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| author | Richard Henderson <rth@gcc.gnu.org> | 2004-07-03 11:57:18 -0700 |
|---|---|---|
| committer | Richard Henderson <rth@gcc.gnu.org> | 2004-07-03 11:57:18 -0700 |
| commit | f05ef4220a4cd6c3c8aafc41efd1f4165865825f (patch) | |
| tree | 4f592787da68b05ca62b4a01784fe39a83f221f2 /gcc/tree-ssa-dom.c | |
| parent | fa9784263f4e37528e0acb57019488a735221b7f (diff) | |
| download | gcc-f05ef4220a4cd6c3c8aafc41efd1f4165865825f.zip gcc-f05ef4220a4cd6c3c8aafc41efd1f4165865825f.tar.gz gcc-f05ef4220a4cd6c3c8aafc41efd1f4165865825f.tar.bz2 | |
tree-ssa-dom.c (simplify_rhs_and_lookup_avail_expr): Don't fold fp plus with minus.
* tree-ssa-dom.c (simplify_rhs_and_lookup_avail_expr): Don't fold
fp plus with minus.
From-SVN: r84061
Diffstat (limited to 'gcc/tree-ssa-dom.c')
| -rw-r--r-- | gcc/tree-ssa-dom.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c index b556b4e..356daac 100644 --- a/gcc/tree-ssa-dom.c +++ b/gcc/tree-ssa-dom.c @@ -1945,6 +1945,25 @@ simplify_rhs_and_lookup_avail_expr (struct dom_walk_data *walk_data, tree type = TREE_TYPE (TREE_OPERAND (stmt, 0)); tree t; + /* If we care about correct floating point results, then + don't fold x + c1 - c2. Note that we need to take both + the codes and the signs to figure this out. */ + if (FLOAT_TYPE_P (type) + && !flag_unsafe_math_optimizations + && (rhs_def_code == PLUS_EXPR + || rhs_def_code == MINUS_EXPR)) + { + bool neg = false; + + neg ^= (rhs_code == MINUS_EXPR); + neg ^= (rhs_def_code == MINUS_EXPR); + neg ^= real_isneg (TREE_REAL_CST_PTR (outer_const)); + neg ^= real_isneg (TREE_REAL_CST_PTR (def_stmt_op1)); + + if (neg) + goto dont_fold_assoc; + } + /* Ho hum. So fold will only operate on the outermost thingy that we give it, so we have to build the new expression in two pieces. This requires that we handle @@ -1979,6 +1998,7 @@ simplify_rhs_and_lookup_avail_expr (struct dom_walk_data *walk_data, } } } + dont_fold_assoc:; } /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR |