Re: [PATCH] [i386] Recompute the frame layout less often

[Bernd Edlinger <bernd.edlinger@hotmail.de>]

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On 05/16/17 19:19, Ian Lance Taylor wrote:
> On Mon, May 15, 2017 at 10:00 PM, Daniel Santos <daniel.santos@pobox.com> wrote:
>>
>> Ian, would you mind looking at this please?  A combination of my
>> -mcall-ms2sysv-xlogues patch with Bernd's patch is causing problems when
>> ix86_expand_split_stack_prologue() calls ix86_expand_call().
>
> I don't have a lot of context here.  I assume that ms2sysv is going to
> be used on Windows systems, where -fsplit-stack isn't really going to
> work anyhow, so I think it would probably be OK that reject that
> combination if it causes trouble.
>
> Also, it's overkill for ix86_expand_split_stack_prologue to call
> ix86_expand_call.  The call is always to __morestack, and __morestack
> is written in assembler, so we could use a simpler version of
> ix86_expand_call if that helps.  In particular we can decide that
> __morestack doesn't clobber any unusual registers, if that is what is
> causing the problem.
>

I think I solved the problem with -fsplit-stack, I am not sure
if ix86_static_chain_on_stack might change after reload due to
final.c possibly calling targetm.calls.static_chain, but if that
is the case, that is an already pre-existing problem.

The goal of this patch is to make all decisions regarding the
frame layout before the reload pass, and to make sure that
the frame layout does not change unexpectedly it asserts
that the data that goes into the decision does not change
after reload_completed.

With the attached patch -fsplit-stack and the attribute ms_hook_prologue
is handed directly at the ix86_expand_call, because that data is
already known before expansion.

The calls_eh_return and ix86_static_chain_on_stack may become
known at a later time, but after reload it should not change any more.
To be sure, I added an assertion at ix86_static_chain, which the
regression test did not trigger, neither with -m64 nor with -m32.

I have bootstrapped the patch several times, and a few times I
encounterd a segfault in the garbage collection, but it did not
happen every time.  Currently I think that is unrelated to this patch.


Bootstrapped and reg-tested on x86_64-pc-linux-gnu with -m64/-m32.
Is it OK for trunk?


Thanks
Bernd.

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2017-05-16  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* config/i386/i386.c (x86_64_ms_sysv_extra_clobbered_registers): Make
	static.
	(xlogue_layout::get_stack_space_used, xlogue_layout::s_instances,
	xlogue_layout::get_instance, logue_layout::xlogue_layout,
	xlogue_layout::get_stub_name, xlogue_layout::get_stub_rtx,
	sp_valid_at, fp_valid_at, choose_basereg): Formatting.
	(xlogue_layout::compute_stub_managed_regs): Clear out param first.
	(stub_managed_regs): Remove.
	(ix86_save_reg): Use xlogue_layout::compute_stub_managed_regs.
	(disable_call_ms2sysv_xlogues): Rename to...
	(warn_once_call_ms2sysv_xlogues): ...this, and warn only once.
	(ix86_initial_elimination_offset, ix86_expand_call): Fix call_ms2sysv
	warning logic.
	(ix86_static_chain): Make sure that ix86_static_chain_on_stack can't
	change after reload_completed.
	(ix86_can_use_return_insn_p): Use the ix86_frame data structure
	directly.
	(ix86_expand_prologue): Likewise.
	(ix86_expand_epilogue): Likewise.
	(ix86_expand_split_stack_prologue): Likewise.
	(ix86_compute_frame_layout): Remove frame parameter ...
	(TARGET_COMPUTE_FRAME_LAYOUT): ... and export it as a target hook.
	(ix86_finalize_stack_realign_flags): Call ix86_compute_frame_layout
	only if necessary.
	(ix86_init_machine_status): Don't set use_fast_prologue_epilogue_nregs.
	(ix86_frame): Move from here ...
	* config/i386/i386.h (ix86_frame): ... to here.
	(machine_function): Remove use_fast_prologue_epilogue_nregs, cache the
	complete ix86_frame data structure instead.

