->regs.reg[i].loc.offset
       = (_Unwind_Ptr)&(sc->sc_regs[i]) + reg_offset - new_cfa;
   }
@@ -115,7 +115,7 @@ mips_fallback_frame_state (struct _Unwind_Context *context,
      Note that setting fs->signal_frame would not work.  As the comment
      above MASK_RETURN_ADDR explains, MIPS unwinders must earch for an
      odd-valued address.  */
-  fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how
+  fs->regs.how[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__]
     = REG_SAVED_VAL_OFFSET;
   fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset
     = (_Unwind_Ptr)(sc->sc_pc) + 2 - new_cfa;
diff --git a/libgcc/config/nds32/linux-unwind.h b/libgcc/config/nds32/linux-unwind.h
index 7a12d3aa7bf..cbb2620ecb8 100644
--- a/libgcc/config/nds32/linux-unwind.h
+++ b/libgcc/config/nds32/linux-unwind.h
@@ -92,7 +92,7 @@ nds32_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa;
 
 #define NDS32_PUT_FS_REG(NUM, NAME) \
-  (fs->regs.reg[NUM].how = REG_SAVED_OFFSET, \
+  (fs->regs.how[NUM] = REG_SAVED_OFFSET, \
    fs->regs.reg[NUM].loc.offset = (_Unwind_Ptr) &(sc_->NAME) - new_cfa)
 
   /* Restore all registers value.  */
diff --git a/libgcc/config/nios2/linux-unwind.h b/libgcc/config/nios2/linux-unwind.h
index 4a8fca46fb4..aa278222fd1 100644
--- a/libgcc/config/nios2/linux-unwind.h
+++ b/libgcc/config/nios2/linux-unwind.h
@@ -61,7 +61,7 @@ nios2_fallback_frame_state (struct _Unwind_Context *context,
     return _URC_END_OF_STACK;
 
 #define NIOS2_REG(NUM,NAME)						\
-  (fs->regs.reg[NUM].how = REG_SAVED_OFFSET,				\
+  (fs->regs.how[NUM] = REG_SAVED_OFFSET,				\
    fs->regs.reg[NUM].loc.offset = (_Unwind_Ptr)&(regs->NAME) - new_cfa)
 
   if (pc[0] == (0x00800004 | (__NR_rt_sigreturn << 6)))
diff --git a/libgcc/config/or1k/linux-unwind.h b/libgcc/config/or1k/linux-unwind.h
index 3cf913720f9..71171c50f11 100644
--- a/libgcc/config/or1k/linux-unwind.h
+++ b/libgcc/config/or1k/linux-unwind.h
@@ -59,10 +59,10 @@ or1k_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
   for (i = 2; i < 32; ++i)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset = (long) &sc->regs.gpr[i] - new_cfa;
     }
-  fs->regs.reg[32].how = REG_SAVED_OFFSET;
+  fs->regs.how[32] = REG_SAVED_OFFSET;
   fs->regs.reg[32].loc.offset = (long)&sc->regs.pc - new_cfa;
   fs->retaddr_column = 32;
   fs->signal_frame = 1;
diff --git a/libgcc/config/pa/hpux-unwind.h b/libgcc/config/pa/hpux-unwind.h
index f14812a3101..b30a67ee000 100644
--- a/libgcc/config/pa/hpux-unwind.h
+++ b/libgcc/config/pa/hpux-unwind.h
@@ -57,19 +57,19 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #endif
 
 #define UPDATE_FS_FOR_SAR(FS, N) \
-  (FS)->regs.reg[N].how = REG_SAVED_OFFSET;				\
+  (FS)->regs.how[N] = REG_SAVED_OFFSET;				\
   (FS)->regs.reg[N].loc.offset = GetSSRegAddr (mc, ss_cr11) - new_cfa
 
 #define UPDATE_FS_FOR_GR(FS, GRN, N) \
-  (FS)->regs.reg[N].how = REG_SAVED_OFFSET;				\
+  (FS)->regs.how[N] = REG_SAVED_OFFSET;				\
   (FS)->regs.reg[N].loc.offset = GetSSRegAddr (mc, ss_gr##GRN) - new_cfa
 
 #define UPDATE_FS_FOR_FR(FS, FRN, N) \
-  (FS)->regs.reg[N].how = REG_SAVED_OFFSET;				\
+  (FS)->regs.how[N] = REG_SAVED_OFFSET;				\
   (FS)->regs.reg[N].loc.offset = (long) &(mc->ss_fr##FRN) - new_cfa;
 
 #define UPDATE_FS_FOR_PC(FS, N) \
-  (FS)->regs.reg[N].how = REG_SAVED_OFFSET;				\
+  (FS)->regs.how[N] = REG_SAVED_OFFSET;				\
   (FS)->regs.reg[N].loc.offset = GetSSRegAddr (mc, ss_pcoq_head) - new_cfa
 
 /* Extract bit field from word using HP's numbering (MSB = 0).  */
@@ -151,7 +151,7 @@ pa_fallback_frame_state (struct _Unwind_Context *context,
       fs->regs.cfa_offset = 0;
 
       fs->retaddr_column = 0;
-      fs->regs.reg[0].how = REG_SAVED_OFFSET;
+      fs->regs.how[0] = REG_SAVED_OFFSET;
       fs->regs.reg[0].loc.offset = -24;
 
