Start using optimization (-O0/-O2/-O3/-Os) and debug (-g) flags from CMAKE_CXX_FLAGS_${CFLAGS_BUILD_TYPE} (#33388)

Author: kubamracek

CMakeLists.txt

@@ -633,6 +633,21 @@ if("${CMAKE_C_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQU
   set(SWIFT_COMPILER_IS_MSVC_LIKE TRUE)
 endif()
 
+if(NOT SWIFT_COMPILER_IS_MSVC_LIKE)
+  # CMake's default for CMAKE_CXX_FLAGS_RELEASE is "-O3 -DNDEBUG". Let's avoid "-O3" for consistency
+  # between Release and RelWithDebInfo. And let's not set -DNDEBUG because we're setting that manually
+  # based on LLVM_ENABLE_ASSERTIONS.
+  set(CMAKE_CXX_FLAGS_RELEASE "-O2")
+
+  _compute_lto_flag("${SWIFT_TOOLS_ENABLE_LTO}" _lto_flag_out)
+  if(_lto_flag_out)
+    set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_RELEASE} -gline-tables-only")
+    set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} -gline-tables-only")
+  endif()
+else()
+  
+endif()
+
 #
 # Configure SDKs.
 #

cmake/modules/AddSwift.cmake

@@ -130,17 +130,18 @@ function(_add_host_variant_c_compile_flags target)
   _add_host_variant_c_compile_link_flags(${target})
 
   is_build_type_optimized("${CMAKE_BUILD_TYPE}" optimized)
-  if(optimized)
-    if("${CMAKE_BUILD_TYPE}" STREQUAL "MinSizeRel")
-      target_compile_options(${target} PRIVATE -Os)
-    else()
-      target_compile_options(${target} PRIVATE -O2)
-    endif()
+  is_build_type_with_debuginfo("${CMAKE_BUILD_TYPE}" debuginfo)
+
+  # Add -O0/-O2/-O3/-Os/-g/-momit-leaf-frame-pointer/... based on CMAKE_BUILD_TYPE.
+  target_compile_options(${target} PRIVATE "${CMAKE_CXX_FLAGS_${CMAKE_BUILD_TYPE}}")
 
+  if(optimized)
     # Omit leaf frame pointers on x86 production builds (optimized, no debug
     # info, and no asserts).
-    is_build_type_with_debuginfo("${CMAKE_BUILD_TYPE}" debug)
-    if(NOT debug AND NOT LLVM_ENABLE_ASSERTIONS)
+    if(NOT debuginfo AND NOT LLVM_ENABLE_ASSERTIONS)
+      # Unfortunately, this cannot be folded into the standard
+      # CMAKE_CXX_FLAGS_... because Apple multi-SDK builds use different
+      # architectures for different SDKs.
       if(SWIFT_HOST_VARIANT_ARCH MATCHES "i?86")
         if(NOT SWIFT_COMPILER_IS_MSVC_LIKE)
           target_compile_options(${target} PRIVATE -momit-leaf-frame-pointer)
@@ -149,27 +150,6 @@ function(_add_host_variant_c_compile_flags target)
         endif()
       endif()
     endif()
-  else()
-    if(NOT SWIFT_COMPILER_IS_MSVC_LIKE)
-      target_compile_options(${target} PRIVATE -O0)
-    else()
-      target_compile_options(${target} PRIVATE /Od)
-    endif()
-  endif()
-
-  # CMake automatically adds the flags for debug info if we use MSVC/clang-cl.
-  if(NOT SWIFT_COMPILER_IS_MSVC_LIKE)
-    is_build_type_with_debuginfo("${CMAKE_BUILD_TYPE}" debuginfo)
-    if(debuginfo)
-      _compute_lto_flag("${SWIFT_TOOLS_ENABLE_LTO}" _lto_flag_out)
-      if(_lto_flag_out)
-        target_compile_options(${target} PRIVATE -gline-tables-only)
-      else()
-        target_compile_options(${target} PRIVATE -g)
-      endif()
-    else()
-      target_compile_options(${target} PRIVATE -g0)
-    endif()
   endif()
 
   if(SWIFT_HOST_VARIANT_SDK STREQUAL WINDOWS)