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Index: gcc/config/i386/i386.c
===================================================================
--- gcc/config/i386/i386.c	(revision 248031)
+++ gcc/config/i386/i386.c	(working copy)
@@ -2425,7 +2425,9 @@ static int const x86_64_int_return_registers[4] =
 
 /* Additional registers that are clobbered by SYSV calls.  */
 
-unsigned const x86_64_ms_sysv_extra_clobbered_registers[12] =
+#define NUM_X86_64_MS_CLOBBERED_REGS 12
+static int const x86_64_ms_sysv_extra_clobbered_registers
+		 [NUM_X86_64_MS_CLOBBERED_REGS] =
 {
   SI_REG, DI_REG,
   XMM6_REG, XMM7_REG,
@@ -2484,13 +2486,13 @@ class xlogue_layout {
      needs to store registers based upon data in the machine_function.  */
   HOST_WIDE_INT get_stack_space_used () const
   {
-    const struct machine_function &m = *cfun->machine;
-    unsigned last_reg = m.call_ms2sysv_extra_regs + MIN_REGS - 1;
+    const struct machine_function *m = cfun->machine;
+    unsigned last_reg = m->call_ms2sysv_extra_regs + MIN_REGS - 1;
 
-    gcc_assert (m.call_ms2sysv_extra_regs <= MAX_EXTRA_REGS);
+    gcc_assert (m->call_ms2sysv_extra_regs <= MAX_EXTRA_REGS);
     return m_regs[last_reg].offset
-	    + (m.call_ms2sysv_pad_out ? 8 : 0)
-	    + STUB_INDEX_OFFSET;
+	   + (m->call_ms2sysv_pad_out ? 8 : 0)
+	   + STUB_INDEX_OFFSET;
   }
 
   /* Returns the offset for the base pointer used by the stub.  */
@@ -2532,7 +2534,7 @@ class xlogue_layout {
   /* Lazy-inited cache of symbol names for stubs.  */
   char m_stub_names[XLOGUE_STUB_COUNT][VARIANT_COUNT][STUB_NAME_MAX_LEN];
 
-  static const struct xlogue_layout GTY(()) s_instances[XLOGUE_SET_COUNT];
+  static const struct GTY(()) xlogue_layout s_instances[XLOGUE_SET_COUNT];
 };
 
 const char * const xlogue_layout::STUB_BASE_NAMES[XLOGUE_STUB_COUNT] = {
@@ -2573,7 +2575,7 @@ const unsigned xlogue_layout::REG_ORDER[xlogue_lay
 };
 
 /* Instantiates all xlogue_layout instances.  */
-const struct xlogue_layout GTY(())
+const struct GTY(()) xlogue_layout
 xlogue_layout::s_instances[XLOGUE_SET_COUNT] = {
   xlogue_layout (0, false),
   xlogue_layout (8, false),
@@ -2583,7 +2585,8 @@ xlogue_layout::s_instances[XLOGUE_SET_COUNT] = {
 
 /* Return an appropriate const instance of xlogue_layout based upon values
    in cfun->machine and crtl.  */
-const struct xlogue_layout &xlogue_layout::get_instance ()
+const struct xlogue_layout &
+xlogue_layout::get_instance ()
 {
   enum xlogue_stub_sets stub_set;
   bool aligned_plus_8 = cfun->machine->call_ms2sysv_pad_in;
@@ -2607,10 +2610,11 @@ unsigned
 xlogue_layout::compute_stub_managed_regs (HARD_REG_SET &stub_managed_regs)
 {
   bool hfp = frame_pointer_needed || stack_realign_fp;
-
   unsigned i, count;
   unsigned regno;
 
+  CLEAR_HARD_REG_SET (stub_managed_regs);
+
   for (i = 0; i < NUM_X86_64_MS_CLOBBERED_REGS; ++i)
     {
       regno = x86_64_ms_sysv_extra_clobbered_registers[i];
@@ -2630,8 +2634,8 @@ xlogue_layout::compute_stub_managed_regs (HARD_REG
       add_to_hard_reg_set (&stub_managed_regs, DImode, regno);
       ++count;
     }
-    gcc_assert (count >= MIN_REGS && count <= MAX_REGS);
-    return count;
+  gcc_assert (count >= MIN_REGS && count <= MAX_REGS);
+  return count;
 }
 