       /* Update context to describe the stub frame.  */
@@ -171,7 +171,7 @@ pa_fallback_frame_state (struct _Unwind_Context *context,
       fs->regs.cfa_offset = 0;
 
       fs->retaddr_column = 0;
-      fs->regs.reg[0].how = REG_SAVED_OFFSET;
+      fs->regs.how[0] = REG_SAVED_OFFSET;
       fs->regs.reg[0].loc.offset = -8;
 
       /* Update context to describe the stub frame.  */
diff --git a/libgcc/config/pa/linux-unwind.h b/libgcc/config/pa/linux-unwind.h
index 7e424c58cef..7efab00e33a 100644
--- a/libgcc/config/pa/linux-unwind.h
+++ b/libgcc/config/pa/linux-unwind.h
@@ -138,22 +138,22 @@ pa32_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
   for (i = 1; i <= 31; i++)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset = (long)&sc->sc_gr[i] - new_cfa;
     }
   for (i = 4; i <= 31; i++)
     {
       /* FP regs have left and right halves */
-      fs->regs.reg[2*i+24].how = REG_SAVED_OFFSET;
+      fs->regs.how[2*i+24] = REG_SAVED_OFFSET;
       fs->regs.reg[2*i+24].loc.offset
 	= (long)&sc->sc_fr[i] - new_cfa;
-      fs->regs.reg[2*i+24+1].how = REG_SAVED_OFFSET;
+      fs->regs.how[2*i+24+1] = REG_SAVED_OFFSET;
       fs->regs.reg[2*i+24+1].loc.offset
 	= (long)&sc->sc_fr[i] + 4 - new_cfa;
     }
-  fs->regs.reg[88].how = REG_SAVED_OFFSET;
+  fs->regs.how[88] = REG_SAVED_OFFSET;
   fs->regs.reg[88].loc.offset = (long) &sc->sc_sar - new_cfa;
-  fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how
+  fs->regs.how[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__]
     = REG_SAVED_OFFSET;
   fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset
     = (long) &sc->sc_iaoq[0] - new_cfa;
diff --git a/libgcc/config/riscv/linux-unwind.h b/libgcc/config/riscv/linux-unwind.h
index c86df2f85bc..c44d1a86cef 100644
--- a/libgcc/config/riscv/linux-unwind.h
+++ b/libgcc/config/riscv/linux-unwind.h
@@ -73,13 +73,13 @@ riscv_fallback_frame_state (struct _Unwind_Context *context,
 
   for (i = 0; i < 32; i++)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset = (_Unwind_Ptr) &sc->gregs[i] - new_cfa;
     }
 
   fs->signal_frame = 1;
   fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__;
-  fs->regs.reg[fs->retaddr_column].how = REG_SAVED_VAL_OFFSET;
+  fs->regs.how[fs->retaddr_column] = REG_SAVED_VAL_OFFSET;
   fs->regs.reg[fs->retaddr_column].loc.offset =
     (_Unwind_Ptr) sc->gregs[0] - new_cfa;
 
diff --git a/libgcc/config/rs6000/aix-unwind.h b/libgcc/config/rs6000/aix-unwind.h
index d7e5f59e2f8..9a1efdc1c6a 100644
--- a/libgcc/config/rs6000/aix-unwind.h
+++ b/libgcc/config/rs6000/aix-unwind.h
@@ -40,7 +40,7 @@
 #ifdef __64BIT__
 #define MD_FROB_UPDATE_CONTEXT(CTX, FS)					\
   do {									\
-    if ((FS)->regs.reg[2].how == REG_UNSAVED)				\
+    if ((FS)->regs.how[2] == REG_UNSAVED)				\
       {									\
 	unsigned int *insn						\
 	  = (unsigned int *)						\
@@ -52,7 +52,7 @@
 #else
 #define MD_FROB_UPDATE_CONTEXT(CTX, FS)					\
   do {									\
-    if ((FS)->regs.reg[2].how == REG_UNSAVED)				\
+    if ((FS)->regs.how[2] == REG_UNSAVED)				\
       {									\
 	unsigned int *insn						\
 	  = (unsigned int *)						\
@@ -207,7 +207,7 @@ ucontext_for (struct _Unwind_Context *context)
 
 #define REGISTER_CFA_OFFSET_FOR(FS,REGNO,ADDR,CFA)\
 do { \
-(FS)->regs.reg[REGNO].how = REG_SAVED_OFFSET; \
+(FS)->regs.how[REGNO] = REG_SAVED_OFFSET; \
 (FS)->regs.reg[REGNO].loc.offset = (long) (ADDR) - (CFA); \
 } while (0)
 
diff --git a/libgcc/config/rs6000/darwin-fallback.c b/libgcc/config/rs6000/darwin-fallback.c
index c6bc69c8649..ad5c19585b5 100644
--- a/libgcc/config/rs6000/darwin-fallback.c
+++ b/libgcc/config/rs6000/darwin-fallback.c
@@ -368,7 +368,7 @@ handle_syscall (_Unwind_FrameState *fs, const reg_unit gprs[32],
     return false;
 
