[gcc r12-1027] C-SKY: Separate FRAME_POINTER_REGNUM into FRAME_POINTER_REGNUM and HARD_FRAME_POINTER_REGNUM.

[gcc r12-1027] C-SKY: Separate FRAME_POINTER_REGNUM into FRAME_POINTER_REGNUM and HARD_FRAME_POINTER_REGNUM.

[qu]

https://gcc.gnu.org/g:d19a00c60c15c253282f72299315261ecaa9c92f

commit r12-1027-gd19a00c60c15c253282f72299315261ecaa9c92f
Author: Geng Qi <gengqi@linux.alibaba.com>
Date:   Mon May 24 20:22:55 2021 +0800

    C-SKY: Separate FRAME_POINTER_REGNUM into FRAME_POINTER_REGNUM and HARD_FRAME_POINTER_REGNUM.
    
    gcc/ChangeLog:
    
            * config/csky/csky.h (FRAME_POINTER_REGNUM): Use
            HARD_FRAME_POINTER_REGNUM and FRAME_POINTER_REGNUM instead of
            the signle definition. The signle definition may not work well
            at simplify_subreg_regno().
            (HARD_FRAME_POINTER_REGNUM): New.
            (ELIMINABLE_REGS): Add for HARD_FRAME_POINTER_REGNUM.
            * config/csky/csky.c (get_csky_live_regs, csky_can_eliminate,
            csky_initial_elimination_offset, csky_expand_prologue,
            csky_expand_epilogue): Add for HARD_FRAME_POINTER_REGNUM.

Diff:
---
 gcc/config/csky/csky.c | 15 +++++++++------
 gcc/config/csky/csky.h |  7 +++++--
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/gcc/config/csky/csky.c b/gcc/config/csky/csky.c
index 1a6cfd70ef7..7f2af82749b 100644
--- a/gcc/config/csky/csky.c
+++ b/gcc/config/csky/csky.c
@@ -1751,12 +1751,12 @@ get_csky_live_regs (int *count)
 	save = true;
 
       /* Frame pointer marked used.  */
-      else if (frame_pointer_needed && reg == FRAME_POINTER_REGNUM)
+      else if (frame_pointer_needed && reg == HARD_FRAME_POINTER_REGNUM)
 	save = true;
 
       /* This is required for CK801/802 where FP is a fixed reg, otherwise
 	 we end up with no FP value available to the DWARF-2 unwinder.  */
-      else if (crtl->calls_eh_return && reg == FRAME_POINTER_REGNUM)
+      else if (crtl->calls_eh_return && reg == HARD_FRAME_POINTER_REGNUM)
 	save = true;
 
       /* CK801/802 also need special handling for LR because it's clobbered
@@ -1832,6 +1832,8 @@ csky_layout_stack_frame (void)
 static bool
 csky_can_eliminate (const int from ATTRIBUTE_UNUSED, const int to)
 {
+  if (to == FRAME_POINTER_REGNUM)
+    return from != ARG_POINTER_REGNUM;
   if (to == STACK_POINTER_REGNUM)
     return !frame_pointer_needed;
   return true;
@@ -1852,6 +1854,7 @@ csky_initial_elimination_offset (int from, int to)
   switch (from)
     {
     case FRAME_POINTER_REGNUM:
+    case HARD_FRAME_POINTER_REGNUM:
       offset = cfun->machine->reg_offset;
       break;
 
@@ -1866,7 +1869,7 @@ csky_initial_elimination_offset (int from, int to)
   /* If we are asked for the offset to the frame pointer instead,
      then subtract the difference between the frame pointer and stack
      pointer.  */
-  if (to == FRAME_POINTER_REGNUM)
+  if (to == FRAME_POINTER_REGNUM || to == HARD_FRAME_POINTER_REGNUM)
     offset -= cfun->machine->reg_offset;
   return offset;
 }
@@ -5785,7 +5788,7 @@ csky_expand_prologue (void)
      of the register save area.  */
   if (frame_pointer_needed)
     {
-      insn = emit_insn (gen_movsi (frame_pointer_rtx, stack_pointer_rtx));
+      insn = emit_insn (gen_movsi (hard_frame_pointer_rtx, stack_pointer_rtx));
       RTX_FRAME_RELATED_P (insn) = 1;
     }
 
@@ -5848,7 +5851,7 @@ csky_expand_epilogue (void)
   /* Restore the SP to the base of the register save area.  */
   if (frame_pointer_needed)
     {
-      insn = emit_move_insn (stack_pointer_rtx, frame_pointer_rtx);
+      insn = emit_move_insn (stack_pointer_rtx, hard_frame_pointer_rtx);
       RTX_FRAME_RELATED_P (insn) = 1;
     }
   else
@@ -6004,7 +6007,7 @@ csky_set_eh_return_address (rtx source, rtx scratch)
 
       if (frame_pointer_needed)
 	{
-	  basereg = frame_pointer_rtx;
+	  basereg = hard_frame_pointer_rtx;
 	  delta = 0;
 	}
       else
diff --git a/gcc/config/csky/csky.h b/gcc/config/csky/csky.h
index 1fd72d0f3ee..f2b0d1cd110 100644
--- a/gcc/config/csky/csky.h
+++ b/gcc/config/csky/csky.h
@@ -342,7 +342,8 @@ extern int csky_arch_isa_features[];
 #define STACK_POINTER_REGNUM  CSKY_SP_REGNUM
 
 /* Base register for access to local variables of the function.  */
-#define FRAME_POINTER_REGNUM  8
+#define FRAME_POINTER_REGNUM  36
+#define HARD_FRAME_POINTER_REGNUM  8
 
 /* Base register for access to arguments of the function.  This is a fake
    register that is always eliminated.  */
@@ -370,7 +371,9 @@ extern int csky_arch_isa_features[];
 #define ELIMINABLE_REGS		  \
 {{ ARG_POINTER_REGNUM,	      STACK_POINTER_REGNUM	      },\
  { ARG_POINTER_REGNUM,	      FRAME_POINTER_REGNUM	      },\
- { FRAME_POINTER_REGNUM,      STACK_POINTER_REGNUM	      }}
+ { ARG_POINTER_REGNUM,	      HARD_FRAME_POINTER_REGNUM       },\
+ { FRAME_POINTER_REGNUM,      STACK_POINTER_REGNUM	      },\
+ { FRAME_POINTER_REGNUM,      HARD_FRAME_POINTER_REGNUM	      }}
 
 /* Define the offset between two registers, one to be eliminated, and the
    other its replacement, at the start of a routine.  */