 /* Constructor for xlogue_layout.  */
@@ -2639,11 +2643,11 @@ xlogue_layout::xlogue_layout (HOST_WIDE_INT stack_
   : m_hfp (hfp) , m_nregs (hfp ? 17 : 18),
     m_stack_align_off_in (stack_align_off_in)
 {
+  HOST_WIDE_INT offset = stack_align_off_in;
+  unsigned i, j;
+
   memset (m_regs, 0, sizeof (m_regs));
   memset (m_stub_names, 0, sizeof (m_stub_names));
-
-  HOST_WIDE_INT offset = stack_align_off_in;
-  unsigned i, j;
   for (i = j = 0; i < MAX_REGS; ++i)
     {
       unsigned regno = REG_ORDER[i];
@@ -2662,11 +2666,12 @@ xlogue_layout::xlogue_layout (HOST_WIDE_INT stack_
       m_regs[j].regno    = regno;
       m_regs[j++].offset = offset - STUB_INDEX_OFFSET;
     }
-    gcc_assert (j == m_nregs);
+  gcc_assert (j == m_nregs);
 }
 
-const char *xlogue_layout::get_stub_name (enum xlogue_stub stub,
-					  unsigned n_extra_regs) const
+const char *
+xlogue_layout::get_stub_name (enum xlogue_stub stub,
+			      unsigned n_extra_regs) const
 {
   xlogue_layout *writey_this = const_cast<xlogue_layout*>(this);
   char *name = writey_this->m_stub_names[stub][n_extra_regs];
@@ -2676,7 +2681,7 @@ xlogue_layout::xlogue_layout (HOST_WIDE_INT stack_
     {
       int res = snprintf (name, STUB_NAME_MAX_LEN, "__%s_%u",
 			  STUB_BASE_NAMES[stub], MIN_REGS + n_extra_regs);
-      gcc_checking_assert (res <= (int)STUB_NAME_MAX_LEN);
+      gcc_checking_assert (res < (int)STUB_NAME_MAX_LEN);
     }
 
   return name;
@@ -2684,7 +2689,8 @@ xlogue_layout::xlogue_layout (HOST_WIDE_INT stack_
 
 /* Return rtx of a symbol ref for the entry point (based upon
    cfun->machine->call_ms2sysv_extra_regs) of the specified stub.  */
-rtx xlogue_layout::get_stub_rtx (enum xlogue_stub stub) const
+rtx
+xlogue_layout::get_stub_rtx (enum xlogue_stub stub) const
 {
   const unsigned n_extra_regs = cfun->machine->call_ms2sysv_extra_regs;
   gcc_checking_assert (n_extra_regs <= MAX_EXTRA_REGS);
@@ -2703,73 +2709,6 @@ struct GTY(()) stack_local_entry {
   struct stack_local_entry *next;
 };
 
-/* Structure describing stack frame layout.
-   Stack grows downward:
-
-   [arguments]
-					<- ARG_POINTER
-   saved pc
-
-   saved static chain			if ix86_static_chain_on_stack
-
-   saved frame pointer			if frame_pointer_needed
-					<- HARD_FRAME_POINTER
-   [saved regs]
-					<- reg_save_offset
-   [padding0]
-					<- stack_realign_offset
-   [saved SSE regs]
-	OR
-   [stub-saved registers for ms x64 --> sysv clobbers
-			<- Start of out-of-line, stub-saved/restored regs
-			   (see libgcc/config/i386/(sav|res)ms64*.S)
-     [XMM6-15]
-     [RSI]
-     [RDI]
-     [?RBX]		only if RBX is clobbered
-     [?RBP]		only if RBP and RBX are clobbered
-     [?R12]		only if R12 and all previous regs are clobbered
-     [?R13]		only if R13 and all previous regs are clobbered
-     [?R14]		only if R14 and all previous regs are clobbered
-     [?R15]		only if R15 and all previous regs are clobbered
-			<- end of stub-saved/restored regs
-     [padding1]
-   ]
-					<- outlined_save_offset
-					<- sse_regs_save_offset
-   [padding2]
-		       |		<- FRAME_POINTER
-   [va_arg registers]  |
-		       |
-   [frame]	       |
-		       |
-   [padding2]	       | = to_allocate
-					<- STACK_POINTER
-  */
-struct ix86_frame
-{
-  int nsseregs;
-  int nregs;
-  int va_arg_size;
-  int red_zone_size;
-  int outgoing_arguments_size;
-
-  /* The offsets relative to ARG_POINTER.  */
-  HOST_WIDE_INT frame_pointer_offset;
-  HOST_WIDE_INT hard_frame_pointer_offset;
-  HOST_WIDE_INT stack_pointer_offset;
-  HOST_WIDE_INT hfp_save_offset;
-  HOST_WIDE_INT reg_save_offset;
-  HOST_WIDE_INT stack_realign_allocate_offset;
-  HOST_WIDE_INT stack_realign_offset;
-  HOST_WIDE_INT outlined_save_offset;
-  HOST_WIDE_INT sse_reg_save_offset;
-
-  /* When save_regs_using_mov is set, emit prologue using
-     move instead of push instructions.  */
-  bool save_regs_using_mov;
-};
-
 /* Which cpu are we scheduling for.  */
 enum attr_cpu ix86_schedule;
 
