Remove some try_compile CMake checks for compiler flags
#92953
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This patch remove 36 checks for compiler flags that are done via invoking the compiler across LLVM, Clang, and LLDB. It's was made possible by raising the bar for supported compilers that has been happening over the years since the checks were added. This is going to improve CMake configuration times. This topic was highlighted in https://discourse.llvm.org/t/cmake-compiler-flag-checks-are-really-slow-ideas-to-speed-them-up/78882.
Endilll
requested review from
rnk,
petrhosek,
MaskRay,
jroelofs,
AaronBallman,
aeubanks,
llvm-beanz and
aganea
|
@llvm/pr-subscribers-lldb @llvm/pr-subscribers-clang Author: Vlad Serebrennikov (Endilll) ChangesThis patch remove 36 checks for compiler flags that are done via invoking the compiler across LLVM, Clang, and LLDB. It's was made possible by raising the bar for supported compilers that has been happening over the years since the checks were added. This is going to improve CMake configuration times. This topic was highlighted in https://discourse.llvm.org/t/cmake-compiler-flag-checks-are-really-slow-ideas-to-speed-them-up/78882. Full diff: https://github.com/llvm/llvm-project/pull/92953.diff 7 Files Affected:
diff --git a/clang/CMakeLists.txt b/clang/CMakeLists.txt
index c20ce47a12abb..a6bcb853a464c 100644
--- a/clang/CMakeLists.txt
+++ b/clang/CMakeLists.txt
@@ -349,10 +349,7 @@ if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pedantic -Wno-long-long")
endif ()
- check_cxx_compiler_flag("-Werror -Wnested-anon-types" CXX_SUPPORTS_NO_NESTED_ANON_TYPES_FLAG)
- if( CXX_SUPPORTS_NO_NESTED_ANON_TYPES_FLAG )
- set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-nested-anon-types" )
- endif()
+ set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-nested-anon-types" )
endif ()
# Determine HOST_LINK_VERSION on Darwin.
diff --git a/clang/tools/scan-build-py/tests/functional/exec/CMakeLists.txt b/clang/tools/scan-build-py/tests/functional/exec/CMakeLists.txt
index 95c6fdb610e0f..cb6ebda183725 100644
--- a/clang/tools/scan-build-py/tests/functional/exec/CMakeLists.txt
+++ b/clang/tools/scan-build-py/tests/functional/exec/CMakeLists.txt
@@ -2,11 +2,7 @@ project(exec C)
cmake_minimum_required(VERSION 3.20.0)
-include(CheckCCompilerFlag)
-check_c_compiler_flag("-std=c99" C99_SUPPORTED)
-if (C99_SUPPORTED)
- set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
-endif()
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
include(CheckFunctionExists)
include(CheckSymbolExists)
diff --git a/lldb/cmake/modules/LLDBConfig.cmake b/lldb/cmake/modules/LLDBConfig.cmake
index 3c6223b015bb1..6458f2e174643 100644
--- a/lldb/cmake/modules/LLDBConfig.cmake
+++ b/lldb/cmake/modules/LLDBConfig.cmake
@@ -187,24 +187,18 @@ include_directories("${CMAKE_CURRENT_BINARY_DIR}/../clang/include")
