From 6bc0fe62b60157a937917d533069ec5672746ed7 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 6 Sep 2021 17:19:39 +0200
Subject: [PATCH] bpo-45115: Enable optimiaztions on Windows debug build

On Windows, enable compiler optimizations on the debug build to make
tests run faster and to reduce the stack memory usage, especially
with static inline functions used in Python public header files.

The Windows GitHub Actions now build Python in debug mode to catch
more bugs.
---
 .github/workflows/build.yml                               | 8 ++++----
 Doc/whatsnew/3.11.rst                                     | 5 +++++
 .../next/Build/2021-09-06-17-22-14.bpo-45115.4n0_eo.rst   | 3 +++
 PCbuild/pythoncore.vcxproj                                | 2 ++
 4 files changed, 14 insertions(+), 4 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Build/2021-09-06-17-22-14.bpo-45115.4n0_eo.rst

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 27e07a5f91bf37..3a32b1fe4e39e0 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -95,11 +95,11 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - name: Build CPython
-      run: .\PCbuild\build.bat -e -p Win32
+      run: .\PCbuild\build.bat -e -p Win32 -d
     - name: Display build info
       run: .\python.bat -m test.pythoninfo
     - name: Tests
-      run: .\PCbuild\rt.bat -p Win32 -q -uall -u-cpu -rwW --slowest --timeout=1200 -j0
+      run: .\PCbuild\rt.bat -p Win32 -d -q -uall -u-cpu -rwW --slowest --timeout=1200 -j0
 
   build_win_amd64:
     name: 'Windows (x64)'
@@ -111,11 +111,11 @@ jobs:
     - name: Register MSVC problem matcher
       run: echo "::add-matcher::.github/problem-matchers/msvc.json"
     - name: Build CPython
-      run: .\PCbuild\build.bat -e -p x64
+      run: .\PCbuild\build.bat -e -p x64 -d
     - name: Display build info
       run: .\python.bat -m test.pythoninfo
     - name: Tests
-      run: .\PCbuild\rt.bat -p x64 -q -uall -u-cpu -rwW --slowest --timeout=1200 -j0
+      run: .\PCbuild\rt.bat -p x64 -d -q -uall -u-cpu -rwW --slowest --timeout=1200 -j0
 
   build_macos:
     name: 'macOS'
diff --git a/Doc/whatsnew/3.11.rst b/Doc/whatsnew/3.11.rst
index 896a292c3356e8..c861324e909127 100644
--- a/Doc/whatsnew/3.11.rst
+++ b/Doc/whatsnew/3.11.rst
@@ -284,6 +284,11 @@ CPython bytecode changes
 Build Changes
 =============
 
+* On Windows, enable compiler optimizations on the debug build to make tests
+  run faster and to reduce the stack memory usage, especially with static
+  inline functions used in Python public header files.
+  (Contributed by Victor Stinner in :issue:`45115`.)
+
 
 Deprecated
 ==========
diff --git a/Misc/NEWS.d/next/Build/2021-09-06-17-22-14.bpo-45115.4n0_eo.rst b/Misc/NEWS.d/next/Build/2021-09-06-17-22-14.bpo-45115.4n0_eo.rst
new file mode 100644
index 00000000000000..01dc50ca0aca78
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2021-09-06-17-22-14.bpo-45115.4n0_eo.rst
@@ -0,0 +1,3 @@
+On Windows, enable compiler optimizations on the debug build to make tests
+run faster and to reduce the stack memory usage, especially with static
+inline functions used in Python public header files.
diff --git a/PCbuild/pythoncore.vcxproj b/PCbuild/pythoncore.vcxproj
index b8cadf469355f4..a2881fa302a6e2 100644
--- a/PCbuild/pythoncore.vcxproj
+++ b/PCbuild/pythoncore.vcxproj
@@ -104,6 +104,8 @@
       <AdditionalIncludeDirectories Condition="$(IncludeExternals)">$(zlibDir);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <PreprocessorDefinitions>_USRDLL;Py_BUILD_CORE;Py_BUILD_CORE_BUILTIN;Py_ENABLE_SHARED;MS_DLL_ID="$(SysWinVer)";%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="$(IncludeExternals)">_Py_HAVE_ZLIB;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <Optimization Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">MaxSpeed</Optimization>
+      <InlineFunctionExpansion Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">Default</InlineFunctionExpansion>
     </ClCompile>
     <Link>
       <AdditionalDependencies>version.lib;shlwapi.lib;ws2_32.lib;pathcch.lib;bcrypt.lib;%(AdditionalDependencies)</AdditionalDependencies>