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[CMake] Support using precompiled headers with ccache in flang #136856

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Merged
merged 2 commits into from
Apr 24, 2025
Merged

[CMake] Support using precompiled headers with ccache in flang #136856

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[CMake] Support using precompiled headers with ccache in flang
mrkajetanp Apr 23, 2025
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mrkajetanp Apr 24, 2025
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9 changes: 9 additions & 0 deletions flang/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -452,6 +452,10 @@ if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -fno-semantic-interposition")
endif()

# GCC requires this flag in order for precompiled headers to work with ccache
if (CMAKE_CXX_COMPILER_ID MATCHES GCC AND NOT CMAKE_DISABLE_PRECOMPILE_HEADERS)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fpch-preprocess")
endif()
endif()

# Clang on Darwin enables non-POSIX extensions by default, which allows the
Expand All @@ -462,6 +466,11 @@ if (APPLE)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -D_POSIX_C_SOURCE=200809")
endif()

# Clang requires this flag in order for precompiled headers to work with ccache
if (CMAKE_CXX_COMPILER_ID MATCHES Clang AND NOT CMAKE_DISABLE_PRECOMPILE_HEADERS)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Xclang -fno-pch-timestamp")
endif()

list(REMOVE_DUPLICATES CMAKE_CXX_FLAGS)

# Determine HOST_LINK_VERSION on Darwin.
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4 changes: 2 additions & 2 deletions llvm/CMakeLists.txt
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Expand Up @@ -273,7 +273,7 @@ if(LLVM_CCACHE_BUILD)
if(CCACHE_PROGRAM)
set(LLVM_CCACHE_MAXSIZE "" CACHE STRING "Size of ccache")
set(LLVM_CCACHE_DIR "" CACHE STRING "Directory to keep ccached data")
set(LLVM_CCACHE_PARAMS "CCACHE_CPP2=yes CCACHE_HASHDIR=yes"
set(LLVM_CCACHE_PARAMS "CCACHE_CPP2=yes CCACHE_HASHDIR=yes CCACHE_SLOPPINESS=pch_defines,time_macros"
CACHE STRING "Parameters to pass through to ccache")

if(NOT CMAKE_SYSTEM_NAME MATCHES "Windows")
Expand All @@ -287,7 +287,7 @@ if(LLVM_CCACHE_BUILD)
set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ${CCACHE_PROGRAM})
else()
if(LLVM_CCACHE_MAXSIZE OR LLVM_CCACHE_DIR OR
NOT LLVM_CCACHE_PARAMS MATCHES "CCACHE_CPP2=yes CCACHE_HASHDIR=yes")
NOT LLVM_CCACHE_PARAMS MATCHES "CCACHE_CPP2=yes CCACHE_HASHDIR=yes CCACHE_SLOPPINESS=pch_defines,time_macros")
message(FATAL_ERROR "Ccache configuration through CMake is not supported on Windows. Please use environment variables.")
endif()
# RULE_LAUNCH_COMPILE should work with Ninja but currently has issues
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