diff options
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/tree-cfg.c | 24 |
2 files changed, 26 insertions, 3 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index e3d670d..9580f3d 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2004-07-12 Diego Novillo <dnovillo@redhat.com> + + * tree-cfg.c (find_taken_edge): Statically compute the truth + value of a predicate comparing an SSA_NAME to itself. + 2004-07-12 Roger Sayle <roger@eyesopen.com> * config/rs6000/rs6000.c (rs6000_rtx_costs): Indicate that the diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c index bd2ec9a..6207fd3 100644 --- a/gcc/tree-cfg.c +++ b/gcc/tree-cfg.c @@ -1991,9 +1991,9 @@ cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi) } -/* Given a control block BB and a constant value VAL, return the edge that - will be taken out of the block. If VAL does not match a unique edge, - NULL is returned. */ +/* Given a control block BB and a predicate VAL, return the edge that + will be taken out of the block. If VAL does not match a unique + edge, NULL is returned. */ edge find_taken_edge (basic_block bb, tree val) @@ -2007,6 +2007,24 @@ find_taken_edge (basic_block bb, tree val) abort (); #endif + /* If VAL is a predicate of the form N RELOP N, where N is an + SSA_NAME, we can always determine its truth value (except when + doing floating point comparisons that may involve NaNs). */ + if (val + && TREE_CODE_CLASS (TREE_CODE (val)) == '<' + && TREE_OPERAND (val, 0) == TREE_OPERAND (val, 1) + && TREE_CODE (TREE_OPERAND (val, 0)) == SSA_NAME + && (TREE_CODE (TREE_TYPE (TREE_OPERAND (val, 0))) != REAL_TYPE + || !HONOR_NANS (TYPE_MODE (TREE_TYPE (TREE_OPERAND (val, 0)))))) + { + enum tree_code code = TREE_CODE (val); + + if (code == EQ_EXPR || code == LE_EXPR || code == GE_EXPR) + val = boolean_true_node; + else if (code == LT_EXPR || code == GT_EXPR || code == NE_EXPR) + val = boolean_false_node; + } + /* If VAL is not a constant, we can't determine which edge might be taken. */ if (val == NULL || !really_constant_p (val)) |