diff options
Diffstat (limited to 'gcc/tree-ssa-loop-niter.c')
| -rw-r--r-- | gcc/tree-ssa-loop-niter.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c index a896d03..9428dd6 100644 --- a/gcc/tree-ssa-loop-niter.c +++ b/gcc/tree-ssa-loop-niter.c @@ -886,7 +886,12 @@ tree_simplify_using_condition (tree cond, tree expr) return tree_simplify_using_condition_1 (cond, expr); } - + +/* The maximum number of dominator BBs we search for conditions + of loop header copies we use for simplifying a conditional + expression. */ +#define MAX_DOMINATORS_TO_WALK 8 + /* Tries to simplify EXPR using the conditions on entry to LOOP. Record the conditions used for simplification to CONDS_USED. Returns the simplified expression (or EXPR unchanged, if no @@ -899,12 +904,16 @@ simplify_using_initial_conditions (struct loop *loop, tree expr, edge e; basic_block bb; tree exp, cond; + int cnt = 0; if (TREE_CODE (expr) == INTEGER_CST) return expr; + /* Limit walking the dominators to avoid quadraticness in + the number of BBs times the number of loops in degenerate + cases. */ for (bb = loop->header; - bb != ENTRY_BLOCK_PTR; + bb != ENTRY_BLOCK_PTR && cnt < MAX_DOMINATORS_TO_WALK; bb = get_immediate_dominator (CDI_DOMINATORS, bb)) { if (!single_pred_p (bb)) @@ -926,6 +935,7 @@ simplify_using_initial_conditions (struct loop *loop, tree expr, cond); expr = exp; + ++cnt; } return expr; |