 #define set_offset(r, addr)					\
-  (fs->regs.reg[r].how = REG_SAVED_OFFSET,			\
+  (fs->regs.how[r] = REG_SAVED_OFFSET,			\
    fs->regs.reg[r].loc.offset = (_Unwind_Ptr)(addr) - new_cfa)
 
   /* Restore even the registers that are not call-saved, since they
diff --git a/libgcc/config/rs6000/freebsd-unwind.h b/libgcc/config/rs6000/freebsd-unwind.h
index af961353bdd..654e7f648b8 100644
--- a/libgcc/config/rs6000/freebsd-unwind.h
+++ b/libgcc/config/rs6000/freebsd-unwind.h
@@ -33,7 +33,7 @@ frob_update_context (struct _Unwind_Context *context,
   const unsigned int *pc = (const unsigned int *) context->ra;
 
 #ifdef __powerpc64__
-  if (fs->regs.reg[2].how == REG_UNSAVED)
+  if (fs->regs.how[2] == REG_UNSAVED)
     {
       /* If the current unwind info (FS) does not contain explicit info
 	 saving R2, then we have to do a minor amount of code reading to
diff --git a/libgcc/config/rs6000/linux-unwind.h b/libgcc/config/rs6000/linux-unwind.h
index 6a7c07f7f04..f6ab9399b36 100644
--- a/libgcc/config/rs6000/linux-unwind.h
+++ b/libgcc/config/rs6000/linux-unwind.h
@@ -215,12 +215,12 @@ ppc_fallback_frame_state (struct _Unwind_Context *context,
   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 
 #ifdef __powerpc64__
-  fs->regs.reg[2].how = REG_SAVED_OFFSET;
+  fs->regs.how[2] = REG_SAVED_OFFSET;
   fs->regs.reg[2].loc.offset = (long) &regs->gpr[2] - new_cfa;
 #endif
   for (i = 14; i < 32; i++)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset = (long) &regs->gpr[i] - new_cfa;
     }
 
@@ -230,20 +230,20 @@ ppc_fallback_frame_state (struct _Unwind_Context *context,
   cr_offset += sizeof (long) - 4;
 #endif
   /* In the ELFv1 ABI, CR2 stands in for the whole CR.  */
-  fs->regs.reg[R_CR2].how = REG_SAVED_OFFSET;
+  fs->regs.how[R_CR2] = REG_SAVED_OFFSET;
   fs->regs.reg[R_CR2].loc.offset = cr_offset;
 #if _CALL_ELF == 2
   /* In the ELFv2 ABI, every CR field has a separate CFI entry.  */
-  fs->regs.reg[R_CR3].how = REG_SAVED_OFFSET;
+  fs->regs.how[R_CR3] = REG_SAVED_OFFSET;
   fs->regs.reg[R_CR3].loc.offset = cr_offset;
-  fs->regs.reg[R_CR4].how = REG_SAVED_OFFSET;
+  fs->regs.how[R_CR4] = REG_SAVED_OFFSET;
   fs->regs.reg[R_CR4].loc.offset = cr_offset;
 #endif
 
-  fs->regs.reg[R_LR].how = REG_SAVED_OFFSET;
+  fs->regs.how[R_LR] = REG_SAVED_OFFSET;
   fs->regs.reg[R_LR].loc.offset = (long) &regs->link - new_cfa;
 
-  fs->regs.reg[ARG_POINTER_REGNUM].how = REG_SAVED_OFFSET;
+  fs->regs.how[ARG_POINTER_REGNUM] = REG_SAVED_OFFSET;
   fs->regs.reg[ARG_POINTER_REGNUM].loc.offset = (long) &regs->nip - new_cfa;
   fs->retaddr_column = ARG_POINTER_REGNUM;
   fs->signal_frame = 1;
@@ -251,7 +251,7 @@ ppc_fallback_frame_state (struct _Unwind_Context *context,
   /* If we have a FPU...  */
   for (i = 14; i < 32; i++)
     {
-      fs->regs.reg[i + 32].how = REG_SAVED_OFFSET;
+      fs->regs.how[i + 32] = REG_SAVED_OFFSET;
       fs->regs.reg[i + 32].loc.offset = (long) &regs->fpr[i] - new_cfa;
     }
 
@@ -265,12 +265,12 @@ ppc_fallback_frame_state (struct _Unwind_Context *context,
     {
       for (i = 20; i < 32; i++)
 	{
-	  fs->regs.reg[i + R_VR0].how = REG_SAVED_OFFSET;
+	  fs->regs.how[i + R_VR0] = REG_SAVED_OFFSET;
 	  fs->regs.reg[i + R_VR0].loc.offset = (long) &vregs->vr[i] - new_cfa;
 	}
     }
 
-  fs->regs.reg[R_VRSAVE].how = REG_SAVED_OFFSET;
+  fs->regs.how[R_VRSAVE] = REG_SAVED_OFFSET;
   fs->regs.reg[R_VRSAVE].loc.offset = (long) &vregs->vsave - new_cfa;
 
