2009-04-08 Thomas Quinot <quinot@adacore.com>

[pf3gnuchains/gcc-fork.git] / gcc / cse.c

diff --git a/gcc/cse.c b/gcc/cse.c
index f52f0a9..04f52fb 100644 (file)
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -1364,17 +1364,6 @@ lookup_as_function (rtx x, enum rtx_code code)
   struct table_elt *p
     = lookup (x, SAFE_HASH (x, VOIDmode), GET_MODE (x));
 
-  /* If we are looking for a CONST_INT, the mode doesn't really matter, as
-     long as we are narrowing.  So if we looked in vain for a mode narrower
-     than word_mode before, look for word_mode now.  */
-  if (p == 0 && code == CONST_INT
-      && GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (word_mode))
-    {
-      x = copy_rtx (x);
-      PUT_MODE (x, word_mode);
-      p = lookup (x, SAFE_HASH (x, VOIDmode), word_mode);
-    }
-
   if (p == 0)
     return 0;
 
@@ -3475,6 +3464,7 @@ fold_rtx (rtx x, rtx insn)
              int is_shift
                = (code == ASHIFT || code == ASHIFTRT || code == LSHIFTRT);
              rtx y, inner_const, new_const;
+             rtx canon_const_arg1 = const_arg1;
              enum rtx_code associate_code;
 
              if (is_shift
@@ -3482,8 +3472,9 @@ fold_rtx (rtx x, rtx insn)
                      || INTVAL (const_arg1) < 0))
                {
                  if (SHIFT_COUNT_TRUNCATED)
-                   const_arg1 = GEN_INT (INTVAL (const_arg1)
-                                         & (GET_MODE_BITSIZE (mode) - 1));
+                   canon_const_arg1 = GEN_INT (INTVAL (const_arg1)
+                                               & (GET_MODE_BITSIZE (mode)
+                                                  - 1));
                  else
                    break;
                }
@@ -3542,7 +3533,8 @@ fold_rtx (rtx x, rtx insn)
              associate_code = (is_shift || code == MINUS ? PLUS : code);
 
              new_const = simplify_binary_operation (associate_code, mode,
-                                                    const_arg1, inner_const);
+                                                    canon_const_arg1,
+                                                    inner_const);
 
              if (new_const == 0)
                break;
@@ -3641,6 +3633,8 @@ equiv_constant (rtx x)
 
   if (GET_CODE (x) == SUBREG)
     {
+      enum machine_mode mode = GET_MODE (x);
+      enum machine_mode imode = GET_MODE (SUBREG_REG (x));
       rtx new_rtx;
 
       /* See if we previously assigned a constant value to this SUBREG.  */
@@ -3649,10 +3643,25 @@ equiv_constant (rtx x)
           || (new_rtx = lookup_as_function (x, CONST_FIXED)) != 0)
         return new_rtx;
 
+      /* If we didn't and if doing so makes sense, see if we previously
+        assigned a constant value to the enclosing word mode SUBREG.  */
+      if (GET_MODE_SIZE (mode) < GET_MODE_SIZE (word_mode)
+         && GET_MODE_SIZE (word_mode) < GET_MODE_SIZE (imode))
+       {
+         int byte = SUBREG_BYTE (x) - subreg_lowpart_offset (mode, word_mode);
+         if (byte >= 0 && (byte % UNITS_PER_WORD) == 0)
+           {
+             rtx y = gen_rtx_SUBREG (word_mode, SUBREG_REG (x), byte);
+             new_rtx = lookup_as_function (y, CONST_INT);
+             if (new_rtx)
+               return gen_lowpart (mode, new_rtx);
+           }
+       }
+
+      /* Otherwise see if we already have a constant for the inner REG.  */
       if (REG_P (SUBREG_REG (x))
          && (new_rtx = equiv_constant (SUBREG_REG (x))) != 0)
-        return simplify_subreg (GET_MODE (x), new_rtx,
-                               GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x));
+        return simplify_subreg (mode, new_rtx, imode, SUBREG_BYTE (x));
 
       return 0;
     }
@@ -4477,7 +4486,8 @@ cse_insn (rtx insn)
          enum machine_mode wider_mode;
 
          for (wider_mode = GET_MODE_WIDER_MODE (mode);
-              GET_MODE_BITSIZE (wider_mode) <= BITS_PER_WORD
+              wider_mode != VOIDmode
+              && GET_MODE_BITSIZE (wider_mode) <= BITS_PER_WORD
               && src_related == 0;
               wider_mode = GET_MODE_WIDER_MODE (wider_mode))
            {