[patch][DF] fix df_find_def and df_find_use

[Steven Bosscher]

Hello,

df_find_def and df_find_use do not work properly for hard registers
because rtx_equal_p returns false for the case where
REGNO(x)==REGNO(y) but the modes are different. This happened as
follows in my case:

Breakpoint 9, df_reg_used (insn=0x3fffb6083c50, reg=0x3fffb5eb72e0) at
../../trunk/gcc/df-core.c:1856
1856      return df_find_use (insn, reg) != NULL;
(gdb) p debug_rtx(reg)
(reg:CCX 100 %icc)
$37 = void
(gdb) p debug_rtx(insn)
(jump_insn 34 33 35 3 (set (pc)
        (if_then_else (le (reg:CCX 100 %icc)
                (const_int 0 [0]))
            (label_ref 44)
            (pc))) t.c:25 48 {*normal_branch}
     (expr_list:REG_DEAD (reg:CCX 100 %icc)
        (expr_list:REG_BR_PROB (const_int 3900 [0xf3c])
            (nil)))
 -> 44)
$38 = void
(gdb) step
df_find_use (insn=0x3fffb6083c50, reg=0x3fffb5eb72e0) at
../../trunk/gcc/df-core.c:1829
...
1837          if (rtx_equal_p (DF_REF_REAL_REG (use), reg))
(gdb) p debug_rtx(reg)
(reg:CCX 100 %icc)
$39 = void
(gdb) p debug_rtx(DF_REF_REAL_REG(use))
(reg:CC 100 %icc)
$40 = void
(gdb) p rtx_equal_p (DF_REF_REAL_REG (use), reg)
$41 = 0


I think we should just compare REGNO instead of going through rtx_equal_p.

Bootstrapped&tested on x86_64-unknown-linux-gnu.
OK for trunk?

Ciao!
Steven



        * df-core.c (df_find_def): Compare register numbers.
        (df_find_use): Compare register numbers.

Index: df-core.c
===================================================================
--- df-core.c   (revision 197610)
+++ df-core.c   (working copy)
@@ -1800,7 +1800,7 @@ df_find_def (rtx insn, rtx reg)
   for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
     {
       df_ref def = *def_rec;
-      if (rtx_equal_p (DF_REF_REAL_REG (def), reg))
+      if (DF_REF_REGNO (def) == REGNO (reg))
        return def;
     }

@@ -1834,14 +1834,14 @@ df_find_use (rtx insn, rtx reg)
   for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)
     {
       df_ref use = *use_rec;
-      if (rtx_equal_p (DF_REF_REAL_REG (use), reg))
+      if (DF_REF_REGNO (use) == REGNO (reg))
        return use;
     }
   if (df->changeable_flags & DF_EQ_NOTES)
     for (use_rec = DF_INSN_UID_EQ_USES (uid); *use_rec; use_rec++)
       {
        df_ref use = *use_rec;
-       if (rtx_equal_p (DF_REF_REAL_REG (use), reg))
+       if (DF_REF_REGNO (use) == REGNO (reg))
          return use;
       }
   return NULL;