From d4147e8992bd7d1b038ef178a6a1d6152d794519 Mon Sep 17 00:00:00 2001
From: Hiroshi Yamauchi <hjyamauchi@gmail.com>
Date: Thu, 22 Feb 2024 09:12:50 -0800
Subject: [PATCH] Add a workaround for Windows ARM64 miscompile

We get libdispatch assert failures with Windows ARM64 release mode in
an internal app. We suspect that it is due to Clang miscompile. This
is a temporary workaround to avoid them.
---
 src/CMakeLists.txt | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 811e131e0..570c9197f 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -124,6 +124,24 @@ else()
   target_compile_options(dispatch PRIVATE -Wall)
 endif()
 
+# Work around a release-mode miscompile on windows arm64
+# Disable /Os and /Ot in /O1 and /O2 on queue.c
+if(("${CMAKE_C_SIMULATE_ID}" STREQUAL "MSVC") AND
+   (("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "ARM64") OR
+    ("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "aarch64")))
+  string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
+  set(FLAGS_BUILD_TYPE "${CMAKE_C_FLAGS_${uppercase_CMAKE_BUILD_TYPE}}")
+  string(REGEX MATCHALL "/[Oo][12]" FLAGS "${CMAKE_C_FLAGS} ${FLAGS_BUILD_TYPE}")
+  if (FLAGS)
+    if (FLAGS MATCHES "1$")
+      set(FLAGS "/Od;/Og;/Oy;/Ob2;/GF;/Gy")
+    elseif (FLAGS MATCHES "2$")
+      set(FLAGS "/Od;/Og;/Oi;/Oy;/Ob2;/GF;/Gy")
+    endif()
+    set_source_files_properties(queue.c PROPERTIES COMPILE_OPTIONS "${FLAGS}")
+  endif()
+endif()
+
 # FIXME(compnerd) add check for -fblocks?
 target_compile_options(dispatch PRIVATE -fblocks)