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -164,17 +164,18 @@ function(_add_target_variant_c_compile_flags)
     MACCATALYST_BUILD_FLAVOR "${CFLAGS_MACCATALYST_BUILD_FLAVOR}")
 
   is_build_type_optimized("${CFLAGS_BUILD_TYPE}" optimized)
-  if(optimized)
-    if("${CFLAGS_BUILD_TYPE}" STREQUAL "MinSizeRel")
-      list(APPEND result "-Os")
-    else()
-      list(APPEND result "-O2")
-    endif()
+  is_build_type_with_debuginfo("${CFLAGS_BUILD_TYPE}" debuginfo)
+
+  # Add -O0/-O2/-O3/-Os/-g/... based on CFLAGS_BUILD_TYPE.
+  list(APPEND result "${CMAKE_CXX_FLAGS_${CFLAGS_BUILD_TYPE}}")
 
+  if(optimized)
     # Omit leaf frame pointers on x86 production builds (optimized, no debug
     # info, and no asserts).
-    is_build_type_with_debuginfo("${CFLAGS_BUILD_TYPE}" debug)
-    if(NOT debug AND NOT CFLAGS_ENABLE_ASSERTIONS)
+    if(NOT debuginfo AND NOT CFLAGS_ENABLE_ASSERTIONS)
+      # Unfortunately, this cannot be folded into the standard
+      # CMAKE_CXX_FLAGS_... because Apple multi-SDK builds use different
+      # architectures for different SDKs (CFLAGS_ARCH isn't constant here).
       if("${CFLAGS_ARCH}" STREQUAL "i386" OR "${CFLAGS_ARCH}" STREQUAL "i686")
         if(NOT SWIFT_COMPILER_IS_MSVC_LIKE)
           list(APPEND result "-momit-leaf-frame-pointer")
@@ -183,27 +184,6 @@ function(_add_target_variant_c_compile_flags)
         endif()
       endif()
     endif()
-  else()
-    if(NOT SWIFT_COMPILER_IS_MSVC_LIKE)
-      list(APPEND result "-O0")
-    else()
-      list(APPEND result "/Od")
-    endif()
-  endif()
-
-  # CMake automatically adds the flags for debug info if we use MSVC/clang-cl.
-  if(NOT SWIFT_COMPILER_IS_MSVC_LIKE)
-    is_build_type_with_debuginfo("${CFLAGS_BUILD_TYPE}" debuginfo)
-    if(debuginfo)
-      _compute_lto_flag("${CFLAGS_ENABLE_LTO}" _lto_flag_out)
-      if(_lto_flag_out)
-        list(APPEND result "-gline-tables-only")
-      else()
-        list(APPEND result "-g")
-      endif()
-    else()
-      list(APPEND result "-g0")
-    endif()
   endif()
 
   if("${CFLAGS_SDK}" STREQUAL "WINDOWS")

utils/build-script-impl

@@ -1576,8 +1576,6 @@ for host in "${ALL_HOSTS[@]}"; do
                     "${cmake_options[@]}"
                     -DCMAKE_C_FLAGS="$(llvm_c_flags ${host})"
                     -DCMAKE_CXX_FLAGS="$(llvm_c_flags ${host})"
-                    -DCMAKE_C_FLAGS_RELWITHDEBINFO="-O2 -DNDEBUG"
-                    -DCMAKE_CXX_FLAGS_RELWITHDEBINFO="-O2 -DNDEBUG"
                     -DCMAKE_BUILD_TYPE:STRING="${LLVM_BUILD_TYPE}"
                     -DLLVM_TOOL_SWIFT_BUILD:BOOL=NO
                     -DLLVM_TOOL_LLD_BUILD:BOOL=TRUE
@@ -1756,8 +1754,6 @@ for host in "${ALL_HOSTS[@]}"; do
                     "${cmake_options[@]}"
                     -DCMAKE_C_FLAGS="$(swift_c_flags ${host})"
                     -DCMAKE_CXX_FLAGS="$(swift_c_flags ${host})"
-                    -DCMAKE_C_FLAGS_RELWITHDEBINFO="-O2 -DNDEBUG"
-                    -DCMAKE_CXX_FLAGS_RELWITHDEBINFO="-O2 -DNDEBUG"
                     -DCMAKE_BUILD_TYPE:STRING="${SWIFT_BUILD_TYPE}"
                     -DLLVM_ENABLE_ASSERTIONS:BOOL=$(true_false "${SWIFT_ENABLE_ASSERTIONS}")
                     -DSWIFT_ANALYZE_CODE_COVERAGE:STRING=$(toupper "${SWIFT_ANALYZE_CODE_COVERAGE}")