@@ -2861,7 +2800,7 @@ static unsigned int ix86_function_arg_boundary (ma
 						const_tree);
 static rtx ix86_static_chain (const_tree, bool);
 static int ix86_function_regparm (const_tree, const_tree);
-static void ix86_compute_frame_layout (struct ix86_frame *);
+static void ix86_compute_frame_layout (void);
 static bool ix86_expand_vector_init_one_nonzero (bool, machine_mode,
 						 rtx, rtx, int);
 static void ix86_add_new_builtins (HOST_WIDE_INT, HOST_WIDE_INT);
@@ -12293,7 +12232,7 @@ ix86_can_use_return_insn_p (void)
   if (crtl->args.pops_args && crtl->args.size >= 32768)
     return 0;
 
-  ix86_compute_frame_layout (&frame);
+  frame = cfun->machine->frame;
   return (frame.stack_pointer_offset == UNITS_PER_WORD
 	  && (frame.nregs + frame.nsseregs) == 0);
 }
@@ -12634,10 +12573,6 @@ ix86_hard_regno_scratch_ok (unsigned int regno)
 	      && df_regs_ever_live_p (regno)));
 }
 
-/* Registers who's save & restore will be managed by stubs called from
-   pro/epilogue.  */
-static HARD_REG_SET GTY(()) stub_managed_regs;
-
 /* Return true if register class CL should be an additional allocno
    class.  */
 
@@ -12718,10 +12653,17 @@ ix86_save_reg (unsigned int regno, bool maybe_eh_r
 	}
     }
 
-  if (ignore_outlined && cfun->machine->call_ms2sysv
-      && in_hard_reg_set_p (stub_managed_regs, DImode, regno))
-    return false;
+  if (ignore_outlined && cfun->machine->call_ms2sysv)
+    {
+      /* Registers who's save & restore will be managed by stubs called from
+	 pro/epilogue.  */
+      HARD_REG_SET stub_managed_regs;
+      xlogue_layout::compute_stub_managed_regs (stub_managed_regs);
 
+      if (in_hard_reg_set_p (stub_managed_regs, DImode, regno))
+	return false;
+    }
+
   if (crtl->drap_reg
       && regno == REGNO (crtl->drap_reg)
       && !cfun->machine->no_drap_save_restore)
@@ -12787,8 +12729,7 @@ ix86_can_eliminate (const int from, const int to)
 HOST_WIDE_INT
 ix86_initial_elimination_offset (int from, int to)
 {
-  struct ix86_frame frame;
-  ix86_compute_frame_layout (&frame);
+  struct ix86_frame frame = cfun->machine->frame;
 
   if (from == ARG_POINTER_REGNUM && to == HARD_FRAME_POINTER_REGNUM)
     return frame.hard_frame_pointer_offset;
@@ -12818,13 +12759,16 @@ ix86_builtin_setjmp_frame_value (void)
   return stack_realign_fp ? hard_frame_pointer_rtx : virtual_stack_vars_rtx;
 }
 
