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 c0f5097726bdd6d5b772b56cf27d44528e8d7edb..550c85b9742c270cbe1d1d7b70c1b701cef5124e 100644 (file)
--- 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 (file)
index 0000000..fd88cc4
--- /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);
+}