From 679becf175c5d7f6b323cd3af0a09c6039b4123d Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Sat, 28 Mar 2020 10:21:52 +0100 Subject: [PATCH] reassoc: Fix -fcompare-debug bug in reassociate_bb [PR94329] The following testcase FAILs with -fcompare-debug, because reassociate_bb mishandles the case when the last stmt in a bb has zero uses. In that case reassoc_remove_stmt (like gsi_remove) moves the iterator to the next stmt, i.e. gsi_end_p is true, which means the code sets the iterator back to gsi_last_bb. The problem is that the for loop does gsi_prev on that before handling the next statement, which means the former penultimate stmt, now last one, is not processed by reassociate_bb. Now, with -g, if there is at least one debug stmt at the end of the bb, reassoc_remove_stmt moves the iterator to that following debug stmt and we just do gsi_prev and continue with the former penultimate non-debug stmt, now last non-debug stmt. The following patch fixes that by not doing the gsi_prev in this case; there are too many continue; cases, so I didn't want to copy over the gsi_prev to all of them, so this patch uses a bool for that instead. The second gsi_end_p check isn't needed anymore, because when we don't do the undesirable gsi_prev after gsi = gsi_last_bb, the loop !gsi_end_p (gsi) condition will catch the removal of the very last stmt from a bb. 2020-03-28 Jakub Jelinek PR tree-optimization/94329 * tree-ssa-reassoc.c (reassociate_bb): When calling reassoc_remove_stmt on the last stmt in a bb, make sure gsi_prev isn't done immediately after gsi_last_bb. * gfortran.dg/pr94329.f90: New test. --- gcc/ChangeLog | 7 +++++++ gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/gfortran.dg/pr94329.f90 | 12 ++++++++++++ gcc/tree-ssa-reassoc.c | 14 +++++++------- 4 files changed, 31 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/gfortran.dg/pr94329.f90 diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 3bfe5ff8f69..52c296c00ae 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2020-03-28 Jakub Jelinek + + PR tree-optimization/94329 + * tree-ssa-reassoc.c (reassociate_bb): When calling reassoc_remove_stmt + on the last stmt in a bb, make sure gsi_prev isn't done immediately + after gsi_last_bb. + 2020-03-27 Alan Modra PR target/94145 diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 7876b57deeb..3e51175368c 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2020-03-28 Jakub Jelinek + + PR tree-optimization/94329 + * gfortran.dg/pr94329.f90: New test. + 2020-03-27 Jakub Jelinek PR c++/94339 diff --git a/gcc/testsuite/gfortran.dg/pr94329.f90 b/gcc/testsuite/gfortran.dg/pr94329.f90 new file mode 100644 index 00000000000..9efcf4b6524 --- /dev/null +++ b/gcc/testsuite/gfortran.dg/pr94329.f90 @@ -0,0 +1,12 @@ +! PR tree-optimization/94329 +! { dg-do compile } +! { dg-options "-O1 -fno-tree-loop-optimize -fwrapv -fcompare-debug" } + +subroutine pr94329 (s, t) + real :: s, t(:,:) + do i = 1,3 + do j = 1,3 + s = t(i,j) + end do + end do +end diff --git a/gcc/tree-ssa-reassoc.c b/gcc/tree-ssa-reassoc.c index 14f9550b094..ec1c033a2cf 100644 --- a/gcc/tree-ssa-reassoc.c +++ b/gcc/tree-ssa-reassoc.c @@ -6224,8 +6224,11 @@ reassociate_bb (basic_block bb) if (stmt && !gimple_visited_p (stmt)) cfg_cleanup_needed |= maybe_optimize_range_tests (stmt); - for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi)) + bool do_prev = false; + for (gsi = gsi_last_bb (bb); + !gsi_end_p (gsi); do_prev ? gsi_prev (&gsi) : (void) 0) { + do_prev = true; stmt = gsi_stmt (gsi); if (is_gimple_assign (stmt) @@ -6246,15 +6249,12 @@ reassociate_bb (basic_block bb) release_defs (stmt); /* We might end up removing the last stmt above which places the iterator to the end of the sequence. - Reset it to the last stmt in this case which might - be the end of the sequence as well if we removed - the last statement of the sequence. In which case - we need to bail out. */ + Reset it to the last stmt in this case and make sure + we don't do gsi_prev in that case. */ if (gsi_end_p (gsi)) { gsi = gsi_last_bb (bb); - if (gsi_end_p (gsi)) - break; + do_prev = false; } } continue; -- 2.30.2