-/* Disables out-of-lined msabi to sysv pro/epilogues and emits a warning if
-   warn_once is null, or *warn_once is zero.  */
-static void disable_call_ms2sysv_xlogues (const char *feature)
+/* Emits a warning for unsupported msabi to sysv pro/epilogues.  */
+static void warn_once_call_ms2sysv_xlogues (const char *feature)
 {
-  cfun->machine->call_ms2sysv = false;
-  warning (OPT_mcall_ms2sysv_xlogues, "not currently compatible with %s.",
-	   feature);
+  static bool warned_once = false;
+  if (!warned_once)
+    {
+      warning (0, "-mcall-ms2sysv-xlogues is not compatible with %s",
+	       feature);
+      warned_once = true;
+    }
 }
 
 /* When using -fsplit-stack, the allocation routines set a field in
@@ -12836,8 +12780,9 @@ ix86_builtin_setjmp_frame_value (void)
 /* Fill structure ix86_frame about frame of currently computed function.  */
 
 static void
-ix86_compute_frame_layout (struct ix86_frame *frame)
+ix86_compute_frame_layout (void)
 {
+  struct ix86_frame *frame = &cfun->machine->frame;
   struct machine_function *m = cfun->machine;
   unsigned HOST_WIDE_INT stack_alignment_needed;
   HOST_WIDE_INT offset;
@@ -12845,46 +12790,41 @@ static void
   HOST_WIDE_INT size = get_frame_size ();
   HOST_WIDE_INT to_allocate;
 
-  CLEAR_HARD_REG_SET (stub_managed_regs);
-
   /* m->call_ms2sysv is initially enabled in ix86_expand_call for all 64-bit
    * ms_abi functions that call a sysv function.  We now need to prune away
    * cases where it should be disabled.  */
   if (TARGET_64BIT && m->call_ms2sysv)
-  {
-    gcc_assert (TARGET_64BIT_MS_ABI);
-    gcc_assert (TARGET_CALL_MS2SYSV_XLOGUES);
-    gcc_assert (!TARGET_SEH);
+    {
+      gcc_assert (TARGET_64BIT_MS_ABI);
+      gcc_assert (TARGET_CALL_MS2SYSV_XLOGUES);
+      gcc_assert (!TARGET_SEH);
+      gcc_assert (TARGET_SSE);
+      gcc_assert (!ix86_using_red_zone ());
 
-    if (!TARGET_SSE)
-      m->call_ms2sysv = false;
+      if (crtl->calls_eh_return)
+	{
+	  gcc_assert (!reload_completed);
+	  m->call_ms2sysv = false;
+	  warn_once_call_ms2sysv_xlogues ("__builtin_eh_return");
+	}
 
-    /* Don't break hot-patched functions.  */
-    else if (ix86_function_ms_hook_prologue (current_function_decl))
-      m->call_ms2sysv = false;
+      else if (ix86_static_chain_on_stack)
+	{
+	  gcc_assert (!reload_completed);
+	  m->call_ms2sysv = false;
+	  warn_once_call_ms2sysv_xlogues ("static call chains");
+	}
 
-    /* TODO: Cases not yet examined.  */
-    else if (crtl->calls_eh_return)
-      disable_call_ms2sysv_xlogues ("__builtin_eh_return");
+      /* Finally, compute which registers the stub will manage.  */
+      else
+        {
+	  HARD_REG_SET stub_managed_regs;
+	  unsigned count = xlogue_layout
+			   ::compute_stub_managed_regs (stub_managed_regs);
+	  m->call_ms2sysv_extra_regs = count - xlogue_layout::MIN_REGS;
+	}
+    }
 
