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Fix an logic error in the clang driver preventing crtfastmath.o from linking when -Ofast is used without -ffast-math

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In gcc using -Ofast forces linking of crtfastmath.o.
In the current clang crtfastmath.o is only linked when -ffast-math/-funsafe-math-optimizations passed. It can lead to performance issues, when using only -Ofast without explicit -ffast-math (I faced with it).
My patch fixes inconsistency with gcc behaviour and also introduces few tests on it.

Patch by Zinovy Nis!

Differential Revision: http://llvm-reviews.chandlerc.com/D3114

llvm-svn: 204742
This commit is contained in:
Benjamin Kramer 2014-03-25 18:02:07 +00:00
parent 3dbe10503a
commit ab88f62614
6 changed files with 43 additions and 18 deletions
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4
clang/include/clang/Driver/Driver.h
View file

@ -415,6 +415,10 @@ public:
bool &HadExtra);
};
/// \return True if the last defined optimization level is -Ofast.
/// And False otherwise.
bool isOptimizationLevelFast(const llvm::opt::ArgList &Args);
} // end namespace driver
} // end namespace clang

2
clang/include/clang/Driver/ToolChain.h
View file

@ -311,7 +311,7 @@ public:
/// AddFastMathRuntimeIfAvailable - If a runtime library exists that sets
/// global flags for unsafe floating point math, add it and return true.
///
/// This checks for presence of the -ffast-math or -funsafe-math flags.
/// This checks for presence of the -Ofast, -ffast-math or -funsafe-math flags.
virtual bool
AddFastMathRuntimeIfAvailable(const llvm::opt::ArgList &Args,
llvm::opt::ArgStringList &CmdArgs) const;

4
clang/lib/Driver/Driver.cpp
View file

@ -2049,3 +2049,7 @@ std::pair<unsigned, unsigned> Driver::getIncludeExcludeOptionFlagMasks() const {
return std::make_pair(IncludedFlagsBitmask, ExcludedFlagsBitmask);
}
bool clang::driver::isOptimizationLevelFast(const llvm::opt::ArgList &Args) {
return Args.hasFlag(options::OPT_Ofast, options::OPT_O_Group, false);
}

21
clang/lib/Driver/ToolChain.cpp
View file

@ -341,16 +341,19 @@ void ToolChain::AddCCKextLibArgs(const ArgList &Args,
bool ToolChain::AddFastMathRuntimeIfAvailable(const ArgList &Args,
ArgStringList &CmdArgs) const {
// Check if -ffast-math or -funsafe-math is enabled.
Arg *A = Args.getLastArg(options::OPT_ffast_math,
options::OPT_fno_fast_math,
options::OPT_funsafe_math_optimizations,
options::OPT_fno_unsafe_math_optimizations);
if (!A || A->getOption().getID() == options::OPT_fno_fast_math ||
A->getOption().getID() == options::OPT_fno_unsafe_math_optimizations)
return false;
// Do not check for -fno-fast-math or -fno-unsafe-math when -Ofast passed
// (to keep the linker options consistent with gcc and clang itself).
if (!isOptimizationLevelFast(Args)) {
// Check if -ffast-math or -funsafe-math.
Arg *A =
Args.getLastArg(options::OPT_ffast_math, options::OPT_fno_fast_math,
options::OPT_funsafe_math_optimizations,
options::OPT_fno_unsafe_math_optimizations);
if (!A || A->getOption().getID() == options::OPT_fno_fast_math ||
A->getOption().getID() == options::OPT_fno_unsafe_math_optimizations)
return false;
}
// If crtfastmath.o exists add it to the arguments.
std::string Path = GetFilePath("crtfastmath.o");
if (Path == "crtfastmath.o") // Not found.

7
clang/lib/Driver/Tools.cpp
View file

@ -2034,13 +2034,6 @@ static void SplitDebugInfo(const ToolChain &TC, Compilation &C,
C.addCommand(new Command(JA, T, Exec, StripArgs));
}
static bool isOptimizationLevelFast(const ArgList &Args) {
if (Arg *A = Args.getLastArg(options::OPT_O_Group))
if (A->getOption().matches(options::OPT_Ofast))
return true;
return false;
}
/// \brief Vectorize at all optimization levels greater than 1 except for -Oz.
static bool shouldEnableVectorizerAtOLevel(const ArgList &Args) {
if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {

23
clang/test/Driver/linux-ld.c
View file

@ -825,7 +825,7 @@
// CHECK-FSL-PPC64: "{{.*}}{{/|\\\\}}crtbegin.o"
// CHECK-FSL-PPC64: "-L[[SYSROOT]]/usr/lib64/powerpc64-fsl-linux/4.6.2/../.."
//
// Check that crtfastmath.o is linked with -ffast-math.
// Check that crtfastmath.o is linked with -ffast-math and with -Ofast.
// RUN: %clang --target=x86_64-unknown-linux -### %s \
// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NOCRTFASTMATH %s
@ -835,9 +835,30 @@
// RUN: %clang --target=x86_64-unknown-linux -### %s -funsafe-math-optimizations\
// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH %s
// RUN: %clang --target=x86_64-unknown-linux -### %s -Ofast\
// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH %s
// RUN: %clang --target=x86_64-unknown-linux -### %s -Ofast -O3\
// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NOCRTFASTMATH %s
// RUN: %clang --target=x86_64-unknown-linux -### %s -O3 -Ofast\
// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH %s
// RUN: %clang --target=x86_64-unknown-linux -### %s -ffast-math -fno-fast-math \
// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-NOCRTFASTMATH %s
// RUN: %clang --target=x86_64-unknown-linux -### %s -Ofast -fno-fast-math \
// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH %s
// RUN: %clang --target=x86_64-unknown-linux -### %s -Ofast -fno-unsafe-math-optimizations \
// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH %s
// RUN: %clang --target=x86_64-unknown-linux -### %s -fno-fast-math -Ofast \
// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH %s
// RUN: %clang --target=x86_64-unknown-linux -### %s -fno-unsafe-math-optimizations -Ofast \
// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
// RUN: | FileCheck --check-prefix=CHECK-CRTFASTMATH %s
// We don't have crtfastmath.o in the i386 tree, use it to check that file
// detection works.
// RUN: %clang --target=i386-unknown-linux -### %s -ffast-math \