Patchwork patch to fix PR55122

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Submitter Vladimir Makarov
Date Nov. 7, 2012, 10:11 p.m.
Message ID <509ADCAE.4060907@redhat.com>
Download mbox | patch
Permalink /patch/197733/
State New
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Comments

Vladimir Makarov - Nov. 7, 2012, 10:11 p.m.
The following patch fixes

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55122

   The problem was in generation of reload pseudo for matching operands 
with uniq value which prevented to assign the same hard register for the 
reload pseudo and the original input pseudo when the choice of hard regs 
was quite small (AD regs).

   The patch was successfully bootstrapped and tested on x86/x86-64.

   Committed as rev. 193310.

2012-11-07  Vladimir Makarov  <vmakarov@redhat.com>

         PR rtl-optimization/55122
         * lra-constraints.c (match_reload): Sync values for dead input
         pseudos.

2012-11-07  Vladimir Makarov  <vmakarov@redhat.com>

         PR rtl-optimization/55122
         * gcc.dg/pr55122.c: New test.
H.J. Lu - Nov. 24, 2012, 6:59 a.m.
On Wed, Nov 7, 2012 at 2:11 PM, Vladimir Makarov <vmakarov@redhat.com> wrote:
>   The following patch fixes
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55122
>
>   The problem was in generation of reload pseudo for matching operands with
> uniq value which prevented to assign the same hard register for the reload
> pseudo and the original input pseudo when the choice of hard regs was quite
> small (AD regs).
>
>   The patch was successfully bootstrapped and tested on x86/x86-64.
>
>   Committed as rev. 193310.
>
> 2012-11-07  Vladimir Makarov  <vmakarov@redhat.com>
>
>         PR rtl-optimization/55122
>         * lra-constraints.c (match_reload): Sync values for dead input
>         pseudos.
>
> 2012-11-07  Vladimir Makarov  <vmakarov@redhat.com>
>
>         PR rtl-optimization/55122
>         * gcc.dg/pr55122.c: New test.
>
>

This caused:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55456

Patch

Index: lra-constraints.c
===================================================================
--- lra-constraints.c	(revision 193303)
+++ lra-constraints.c	(working copy)
@@ -682,6 +682,11 @@  match_reload (signed char out, signed ch
 	    new_out_reg = gen_lowpart_SUBREG (outmode, reg);
 	  else
 	    new_out_reg = gen_rtx_SUBREG (outmode, reg, 0);
+	  /* If the input reg is dying here, we can use the same hard
+	     register for REG and IN_RTX.  */
+	  if (REG_P (in_rtx)
+	      && find_regno_note (curr_insn, REG_DEAD, REGNO (in_rtx)))
+	    lra_reg_info[REGNO (reg)].val = lra_reg_info[REGNO (in_rtx)].val;
 	}
       else
 	{
@@ -698,6 +703,19 @@  match_reload (signed char out, signed ch
 	     it at the end of LRA work.  */
 	  clobber = emit_clobber (new_out_reg);
 	  LRA_TEMP_CLOBBER_P (PATTERN (clobber)) = 1;
+	  if (GET_CODE (in_rtx) == SUBREG)
+	    {
+	      rtx subreg_reg = SUBREG_REG (in_rtx);
+	      
+	      /* If SUBREG_REG is dying here and sub-registers IN_RTX
+		 and NEW_IN_REG are similar, we can use the same hard
+		 register for REG and SUBREG_REG.  */
+	      if (REG_P (subreg_reg) && GET_MODE (subreg_reg) == outmode
+		  && SUBREG_BYTE (in_rtx) == SUBREG_BYTE (new_in_reg)
+		  && find_regno_note (curr_insn, REG_DEAD, REGNO (subreg_reg)))
+		lra_reg_info[REGNO (reg)].val
+		  = lra_reg_info[REGNO (subreg_reg)].val;
+	    }
 	}
     }
   else
Index: testsuite/gcc.dg/pr55122.c
===================================================================
--- testsuite/gcc.dg/pr55122.c	(revision 0)
+++ testsuite/gcc.dg/pr55122.c	(working copy)
@@ -0,0 +1,14 @@ 
+/* PR rtl-optimization/55122 */
+/* { dg-do compile } */
+/* { dg-options "-O3" } */
+
+int i, a;
+unsigned long long b;
+
+void f(void)
+{
+    for(i = 0; i < 15; i++)
+        b *= b;
+
+    b *= a ? 0 : b;
+}