[PATCH] Improve EQ_EXPR/NE_EXPR folding (PR middle-end/38878)
Jakub Jelinek
jakub@redhat.com
Thu Feb 3 18:11:00 GMT 2011
Hi!
== and != doesn't care about signedness of the operands, so we
can IMHO use STRIP_NOPS instead of just STRIP_SIGN_NOPS.
Additionally, for X +- C == X and C - X == X folding we can also
strip nops from the +/-/p+ operand for the purpose of operand_equal_p
checking. This together fixes PR38878 regression (P2), though I'm
not 100% sure we want to do that this late, perhaps we can defer
it till stage1.
Nevertheless, bootstrapped/regtested on x86_64-linux and i686-linux.
2011-02-03 Jakub Jelinek <jakub@redhat.com>
PR middle-end/38878
* fold-const.c (fold_binary_loc) <case EQ_EXPR, NE_EXPR>: Add
STRIP_NOPS on arg0 and arg1. When optimizing X +- C == X
and C - X == X also strip nops from +/-/p+ operand.
When optimizing -X == C, fold C to arg0's type.
* gcc.dg/tree-ssa/foldaddr-1.c: Remove xfail.
--- gcc/fold-const.c.jj 2010-12-02 11:51:31.000000000 +0100
+++ gcc/fold-const.c 2011-02-03 15:45:27.000000000 +0100
@@ -12111,6 +12111,9 @@ fold_binary_loc (location_t loc,
case EQ_EXPR:
case NE_EXPR:
+ STRIP_NOPS (arg0);
+ STRIP_NOPS (arg1);
+
tem = fold_comparison (loc, code, type, op0, op1);
if (tem != NULL_TREE)
return tem;
@@ -12193,7 +12196,8 @@ fold_binary_loc (location_t loc,
/* Similarly for a NEGATE_EXPR. */
if (TREE_CODE (arg0) == NEGATE_EXPR
&& TREE_CODE (arg1) == INTEGER_CST
- && 0 != (tem = negate_expr (arg1))
+ && 0 != (tem = negate_expr (fold_convert_loc (loc, TREE_TYPE (arg0),
+ arg1)))
&& TREE_CODE (tem) == INTEGER_CST
&& !TREE_OVERFLOW (tem))
return fold_build2_loc (loc, code, type, TREE_OPERAND (arg0, 0), tem);
@@ -12213,7 +12217,9 @@ fold_binary_loc (location_t loc,
if ((TREE_CODE (arg0) == PLUS_EXPR
|| TREE_CODE (arg0) == POINTER_PLUS_EXPR
|| TREE_CODE (arg0) == MINUS_EXPR)
- && operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0)
+ && operand_equal_p (tree_strip_nop_conversions (TREE_OPERAND (arg0,
+ 0)),
+ arg1, 0)
&& (INTEGRAL_TYPE_P (TREE_TYPE (arg0))
|| POINTER_TYPE_P (TREE_TYPE (arg0))))
{
@@ -12229,7 +12235,9 @@ fold_binary_loc (location_t loc,
/* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
if (TREE_CODE (arg0) == MINUS_EXPR
&& TREE_CODE (TREE_OPERAND (arg0, 0)) == INTEGER_CST
- && operand_equal_p (TREE_OPERAND (arg0, 1), arg1, 0)
+ && operand_equal_p (tree_strip_nop_conversions (TREE_OPERAND (arg0,
+ 1)),
+ arg1, 0)
&& (TREE_INT_CST_LOW (TREE_OPERAND (arg0, 0)) & 1) == 1)
{
return omit_two_operands_loc (loc, type,
--- gcc/testsuite/gcc.dg/tree-ssa/foldaddr-1.c.jj 2009-01-26 15:24:36.000000000 +0100
+++ gcc/testsuite/gcc.dg/tree-ssa/foldaddr-1.c 2011-02-03 15:51:24.000000000 +0100
@@ -11,6 +11,6 @@ int foo(char *b)
/* Folding should have determined that the two addresses were
not identical and thus collapsed the function into a trivial
"return 0". */
-/* { dg-final { scan-tree-dump-times "return 0" 1 "original" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump-times "return 0" 1 "original" } } */
/* { dg-final { cleanup-tree-dump "original" } } */
Jakub
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