From: Martin v. Löwis <martin@v.loewis.de>
Date: Wed, 1 Aug 2012 08:32:11 +0000 (+0200)
Subject: Issue #8847: Disable COMDAT folding in Windows PGO builds.
X-Git-Tag: v3.3.0b2~75^2
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4c1730db7c8735d2424471e63a2fa7d690192899;p=python

Issue #8847: Disable COMDAT folding in Windows PGO builds.
Analysis by Victor Stinner. Patch by Stefan Krah.
---

diff --git a/Lib/test/test_list.py b/Lib/test/test_list.py
index d7e6629ba7..84b8afe3a4 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 1464a0e50f..6e934fb882 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 9a5aff4108..671878f44a 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 38c5f18ed3..99c117b152 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"