# form -W<foo>, and if supported, add the corresponding -Wno-<foo> option.
# Disable GCC warnings
-check_cxx_compiler_flag("-Wdeprecated-declarations" CXX_SUPPORTS_DEPRECATED_DECLARATIONS)
-append_if(CXX_SUPPORTS_DEPRECATED_DECLARATIONS "-Wno-deprecated-declarations" CMAKE_CXX_FLAGS)
-
-check_cxx_compiler_flag("-Wunknown-pragmas" CXX_SUPPORTS_UNKNOWN_PRAGMAS)
-append_if(CXX_SUPPORTS_UNKNOWN_PRAGMAS "-Wno-unknown-pragmas" CMAKE_CXX_FLAGS)
-
-check_cxx_compiler_flag("-Wstrict-aliasing" CXX_SUPPORTS_STRICT_ALIASING)
-append_if(CXX_SUPPORTS_STRICT_ALIASING "-Wno-strict-aliasing" CMAKE_CXX_FLAGS)
+append("-Wno-deprecated-declarations" CMAKE_CXX_FLAGS)
+append("-Wno-unknown-pragmas" CMAKE_CXX_FLAGS)
+append("-Wno-strict-aliasing" CMAKE_CXX_FLAGS)
check_cxx_compiler_flag("-Wstringop-truncation" CXX_SUPPORTS_STRINGOP_TRUNCATION)
append_if(CXX_SUPPORTS_STRINGOP_TRUNCATION "-Wno-stringop-truncation" CMAKE_CXX_FLAGS)
# Disable Clang warnings
-check_cxx_compiler_flag("-Wdeprecated-register" CXX_SUPPORTS_DEPRECATED_REGISTER)
-append_if(CXX_SUPPORTS_DEPRECATED_REGISTER "-Wno-deprecated-register" CMAKE_CXX_FLAGS)
-
-check_cxx_compiler_flag("-Wvla-extension" CXX_SUPPORTS_VLA_EXTENSION)
-append_if(CXX_SUPPORTS_VLA_EXTENSION "-Wno-vla-extension" CMAKE_CXX_FLAGS)
+if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+ append("-Wno-deprecated-register" CMAKE_CXX_FLAGS)
+ append("-Wno-vla-extension" CMAKE_CXX_FLAGS)
+endif()
# Disable MSVC warnings
if( MSVC )
diff --git a/llvm/cmake/config-ix.cmake b/llvm/cmake/config-ix.cmake
index bf1b110245bb2..0900e1107076e 100644
--- a/llvm/cmake/config-ix.cmake
+++ b/llvm/cmake/config-ix.cmake
@@ -415,15 +415,14 @@ if( LLVM_ENABLE_PIC )
set(ENABLE_PIC 1)
else()
set(ENABLE_PIC 0)
- check_cxx_compiler_flag("-fno-pie" SUPPORTS_NO_PIE_FLAG)
- if(SUPPORTS_NO_PIE_FLAG)
- set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -fno-pie")
- endif()
+ set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -fno-pie")
endif()
-check_cxx_compiler_flag("-Wvariadic-macros" SUPPORTS_VARIADIC_MACROS_FLAG)
-check_cxx_compiler_flag("-Wgnu-zero-variadic-macro-arguments"
- SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
+if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+ set(SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG 1)
+else()
+ set(SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG 0)
+endif()
set(USE_NO_MAYBE_UNINITIALIZED 0)
set(USE_NO_UNINITIALIZED 0)
@@ -433,11 +432,9 @@ set(USE_NO_UNINITIALIZED 0)
if (CMAKE_COMPILER_IS_GNUCXX)
# Disable all -Wuninitialized warning for old GCC versions.
if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 12.0)
- check_cxx_compiler_flag("-Wuninitialized" HAS_UNINITIALIZED)
- set(USE_NO_UNINITIALIZED ${HAS_UNINITIALIZED})
+ set(USE_NO_UNINITIALIZED 1)
else()
- check_cxx_compiler_flag("-Wmaybe-uninitialized" HAS_MAYBE_UNINITIALIZED)
- set(USE_NO_MAYBE_UNINITIALIZED ${HAS_MAYBE_UNINITIALIZED})
+ set(USE_NO_MAYBE_UNINITIALIZED 1)
endif()
endif()
diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
index 693fd5669f63f..91f371e1ad621 100644
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -1639,9 +1639,7 @@ function(add_unittest test_suite test_name)
set(EXCLUDE_FROM_ALL ON)
endif()
- if (SUPPORTS_VARIADIC_MACROS_FLAG)
- list(APPEND LLVM_COMPILE_FLAGS "-Wno-variadic-macros")
- endif ()
+ list(APPEND LLVM_COMPILE_FLAGS "-Wno-variadic-macros")
# Some parts of gtest rely on this GNU extension, don't warn on it.
if(SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
list(APPEND LLVM_COMPILE_FLAGS "-Wno-gnu-zero-variadic-macro-arguments")
diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
index d16641d831900..46b17711b9df2 100644
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -425,7 +425,7 @@ if( LLVM_ENABLE_PIC )
