]> git.ipfire.org Git - thirdparty/gcc.git/commitdiff
tree-ssa-dce: Avoid creating invalid BBs with no outgoing edge (PR117892)
authorMartin Jambor <mjambor@suse.cz>
Wed, 29 Jan 2025 09:51:08 +0000 (10:51 +0100)
committerMartin Jambor <jamborm@gcc.gnu.org>
Wed, 29 Jan 2025 09:51:34 +0000 (10:51 +0100)
Zhendong Su and Michal Jireš found out that our gimple DSE pass can,
under fairly specific conditions, remove a noreturn call which then
leaves behind a "normal" BB with no successor edges which following
passes do not expect.  This patch simply tells the pass to leave such
calls alone even when they otherwise appear to be dead.

Interestingly, our CFG verifier does not report this.  I'll put on my
todo list to add a test for it in the next stage 1.

gcc/ChangeLog:

2025-01-28  Martin Jambor  <mjambor@suse.cz>

PR tree-optimization/117892
* tree-ssa-dse.cc (dse_optimize_call): Leave control-altering
noreturn calls alone.

gcc/testsuite/ChangeLog:

2025-01-27  Martin Jambor  <mjambor@suse.cz>

PR tree-optimization/117892
* gcc.dg/tree-ssa/pr117892.c: New test.
* gcc.dg/tree-ssa/pr118517.c: Likewise.

co-authored-by: Michal Jireš <mjires@suse.cz>

gcc/testsuite/gcc.dg/tree-ssa/pr117892.c [new file with mode: 0644]
gcc/testsuite/gcc.dg/tree-ssa/pr118517.c [new file with mode: 0644]
gcc/tree-ssa-dse.cc

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr117892.c b/gcc/testsuite/gcc.dg/tree-ssa/pr117892.c
new file mode 100644 (file)
index 0000000..d9b9c15
--- /dev/null
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+
+volatile int a;
+void b(int *c) {
+  int *d = 0;
+  *c = 0;
+  *d = 0;
+  __builtin_abort();
+}
+int main() {
+  int f;
+  if (a)
+    b(&f);
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr118517.c b/gcc/testsuite/gcc.dg/tree-ssa/pr118517.c
new file mode 100644 (file)
index 0000000..3a34f67
--- /dev/null
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fno-ipa-pure-const" } */
+
+void __attribute__((noreturn)) bar(void) {
+  __builtin_unreachable ();
+}
+
+int p;
+void foo() {
+  if (p) bar();
+}
index 753d7ef148ba1cf12d6bb48287244a8ac2e18fcf..bc632e384841dcef1a2e92231635e5e81062767a 100644 (file)
@@ -1396,8 +1396,10 @@ dse_optimize_call (gimple_stmt_iterator *gsi, sbitmap live_bytes)
   if (!node)
     return false;
 
-  if (stmt_could_throw_p (cfun, stmt)
-      && !cfun->can_delete_dead_exceptions)
+  if ((stmt_could_throw_p (cfun, stmt)
+       && !cfun->can_delete_dead_exceptions)
+      || ((gimple_call_flags (stmt) & ECF_NORETURN)
+         && gimple_call_ctrl_altering_p (stmt)))
     return false;
 
   /* If return value is used the call is not dead.  */