-    else if (ix86_static_chain_on_stack)
-      disable_call_ms2sysv_xlogues ("static call chains");
-
-    else if (ix86_using_red_zone ())
-      disable_call_ms2sysv_xlogues ("red zones");
-
-    else if (flag_split_stack)
-      disable_call_ms2sysv_xlogues ("split stack");
-
-    /* Finally, compute which registers the stub will manage.  */
-    else
-      {
-	unsigned count = xlogue_layout
-			 ::compute_stub_managed_regs (stub_managed_regs);
-	m->call_ms2sysv_extra_regs = count - xlogue_layout::MIN_REGS;
-      }
-  }
-
   frame->nregs = ix86_nsaved_regs ();
   frame->nsseregs = ix86_nsaved_sseregs ();
   m->call_ms2sysv_pad_in = 0;
@@ -12916,19 +12856,11 @@ static void
      in doing anything except PUSHs.  */
   if (TARGET_SEH)
     m->use_fast_prologue_epilogue = false;
-
-  /* During reload iteration the amount of registers saved can change.
-     Recompute the value as needed.  Do not recompute when amount of registers
-     didn't change as reload does multiple calls to the function and does not
-     expect the decision to change within single iteration.  */
-  else if (!optimize_bb_for_size_p (ENTRY_BLOCK_PTR_FOR_FN (cfun))
-	   && m->use_fast_prologue_epilogue_nregs != frame->nregs)
+  else if (!optimize_bb_for_size_p (ENTRY_BLOCK_PTR_FOR_FN (cfun)))
     {
       int count = frame->nregs;
       struct cgraph_node *node = cgraph_node::get (current_function_decl);
 
-      m->use_fast_prologue_epilogue_nregs = count;
-
       /* The fast prologue uses move instead of push to save registers.  This
          is significantly longer, but also executes faster as modern hardware
          can execute the moves in parallel, but can't do that for push/pop.
@@ -13145,7 +13077,8 @@ choose_baseaddr_len (unsigned int regno, HOST_WIDE
 
 /* Determine if the stack pointer is valid for accessing the cfa_offset.  */
 
-static inline bool sp_valid_at (HOST_WIDE_INT cfa_offset)
+static inline bool
+sp_valid_at (HOST_WIDE_INT cfa_offset)
 {
   const struct machine_frame_state &fs = cfun->machine->fs;
   return fs.sp_valid && !(fs.sp_realigned
@@ -13154,7 +13087,8 @@ choose_baseaddr_len (unsigned int regno, HOST_WIDE
 
 /* Determine if the frame pointer is valid for accessing the cfa_offset.  */
 
-static inline bool fp_valid_at (HOST_WIDE_INT cfa_offset)
+static inline bool
+fp_valid_at (HOST_WIDE_INT cfa_offset)
 {
   const struct machine_frame_state &fs = cfun->machine->fs;
   return fs.fp_valid && !(fs.sp_valid && fs.sp_realigned
@@ -13164,9 +13098,10 @@ choose_baseaddr_len (unsigned int regno, HOST_WIDE
 /* Choose a base register based upon alignment requested, speed and/or
    size.  */
 
-static void choose_basereg (HOST_WIDE_INT cfa_offset, rtx &base_reg,
-			    HOST_WIDE_INT &base_offset,
-			    unsigned int align_reqested, unsigned int *align)
+static void
+choose_basereg (HOST_WIDE_INT cfa_offset, rtx &base_reg,
+		HOST_WIDE_INT &base_offset,
+		unsigned int align_reqested, unsigned int *align)
 {
   const struct machine_function *m = cfun->machine;
   unsigned int hfp_align;
@@ -14159,6 +14094,7 @@ ix86_finalize_stack_realign_flags (void)
        < (crtl->is_leaf && !ix86_current_function_calls_tls_descriptor
 	  ? crtl->max_used_stack_slot_alignment
 	  : crtl->stack_alignment_needed));
+  bool recompute_frame_layout_p = false;
 
   if (crtl->stack_realign_finalized)
     {
@@ -14208,8 +14144,12 @@ ix86_finalize_stack_realign_flags (void)
 		&& requires_stack_frame_p (insn, prologue_used,
 					   set_up_by_prologue))
 	      {
+		if (crtl->stack_realign_needed != stack_realign)
+		  recompute_frame_layout_p = true;
 		crtl->stack_realign_needed = stack_realign;
 		crtl->stack_realign_finalized = true;
+		if (recompute_frame_layout_p)
+		  ix86_compute_frame_layout ();
 		return;
 	      }
 	}
@@ -14240,10 +14180,15 @@ ix86_finalize_stack_realign_flags (void)
       df_scan_blocks ();
       df_compute_regs_ever_live (true);
       df_analyze ();
+      recompute_frame_layout_p = true;
     }
 
