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* [gcc r13-5958] tree-optimization/106722 - fix CD-DCE edge marking
@ 2023-02-13 7:27 Richard Biener
0 siblings, 0 replies; only message in thread
From: Richard Biener @ 2023-02-13 7:27 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:338739645b8e5bf34636d8d4829d7650001ad08c
commit r13-5958-g338739645b8e5bf34636d8d4829d7650001ad08c
Author: Richard Biener <rguenther@suse.de>
Date: Fri Feb 10 10:28:29 2023 +0100
tree-optimization/106722 - fix CD-DCE edge marking
The following fixes a latent issue when we mark control edges but
end up with marking a block with no stmts necessary. In this case
we fail to mark dependent control edges of that block.
PR tree-optimization/106722
* tree-ssa-dce.cc (mark_last_stmt_necessary): Return
whether we marked a stmt.
(mark_control_dependent_edges_necessary): When
mark_last_stmt_necessary didn't mark any stmt make sure
to mark its control dependent edges.
(propagate_necessity): Likewise.
* gcc.dg/torture/pr108737.c: New testcase.
Diff:
---
gcc/testsuite/gcc.dg/torture/pr108737.c | 19 +++++++++++++++++++
gcc/tree-ssa-dce.cc | 20 +++++++++++++-------
2 files changed, 32 insertions(+), 7 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/torture/pr108737.c b/gcc/testsuite/gcc.dg/torture/pr108737.c
new file mode 100644
index 00000000000..c8388bcabeb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr108737.c
@@ -0,0 +1,19 @@
+/* { dg-do run } */
+
+extern void exit (int);
+extern void abort (void);
+
+void __attribute__((noipa)) foo () { exit (0); }
+
+void __attribute__((noipa)) blah (int x)
+{
+ while (1) {
+ if(x) foo();
+ }
+}
+
+int main()
+{
+ blah (1);
+ abort ();
+}
diff --git a/gcc/tree-ssa-dce.cc b/gcc/tree-ssa-dce.cc
index 1f1ec2c8710..ceeb0ad5ab3 100644
--- a/gcc/tree-ssa-dce.cc
+++ b/gcc/tree-ssa-dce.cc
@@ -327,17 +327,23 @@ mark_stmt_if_obviously_necessary (gimple *stmt, bool aggressive)
/* Mark the last statement of BB as necessary. */
-static void
+static bool
mark_last_stmt_necessary (basic_block bb)
{
gimple *stmt = last_stmt (bb);
- bitmap_set_bit (last_stmt_necessary, bb->index);
+ if (!bitmap_set_bit (last_stmt_necessary, bb->index))
+ return true;
+
bitmap_set_bit (bb_contains_live_stmts, bb->index);
/* We actually mark the statement only if it is a control statement. */
if (stmt && is_ctrl_stmt (stmt))
- mark_stmt_necessary (stmt, true);
+ {
+ mark_stmt_necessary (stmt, true);
+ return true;
+ }
+ return false;
}
@@ -369,8 +375,8 @@ mark_control_dependent_edges_necessary (basic_block bb, bool ignore_self)
continue;
}
- if (!bitmap_bit_p (last_stmt_necessary, cd_bb->index))
- mark_last_stmt_necessary (cd_bb);
+ if (!mark_last_stmt_necessary (cd_bb))
+ mark_control_dependent_edges_necessary (cd_bb, false);
}
if (!skipped)
@@ -790,8 +796,8 @@ propagate_necessity (bool aggressive)
if (gimple_bb (stmt)
!= get_immediate_dominator (CDI_POST_DOMINATORS, arg_bb))
{
- if (!bitmap_bit_p (last_stmt_necessary, arg_bb->index))
- mark_last_stmt_necessary (arg_bb);
+ if (!mark_last_stmt_necessary (arg_bb))
+ mark_control_dependent_edges_necessary (arg_bb, false);
}
else if (arg_bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)
&& !bitmap_bit_p (visited_control_parents,
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