From a591c71b41e18e4ff86852a974592af4962aef57 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Fri, 28 Jan 2022 19:02:26 +0100 Subject: [PATCH] store-merging: Fix up a -fcompare-debug bug in get_status_for_store_merging [PR104263] As mentioned in the PRthe following testcase fails, because the last stmt of a bb with -g is a debug stmt and get_status_for_store_merging uses gimple_seq_last_stmt (bb_seq (bb)) when testing if it is valid for store merging. The debug stmt isn't valid, while a stmt at that position with -g0 is valid and so the divergence. As we walk the whole bb already, this patch just remembers the last non-debug stmt, so that we don't need to skip backwards debug stmts at the end of the bb to find last real stmt. 2022-01-28 Jakub Jelinek PR tree-optimization/104263 * gimple-ssa-store-merging.cc (get_status_for_store_merging): For cfun->can_throw_non_call_exceptions && cfun->eh test whether last non-debug stmt in the bb is store_valid_for_store_merging_p rather than last stmt. * gcc.dg/pr104263.c: New test. --- gcc/gimple-ssa-store-merging.cc | 5 ++++- gcc/testsuite/gcc.dg/pr104263.c | 25 +++++++++++++++++++++++++ 2 files changed, 29 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/pr104263.c diff --git a/gcc/gimple-ssa-store-merging.cc b/gcc/gimple-ssa-store-merging.cc index eb70d90a45c9..e2e2157f1cb7 100644 --- a/gcc/gimple-ssa-store-merging.cc +++ b/gcc/gimple-ssa-store-merging.cc @@ -5364,6 +5364,7 @@ get_status_for_store_merging (basic_block bb) unsigned int num_constructors = 0; gimple_stmt_iterator gsi; edge e; + gimple *last_stmt = NULL; for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { @@ -5372,6 +5373,8 @@ get_status_for_store_merging (basic_block bb) if (is_gimple_debug (stmt)) continue; + last_stmt = stmt; + if (store_valid_for_store_merging_p (stmt) && ++num_statements >= 2) break; @@ -5398,7 +5401,7 @@ get_status_for_store_merging (basic_block bb) return BB_INVALID; if (cfun->can_throw_non_call_exceptions && cfun->eh - && store_valid_for_store_merging_p (gimple_seq_last_stmt (bb_seq (bb))) + && store_valid_for_store_merging_p (last_stmt) && (e = find_fallthru_edge (bb->succs)) && e->dest == bb->next_bb) return BB_EXTENDED_VALID; diff --git a/gcc/testsuite/gcc.dg/pr104263.c b/gcc/testsuite/gcc.dg/pr104263.c new file mode 100644 index 000000000000..79b548c629ce --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr104263.c @@ -0,0 +1,25 @@ +/* PR tree-optimization/104263 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fcompare-debug -fnon-call-exceptions -fno-inline-small-functions" } */ + +int n; + +int +bar (void) +{ + int a; + + n = 0; + a = 0; + + return n; +} + +__attribute__ ((pure, returns_twice)) int +foo (void) +{ + n = bar () + 1; + foo (); + + return 0; +} -- 2.47.2