+  if (crtl->stack_realign_needed != stack_realign)
+    recompute_frame_layout_p = true;
   crtl->stack_realign_needed = stack_realign;
   crtl->stack_realign_finalized = true;
+  if (recompute_frame_layout_p)
+    ix86_compute_frame_layout ();
 }
 
 /* Delete SET_GOT right after entry block if it is allocated to reg.  */
@@ -14372,7 +14317,7 @@ ix86_expand_prologue (void)
   m->fs.sp_valid = true;
   m->fs.sp_realigned = false;
 
-  ix86_compute_frame_layout (&frame);
+  frame = m->frame;
 
   if (!TARGET_64BIT && ix86_function_ms_hook_prologue (current_function_decl))
     {
@@ -15212,7 +15157,7 @@ ix86_expand_epilogue (int style)
   bool restore_stub_is_tail = false;
 
   ix86_finalize_stack_realign_flags ();
-  ix86_compute_frame_layout (&frame);
+  frame = m->frame;
 
   m->fs.sp_realigned = stack_realign_fp;
   m->fs.sp_valid = stack_realign_fp
@@ -15757,7 +15702,7 @@ ix86_expand_split_stack_prologue (void)
   gcc_assert (flag_split_stack && reload_completed);
 
   ix86_finalize_stack_realign_flags ();
-  ix86_compute_frame_layout (&frame);
+  frame = cfun->machine->frame;
   allocate = frame.stack_pointer_offset - INCOMING_FRAME_SP_OFFSET;
 
   /* This is the label we will branch to if we have enough stack
@@ -29320,7 +29265,24 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx call
 
       /* Set here, but it may get cleared later.  */
       if (TARGET_CALL_MS2SYSV_XLOGUES)
-	cfun->machine->call_ms2sysv = true;
+	{
+	  if (!TARGET_SSE)
+	    ;
+
+	  /* Don't break hot-patched functions.  */
+	  else if (ix86_function_ms_hook_prologue (current_function_decl))
+	    ;
+
+	  /* TODO: Cases not yet examined.  */
+	  else if (flag_split_stack)
+	    warn_once_call_ms2sysv_xlogues ("-fsplit-stack");
+
+	  else
+	    {
+	      gcc_assert (!reload_completed);
+	      cfun->machine->call_ms2sysv = true;
+	    }
+	}
     }
 
   if (vec_len > 1)
@@ -29455,7 +29417,6 @@ ix86_init_machine_status (void)
   struct machine_function *f;
 
   f = ggc_cleared_alloc<machine_function> ();
-  f->use_fast_prologue_epilogue_nregs = -1;
   f->call_abi = ix86_abi;
 
   return f;
@@ -31516,7 +31477,10 @@ ix86_static_chain (const_tree fndecl_or_type, bool
 	  if (incoming_p)
 	    {
 	      if (fndecl == current_function_decl)
-		ix86_static_chain_on_stack = true;
+		{
+		  gcc_assert (!reload_completed);
+		  ix86_static_chain_on_stack = true;
+		}
 	      return gen_frame_mem (SImode,
 				    plus_constant (Pmode,
 						   arg_pointer_rtx, -8));
@@ -52828,6 +52792,9 @@ ix86_run_selftests (void)
 #undef TARGET_LEGITIMATE_CONSTANT_P
 #define TARGET_LEGITIMATE_CONSTANT_P ix86_legitimate_constant_p
 
+#undef TARGET_COMPUTE_FRAME_LAYOUT
+#define TARGET_COMPUTE_FRAME_LAYOUT ix86_compute_frame_layout
+
 #undef TARGET_FRAME_POINTER_REQUIRED
 #define TARGET_FRAME_POINTER_REQUIRED ix86_frame_pointer_required
 