   /* If we have SPE register high-parts... we check at compile-time to
@@ -278,7 +278,7 @@ ppc_fallback_frame_state (struct _Unwind_Context *context,
 #ifdef __SPE__
   for (i = 14; i < 32; i++)
     {
-      fs->regs.reg[i + FIRST_SPE_HIGH_REGNO - 4].how = REG_SAVED_OFFSET;
+      fs->regs.how[i + FIRST_SPE_HIGH_REGNO - 4] = REG_SAVED_OFFSET;
       fs->regs.reg[i + FIRST_SPE_HIGH_REGNO - 4].loc.offset
 	= (long) &regs->vregs - new_cfa + 4 * i;
     }
@@ -315,7 +315,7 @@ frob_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs ATT
 #endif
 
 #ifdef __powerpc64__
-  if (fs->regs.reg[2].how == REG_UNSAVED)
+  if (fs->regs.how[2] == REG_UNSAVED)
     {
       /* If the current unwind info (FS) does not contain explicit info
 	 saving R2, then we have to do a minor amount of code reading to
diff --git a/libgcc/config/s390/linux-unwind.h b/libgcc/config/s390/linux-unwind.h
index f3f1337e1b1..904bbaae732 100644
--- a/libgcc/config/s390/linux-unwind.h
+++ b/libgcc/config/s390/linux-unwind.h
@@ -106,20 +106,20 @@ s390_fallback_frame_state (struct _Unwind_Context *context,
 
   for (i = 0; i < 16; i++)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset =
 	(long)&regs->gprs[i] - new_cfa;
     }
   for (i = 0; i < 16; i++)
     {
-      fs->regs.reg[16+i].how = REG_SAVED_OFFSET;
+      fs->regs.how[16+i] = REG_SAVED_OFFSET;
       fs->regs.reg[16+i].loc.offset =
 	(long)&regs->fprs[dwarf_to_fpr_map[i]] - new_cfa;
     }
 
   /* Load return addr from PSW into dummy register 32.  */
 
-  fs->regs.reg[32].how = REG_SAVED_OFFSET;
+  fs->regs.how[32] = REG_SAVED_OFFSET;
   fs->regs.reg[32].loc.offset = (long)&regs->psw_addr - new_cfa;
   fs->retaddr_column = 32;
   /* SIGILL, SIGFPE and SIGTRAP are delivered with psw_addr
diff --git a/libgcc/config/s390/tpf-unwind.h b/libgcc/config/s390/tpf-unwind.h
index 526bdbaf877..992cffce117 100644
--- a/libgcc/config/s390/tpf-unwind.h
+++ b/libgcc/config/s390/tpf-unwind.h
@@ -88,18 +88,18 @@ s390_fallback_frame_state (struct _Unwind_Context *context,
       /* All registers remain unchanged ...  */
       for (i = 0; i < 32; i++)
 	{
-	  fs->regs.reg[i].how = REG_SAVED_REG;
+	  fs->regs.how[i] = REG_SAVED_REG;
 	  fs->regs.reg[i].loc.reg = i;
 	}
 
       /* ... except for %r14, which is stored at CFA+offset where offset
 	 is displacment of ICST_CRET or ICST_SRET from CFA */
       if ( __isPATrange(context->ra) )  {
-	   fs->regs.reg[14].how = REG_SAVED_OFFSET;
+	   fs->regs.how[14] = REG_SAVED_OFFSET;
 	   fs->regs.reg[14].loc.offset = ICST_CRET - STACK_POINTER_OFFSET;
 	   fs->retaddr_column = 14;
       }  else  {
-	   fs->regs.reg[14].how = REG_SAVED_OFFSET;
+	   fs->regs.how[14] = REG_SAVED_OFFSET;
 	   fs->regs.reg[14].loc.offset = ICST_SRET - STACK_POINTER_OFFSET;
 	   fs->retaddr_column = 14;
 
@@ -119,13 +119,13 @@ s390_fallback_frame_state (struct _Unwind_Context *context,
 
   for (i = 0; i < 16; i++)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset = regs + i*8 - new_cfa;
     }
 
   for (i = 0; i < 4; i++)
     {
-      fs->regs.reg[16 + i].how = REG_SAVED_OFFSET;
+      fs->regs.how[16 + i] = REG_SAVED_OFFSET;
       fs->regs.reg[16 + i].loc.offset = regs + 16*8 + i*8 - new_cfa;
     }
 
diff --git a/libgcc/config/sh/linux-unwind.h b/libgcc/config/sh/linux-unwind.h
index 8cd30f43dde..8088e3c08a1 100644
--- a/libgcc/config/sh/linux-unwind.h
+++ b/libgcc/config/sh/linux-unwind.h
@@ -99,24 +99,24 @@ sh_fallback_frame_state (struct _Unwind_Context *context,
 
   for (i = 0; i < 15; i++)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset
 	= (long)&(sc->sc_regs[i]) - new_cfa;
     }
 
