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| author | Richard Biener <rguenther@suse.de> | 2014-05-28 12:44:11 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2014-05-28 12:44:11 +0000 |
| commit | b017a17489a1e89510a224a3796275ec5cac97c4 (patch) | |
| tree | 1be500648cca150639fee9e44beec23154844c0d /gcc/fold-const.c | |
| parent | a4d6bf7e9fb614acec6d0df6932b60a88c13007c (diff) | |
| download | gcc-b017a17489a1e89510a224a3796275ec5cac97c4.zip gcc-b017a17489a1e89510a224a3796275ec5cac97c4.tar.gz gcc-b017a17489a1e89510a224a3796275ec5cac97c4.tar.bz2 | |
re PR middle-end/61045 (Wrong constant folding)
2014-05-28 Richard Biener <rguenther@suse.de>
PR middle-end/61045
* fold-const.c (fold_comparison): When folding
X +- C1 CMP Y +- C2 to X CMP Y +- C2 +- C1 also ensure
the sign of the remaining constant operand stays the same.
* gcc.dg/pr61045.c: New testcase.
From-SVN: r211018
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 25 |
1 files changed, 14 insertions, 11 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index b300934..0451b6a 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -9239,7 +9239,7 @@ fold_comparison (location_t loc, enum tree_code code, tree type, /* Transform comparisons of the form X +- C1 CMP Y +- C2 to X CMP Y +- C2 +- C1 for signed X, Y. This is valid if the resulting offset is smaller in absolute value than the - original one. */ + original one and has the same sign. */ if (TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (arg0)) && (TREE_CODE (arg0) == PLUS_EXPR || TREE_CODE (arg0) == MINUS_EXPR) && (TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST @@ -9258,32 +9258,35 @@ fold_comparison (location_t loc, enum tree_code code, tree type, "a comparison"); /* Put the constant on the side where it doesn't overflow and is - of lower absolute value than before. */ + of lower absolute value and of same sign than before. */ cst = int_const_binop (TREE_CODE (arg0) == TREE_CODE (arg1) ? MINUS_EXPR : PLUS_EXPR, const2, const1); if (!TREE_OVERFLOW (cst) - && tree_int_cst_compare (const2, cst) == tree_int_cst_sgn (const2)) + && tree_int_cst_compare (const2, cst) == tree_int_cst_sgn (const2) + && tree_int_cst_sgn (cst) == tree_int_cst_sgn (const2)) { fold_overflow_warning (warnmsg, WARN_STRICT_OVERFLOW_COMPARISON); return fold_build2_loc (loc, code, type, - variable1, - fold_build2_loc (loc, - TREE_CODE (arg1), TREE_TYPE (arg1), - variable2, cst)); + variable1, + fold_build2_loc (loc, TREE_CODE (arg1), + TREE_TYPE (arg1), + variable2, cst)); } cst = int_const_binop (TREE_CODE (arg0) == TREE_CODE (arg1) ? MINUS_EXPR : PLUS_EXPR, const1, const2); if (!TREE_OVERFLOW (cst) - && tree_int_cst_compare (const1, cst) == tree_int_cst_sgn (const1)) + && tree_int_cst_compare (const1, cst) == tree_int_cst_sgn (const1) + && tree_int_cst_sgn (cst) == tree_int_cst_sgn (const1)) { fold_overflow_warning (warnmsg, WARN_STRICT_OVERFLOW_COMPARISON); return fold_build2_loc (loc, code, type, - fold_build2_loc (loc, TREE_CODE (arg0), TREE_TYPE (arg0), - variable1, cst), - variable2); + fold_build2_loc (loc, TREE_CODE (arg0), + TREE_TYPE (arg0), + variable1, cst), + variable2); } } |