Index: gcc/config/i386/i386.h
===================================================================
--- gcc/config/i386/i386.h	(revision 248031)
+++ gcc/config/i386/i386.h	(working copy)
@@ -2163,10 +2163,6 @@ extern int const dbx_register_map[FIRST_PSEUDO_REG
 extern int const dbx64_register_map[FIRST_PSEUDO_REGISTER];
 extern int const svr4_dbx_register_map[FIRST_PSEUDO_REGISTER];
 
-extern unsigned const x86_64_ms_sysv_extra_clobbered_registers[12];
-#define NUM_X86_64_MS_CLOBBERED_REGS \
-  (ARRAY_SIZE (x86_64_ms_sysv_extra_clobbered_registers))
-
 /* Before the prologue, RA is at 0(%esp).  */
 #define INCOMING_RETURN_ADDR_RTX \
   gen_rtx_MEM (Pmode, gen_rtx_REG (Pmode, STACK_POINTER_REGNUM))
@@ -2448,9 +2444,76 @@ enum avx_u128_state
 \f
 #define FASTCALL_PREFIX '@'
 \f
+#ifndef USED_FOR_TARGET
+/* Structure describing stack frame layout.
+   Stack grows downward:
+
+   [arguments]
+					<- ARG_POINTER
+   saved pc
+
+   saved static chain			if ix86_static_chain_on_stack
+
+   saved frame pointer			if frame_pointer_needed
+					<- HARD_FRAME_POINTER
+   [saved regs]
+					<- reg_save_offset
+   [padding0]
+					<- stack_realign_offset
+   [saved SSE regs]
+	OR
+   [stub-saved registers for ms x64 --> sysv clobbers
+			<- Start of out-of-line, stub-saved/restored regs
+			   (see libgcc/config/i386/(sav|res)ms64*.S)
+     [XMM6-15]
+     [RSI]
+     [RDI]
+     [?RBX]		only if RBX is clobbered
+     [?RBP]		only if RBP and RBX are clobbered
+     [?R12]		only if R12 and all previous regs are clobbered
+     [?R13]		only if R13 and all previous regs are clobbered
+     [?R14]		only if R14 and all previous regs are clobbered
+     [?R15]		only if R15 and all previous regs are clobbered
+			<- end of stub-saved/restored regs
+     [padding1]
+   ]
+					<- outlined_save_offset
+					<- sse_regs_save_offset
+   [padding2]
+		       |		<- FRAME_POINTER
+   [va_arg registers]  |
+		       |
+   [frame]	       |
+		       |
+   [padding2]	       | = to_allocate
+					<- STACK_POINTER
+  */
+struct GTY(()) ix86_frame
+{
+  int nsseregs;
+  int nregs;
+  int va_arg_size;
+  int red_zone_size;
+  int outgoing_arguments_size;
+
+  /* The offsets relative to ARG_POINTER.  */
+  HOST_WIDE_INT frame_pointer_offset;
+  HOST_WIDE_INT hard_frame_pointer_offset;
+  HOST_WIDE_INT stack_pointer_offset;
+  HOST_WIDE_INT hfp_save_offset;
+  HOST_WIDE_INT reg_save_offset;
+  HOST_WIDE_INT stack_realign_allocate_offset;
+  HOST_WIDE_INT stack_realign_offset;
+  HOST_WIDE_INT outlined_save_offset;
+  HOST_WIDE_INT sse_reg_save_offset;
+
+  /* When save_regs_using_mov is set, emit prologue using
+     move instead of push instructions.  */
+  bool save_regs_using_mov;
+};
+
 /* Machine specific frame tracking during prologue/epilogue generation.  */
 
-#ifndef USED_FOR_TARGET
 struct GTY(()) machine_frame_state
 {
   /* This pair tracks the currently active CFA as reg+offset.  When reg
@@ -2520,9 +2583,8 @@ struct GTY(()) machine_function {
   int varargs_fpr_size;
   int optimize_mode_switching[MAX_386_ENTITIES];
 
-  /* Number of saved registers USE_FAST_PROLOGUE_EPILOGUE
-     has been computed for.  */
-  int use_fast_prologue_epilogue_nregs;
+  /* Cached initial frame layout for the current function.  */
+  struct ix86_frame frame;
 
   /* For -fsplit-stack support: A stack local which holds a pointer to
      the stack arguments for a function with a variable number of