# GCC for MIPS can miscompile LLVM due to PR37701.
if(CMAKE_COMPILER_IS_GNUCXX AND LLVM_NATIVE_ARCH STREQUAL "Mips" AND
NOT Uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG")
- add_flag_or_print_warning("-fno-shrink-wrap" FNO_SHRINK_WRAP)
+ append("-fno-shrink-wrap" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
endif()
# gcc with -O3 -fPIC generates TLS sequences that violate the spec on
# Solaris/sparcv9, causing executables created with the system linker
@@ -635,18 +635,16 @@ if( MSVC )
# This checks CMAKE_CXX_COMPILER_ID in addition to check_cxx_compiler_flag()
# because cl.exe does not emit an error on flags it doesn't understand,
# letting check_cxx_compiler_flag() claim it understands all flags.
- check_cxx_compiler_flag("/Brepro" SUPPORTS_BREPRO)
- if (SUPPORTS_BREPRO)
- # Check if /INCREMENTAL is passed to the linker and complain that it
- # won't work with /Brepro.
- has_msvc_incremental_no_flag("${CMAKE_EXE_LINKER_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${CMAKE_EXE_LINKER_FLAGS}" NO_INCR_EXE)
- has_msvc_incremental_no_flag("${CMAKE_MODULE_LINKER_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${CMAKE_MODULE_LINKER_FLAGS}" NO_INCR_MODULE)
- has_msvc_incremental_no_flag("${CMAKE_SHARED_LINKER_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${CMAKE_SHARED_LINKER_FLAGS}" NO_INCR_SHARED)
- if (NO_INCR_EXE AND NO_INCR_MODULE AND NO_INCR_SHARED)
- append("/Brepro" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
- else()
- message(WARNING "/Brepro not compatible with /INCREMENTAL linking - builds will be non-deterministic")
- endif()
+
+ # Check if /INCREMENTAL is passed to the linker and complain that it
+ # won't work with /Brepro.
+ has_msvc_incremental_no_flag("${CMAKE_EXE_LINKER_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${CMAKE_EXE_LINKER_FLAGS}" NO_INCR_EXE)
+ has_msvc_incremental_no_flag("${CMAKE_MODULE_LINKER_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${CMAKE_MODULE_LINKER_FLAGS}" NO_INCR_MODULE)
+ has_msvc_incremental_no_flag("${CMAKE_SHARED_LINKER_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${CMAKE_SHARED_LINKER_FLAGS}" NO_INCR_SHARED)
+ if (NO_INCR_EXE AND NO_INCR_MODULE AND NO_INCR_SHARED)
+ append("/Brepro" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+ else()
+ message(WARNING "/Brepro not compatible with /INCREMENTAL linking - builds will be non-deterministic")
endif()
endif()
# By default MSVC has a 2^16 limit on the number of sections in an object file,
@@ -667,19 +665,22 @@ endif( LLVM_COMPILER_IS_GCC_COMPATIBLE )
# Specific default warnings-as-errors for compilers accepting GCC-compatible warning flags:
if ( LLVM_COMPILER_IS_GCC_COMPATIBLE OR CMAKE_CXX_COMPILER_ID MATCHES "XL" )
- add_flag_if_supported("-Werror=date-time" WERROR_DATE_TIME)
- add_flag_if_supported("-Werror=unguarded-availability-new" WERROR_UNGUARDED_AVAILABILITY_NEW)
+ append("-Werror=date-time" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
endif( LLVM_COMPILER_IS_GCC_COMPATIBLE OR CMAKE_CXX_COMPILER_ID MATCHES "XL" )
-if ( LLVM_COMPILER_IS_GCC_COMPATIBLE )
+if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+ append("-Werror=unguarded-availability-new" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+endif()
+
+if (CMAKE_CXX_COMPILER_ID STREQUAL "GCC")
