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| author | Jeff Law <law@redhat.com> | 2016-01-18 23:43:54 -0700 |
|---|---|---|
| committer | Jeff Law <law@gcc.gnu.org> | 2016-01-18 23:43:54 -0700 |
| commit | 2bedb645f2aef48d7cbb70bf5ddb8bf0a4342019 (patch) | |
| tree | 01f06939e38904f487d71de67d847c5e7cc30273 /gcc/tree-ssa-dom.c | |
| parent | 17c15cb932563bb814865c39abc2b952c7707f79 (diff) | |
| download | gcc-2bedb645f2aef48d7cbb70bf5ddb8bf0a4342019.zip gcc-2bedb645f2aef48d7cbb70bf5ddb8bf0a4342019.tar.gz gcc-2bedb645f2aef48d7cbb70bf5ddb8bf0a4342019.tar.bz2 | |
re PR tree-optimization/69320 (wrong code generation at -O2 and higher)
2016-01-18 Jeff Law <law@redhat.com>
PR tree-optimization/69320
* tree-ssa-dom.c (record_edge_info): For comparisons against a boolean
ranged object, do nothing if the RHS constant is not [0..1].
(optimize_stmt): Comparing a boolean ranged object against a
constant outside [0..1] results in a compile-time constant.
* tree-ssanames.c (ssa_name_has_boolean_range): Remove unnecessary
test.
PR tree-optimization/69320
* gcc.c-torture/pr69320-1.c: New test.
* gcc.c-torture/pr69320-2.c: New test.
* gcc.c-torture/pr69320-3.c: New test.
* gcc.c-torture/pr69320-4.c: New test.
From-SVN: r232548
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 8298637..3eeaa9c 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); |