From 8865b4f95b32097099d252111669b88ec7c1eb7f Mon Sep 17 00:00:00 2001
From: Steve Dower <steve.dower@python.org>
Date: Fri, 30 May 2025 19:37:29 +0100
Subject: [PATCH] gh-134923: Use /GENPROFILE and /USEPROFILE for Windows PGO
 builds (GH-134924)

---
 .../2025-05-30-11-02-30.gh-issue-134923.gBkRg4.rst    |  3 +++
 PCbuild/_testclinic_limited.vcxproj                   |  1 +
 PCbuild/pyproject.props                               | 11 ++++-------
 3 files changed, 8 insertions(+), 7 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Build/2025-05-30-11-02-30.gh-issue-134923.gBkRg4.rst

diff --git a/Misc/NEWS.d/next/Build/2025-05-30-11-02-30.gh-issue-134923.gBkRg4.rst b/Misc/NEWS.d/next/Build/2025-05-30-11-02-30.gh-issue-134923.gBkRg4.rst
new file mode 100644
index 000000000000..a742a6add8ae
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2025-05-30-11-02-30.gh-issue-134923.gBkRg4.rst
@@ -0,0 +1,3 @@
+Windows builds with profile-guided optimization enabled now use
+``/GENPROFILE`` and ``/USEPROFILE`` instead of deprecated ``/LTCG:``
+options.
diff --git a/PCbuild/_testclinic_limited.vcxproj b/PCbuild/_testclinic_limited.vcxproj
index 183a55080e86..95c205309b1f 100644
--- a/PCbuild/_testclinic_limited.vcxproj
+++ b/PCbuild/_testclinic_limited.vcxproj
@@ -70,6 +70,7 @@
     <ProjectGuid>{01FDF29A-40A1-46DF-84F5-85EBBD2A2410}</ProjectGuid>
     <RootNamespace>_testclinic_limited</RootNamespace>
     <Keyword>Win32Proj</Keyword>
+    <SupportPGO>false</SupportPGO>
   </PropertyGroup>
   <Import Project="python.props" />
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
diff --git a/PCbuild/pyproject.props b/PCbuild/pyproject.props
index 7272542e13a5..ce51e3422416 100644
--- a/PCbuild/pyproject.props
+++ b/PCbuild/pyproject.props
@@ -96,19 +96,16 @@
       <TargetMachine Condition="'$(Platform)' == 'x64'">MachineX64</TargetMachine>
       <TargetMachine Condition="'$(Platform)'=='ARM'">MachineARM</TargetMachine>
       <TargetMachine Condition="'$(Platform)'=='ARM64'">MachineARM64</TargetMachine>
-      <ProfileGuidedDatabase Condition="$(SupportPGO)">$(OutDir)$(TargetName).pgd</ProfileGuidedDatabase>
-      <LinkTimeCodeGeneration Condition="$(Configuration) == 'Release'">UseLinkTimeCodeGeneration</LinkTimeCodeGeneration>
-      <LinkTimeCodeGeneration Condition="$(SupportPGO) and $(Configuration) == 'PGInstrument'">PGInstrument</LinkTimeCodeGeneration>
-      <LinkTimeCodeGeneration Condition="$(SupportPGO) and $(Configuration) == 'PGUpdate'">PGUpdate</LinkTimeCodeGeneration>
+      <LinkTimeCodeGeneration Condition="$(Configuration) != 'Debug'">UseLinkTimeCodeGeneration</LinkTimeCodeGeneration>
       <AdditionalDependencies>advapi32.lib;shell32.lib;ole32.lib;oleaut32.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <AdditionalOptions Condition="$(Configuration) != 'Debug'">/OPT:REF,NOICF %(AdditionalOptions)</AdditionalOptions>
       <AdditionalOptions Condition="$(MSVCHasBrokenARM64Clamping) == 'true' and $(Platform) == 'ARM64'">-d2:-pattern-opt-disable:-932189325 %(AdditionalOptions)</AdditionalOptions>
+      <AdditionalOptions Condition="$(SupportPGO) and $(Configuration) == 'PGInstrument'">/GENPROFILE %(AdditionalOptions)</AdditionalOptions>
+      <AdditionalOptions Condition="$(SupportPGO) and $(Configuration) == 'PGUpdate'">/USEPROFILE %(AdditionalOptions)</AdditionalOptions>
     </Link>
     <Lib>
       <LinkTimeCodeGeneration>false</LinkTimeCodeGeneration>
-      <LinkTimeCodeGeneration Condition="$(Configuration) == 'Release'">true</LinkTimeCodeGeneration>
-      <LinkTimeCodeGeneration Condition="$(SupportPGO) and $(Configuration) == 'PGInstrument'">true</LinkTimeCodeGeneration>
-      <LinkTimeCodeGeneration Condition="$(SupportPGO) and $(Configuration) == 'PGUpdate'">true</LinkTimeCodeGeneration>
+      <LinkTimeCodeGeneration Condition="$(Configuration) != 'Debug'">true</LinkTimeCodeGeneration>
     </Lib>
     <ResourceCompile>
       <AdditionalIncludeDirectories>$(PySourcePath)PC;$(PySourcePath)Include;$(IntDir);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>