# LLVM data structures like llvm::User and llvm::MDNode rely on
# the value of object storage persisting beyond the lifetime of the
# object (#24952). This is not standard compliant and causes a runtime
# crash if LLVM is built with GCC and LTO enabled (#57740). Until
# these bugs are fixed, we need to disable dead store eliminations
# based on object lifetime.
- add_flag_if_supported("-fno-lifetime-dse" CMAKE_CXX_FLAGS)
-endif ( LLVM_COMPILER_IS_GCC_COMPATIBLE )
+ append("-fno-lifetime-dse" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+endif ()
# Modules enablement for GCC-compatible compilers:
if ( LLVM_COMPILER_IS_GCC_COMPATIBLE AND LLVM_ENABLE_MODULES )
@@ -697,22 +698,7 @@ if ( LLVM_COMPILER_IS_GCC_COMPATIBLE AND LLVM_ENABLE_MODULES )
(uppercase_CMAKE_BUILD_TYPE STREQUAL "RELWITHDEBINFO")))
set(module_flags "${module_flags} -gmodules")
endif()
- set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${module_flags}")
-
- # Check that we can build code with modules enabled, and that repeatedly
- # including <cassert> still manages to respect NDEBUG properly.
- CHECK_CXX_SOURCE_COMPILES("#undef NDEBUG
- #include <cassert>
- #define NDEBUG
- #include <cassert>
- int main() { assert(this code is not compiled); }"
- CXX_SUPPORTS_MODULES)
- set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
- if (CXX_SUPPORTS_MODULES)
- append("${module_flags}" CMAKE_CXX_FLAGS)
- else()
- message(FATAL_ERROR "LLVM_ENABLE_MODULES is not supported by this compiler")
- endif()
+ append("${module_flags}" CMAKE_CXX_FLAGS)
endif( LLVM_COMPILER_IS_GCC_COMPATIBLE AND LLVM_ENABLE_MODULES )
if (MSVC)
@@ -814,13 +800,10 @@ if (LLVM_ENABLE_WARNINGS AND (LLVM_COMPILER_IS_GCC_COMPATIBLE OR CLANG_CL))
# Turn off missing field initializer warnings for gcc to avoid noise from
# false positives with empty {}. Turn them on otherwise (they're off by
# default for clang).
- check_cxx_compiler_flag("-Wmissing-field-initializers" CXX_SUPPORTS_MISSING_FIELD_INITIALIZERS_FLAG)
- if (CXX_SUPPORTS_MISSING_FIELD_INITIALIZERS_FLAG)
- if (CMAKE_COMPILER_IS_GNUCXX)
- append("-Wno-missing-field-initializers" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
- else()
- append("-Wmissing-field-initializers" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
- endif()
+ if (CMAKE_COMPILER_IS_GNUCXX)
+ append("-Wno-missing-field-initializers" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+ else()
+ append("-Wmissing-field-initializers" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
endif()
if (LLVM_ENABLE_PEDANTIC AND LLVM_COMPILER_IS_GCC_COMPATIBLE)
@@ -833,8 +816,10 @@ if (LLVM_ENABLE_WARNINGS AND (LLVM_COMPILER_IS_GCC_COMPATIBLE OR CLANG_CL))
add_flag_if_supported("-Wc++98-compat-extra-semi" CXX98_COMPAT_EXTRA_SEMI_FLAG)
endif()
- add_flag_if_supported("-Wimplicit-fallthrough" IMPLICIT_FALLTHROUGH_FLAG)
- add_flag_if_supported("-Wcovered-switch-default" COVERED_SWITCH_DEFAULT_FLAG)
+ append("-Wimplicit-fallthrough" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+ if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+ append("-Wcovered-switch-default" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+ endif()
append_if(USE_NO_UNINITIALIZED "-Wno-uninitialized" CMAKE_CXX_FLAGS)
append_if(USE_NO_MAYBE_UNINITIALIZED "-Wno-maybe-uninitialized" CMAKE_CXX_FLAGS)
@@ -845,38 +830,30 @@ if (LLVM_ENABLE_WARNINGS AND (LLVM_COMPILER_IS_GCC_COMPATIBLE OR CLANG_CL))
