https://gcc.gnu.org/g:e1da6283a1cbd5db474c0f7e5cca9b9876768199
commit r15-7946-ge1da6283a1cbd5db474c0f7e5cca9b9876768199
Author: Jakub Jelinek <ja...@redhat.com>
Date: Tue Mar 11 10:57:30 2025 +0100
complex: Don't DCE unused COMPLEX_EXPRs for -O0 [PR119190]
The PR116463 r15-3128 change regressed the following testcase at -O0.
While for -O1+ we can do -fvar-tracking-assignments, for -O0 we don't
(partly because it is compile time expensive and partly because at -O0
most of the vars live most of their lifetime in memory slots), so if we
DCE some statements, it can mean that DW_AT_location for some vars won't
be available or even it won't be possible to put a breakpoint at some
particular line in the source.
We normally perform dce just in the subpasses of
pass_local_optimization_passes or pass_all_optimizations or
pass_all_optimizations_g, so don't do that at all for -O0. So the complex
change is an exception. And it was described as a way to help forwprop and
reassoc, neither applies to -O0.
This regresses PR119120 again though, I'll post a patch for that
momentarily.
2025-03-11 Jakub Jelinek <ja...@redhat.com>
PR debug/119190
* tree-complex.cc (update_complex_assignment, tree_lower_complex):
Perform simple dce on dce_worklist only if optimize.
* gfortran.dg/guality/pr119190.f90: New test.
Diff:
---
gcc/testsuite/gfortran.dg/guality/pr119190.f90 | 13 +++++++++++++
gcc/tree-complex.cc | 13 +++++++++----
2 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/gcc/testsuite/gfortran.dg/guality/pr119190.f90
b/gcc/testsuite/gfortran.dg/guality/pr119190.f90
new file mode 100644
index 000000000000..00ed67ea1e21
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/guality/pr119190.f90
@@ -0,0 +1,13 @@
+! PR debug/119190
+! { dg-do run }
+! { dg-options "-g" }
+
+program foo
+ integer :: ia, ib
+ complex :: ci
+ ia = 1
+ ib = 2
+ ci = cmplx(ia, ib)
+ print *, ia
+ print *, ib ! { dg-final { gdb-test 12 "ci" "(1,2)" } }
+end program
diff --git a/gcc/tree-complex.cc b/gcc/tree-complex.cc
index f54e7e3e443d..8a812d4bf9b0 100644
--- a/gcc/tree-complex.cc
+++ b/gcc/tree-complex.cc
@@ -735,7 +735,8 @@ update_complex_assignment (gimple_stmt_iterator *gsi, tree
r, tree i)
update_stmt (stmt);
if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
bitmap_set_bit (need_eh_cleanup, gimple_bb (stmt)->index);
- bitmap_set_bit (dce_worklist, SSA_NAME_VERSION (gimple_assign_lhs (stmt)));
+ if (optimize)
+ bitmap_set_bit (dce_worklist, SSA_NAME_VERSION (gimple_assign_lhs (stmt)));
update_complex_components (gsi, gsi_stmt (*gsi), r, i);
}
@@ -1967,7 +1968,8 @@ tree_lower_complex (void)
complex_propagate.ssa_propagate ();
need_eh_cleanup = BITMAP_ALLOC (NULL);
- dce_worklist = BITMAP_ALLOC (NULL);
+ if (optimize)
+ dce_worklist = BITMAP_ALLOC (NULL);
complex_variable_components = new int_tree_htab_type (10);
@@ -2014,8 +2016,11 @@ tree_lower_complex (void)
gsi_commit_edge_inserts ();
- simple_dce_from_worklist (dce_worklist, need_eh_cleanup);
- BITMAP_FREE (dce_worklist);
+ if (optimize)
+ {
+ simple_dce_from_worklist (dce_worklist, need_eh_cleanup);
+ BITMAP_FREE (dce_worklist);
+ }
unsigned todo
= gimple_purge_all_dead_eh_edges (need_eh_cleanup) ? TODO_cleanup_cfg : 0;
