From: Richard Biener <rguenther@suse.de>
Date: Fri, 17 Aug 2018 14:17:10 +0000 (+0000)
Subject: backport: re PR c++/86763 (Wrong code comparing member of copy of a 237 byte object... 
X-Git-Tag: releases/gcc-7.4.0~200
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bb094fdeb21f96b623d2c89c98d477c0871276a2;p=thirdparty%2Fgcc.git

backport: re PR c++/86763 (Wrong code comparing member of copy of a 237 byte object with nontrivial default constructor on x86-64 arch)

2018-08-17  Richard Biener  <rguenther@suse.de>

	Backport from mainline
	2018-08-02  Richard Biener  <rguenther@suse.de>

	PR c++/86763
	* class.c (layout_class_type): Copy TYPE_TYPELESS_STORAGE
	to the CLASSTYPE_AS_BASE.

	* g++.dg/torture/pr86763.C: New testcase.

From-SVN: r263621
---

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index af9feea0bc61..4bb74d28f6d6 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,12 @@
+2018-08-17  Richard Biener  <rguenther@suse.de>
+
+	Backport from mainline
+	2018-08-02  Richard Biener  <rguenther@suse.de>
+
+	PR c++/86763
+	* class.c (layout_class_type): Copy TYPE_TYPELESS_STORAGE
+	to the CLASSTYPE_AS_BASE.
+
 2018-08-10  Jason Merrill  <jason@redhat.com>
 
 	PR c++/86728 - C variadic generic lambda.
diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index a1bf77589dcb..688cc0e58d33 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -6662,6 +6662,7 @@ layout_class_type (tree t, tree *virtuals_p)
 				  bitsize_int (BITS_PER_UNIT)));
       SET_TYPE_ALIGN (base_t, rli->record_align);
       TYPE_USER_ALIGN (base_t) = TYPE_USER_ALIGN (t);
+      TYPE_TYPELESS_STORAGE (base_t) = TYPE_TYPELESS_STORAGE (t);
 
       /* Copy the fields from T.  */
       next_field = &TYPE_FIELDS (base_t);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 67b025aa5c3a..cd81a5060715 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2018-08-17  Richard Biener  <rguenther@suse.de>
+
+	Backport from mainline
+	2018-08-02  Richard Biener  <rguenther@suse.de>
+
+	PR c++/86763
+	* g++.dg/torture/pr86763.C: New testcase.
+
 2018-07-17  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gnat.dg/discr55.adb: New test.
diff --git a/gcc/testsuite/g++.dg/torture/pr86763.C b/gcc/testsuite/g++.dg/torture/pr86763.C
new file mode 100644
index 000000000000..6b79d561a60b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr86763.C
@@ -0,0 +1,36 @@
+// { dg-do run }
+// { dg-additional-options "-fschedule-insns2 -fstrict-aliasing" }
+
+#include <cstdint>
+#include <cassert>
+#include <time.h>
+struct ID {
+  uint64_t value;
+};
+uint64_t value(ID id) { return id.value; }
+uint64_t gen { 1000 };
+struct Msg {
+  uint64_t time;
+  ID id;
+};
+struct V {
+  V() { }
+  V(Msg const & msg) : msg(msg) { }
+  Msg & get() { return msg; }
+  Msg msg;
+  char pad[237 - sizeof(Msg)];
+};
+struct T : V { using V::V; };
+Msg init_msg() {
+  Msg msg;
+  timespec t;
+  clock_gettime(CLOCK_REALTIME, &t);
+  msg.time = t.tv_sec + t.tv_nsec;
+  msg.id.value = ++gen;
+  return msg;
+}
+int main() {
+  T t;
+  t = init_msg();
+  assert(value(t.get().id) == 1001);
+}