# Disable -Wclass-memaccess, a C++-only warning from GCC 8 that fires on
# LLVM's ADT classes.
- check_cxx_compiler_flag("-Wclass-memaccess" CXX_SUPPORTS_CLASS_MEMACCESS_FLAG)
- append_if(CXX_SUPPORTS_CLASS_MEMACCESS_FLAG "-Wno-class-memaccess" CMAKE_CXX_FLAGS)
+ if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+ if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 8.1)
+ append("-Wno-class-memaccess" CMAKE_CXX_FLAGS)
+ endif()
+ endif()
# Disable -Wredundant-move and -Wpessimizing-move on GCC>=9. GCC wants to
- # remove std::move in code like "A foo(ConvertibleToA a) {
- # return std::move(a); }", but this code does not compile (or uses the copy
+ # remove std::move in code like
+ # "A foo(ConvertibleToA a) { return std::move(a); }",
+ # but this code does not compile (or uses the copy
# constructor instead) on clang<=3.8. Clang also has a -Wredundant-move and
# -Wpessimizing-move, but they only fire when the types match exactly, so we
# can keep them here.
if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
- check_cxx_compiler_flag("-Wredundant-move" CXX_SUPPORTS_REDUNDANT_MOVE_FLAG)
- append_if(CXX_SUPPORTS_REDUNDANT_MOVE_FLAG "-Wno-redundant-move" CMAKE_CXX_FLAGS)
- check_cxx_compiler_flag("-Wpessimizing-move" CXX_SUPPORTS_PESSIMIZING_MOVE_FLAG)
- append_if(CXX_SUPPORTS_PESSIMIZING_MOVE_FLAG "-Wno-pessimizing-move" CMAKE_CXX_FLAGS)
+ if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 9.1)
+ append("-Wno-redundant-move" CMAKE_CXX_FLAGS)
+ append("-Wno-pessimizing-move" CMAKE_CXX_FLAGS)
+ endif()
endif()
# The LLVM libraries have no stable C++ API, so -Wnoexcept-type is not useful.
- check_cxx_compiler_flag("-Wnoexcept-type" CXX_SUPPORTS_NOEXCEPT_TYPE_FLAG)
- append_if(CXX_SUPPORTS_NOEXCEPT_TYPE_FLAG "-Wno-noexcept-type" CMAKE_CXX_FLAGS)
-
- # Check if -Wnon-virtual-dtor warns for a class marked final, when it has a
- # friend declaration. If it does, don't add -Wnon-virtual-dtor. The case is
- # considered unhelpful (https://gcc.gnu.org/PR102168).
- set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
- set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror=non-virtual-dtor")
- CHECK_CXX_SOURCE_COMPILES("class f {};
- class base {friend f; public: virtual void anchor();protected: ~base();};
- int main() { return 0; }"
- CXX_WONT_WARN_ON_FINAL_NONVIRTUALDTOR)
- set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
- append_if(CXX_WONT_WARN_ON_FINAL_NONVIRTUALDTOR "-Wnon-virtual-dtor" CMAKE_CXX_FLAGS)
+ append("-Wno-noexcept-type" CMAKE_CXX_FLAGS)
+ append("-Wnon-virtual-dtor" CMAKE_CXX_FLAGS)
append("-Wdelete-non-virtual-dtor" CMAKE_CXX_FLAGS)
# Enable -Wsuggest-override if it's available, and only if it doesn't
@@ -906,14 +883,15 @@ if (LLVM_ENABLE_WARNINGS AND (LLVM_COMPILER_IS_GCC_COMPATIBLE OR CLANG_CL))
endif()
# Enable -Wstring-conversion to catch misuse of string literals.
- add_flag_if_supported("-Wstring-conversion" STRING_CONVERSION_FLAG)
+ if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+ append("-Wstring-conversion" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+ endif()
