From 9bb06c2a9f8b83179cb76ba928b22aa3a2b57501 Mon Sep 17 00:00:00 2001 From: Richard Guenther Date: Wed, 22 Aug 2012 13:17:26 +0000 Subject: re PR tree-optimization/46590 (long compile time with -O2 and many loops) 2012-08-22 Richard Guenther PR tree-optimization/46590 * tree-ssa-alias.h (get_continuation_for_phi): Add alias query counter output argument. (walk_non_aliased_vuses): Add alias query counter argument to the walker callback. * tree-ssa-alias.c (maybe_skip_until): Add alias query counter output argument and count alias queries. (get_continuation_for_phi_1): Likewise. (get_continuation_for_phi): Likewise. (walk_non_aliased_vuses): Add alias query counter argument to the walker callback and allow it to abort the walk by returning -1. * tree-ssa-pre.c (translate_vuse_through_block): Adjust. * tree-ssa-sccvn.c (vn_reference_lookup_2): Add alias query counter parmeter, abort walk if that is bigger than --param sccvn-max-alias-queries-per-access. * params.def (sccvn-max-alias-queries-per-access): New param. * doc/invoke.texi (sccvn-max-alias-queries-per-access): Document. From-SVN: r190594 --- gcc/tree-ssa-sccvn.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'gcc/tree-ssa-sccvn.c') diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index 216d3f6..5d5a91c 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -1330,12 +1330,19 @@ static vn_lookup_kind default_vn_walk_kind; with the current VUSE and performs the expression lookup. */ static void * -vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree vuse, void *vr_) +vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree vuse, + unsigned int cnt, void *vr_) { vn_reference_t vr = (vn_reference_t)vr_; void **slot; hashval_t hash; + /* This bounds the stmt walks we perform on reference lookups + to O(1) instead of O(N) where N is the number of dominating + stores. */ + if (cnt > (unsigned) PARAM_VALUE (PARAM_SCCVN_MAX_ALIAS_QUERIES_PER_ACCESS)) + return (void *)-1; + if (last_vuse_ptr) *last_vuse_ptr = vuse; -- cgit v1.1