* simplify-rtx.c (simplify_relational_operation_1): Implement some

	canonicalization transformations that attempt to simplify integer
	constant comparisons to become comparisons against zero.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@121544 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6fa2af1..e6cfa7c 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2007-02-03  Roger Sayle  <roger@eyesopen.com>
+
+       * simplify-rtx.c (simplify_relational_operation_1): Implement some
+       canonicalization transformations that attempt to simplify integer
+       constant comparisons to become comparisons against zero.
+
 2007-02-03  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
        * builtins.c (fold_builtin_cabs): Fold cabs(x+xi) into

diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 0ce80c7..f04f052 100644 (file)
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -3595,28 +3595,68 @@ simplify_relational_operation_1 (enum rtx_code code, enum machine_mode mode,
 {
   enum rtx_code op0code = GET_CODE (op0);
 
-  if (GET_CODE (op1) == CONST_INT)
+  if (op1 == const0_rtx && COMPARISON_P (op0))
     {
-      if (INTVAL (op1) == 0 && COMPARISON_P (op0))
+      /* If op0 is a comparison, extract the comparison arguments
+         from it.  */
+      if (code == NE)
        {
-         /* If op0 is a comparison, extract the comparison arguments
-            from it.  */
-         if (code == NE)
-           {
-             if (GET_MODE (op0) == mode)
-               return simplify_rtx (op0);
-             else
-               return simplify_gen_relational (GET_CODE (op0), mode, VOIDmode,
-                                               XEXP (op0, 0), XEXP (op0, 1));
-           }
-         else if (code == EQ)
-           {
-             enum rtx_code new_code = reversed_comparison_code (op0, NULL_RTX);
-             if (new_code != UNKNOWN)
-               return simplify_gen_relational (new_code, mode, VOIDmode,
-                                               XEXP (op0, 0), XEXP (op0, 1));
-           }
+         if (GET_MODE (op0) == mode)
+           return simplify_rtx (op0);
+         else
+           return simplify_gen_relational (GET_CODE (op0), mode, VOIDmode,
+                                           XEXP (op0, 0), XEXP (op0, 1));
        }
+      else if (code == EQ)
+       {
+         enum rtx_code new_code = reversed_comparison_code (op0, NULL_RTX);
+         if (new_code != UNKNOWN)
+           return simplify_gen_relational (new_code, mode, VOIDmode,
+                                           XEXP (op0, 0), XEXP (op0, 1));
+       }
+    }
+
+  if (op1 == const0_rtx)
+    {
+      /* Canonicalize (GTU x 0) as (NE x 0).  */
+      if (code == GTU)
+        return simplify_gen_relational (NE, mode, cmp_mode, op0, op1);
+      /* Canonicalize (LEU x 0) as (EQ x 0).  */
+      if (code == LEU)
+        return simplify_gen_relational (EQ, mode, cmp_mode, op0, op1);
+    }
+  else if (op1 == const1_rtx)
+    {
+      switch (code)
+        {
+        case GE:
+         /* Canonicalize (GE x 1) as (GT x 0).  */
+         return simplify_gen_relational (GT, mode, cmp_mode,
+                                         op0, const0_rtx);
+       case GEU:
+         /* Canonicalize (GEU x 1) as (NE x 0).  */
+         return simplify_gen_relational (NE, mode, cmp_mode,
+                                         op0, const0_rtx);
+       case LT:
+         /* Canonicalize (LT x 1) as (LE x 0).  */
+         return simplify_gen_relational (LE, mode, cmp_mode,
+                                         op0, const0_rtx);
+       case LTU:
+         /* Canonicalize (LTU x 1) as (EQ x 0).  */
+         return simplify_gen_relational (EQ, mode, cmp_mode,
+                                         op0, const0_rtx);
+       default:
+         break;
+       }
+    }
+  else if (op1 == constm1_rtx)
+    {
+      /* Canonicalize (LE x -1) as (LT x 0).  */
+      if (code == LE)
+        return simplify_gen_relational (LT, mode, cmp_mode, op0, const0_rtx);
+      /* Canonicalize (GT x -1) as (GE x 0).  */
+      if (code == GT)
+        return simplify_gen_relational (GE, mode, cmp_mode, op0, const0_rtx);
     }
 
   /* (eq/ne (plus x cst1) cst2) simplifies to (eq/ne x (cst2 - cst1))  */