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[CMake][Fuchsia] Define asan+noexcept multilib 

Using noexcept multilib with -fno-exceptions can lead to significant
space savings when statically linking libc++abi because we don't need
all the unwinding and demangling code.

When compiling with ASan, we already get a lot of overhead from the
instrumentation itself, when statically linking libc++abi, that overhead
is even larger.

Having the noexcept variant for ASan can help significantly, we've seen
more than 50% size reduction in our system image, which offsets the cost
of having to build another multilib.

Differential Revision: https://reviews.llvm.org/D64140

llvm-svn: 365994
This commit is contained in:
Petr Hosek 2019-07-13 08:07:10 +00:00
parent 36fbd0da5f
commit 20d34eacf3
5 changed files with 16 additions and 2 deletions
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10
clang/cmake/caches/Fuchsia-stage2.cmake
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@ -153,13 +153,21 @@ if(FUCHSIA_SDK)
set(RUNTIMES_${target}-unknown-fuchsia+noexcept_LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
set(RUNTIMES_${target}-unknown-fuchsia+noexcept_LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LLVM_BUILD_COMPILER_RT OFF CACHE BOOL "")
set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LLVM_USE_SANITIZER "Address" CACHE STRING "")
set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
# Use .build-id link.
list(APPEND RUNTIME_BUILD_ID_LINK "${target}-unknown-fuchsia")
endforeach()
set(LLVM_RUNTIME_MULTILIBS "asan;noexcept" CACHE STRING "")
set(LLVM_RUNTIME_MULTILIBS "asan;noexcept;asan+noexcept" CACHE STRING "")
set(LLVM_RUNTIME_MULTILIB_asan_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
set(LLVM_RUNTIME_MULTILIB_noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
set(LLVM_RUNTIME_MULTILIB_asan+noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
endif()
set(LLVM_BUILTIN_TARGETS "${BUILTIN_TARGETS}" CACHE STRING "")

5
clang/lib/Driver/ToolChains/Fuchsia.cpp
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@ -192,6 +192,11 @@ Fuchsia::Fuchsia(const Driver &D, const llvm::Triple &Triple,
// ASan has higher priority because we always want the instrumentated version.
Multilibs.push_back(Multilib("asan", {}, {}, 2)
.flag("+fsanitize=address"));
// Use the asan+noexcept variant with ASan and -fno-exceptions.
Multilibs.push_back(Multilib("asan+noexcept", {}, {}, 3)
.flag("+fsanitize=address")
.flag("-fexceptions")
.flag("+fno-exceptions"));
Multilibs.FilterOut([&](const Multilib &M) {
std::vector<std::string> RD = FilePaths(M);
return std::all_of(RD.begin(), RD.end(), [&](std::string P) {

0
clang/test/Driver/Inputs/basic_fuchsia_tree/lib/aarch64-fuchsia/c++/asan+noexcept/libc++.so Normal file
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0
clang/test/Driver/Inputs/basic_fuchsia_tree/lib/x86_64-fuchsia/c++/asan+noexcept/libc++.so Normal file
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3
clang/test/Driver/fuchsia.cpp
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@ -70,8 +70,9 @@
// RUN: -ccc-install-dir %S/Inputs/basic_fuchsia_tree/bin \
// RUN: -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
// RUN: -fuse-ld=lld 2>&1\
// RUN: | FileCheck %s -check-prefixes=CHECK-MULTILIB-X86,CHECK-MULTILIB-ASAN-X86
// RUN: | FileCheck %s -check-prefixes=CHECK-MULTILIB-X86,CHECK-MULTILIB-ASAN-NOEXCEPT-X86
// CHECK-MULTILIB-X86: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
// CHECK-MULTILIB-ASAN-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++{{/|\\\\}}asan"
// CHECK-MULTILIB-NOEXCEPT-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++{{/|\\\\}}noexcept"
// CHECK-MULTILIB-ASAN-NOEXCEPT-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++{{/|\\\\}}asan+noexcept"
// CHECK-MULTILIB-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++"