From 4c1730db7c8735d2424471e63a2fa7d690192899 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20v=2E=20L=C3=B6wis?= <martin@v.loewis.de>
Date: Wed, 1 Aug 2012 10:32:11 +0200
Subject: Issue #8847: Disable COMDAT folding in Windows PGO builds. Analysis
 by Victor Stinner. Patch by Stefan Krah.

---
 Lib/test/test_list.py        | 8 ++++++++
 Lib/test/test_tuple.py       | 8 ++++++++
 Misc/NEWS                    | 2 ++
 PCbuild/pginstrument.vsprops | 2 +-
 4 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_list.py b/Lib/test/test_list.py
index d7e6629..84b8afe 100644
--- a/Lib/test/test_list.py
+++ b/Lib/test/test_list.py
@@ -70,6 +70,14 @@ class ListTest(list_tests.CommonTest):
         check(1000000)
 
 
+    def test_no_comdat_folding(self):
+        # Issue 8847: In the PGO build, the MSVC linker's COMDAT folding
+        # optimization causes failures in code that relies on distinct
+        # function addresses.
+        class L(list): pass
+        with self.assertRaises(TypeError):
+            (3,) + L([1,2])
+
 def test_main(verbose=None):
     support.run_unittest(ListTest)
 
diff --git a/Lib/test/test_tuple.py b/Lib/test/test_tuple.py
index 1464a0e..6e934fb 100644
--- a/Lib/test/test_tuple.py
+++ b/Lib/test/test_tuple.py
@@ -164,6 +164,14 @@ class TupleTest(seq_tests.CommonTest):
         check(10)       # check our checking code
         check(1000000)
 
+    def test_no_comdat_folding(self):
+        # Issue 8847: In the PGO build, the MSVC linker's COMDAT folding
+        # optimization causes failures in code that relies on distinct
+        # function addresses.
+        class T(tuple): pass
+        with self.assertRaises(TypeError):
+            [3,] + T((1,2))
+
 def test_main():
     support.run_unittest(TupleTest)
 
diff --git a/Misc/NEWS b/Misc/NEWS
index 9a5aff4..671878f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -425,6 +425,8 @@ Tests
 Build
 -----
 
+- Issue #8847: Disable COMDAT folding in Windows PGO builds.
+
 - Issue #14197: For OS X framework builds, ensure links to the shared
   library are created with the proper ABI suffix.
 
diff --git a/PCbuild/pginstrument.vsprops b/PCbuild/pginstrument.vsprops
index 38c5f18..99c117b 100644
--- a/PCbuild/pginstrument.vsprops
+++ b/PCbuild/pginstrument.vsprops
@@ -22,7 +22,7 @@
 	<Tool
 		Name="VCLinkerTool"
 		OptimizeReferences="2"
-		EnableCOMDATFolding="2"
+		EnableCOMDATFolding="1"
 		LinkTimeCodeGeneration="2"
 		ProfileGuidedDatabase="$(SolutionDir)$(PlatformName)-pgi\$(TargetName).pgd"
 		ImportLibrary="$(OutDirPGI)\$(TargetName).lib"
-- 
cgit v0.12