if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
# Disable the misleading indentation warning with GCC; GCC can
# produce noisy notes about this getting disabled in large files.
# See e.g. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89549
- check_cxx_compiler_flag("-Wmisleading-indentation" CXX_SUPPORTS_MISLEADING_INDENTATION_FLAG)
- append_if(CXX_SUPPORTS_MISLEADING_INDENTATION_FLAG "-Wno-misleading-indentation" CMAKE_CXX_FLAGS)
+ append("-Wno-misleading-indentation" CMAKE_CXX_FLAGS)
else()
# Prevent bugs that can happen with llvm's brace style.
add_flag_if_supported("-Wmisleading-indentation" MISLEADING_INDENTATION_FLAG)
@@ -931,14 +909,15 @@ macro(append_common_sanitizer_flags)
if (NOT MSVC OR CLANG_CL)
# Append -fno-omit-frame-pointer and turn on debug info to get better
# stack traces.
- add_flag_if_supported("-fno-omit-frame-pointer" FNO_OMIT_FRAME_POINTER)
+ append("-fno-omit-frame-pointer" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
if (NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" AND
- NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "RELWITHDEBINFO")
- add_flag_if_supported("-gline-tables-only" GLINE_TABLES_ONLY)
+ NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "RELWITHDEBINFO" AND
+ CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+ append("-gline-tables-only" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
endif()
# Use -O1 even in debug mode, otherwise sanitizers slowdown is too large.
if (uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" AND LLVM_OPTIMIZE_SANITIZED_BUILDS)
- add_flag_if_supported("-O1" O1)
+ append("-O1" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
endif()
else()
# Always ask the linker to produce symbols with asan.
@@ -1112,15 +1091,12 @@ endif()
if(NOT CYGWIN AND NOT MSVC)
if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "Darwin" AND
NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG")
- check_c_compiler_flag("-Werror -fno-function-sections" C_SUPPORTS_FNO_FUNCTION_SECTIONS)
- if (C_SUPPORTS_FNO_FUNCTION_SECTIONS)
- # Don't add -ffunction-sections if it can't be disabled with -fno-function-sections.
- # Doing so will break sanitizers.
- add_flag_if_supported("-ffunction-sections" FFUNCTION_SECTIONS)
- elseif (CMAKE_CXX_COMPILER_ID MATCHES "XL")
+ if (CMAKE_CXX_COMPILER_ID MATCHES "XL")
append("-qfuncsect" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+ else()
+ append("-ffunction-sections" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
endif()
- add_flag_if_supported("-fdata-sections" FDATA_SECTIONS)
+ append("-fdata-sections" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
endif()
elseif(MSVC)
if( NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" )
@@ -1385,7 +1361,9 @@ if(LLVM_USE_RELATIVE_PATHS_IN_DEBUG_INFO)
file(RELATIVE_PATH relative_root "${CMAKE_BINARY_DIR}" "${source_root}")
append_if(SUPPORTS_FDEBUG_PREFIX_MAP "-fdebug-prefix-map=${CMAKE_BINARY_DIR}=${relative_root}" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
append_if(SUPPORTS_FDEBUG_PREFIX_MAP "-fdebug-prefix-map=${source_root}/=${LLVM_SOURCE_PREFIX}" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
- add_flag_if_supported("-no-canonical-prefixes" NO_CANONICAL_PREFIXES)
+ if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
+ append("-no-canonical-prefixes" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+ endif()
endif()
option(LLVM_USE_RELATIVE_PATHS_IN_FILES "Use relative paths in sources and debug info" OFF)
@@ -1400,7 +1378,9 @@ if(LLVM_USE_RELATIVE_PATHS_IN_FILES)
file(RELATIVE_PATH relative_root "${CMAKE_BINARY_DIR}" "${source_root}")
append_if(SUPPORTS_FFILE_PREFIX_MAP "-ffile-prefix-map=${CMAKE_BINARY_DIR}=${relative_root}" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
append_if(SUPPORTS_FFILE_PREFIX_MAP "-ffile-prefix-map=${source_root}/=${LLVM_SOURCE_PREFIX}" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
- add_flag_if_supported("-no-canonical-prefixes" NO_CANONICAL_PREFIXES)
+ if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
+ append("-no-canonical-prefixes" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+ endif()
endif()
set(LLVM_THIRD_PARTY_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../third-party CACHE STRING
diff --git a/third-party/unittest/CMakeLists.txt b/third-party/unittest/CMakeLists.txt
index bf6ef54555144..e85fe045a60bb 100644
--- a/third-party/unittest/CMakeLists.txt
+++ b/third-party/unittest/CMakeLists.txt
@@ -21,9 +21,7 @@ if (UNIX AND ${CMAKE_SYSTEM_NAME} MATCHES "AIX")
add_definitions("-D_ALL_SOURCE")
endif()
