Simplify -x<0 to x>0

[Marc Glisse <marc dot glisse at inria dot fr>]

Hello,

I noticed we were only doing this transformation for floats and not for 
integers, so I took the chance to move it to match.pd. Regtested on 
ppc64le-redhat-linux.

2015-05-25  Marc Glisse  <marc.glisse@inria.fr>

	* match.pd (swapped_tcc_comparison): New operator list.
	(-A CMP -B): New simplification.
	* fold-const.c (fold_comparison): Remove corresponding code.

--
Marc Glisse

Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c	(revision 223630)
+++ gcc/fold-const.c	(working copy)
@@ -9176,38 +9176,25 @@ fold_comparison (location_t loc, enum tr
 
       if (TYPE_PRECISION (TREE_TYPE (targ1)) > TYPE_PRECISION (newtype))
 	newtype = TREE_TYPE (targ1);
 
       /* Fold (double)float1 CMP (double)float2 into float1 CMP float2.  */
       if (TYPE_PRECISION (newtype) < TYPE_PRECISION (TREE_TYPE (arg0)))
 	return fold_build2_loc (loc, code, type,
 			    fold_convert_loc (loc, newtype, targ0),
 			    fold_convert_loc (loc, newtype, targ1));
 
-      /* (-a) CMP (-b) -> b CMP a  */
-      if (TREE_CODE (arg0) == NEGATE_EXPR
-	  && TREE_CODE (arg1) == NEGATE_EXPR)
-	return fold_build2_loc (loc, code, type, TREE_OPERAND (arg1, 0),
-			    TREE_OPERAND (arg0, 0));
-
       if (TREE_CODE (arg1) == REAL_CST)
 	{
 	  REAL_VALUE_TYPE cst;
 	  cst = TREE_REAL_CST (arg1);
 
-	  /* (-a) CMP CST -> a swap(CMP) (-CST)  */
-	  if (TREE_CODE (arg0) == NEGATE_EXPR)
-	    return fold_build2_loc (loc, swap_tree_comparison (code), type,
-				TREE_OPERAND (arg0, 0),
-				build_real (TREE_TYPE (arg1),
-					    real_value_negate (&cst)));
-
 	  /* IEEE doesn't distinguish +0 and -0 in comparisons.  */
 	  /* a CMP (-0) -> a CMP 0  */
 	  if (REAL_VALUE_MINUS_ZERO (cst))
 	    return fold_build2_loc (loc, code, type, arg0,
 				build_real (TREE_TYPE (arg1), dconst0));
 
 	  /* x != NaN is always true, other ops are always false.  */
 	  if (REAL_VALUE_ISNAN (cst)
 	      && ! HONOR_SNANS (arg1))
 	    {
Index: gcc/match.pd
===================================================================
--- gcc/match.pd	(revision 223630)
+++ gcc/match.pd	(working copy)
@@ -31,20 +31,22 @@ along with GCC; see the file COPYING3.
    CONSTANT_CLASS_P
    tree_expr_nonnegative_p)
 
 /* Operator lists.  */
 (define_operator_list tcc_comparison
   lt   le   eq ne ge   gt   unordered ordered   unlt unle ungt unge uneq ltgt)
 (define_operator_list inverted_tcc_comparison
   ge   gt   ne eq lt   le   ordered   unordered ge   gt   le   lt   ltgt uneq)
 (define_operator_list inverted_tcc_comparison_with_nans
   unge ungt ne eq unlt unle ordered   unordered ge   gt   le   lt   ltgt uneq)
+(define_operator_list swapped_tcc_comparison
+  gt   ge   eq ne le   lt   unordered ordered   ungt unge unlt unle uneq ltgt)
 
 
 /* Simplifications of operations with one constant operand and
    simplifications to constants or single values.  */
 
 (for op (plus pointer_plus minus bit_ior bit_xor)
   (simplify
     (op @0 integer_zerop)
     (non_lvalue @0)))
 
@@ -973,20 +975,38 @@ along with GCC; see the file COPYING3.
  (bit_and (ordered @0 @0) (ordered @1 @1))
  (if (types_match (@0, @1))
   (ordered @0 @1)))
 (simplify
  (bit_ior:c (unordered @0 @0) (unordered:c@2 @0 @1))
  @2)
 (simplify
  (bit_and:c (ordered @0 @0) (ordered:c@2 @0 @1))
  @2)
 
+/* -A CMP -B -> B CMP A.  */
+(for cmp (tcc_comparison)
+     scmp (swapped_tcc_comparison)
+ (simplify
+  (cmp (negate @0) (negate @1))
+  (if (FLOAT_TYPE_P (TREE_TYPE (@0))
+       || (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+	   && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))))
+   (scmp @0 @1)))
+ (simplify
+  (cmp (negate @0) CONSTANT_CLASS_P@1)
+  (if (FLOAT_TYPE_P (TREE_TYPE (@0))
+       || (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
+	   && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))))
+   (with { tree tem = fold_unary (NEGATE_EXPR, TREE_TYPE (@0), @1); }
+    (if (tem && !TREE_OVERFLOW (tem))
+     (scmp @0 { tem; }))))))
+
 /* Simplification of math builtins.  */
 
 (define_operator_list LOG BUILT_IN_LOGF BUILT_IN_LOG BUILT_IN_LOGL)
 (define_operator_list EXP BUILT_IN_EXPF BUILT_IN_EXP BUILT_IN_EXPL)
 (define_operator_list LOG2 BUILT_IN_LOG2F BUILT_IN_LOG2 BUILT_IN_LOG2L)
 (define_operator_list EXP2 BUILT_IN_EXP2F BUILT_IN_EXP2 BUILT_IN_EXP2L)
 (define_operator_list LOG10 BUILT_IN_LOG10F BUILT_IN_LOG10 BUILT_IN_LOG10L)
 (define_operator_list EXP10 BUILT_IN_EXP10F BUILT_IN_EXP10 BUILT_IN_EXP10L)
 (define_operator_list POW BUILT_IN_POWF BUILT_IN_POW BUILT_IN_POWL)
 (define_operator_list POW10 BUILT_IN_POW10F BUILT_IN_POW10 BUILT_IN_POW10L)