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Add flags to let GCC/Clang auto initialize trivial variables 

GCC 12 and Clang include a flag allowing initialization of trivial
variables with a known pattern or with 0. Enable zero init by default in
everything but debug mode, and pattern init for debug mode. Also provide
an option to completely disable this, giving unitialized variables.

ADDED: Add compile flag -ftrivial-auto-var-init to build
This commit is contained in:
Ian McInerney 2023-02-23 01:39:59 +00:00
parent c2a4dd93e8
commit 6803976ab3
2 changed files with 47 additions and 3 deletions
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47
CMakeLists.txt
View File

@ -45,6 +45,7 @@ set(CMAKE_CXX_FLAGS_QABUILD "-Os -g1 -ggdb1")
include( GNUInstallDirs )
include( CMakeDependentOption )
include( CheckCXXCompilerFlag )
# Output compile_commands.json for various LSP and other users
set( CMAKE_EXPORT_COMPILE_COMMANDS ON )
@ -193,6 +194,13 @@ cmake_dependent_option( KICAD_MAKE_LINK_MAPS
OFF )
mark_as_advanced( KICAD_MAKE_LINK_MAPS )
set( KICAD_INIT_VARIABLES "Default" CACHE STRING "Specify how compiler should initialize variables" )
set_property( CACHE KICAD_INIT_VARIABLES PROPERTY STRINGS
"Default" # Equivalent to pattern in debug mode (but not when Valgrind is used), zero in release mode
"Off" # Don't initialize anything
"Zero" # Initialize trivial variables to 0
"Pattern" ) # Initialize trivial variables to a non-zero pattern to flag them (usually 0xAA...)
####################################
# Debugging/profiling
####################################
@ -397,6 +405,45 @@ if( CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang" )
set( CMAKE_CXX_FLAGS_DEBUG "-g3 -ggdb3" )
endif()
check_cxx_compiler_flag( "-ftrivial-auto-var-init=pattern" COMPILER_SUPPORTS_TRIVIAL_PATTERN_INIT )
if( COMPILER_SUPPORTS_TRIVIAL_PATTERN_INIT )
set( VAR_PATTERN_INIT_FLAGS -ftrivial-auto-var-init=pattern )
endif()
check_cxx_compiler_flag( "-ftrivial-auto-var-init=zero" COMPILER_SUPPORTS_TRIVIAL_ZERO_INIT )
if( COMPILER_SUPPORTS_TRIVIAL_ZERO_INIT )
set( VAR_ZERO_INIT_FLAGS -ftrivial-auto-var-init=zero )
else()
# Clang 15 and below required a special flag to enable the zero-init flag, so try that
check_cxx_compiler_flag( "-ftrivial-auto-var-init=zero -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang"
COMPILER_REQUIRES_ENABLE_TRIVIAL_ZERO_INIT )
if( COMPILER_REQUIRES_ENABLE_TRIVIAL_ZERO_INIT )
set( VAR_ZERO_INIT_FLAGS -ftrivial-auto-var-init=zero -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang )
endif()
endif()
if( NOT KICAD_INIT_VARIABLES STREQUAL "Off" )
if( KICAD_INIT_VARIABLES STREQUAL "Default" )
# Disable when using valgrind to preserve reporting of uninitialized variables
if( NOT KICAD_USE_VALGRIND )
# Use pattern init in debug mode only, use zero init every other time
if( CMAKE_BUILD_TYPE STREQUAL "Debug" )
set( VAR_INIT_FLAGS ${VAR_PATTERN_INIT_FLAGS} )
else()
set( VAR_INIT_FLAGS ${VAR_ZERO_INIT_FLAGS} )
endif()
endif()
elseif( KICAD_INIT_VARIABLES STREQUAL "Zero" )
set( VAR_INIT_FLAGS ${VAR_ZERO_INIT_FLAGS} )
elseif( KICAD_INIT_VARIABLES STREQUAL "Pattern" )
set( VAR_INIT_FLAGS ${VAR_PATTERN_INIT_FLAGS} )
endif()
if( VAR_INIT_FLAGS )
add_compile_options( ${VAR_INIT_FLAGS} )
message( STATUS "Initializing trivial variables (${VAR_INIT_FLAGS})" )
endif()
endif()
if( KICAD_SANITIZE_ADDRESS )
add_compile_definitions( KICAD_SANITIZE_ADDRESS )

3
cmake/Warnings.cmake
View File

@ -23,9 +23,6 @@
# Only configure warnings for Clang and GCC
if( CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang" )
include( CheckCXXCompilerFlag )
# The SWIG-generated files tend to throw a lot of warnings, so
# we do not add the warnings directly to the flags here but instead
# keep track of them and add them to the flags later in a controlled manner