From: Sergei Trofimovich <siarh...@google.com>
Before the change RVO gimple statements were treated as local
stores by modres analysis. But in practice RVO escapes target.
2021-01-30 Sergei Trofimovich <siarh...@google.com>
gcc/ChangeLog:
PR tree-optimization/98499
* ipa-modref.c: treat RVO conservatively and assume
all possible side-effects.
gcc/testsuite/ChangeLog:
PR tree-optimization/98499
* g++.dg/pr98499.C: new test.
---
gcc/ipa-modref.c | 14 ++++++++++++--
gcc/testsuite/g++.dg/pr98499.C | 31 +++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/pr98499.C
diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
index b362de77e74..7aaf53be8f4 100644
--- a/gcc/ipa-modref.c
+++ b/gcc/ipa-modref.c
@@ -1621,9 +1621,19 @@ analyze_ssa_name_flags (tree name, vec<modref_lattice>
&lattice, int depth,
else if (gcall *call = dyn_cast <gcall *> (use_stmt))
{
tree callee = gimple_call_fndecl (call);
-
+ /* Return slot optiomization would require bit of propagation;
+ give up for now. */
+ if (gimple_call_return_slot_opt_p (call)
+ && gimple_call_lhs (call) != NULL_TREE
+ && TREE_ADDRESSABLE (TREE_TYPE (gimple_call_lhs (call))))
+ {
+ if (dump_file)
+ fprintf (dump_file, "%*s Unhandled return slot opt\n",
+ depth * 4, "");
+ lattice[index].merge (0);
+ }
/* Recursion would require bit of propagation; give up for now. */
- if (callee && !ipa && recursive_call_p (current_function_decl,
+ else if (callee && !ipa && recursive_call_p (current_function_decl,
callee))
lattice[index].merge (0);
else
diff --git a/gcc/testsuite/g++.dg/pr98499.C b/gcc/testsuite/g++.dg/pr98499.C
new file mode 100644
index 00000000000..ace088aeed9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr98499.C
@@ -0,0 +1,31 @@
+/* PR tree-optimization/98499. */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+struct string {
+ // pointer to local store
+ char * _M_buf;
+ // local store
+ char _M_local_buf[16];
+
+ __attribute__((noinline)) string() : _M_buf(_M_local_buf) {}
+
+ ~string() {
+ if (_M_buf != _M_local_buf)
+ __builtin_trap();
+ }
+
+ string(const string &__str); // no copies
+};
+
+__attribute__((noinline)) static string dir_name() { return string(); }
+class Importer {
+ string base_path;
+
+public:
+ __attribute__((noinline)) Importer() : base_path (dir_name()) {}
+};
+
+int main() {
+ Importer imp;
+}
--
2.30.0
