diff options
Diffstat (limited to 'gcc/tree-ssa-dom.c')
| -rw-r--r-- | gcc/tree-ssa-dom.c | 38 |
1 files changed, 34 insertions, 4 deletions
diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c index 829863794a3..3eeaa9cdcf9 100644 --- a/gcc/tree-ssa-dom.c +++ b/gcc/tree-ssa-dom.c @@ -387,11 +387,16 @@ record_edge_info (basic_block bb) /* Special case comparing booleans against a constant as we know the value of OP0 on both arms of the branch. i.e., we - can record an equivalence for OP0 rather than COND. */ - if ((code == EQ_EXPR || code == NE_EXPR) - && TREE_CODE (op0) == SSA_NAME + can record an equivalence for OP0 rather than COND. + + However, don't do this if the constant isn't zero or one. + Such conditionals will get optimized more thoroughly during + the domwalk. */ + if ((code == EQ_EXPR || code == NE_EXPR) + && TREE_CODE (op0) == SSA_NAME && ssa_name_has_boolean_range (op0) - && is_gimple_min_invariant (op1)) + && is_gimple_min_invariant (op1) + && (integer_zerop (op1) || integer_onep (op1))) { tree true_val = constant_boolean_node (true, TREE_TYPE (op0)); tree false_val = constant_boolean_node (false, TREE_TYPE (op0)); @@ -1828,6 +1833,31 @@ optimize_stmt (basic_block bb, gimple_stmt_iterator si, } } + if (gimple_code (stmt) == GIMPLE_COND) + { + tree lhs = gimple_cond_lhs (stmt); + tree rhs = gimple_cond_rhs (stmt); + + /* If the LHS has a range [0..1] and the RHS has a range ~[0..1], + then this conditional is computable at compile time. We can just + shove either 0 or 1 into the LHS, mark the statement as modified + and all the right things will just happen below. + + Note this would apply to any case where LHS has a range + narrower than its type implies and RHS is outside that + narrower range. Future work. */ + if (TREE_CODE (lhs) == SSA_NAME + && ssa_name_has_boolean_range (lhs) + && TREE_CODE (rhs) == INTEGER_CST + && ! (integer_zerop (rhs) || integer_onep (rhs))) + { + gimple_cond_set_lhs (as_a <gcond *> (stmt), + fold_convert (TREE_TYPE (lhs), + integer_zero_node)); + gimple_set_modified (stmt, true); + } + } + update_stmt_if_modified (stmt); eliminate_redundant_computations (&si, const_and_copies, avail_exprs_stack); |