Re: Add unwind information to mips epilogues

[Richard Sandiford]

Bernd Schmidt <ber...@codesourcery.com> writes:
> Testing with the shrink-wrapping patch added reveals a problem with the
> mips16 "save" insn: sometimes we store registers that shouldn't be
> considered saved registers; we have to clear RTX_FRAME_RELATED_P for
> these. Testing in progress with mips-elf, "ips16/arch=mips32r2/abi=32"
> and some other multilibs. Ok?
>
>
> Bernd
>
>       * config/mips/mips.c (mips16e_build_save_restore): Clear
>       RTX_FRAME_RELATED_P for argument stores stolen from the first
>       block.
>
> Index: gcc/config/mips/mips.c
> ===================================================================
> --- gcc/config/mips/mips.c    (revision 178135)
> +++ gcc/config/mips/mips.c    (working copy)
> @@ -8448,6 +8456,7 @@ mips16e_build_save_restore (bool restore
>        offset = top_offset + i * UNITS_PER_WORD;
>        set = mips16e_save_restore_reg (restore_p, offset, GP_ARG_FIRST + i);
>        XVECEXP (pattern, 0, n++) = set;
> +      RTX_FRAME_RELATED_P (set) = 0;
>      }
>  
>    /* Then fill in the other register moves.  */

Sorry to be a pain, but I'd prefer the attached, which feels a bit
more direct.  (It's also completely untested, but I'll try to give
it a spin this weekend.)

Richard


gcc/
        * config/mips/mips.c (mips16e_save_restore_reg): Add a reg_parm_p
        argument.
        (mips16e_build_save_restore): Update accordingly.

Index: gcc/config/mips/mips.c
===================================================================
--- gcc/config/mips/mips.c      2011-09-06 12:01:22.000000000 +0100
+++ gcc/config/mips/mips.c      2011-09-08 14:53:22.885218099 +0100
@@ -8365,20 +8365,22 @@ mips16e_collect_argument_saves (void)
 }
 
 /* Return a move between register REGNO and memory location SP + OFFSET.
-   Make the move a load if RESTORE_P, otherwise make it a frame-related
-   store.  */
+   REG_PARM_P is true if SP + OFFSET belongs to REG_PARM_STACK_SPACE.
+   Make the move a load if RESTORE_P, otherwise make it a store.  */
 
 static rtx
-mips16e_save_restore_reg (bool restore_p, HOST_WIDE_INT offset,
-                         unsigned int regno)
+mips16e_save_restore_reg (bool restore_p, bool reg_parm_p,
+                         HOST_WIDE_INT offset, unsigned int regno)
 {
   rtx reg, mem;
 
   mem = gen_frame_mem (SImode, plus_constant (stack_pointer_rtx, offset));
   reg = gen_rtx_REG (SImode, regno);
-  return (restore_p
-         ? gen_rtx_SET (VOIDmode, reg, mem)
-         : mips_frame_set (mem, reg));
+  if (restore_p)
+    return gen_rtx_SET (VOIDmode, reg, mem);
+  if (reg_parm_p)
+    return gen_rtx_SET (VOIDmode, mem, reg);
+  return mips_frame_set (mem, reg);
 }
 
 /* Return RTL for a MIPS16e SAVE or RESTORE instruction; RESTORE_P says which.
@@ -8440,7 +8442,8 @@ mips16e_build_save_restore (bool restore
   for (i = 0; i < nargs; i++)
     {
       offset = top_offset + i * UNITS_PER_WORD;
-      set = mips16e_save_restore_reg (restore_p, offset, GP_ARG_FIRST + i);
+      set = mips16e_save_restore_reg (restore_p, true, offset,
+                                     GP_ARG_FIRST + i);
       XVECEXP (pattern, 0, n++) = set;
     }
 
@@ -8452,7 +8455,7 @@ mips16e_build_save_restore (bool restore
       if (BITSET_P (*mask_ptr, regno))
        {
          offset -= UNITS_PER_WORD;
-         set = mips16e_save_restore_reg (restore_p, offset, regno);
+         set = mips16e_save_restore_reg (restore_p, false, offset, regno);
          XVECEXP (pattern, 0, n++) = set;
          *mask_ptr &= ~(1 << regno);
        }