-  fs->regs.reg[SH_DWARF_FRAME_PR].how = REG_SAVED_OFFSET;
+  fs->regs.how[SH_DWARF_FRAME_PR] = REG_SAVED_OFFSET;
   fs->regs.reg[SH_DWARF_FRAME_PR].loc.offset
     = (long)&(sc->sc_pr) - new_cfa;
-  fs->regs.reg[SH_DWARF_FRAME_SR].how = REG_SAVED_OFFSET;
+  fs->regs.how[SH_DWARF_FRAME_SR] = REG_SAVED_OFFSET;
   fs->regs.reg[SH_DWARF_FRAME_SR].loc.offset
     = (long)&(sc->sc_sr) - new_cfa;
-  fs->regs.reg[SH_DWARF_FRAME_GBR].how = REG_SAVED_OFFSET;
+  fs->regs.how[SH_DWARF_FRAME_GBR] = REG_SAVED_OFFSET;
   fs->regs.reg[SH_DWARF_FRAME_GBR].loc.offset
     = (long)&(sc->sc_gbr) - new_cfa;
-  fs->regs.reg[SH_DWARF_FRAME_MACH].how = REG_SAVED_OFFSET;
+  fs->regs.how[SH_DWARF_FRAME_MACH] = REG_SAVED_OFFSET;
   fs->regs.reg[SH_DWARF_FRAME_MACH].loc.offset
     = (long)&(sc->sc_mach) - new_cfa;
-  fs->regs.reg[SH_DWARF_FRAME_MACL].how = REG_SAVED_OFFSET;
+  fs->regs.how[SH_DWARF_FRAME_MACL] = REG_SAVED_OFFSET;
   fs->regs.reg[SH_DWARF_FRAME_MACL].loc.offset
     = (long)&(sc->sc_macl) - new_cfa;
 
@@ -124,7 +124,7 @@ sh_fallback_frame_state (struct _Unwind_Context *context,
   r = SH_DWARF_FRAME_FP0;
   for (i = 0; i < 16; i++)
     {
-      fs->regs.reg[r+i].how = REG_SAVED_OFFSET;
+      fs->regs.how[r+i] = REG_SAVED_OFFSET;
       fs->regs.reg[r+i].loc.offset
 	= (long)&(sc->sc_fpregs[i]) - new_cfa;
     }
@@ -132,20 +132,20 @@ sh_fallback_frame_state (struct _Unwind_Context *context,
   r = SH_DWARF_FRAME_XD0;
   for (i = 0; i < 8; i++)
     {
-      fs->regs.reg[r+i].how = REG_SAVED_OFFSET;
+      fs->regs.how[r+i] = REG_SAVED_OFFSET;
       fs->regs.reg[r+i].loc.offset
 	= (long)&(sc->sc_xfpregs[2*i]) - new_cfa;
     }
 
-  fs->regs.reg[SH_DWARF_FRAME_FPUL].how = REG_SAVED_OFFSET;
+  fs->regs.how[SH_DWARF_FRAME_FPUL] = REG_SAVED_OFFSET;
   fs->regs.reg[SH_DWARF_FRAME_FPUL].loc.offset
     = (long)&(sc->sc_fpul) - new_cfa;
-  fs->regs.reg[SH_DWARF_FRAME_FPSCR].how = REG_SAVED_OFFSET;
+  fs->regs.how[SH_DWARF_FRAME_FPSCR] = REG_SAVED_OFFSET;
   fs->regs.reg[SH_DWARF_FRAME_FPSCR].loc.offset
     = (long)&(sc->sc_fpscr) - new_cfa;
 #endif
 
-  fs->regs.reg[SH_DWARF_FRAME_PC].how = REG_SAVED_OFFSET;
+  fs->regs.how[SH_DWARF_FRAME_PC] = REG_SAVED_OFFSET;
   fs->regs.reg[SH_DWARF_FRAME_PC].loc.offset
     = (long)&(sc->sc_pc) - new_cfa;
   fs->retaddr_column = SH_DWARF_FRAME_PC;
diff --git a/libgcc/config/sparc/linux-unwind.h b/libgcc/config/sparc/linux-unwind.h
index 001429eef35..0095b43c26e 100644
--- a/libgcc/config/sparc/linux-unwind.h
+++ b/libgcc/config/sparc/linux-unwind.h
@@ -65,13 +65,13 @@ sparc64_fallback_frame_state (struct _Unwind_Context *context,
       if ((unsigned int) i == __builtin_dwarf_sp_column ())
 	continue;
 
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset
 	= this_cfa + regs_off + (i * 8) - new_cfa;
     }
   for (i = 0; i < 16; i++)
     {
-      fs->regs.reg[i + 16].how = REG_SAVED_OFFSET;
+      fs->regs.how[i + 16] = REG_SAVED_OFFSET;
       fs->regs.reg[i + 16].loc.offset
 	= this_cfa + (i * 8) - new_cfa;
     }
@@ -81,7 +81,7 @@ sparc64_fallback_frame_state (struct _Unwind_Context *context,
 	{
 	  if (i > 32 && (i & 0x1))
 	    continue;
-	  fs->regs.reg[i + 32].how = REG_SAVED_OFFSET;
+	  fs->regs.how[i + 32] = REG_SAVED_OFFSET;
 	  fs->regs.reg[i + 32].loc.offset
 	    = fpu_save + (i * 4) - new_cfa;
 	}
@@ -95,7 +95,7 @@ sparc64_fallback_frame_state (struct _Unwind_Context *context,
   shifted_ra_location = this_cfa + regs_off + 19 * 8; /* Y register */
   *(long *)shifted_ra_location = *(long *)ra_location - 8;
   fs->retaddr_column = 0;
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = shifted_ra_location - new_cfa;
   fs->signal_frame = 1;
 
