[gcc r13-5728] ipa-split: Don't split returns_twice functions [PR106923]

[gcc r13-5728] ipa-split: Don't split returns_twice functions [PR106923]

[Jakub Jelinek]

https://gcc.gnu.org/g:5321d53279a60ee589a3c9779beb46503f9fc49f

commit r13-5728-g5321d53279a60ee589a3c9779beb46503f9fc49f
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Feb 7 10:34:45 2023 +0100

    ipa-split: Don't split returns_twice functions [PR106923]
    
    As discussed in the PR, returns_twice functions are rare/special beasts
    that need special treatment in the cfg, and inside of their bodies
    we don't know which part actually works the weird returns twice way
    (either in the fork/vfork sense, or in the setjmp) and aren't updating
    ab edges to reflect that.
    
    I think easiest is just to never split these, like we already never
    split noreturn or malloc functions.
    
    2023-02-07  Jakub Jelinek  <jakub@redhat.com>
    
            PR tree-optimization/106923
            * ipa-split.cc (execute_split_functions): Don't split returns_twice
            functions.
    
            * gcc.dg/pr106923.c: New test.

Diff:
---
 gcc/ipa-split.cc                |  5 +++--
 gcc/testsuite/gcc.dg/pr106923.c | 23 +++++++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/gcc/ipa-split.cc b/gcc/ipa-split.cc
index 0113461065c..6730f4f9d0e 100644
--- a/gcc/ipa-split.cc
+++ b/gcc/ipa-split.cc
@@ -1715,10 +1715,11 @@ execute_split_functions (void)
   struct cgraph_node *node = cgraph_node::get (current_function_decl);
 
   if (flags_from_decl_or_type (current_function_decl)
-      & (ECF_NORETURN|ECF_MALLOC))
+      & (ECF_NORETURN|ECF_MALLOC|ECF_RETURNS_TWICE))
     {
       if (dump_file)
-	fprintf (dump_file, "Not splitting: noreturn/malloc function.\n");
+	fprintf (dump_file, "Not splitting: noreturn/malloc/returns_twice "
+			    "function.\n");
       return 0;
     }
   if (MAIN_NAME_P (DECL_NAME (current_function_decl)))
diff --git a/gcc/testsuite/gcc.dg/pr106923.c b/gcc/testsuite/gcc.dg/pr106923.c
new file mode 100644
index 00000000000..1c89f418810
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr106923.c
@@ -0,0 +1,23 @@
+/* PR tree-optimization/106923 */
+/* { dg-do compile } */
+/* { dg-options "-O1 -finline-small-functions -fpartial-inlining --param max-inline-insns-single=1 --param uninlined-function-insns=10000" } */
+
+int n;
+
+int
+baz (void);
+
+__attribute__ ((returns_twice)) int
+bar (void)
+{
+  if (baz ())
+    ++n;
+
+  return 0;
+}
+
+int
+foo (void)
+{
+  return bar ();
+}