From: Jakub Jelinek <jakub@redhat.com>
Date: Tue, 1 Apr 2025 09:45:16 +0000 (+0200)
Subject: profile: Another profiling musttail call fix [PR119535]
X-Git-Tag: basepoints/gcc-16~427
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b8de7704428dfe008d195d8da95d6772153b0cc7;p=thirdparty%2Fgcc.git

profile: Another profiling musttail call fix [PR119535]

As the following testcase shows, EDGE_FAKE edges from musttail calls to
EXIT aren't the only edges we should ignore, we need to ignore also
edges created by the splitting of blocks for the EDGE_FAKE creation that
point from the musttail calls to the fallthrough block, which typically does
the return or with PHIs for the return value.

2025-04-01  Jakub Jelinek  <jakub@redhat.com>

	PR gcov-profile/119535
	* profile.cc (branch_prob): Ignore any edges from bbs ending with
	musttail call, rather than only EDGE_FAKE edges from those to EXIT.

	* c-c++-common/pr119535.c: New test.
---

diff --git a/gcc/profile.cc b/gcc/profile.cc
index c0f5097726b..550c85b9742 100644
--- a/gcc/profile.cc
+++ b/gcc/profile.cc
@@ -1340,9 +1340,8 @@ branch_prob (bool thunk)
 	  EDGE_INFO (e)->ignore = 1;
 	  ignored_edges++;
 	}
-      /* Ignore fake edges after musttail calls.  */
-      if ((e->flags & EDGE_FAKE)
-	  && e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
+      /* Ignore edges after musttail calls.  */
+      if (e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun))
 	{
 	  gimple_stmt_iterator gsi = gsi_last_bb (e->src);
 	  gimple *stmt = gsi_stmt (gsi);
diff --git a/gcc/testsuite/c-c++-common/pr119535.c b/gcc/testsuite/c-c++-common/pr119535.c
new file mode 100644
index 00000000000..fd88cc44d69
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr119535.c
@@ -0,0 +1,31 @@
+/* PR gcov-profile/119535
+/* { dg-do compile { target musttail } } */
+/* { dg-options "-fprofile-generate -O2" } */
+/* { dg-require-profiling "-fprofile-generate" } */
+
+[[gnu::noipa]] int
+foo (int x)
+{
+  return 42 + x;
+}
+
+int
+bar (int x)
+{
+  foo (x);
+  foo (2);
+  [[clang::musttail]] return foo (3);
+}
+
+int
+baz (int x)
+{
+  if (x == 42)
+    return -1;
+  else if (x == 15)
+    return 25;
+  else if (x == 26)
+    [[clang::musttail]] return foo (4);
+  else
+    [[clang::musttail]] return foo (5);
+}