[PATCH] IPA: MODREF should skip EAF_* flags for indirect calls

[Martin Liška]

Hello.

As showed in the PR, returning (EAF_NOCLOBBER | EAF_NOESCAPE) for an argument
that is a function pointer is problematic. Doing such a function call is a 
clobber.

Patch can bootstrap on x86_64-linux-gnu and survives regression tests.

Ready to be installed?
Thanks,
Martin

        PR 101949

gcc/ChangeLog:

        * ipa-modref.c (analyze_ssa_name_flags): Do not propagate EAF
          flags arguments for indirect functions.

gcc/testsuite/ChangeLog:

        * gcc.dg/lto/pr101949_0.c: New test.
        * gcc.dg/lto/pr101949_1.c: New test.

Co-Authored-By: Richard Biener <rguent...@suse.de>
---
 gcc/ipa-modref.c                      |  3 +++
 gcc/testsuite/gcc.dg/lto/pr101949_0.c | 20 ++++++++++++++++++++
 gcc/testsuite/gcc.dg/lto/pr101949_1.c |  4 ++++
 3 files changed, 27 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/lto/pr101949_0.c
 create mode 100644 gcc/testsuite/gcc.dg/lto/pr101949_1.c

diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
index fafd804d4ba..380ba6926b9 100644
--- a/gcc/ipa-modref.c
+++ b/gcc/ipa-modref.c
@@ -1715,6 +1715,9 @@ analyze_ssa_name_flags (tree name, vec<modref_lattice> 
&lattice, int depth,
          else if (callee && !ipa && recursive_call_p (current_function_decl,
                                                  callee))
            lattice[index].merge (0);
+         /* Ignore indirect calls (PR101949).  */
+         else if (callee == NULL_TREE)
+           lattice[index].merge (0);
          else
            {
              int ecf_flags = gimple_call_flags (call);
diff --git a/gcc/testsuite/gcc.dg/lto/pr101949_0.c 
b/gcc/testsuite/gcc.dg/lto/pr101949_0.c
new file mode 100644
index 00000000000..142dffe8780
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/pr101949_0.c
@@ -0,0 +1,20 @@
+/* { dg-lto-do run } */
+/* { dg-lto-options { "-O2 -fipa-pta -flto -flto-partition=1to1" } } */
+
+extern int bar (int (*)(int *), int *);
+
+static int x;
+
+static int __attribute__ ((noinline)) foo (int *p)
+{
+  *p = 1;
+  x = 0;
+  return *p;
+}
+
+int main ()
+{
+  if (bar (foo, &x) != 0)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/lto/pr101949_1.c 
b/gcc/testsuite/gcc.dg/lto/pr101949_1.c
new file mode 100644
index 00000000000..871d15c9bfb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/pr101949_1.c
@@ -0,0 +1,4 @@
+int __attribute__((noinline,noclone)) bar (int (*fn)(int *), int *p)
+{
+  return fn (p);
+}
--
2.32.0