On Mon, Mar 24, 2025 at 09:50:26AM -0700, Andi Kleen wrote:
> gcc/ChangeLog:
>
> PR gcov-profile/118442
> * cfg-flags.def (MUSTTAIL):
> * profile.cc (branch_prob):
> * tree-cfg.cc (gimple_flow_call_edges_add):
Descriptions missing.
> --- a/gcc/cfg-flags.def
> +++ b/gcc/cfg-flags.def
> @@ -182,6 +182,9 @@ DEF_EDGE_FLAG(TM_ABORT, 16)
> of any pass. */
> DEF_EDGE_FLAG(IGNORE, 17)
>
> +/* An edge from a musttail call to the exit. */
> +DEF_EDGE_FLAG(MUSTTAIL, 18)
> +
> #endif
>
> /*
Why? The flag looks like overkill to me.
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/pr118442.c
> @@ -0,0 +1,15 @@
> +/* PR118442 */
> +/* { dg-do compile { target { struct_musttail && external_musttail && { c ||
> c++11 } } } } */
> +/* { dg-options "-fprofile-generate -O2" } */
I don't see how this could have worked, it is invalid syntax in dejagnu.
&& or || can only have 2 arguments and one needs to use {}s around if one
needs more.
Furthermore, dg-require-profile was missing.
So what about the following patch instead (so far just lightly tested on
the testcase and nothing else)?
2025-03-25 Jakub Jelinek <[email protected]>
Andi Kleen <[email protected]>
PR gcov-profile/118442
* profile.cc (branch_prob): Ignore EDGE_FAKE edges from musttail calls
to EXIT.
* c-c++-common/pr118442.c: New test.
--- gcc/profile.cc.jj 2025-01-02 11:23:16.458517673 +0100
+++ gcc/profile.cc 2025-03-25 09:57:21.860398601 +0100
@@ -1340,6 +1340,20 @@ 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))
+ {
+ gimple_stmt_iterator gsi = gsi_last_bb (e->src);
+ gimple *stmt = gsi_stmt (gsi);
+ if (stmt
+ && is_gimple_call (stmt)
+ && gimple_call_must_tail_p (as_a <const gcall *> (stmt)))
+ {
+ EDGE_INFO (e)->ignore = 1;
+ ignored_edges++;
+ }
+ }
}
/* Create spanning tree from basic block graph, mark each edge that is
--- gcc/testsuite/c-c++-common/pr118442.c.jj 2025-03-25 09:45:31.754100696
+0100
+++ gcc/testsuite/c-c++-common/pr118442.c 2025-03-25 09:47:20.960608623
+0100
@@ -0,0 +1,17 @@
+/* PR118442 */
+/* { dg-do compile { target { struct_musttail && { external_musttail && { c ||
c++11 } } } } } */
+/* { dg-options "-fprofile-generate -O2" } */
+/* { dg-require-profiling "-fprofile-generate" } */
+
+struct Span {
+ int test[5];
+};
+
+extern void resolveToBufferSlow (struct Span *buffer);
+
+void
+resolveToBuffer (struct Span *buffer)
+{
+ buffer->test[0] = 4;
+ [[clang::musttail]] return resolveToBufferSlow (buffer);
+}
Jakub