@@ -122,7 +122,7 @@ sparc64_frob_update_context (struct _Unwind_Context *context,
       context->cfa -= STACK_BIAS;
 
       for (i = 0; i < __LIBGCC_DWARF_FRAME_REGISTERS__ + 1; ++i)
-	if (fs->regs.reg[i].how == REG_SAVED_OFFSET)
+	if (fs->regs.how[i] == REG_SAVED_OFFSET)
 	  _Unwind_SetGRPtr (context, i,
 			    _Unwind_GetGRPtr (context, i) - STACK_BIAS);
     }
@@ -177,13 +177,13 @@ sparc_fallback_frame_state (struct _Unwind_Context *context,
       if ((unsigned int) i == __builtin_dwarf_sp_column ())
 	continue;
 
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset
 	= this_cfa + regs_off + (4 * 4) + (i * 4) - new_cfa;
     }
   for (i = 0; i < 16; i++)
     {
-      fs->regs.reg[i + 16].how = REG_SAVED_OFFSET;
+      fs->regs.how[i + 16] = REG_SAVED_OFFSET;
       fs->regs.reg[i + 16].loc.offset
 	= this_cfa + (i * 4) - new_cfa;
     }
@@ -191,7 +191,7 @@ sparc_fallback_frame_state (struct _Unwind_Context *context,
     {
       for (i = 0; i < 32; i++)
 	{
-	  fs->regs.reg[i + 32].how = REG_SAVED_OFFSET;
+	  fs->regs.how[i + 32] = REG_SAVED_OFFSET;
 	  fs->regs.reg[i + 32].loc.offset
 	    = fpu_save + (i * 4) - new_cfa;
 	}
@@ -205,7 +205,7 @@ sparc_fallback_frame_state (struct _Unwind_Context *context,
   shifted_ra_location = this_cfa + regs_off + 3 * 4; /* Y register */
   *(int *)shifted_ra_location = *(int *)ra_location - 8;
   fs->retaddr_column = 0;
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = shifted_ra_location - new_cfa;
   fs->signal_frame = 1;
 
diff --git a/libgcc/config/sparc/sol2-unwind.h b/libgcc/config/sparc/sol2-unwind.h
index 06cc538c1a5..4da5a7c332f 100644
--- a/libgcc/config/sparc/sol2-unwind.h
+++ b/libgcc/config/sparc/sol2-unwind.h
@@ -96,7 +96,7 @@ sparc64_frob_update_context (struct _Unwind_Context *context,
       context->cfa -= STACK_BIAS;
 
       for (i = 0; i < __LIBGCC_DWARF_FRAME_REGISTERS__ + 1; ++i)
-	if (fs->regs.reg[i].how == REG_SAVED_OFFSET)
+	if (fs->regs.how[i] == REG_SAVED_OFFSET)
 	  _Unwind_SetGRPtr (context, i,
 			    _Unwind_GetGRPtr (context, i) - STACK_BIAS);
     }
@@ -221,7 +221,7 @@ MD_FALLBACK_FRAME_STATE_FOR (struct _Unwind_Context *context,
 	continue;
 
       /* First the global registers and then the out registers.  */
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset = (long)&mctx->gregs[REG_Y + i] - new_cfa;
     }
 
@@ -229,7 +229,7 @@ MD_FALLBACK_FRAME_STATE_FOR (struct _Unwind_Context *context,
      the register window (in and local registers) was saved.  */
   for (i = 0; i < 16; i++)
     {
-      fs->regs.reg[i + 16].how = REG_SAVED_OFFSET;
+      fs->regs.how[i + 16] = REG_SAVED_OFFSET;
       fs->regs.reg[i + 16].loc.offset = i * sizeof(long);
     }
 
@@ -238,7 +238,7 @@ MD_FALLBACK_FRAME_STATE_FOR (struct _Unwind_Context *context,
     {
       for (i = 0; i < 32; i++)
 	{
-	  fs->regs.reg[i + 32].how = REG_SAVED_OFFSET;
+	  fs->regs.how[i + 32] = REG_SAVED_OFFSET;
 	  fs->regs.reg[i + 32].loc.offset
 	    = (long)&mctx->fpregs.fpu_fr.fpu_regs[i] - new_cfa;
 	}
@@ -250,7 +250,7 @@ MD_FALLBACK_FRAME_STATE_FOR (struct _Unwind_Context *context,
 	  if (i > 32 && (i & 1))
 	    continue;
 
-	  fs->regs.reg[i + 32].how = REG_SAVED_OFFSET;
+	  fs->regs.how[i + 32] = REG_SAVED_OFFSET;
 	  fs->regs.reg[i + 32].loc.offset
 	    = (long)&mctx->fpregs.fpu_fr.fpu_dregs[i/2] - new_cfa;
 	}
@@ -265,7 +265,7 @@ MD_FALLBACK_FRAME_STATE_FOR (struct _Unwind_Context *context,
   shifted_ra_location = &mctx->gregs[REG_Y];
   *(void **)shifted_ra_location = *(void **)ra_location - 8;
   fs->retaddr_column = 0;
-  fs->regs.reg[0].how = REG_SAVED_OFFSET;
+  fs->regs.how[0] = REG_SAVED_OFFSET;
   fs->regs.reg[0].loc.offset = (long)shifted_ra_location - new_cfa;
 
