diff options
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 |