-if(SUPPORTS_VARIADIC_MACROS_FLAG)
- add_definitions("-Wno-variadic-macros")
-endif()
+add_definitions("-Wno-variadic-macros")
if(SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
add_definitions("-Wno-gnu-zero-variadic-macro-arguments")
endif()
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On my setup, this patch improves CMake configuration times (from a clean state) from 51 seconds down to 46 seconds (average of 3 measurements). My setup: ancient x86 hardware, Debian Sid, nightly Clang, build directory on a RAM disk. CMake invocation: |
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Here are CE links with the set of minimum required compilers that should cover almost all the changes I made: |
cor3ntin
approved these changes
May 21, 2024
JDevlieghere
approved these changes
May 21, 2024
|
Quite expectedly, I see buildbot failures. Working on them. |
Endilll
added a commit
that referenced
this pull request
May 23, 2024
…variable A follow-up for #92953. Addresses the following buildbot failures: https://lab.llvm.org/buildbot/#/builders/36/builds/45836 https://lab.llvm.org/buildbot/#/builders/57/builds/35200
Endilll
added a commit
that referenced
this pull request
May 23, 2024
Another follow-up for #92953. Addresses buildbot failure https://lab.llvm.org/buildbot/#/builders/193/builds/52421
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FYI this causes a minor compile-time improvement in stage1 builds using gcc: https://llvm-compile-time-tracker.com/compare.php?from=32c3561d44aa792ef08d72b5a4c342c9965bc4c2&to=4feae05c6abda364a9295aecfa600d7d4e7dfeb6&stat=instructions:u While that's nice, it does suggest that the flags are not the same as before. |
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These types of changes touching a lot of projects at once can benefit from multiple PRs, one per project, as it makes partial reverts a lot easier and doesn't cause as much churn downstream (plus we can get more targeted comments from individual project owners) |
@nikic Can you elaborate on those numbers? Do you say that Clang (compiled with GCC) which compiles those tests works faster now? |
Yes, exactly. Clang compiled with GCC is faster. Clang compiled with Clang is not. So it seems like something changed in the options for GCC. |
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I think the issue is that we no longer passed |
Endilll
added a commit
that referenced
this pull request
May 30, 2024
A follow-up to #92953. This should fix unexpected performance gains when Clang is built with GCC, and fix downstream LTO crashes reported in 4feae05#r142466703
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Hi @Endilll , these changes break MSVC build of the projects including LLDB. The Here is the command line: This is the cl error: UPDATE: probably a guarding of these lines in |
Endilll
added a commit
that referenced
this pull request
Jun 1, 2024
A follow up to #92953. Suggested in #92953 (comment)
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@vvereschaka Thank you for letting me know! I wonder how this got past our pre- and post-commit CI, because we do build lldb with MSVC there. You fix makes total sense, so I applied it. |
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Hi @Endilll I did a git bisect that pointed to this change as the one blocking my compilation on an Ubuntu docker image with clang 14.0 The error I see: My compiler info, printed from CMake: More info from the command line: Let me know what other information may be helpful, or if this is user error. It seems from your godbolt links above, clang 5.0 and higher should work, so I'm surprised that 14.0 is dying in this environment |
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Yes, some try_compile checks where replaced with a check for |
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Thanks for your help! You were correct that cc was pointing to gcc. This is fixed when I updated my machine to use my known clang as the default compiler. For future archeologists, this meant (from this answer) |
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This patch remove 36 checks for compiler flags that are done via invoking the compiler across LLVM, Clang, and LLDB. It's was made possible by raising the bar for supported compilers that has been happening over the years since the checks were added.
This is going to improve CMake configuration times. This topic was highlighted in https://discourse.llvm.org/t/cmake-compiler-flag-checks-are-really-slow-ideas-to-speed-them-up/78882.