   /* SIGFPE for IEEE-754 exceptions is delivered after the faulting insn
diff --git a/libgcc/config/xtensa/linux-unwind.h b/libgcc/config/xtensa/linux-unwind.h
index fed118e19ae..868624e2d94 100644
--- a/libgcc/config/xtensa/linux-unwind.h
+++ b/libgcc/config/xtensa/linux-unwind.h
@@ -105,11 +105,11 @@ xtensa_fallback_frame_state (struct _Unwind_Context *context,
 
   for (i = 0; i < 16; i++)
     {
-      fs->regs.reg[i].how = REG_SAVED_OFFSET;
+      fs->regs.how[i] = REG_SAVED_OFFSET;
       fs->regs.reg[i].loc.offset = (_Unwind_Ptr) &(sc->sc_a[i]) - new_cfa;
     }
 
-  fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how =
+  fs->regs.how[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__] =
     REG_SAVED_VAL_OFFSET;
   fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset =
     (_Unwind_Ptr) (sc->sc_pc) - new_cfa;
diff --git a/libgcc/unwind-dw2.c b/libgcc/unwind-dw2.c
index a2eb66dc0de..eaceace2029 100644
--- a/libgcc/unwind-dw2.c
+++ b/libgcc/unwind-dw2.c
@@ -36,6 +36,7 @@
 #include "unwind-dw2-fde.h"
 #include "gthr.h"
 #include "unwind-dw2.h"
+#include <stddef.h>
 
 #ifdef HAVE_SYS_SDT_H
 #include <sys/sdt.h>
@@ -983,7 +984,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
 	    {
-	      fs->regs.reg[reg].how = REG_SAVED_OFFSET;
+	      fs->regs.how[reg] = REG_SAVED_OFFSET;
 	      fs->regs.reg[reg].loc.offset = offset;
 	    }
 	}
@@ -992,7 +993,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	  reg = insn & 0x3f;
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
-	    fs->regs.reg[reg].how = REG_UNSAVED;
+	    fs->regs.how[reg] = REG_UNSAVED;
 	}
       else switch (insn)
 	{
@@ -1026,7 +1027,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
 	    {
-	      fs->regs.reg[reg].how = REG_SAVED_OFFSET;
+	      fs->regs.how[reg] = REG_SAVED_OFFSET;
 	      fs->regs.reg[reg].loc.offset = offset;
 	    }
 	  break;
@@ -1037,21 +1038,21 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	     register was saved somewhere.  */
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
-	    fs->regs.reg[reg].how = REG_UNSAVED;
+	    fs->regs.how[reg] = REG_UNSAVED;
 	  break;
 
 	case DW_CFA_same_value:
 	  insn_ptr = read_uleb128 (insn_ptr, &reg);
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
-	    fs->regs.reg[reg].how = REG_UNSAVED;
+	    fs->regs.how[reg] = REG_UNSAVED;
 	  break;
 
 	case DW_CFA_undefined:
 	  insn_ptr = read_uleb128 (insn_ptr, &reg);
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
-	    fs->regs.reg[reg].how = REG_UNDEFINED;
+	    fs->regs.how[reg] = REG_UNDEFINED;
 	  break;
 
 	case DW_CFA_nop:
@@ -1065,7 +1066,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	    reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	    if (UNWIND_COLUMN_IN_RANGE (reg))
 	      {
-	        fs->regs.reg[reg].how = REG_SAVED_REG;
+		fs->regs.how[reg] = REG_SAVED_REG;
 	        fs->regs.reg[reg].loc.reg = (_Unwind_Word)reg2;
 	      }
 	  }
@@ -1128,7 +1129,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
 	    {
-	      fs->regs.reg[reg].how = REG_SAVED_EXP;
+	      fs->regs.how[reg] = REG_SAVED_EXP;
 	      fs->regs.reg[reg].loc.exp = insn_ptr;
 	    }
 	  insn_ptr = read_uleb128 (insn_ptr, &utmp);
@@ -1143,7 +1144,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
 	    {
-	      fs->regs.reg[reg].how = REG_SAVED_OFFSET;
+	      fs->regs.how[reg] = REG_SAVED_OFFSET;
 	      fs->regs.reg[reg].loc.offset = offset;
 	    }
 	  break;
@@ -1171,7 +1172,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
 	    {
-	      fs->regs.reg[reg].how = REG_SAVED_VAL_OFFSET;
+	      fs->regs.how[reg] = REG_SAVED_VAL_OFFSET;
 	      fs->regs.reg[reg].loc.offset = offset;
 	    }
 	  break;
@@ -1183,7 +1184,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
 	    {
-	      fs->regs.reg[reg].how = REG_SAVED_VAL_OFFSET;
+	      fs->regs.how[reg] = REG_SAVED_VAL_OFFSET;
 	      fs->regs.reg[reg].loc.offset = offset;
 	    }
 	  break;
@@ -1193,7 +1194,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
 	    {
-	      fs->regs.reg[reg].how = REG_SAVED_VAL_EXP;
+	      fs->regs.how[reg] = REG_SAVED_VAL_EXP;
 	      fs->regs.reg[reg].loc.exp = insn_ptr;
 	    }
 	  insn_ptr = read_uleb128 (insn_ptr, &utmp);
@@ -1205,14 +1206,14 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	  /* This CFA is multiplexed with Sparc.  On AArch64 it's used to toggle
 	     return address signing status.  */
 	  reg = DWARF_REGNUM_AARCH64_RA_STATE;
-	  gcc_assert (fs->regs.reg[reg].how == REG_UNSAVED);
+	  gcc_assert (fs->regs.how[reg] == REG_UNSAVED);
 	  fs->regs.reg[reg].loc.offset ^= 1;
 #else
 	  /* ??? Hardcoded for SPARC register window configuration.  */
 	  if (__LIBGCC_DWARF_FRAME_REGISTERS__ >= 32)
 	    for (reg = 16; reg < 32; ++reg)
 	      {
-		fs->regs.reg[reg].how = REG_SAVED_OFFSET;
+		fs->regs.how[reg] = REG_SAVED_OFFSET;
 		fs->regs.reg[reg].loc.offset = (reg - 16) * sizeof (void *);
 	      }
 #endif
@@ -1232,7 +1233,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
 	  reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
 	  if (UNWIND_COLUMN_IN_RANGE (reg))
 	    {
-	      fs->regs.reg[reg].how = REG_SAVED_OFFSET;
+	      fs->regs.how[reg] = REG_SAVED_OFFSET;
 	      fs->regs.reg[reg].loc.offset = -offset;
 	    }
 	  break;
@@ -1255,7 +1256,8 @@ uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
   const struct dwarf_cie *cie;
   const unsigned char *aug, *insn, *end;
 
-  memset (fs, 0, sizeof (*fs));
+  memset (&fs->regs.how[0], 0,
+	  sizeof (*fs) - offsetof (_Unwind_FrameState, regs.how[0]));
   context->args_size = 0;
   context->lsda = 0;
 
@@ -1355,7 +1357,7 @@ __frame_state_for (void *pc_target, struct frame_state *state_in)
 
   for (reg = 0; reg < PRE_GCC3_DWARF_FRAME_REGISTERS + 1; reg++)
     {
-      state_in->saved[reg] = fs.regs.reg[reg].how;
+      state_in->saved[reg] = fs.regs.how[reg];
       switch (state_in->saved[reg])
 	{
 	case REG_SAVED_REG:
@@ -1453,7 +1455,7 @@ uw_update_context_1 (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 
   /* Compute the addresses of all registers saved in this frame.  */
   for (i = 0; i < __LIBGCC_DWARF_FRAME_REGISTERS__ + 1; ++i)
-    switch (fs->regs.reg[i].how)
+    switch (fs->regs.how[i])
       {
       case REG_UNSAVED:
       case REG_UNDEFINED:
@@ -1531,7 +1533,7 @@ uw_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs)
      rule is handled like same_value.  The only exception is
      DW_CFA_undefined on retaddr_column which is supposed to
      mark outermost frame in DWARF 3.  */
-  if (fs->regs.reg[DWARF_REG_TO_UNWIND_COLUMN (fs->retaddr_column)].how
+  if (fs->regs.how[DWARF_REG_TO_UNWIND_COLUMN (fs->retaddr_column)]
       == REG_UNDEFINED)
     /* uw_frame_state_for uses context->ra == 0 check to find outermost
        stack frame.  */
diff --git a/libgcc/unwind-dw2.h b/libgcc/unwind-dw2.h
index 0c478e56c02..af34e000f07 100644
--- a/libgcc/unwind-dw2.h
+++ b/libgcc/unwind-dw2.h
@@ -22,6 +22,16 @@
    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
+enum {
+  REG_UNSAVED,
+  REG_SAVED_OFFSET,
+  REG_SAVED_REG,
+  REG_SAVED_EXP,
+  REG_SAVED_VAL_OFFSET,
+  REG_SAVED_VAL_EXP,
+  REG_UNDEFINED
+};
+
 /* The result of interpreting the frame unwind info for a frame.
    This is all symbolic at this point, as none of the values can
    be resolved until the target pc is located.  */
@@ -37,16 +47,8 @@ typedef struct
 	_Unwind_Sword offset;
 	const unsigned char *exp;
       } loc;
-      enum {
-	REG_UNSAVED,
-	REG_SAVED_OFFSET,
-	REG_SAVED_REG,
-	REG_SAVED_EXP,
-	REG_SAVED_VAL_OFFSET,
-	REG_SAVED_VAL_EXP,
-	REG_UNDEFINED
-      } how;
     } reg[__LIBGCC_DWARF_FRAME_REGISTERS__+1];
+    unsigned char how[__LIBGCC_DWARF_FRAME_REGISTERS__+1];
 
     /* Used to implement DW_CFA_remember_state.  */
     struct frame_state_reg_info *prev;

                 reply	other threads:[~2022-10-06  9:06 UTC|newest]

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