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[LTO] Fix Veclib flags correctly pass to LTO flags #78749

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Merged
merged 3 commits into from
Jan 25, 2024
Merged

[LTO] Fix Veclib flags correctly pass to LTO flags #78749

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f664bee
[LTO] Fix Veclib flags correctly pass to LTO flags
paschalis-mpeis Jan 19, 2024
f1baf76
Add targets to tests that call addLTOOptions
paschalis-mpeis Jan 22, 2024
edb1833
Addressing reviewers
paschalis-mpeis Jan 23, 2024
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22 changes: 22 additions & 0 deletions clang/lib/Driver/ToolChains/CommonArgs.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -783,6 +783,28 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
"-generate-arange-section"));
}

// Pass vector library arguments to LTO.
Arg *ArgVecLib = Args.getLastArg(options::OPT_fveclib);
if (ArgVecLib && ArgVecLib->getNumValues() == 1) {
// Map the vector library names from clang front-end to opt front-end. The
// values are taken from the TargetLibraryInfo class command line options.
std::optional<StringRef> OptVal =
llvm::StringSwitch<std::optional<StringRef>>(ArgVecLib->getValue())
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Is it possible to refactor and reuse existing TargetLibraryInfo code, i.e. create a common static function that maps the values so that it can be called in multiple places?

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Reusing code for mapping the strings is a great suggestion, however, TargetLibraryInfo statically creates some cl::opt (command line options) and I'm not sure ATM what would be a clean way to do this.

I would suggest such change (if is doable in a clean way) to be dealt in a separate patch.

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the TLI belongs to llvm world, while clang driver from what I can see is only linked with following llvm components:
set(LLVM_LINK_COMPONENTS
BinaryFormat
MC
Object
Option
ProfileData
Support
TargetParser
WindowsDriver
)
so I don't think it is possible to do it.

Unfortunately at the early stage when the tools::addLTOOptions function is called the CodeGenOptions are not even created, perhaps we could have a function defined which does the strings checking in include/llvm/Analysis/TargetLibraryInfo.h and include it in the CommonArgs.cpp? a least everything would be in one place? what do you think @david-arm ?

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Yes I think that would work, i.e. having a static function in TargetLibraryInfo.h that can be called in two places and doesn't have a dependency on the component/library. Having said that, I won't hold this patch up for this if it's too difficult!

.Case("Accelerate", "Accelerate")
.Case("LIBMVEC", "LIBMVEC-X86")
.Case("MASSV", "MASSV")
.Case("SVML", "SVML")
.Case("SLEEF", "sleefgnuabi")
.Case("Darwin_libsystem_m", "Darwin_libsystem_m")
.Case("ArmPL", "ArmPL")
.Case("none", "none")
.Default(std::nullopt);

if (OptVal)
CmdArgs.push_back(Args.MakeArgString(
Twine(PluginOptPrefix) + "-vector-library=" + OptVal.value()));
}

// Try to pass driver level flags relevant to LTO code generation down to
// the plugin.

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18 changes: 18 additions & 0 deletions clang/test/Driver/fveclib.c
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Expand Up @@ -31,3 +31,21 @@

// RUN: %clang -fveclib=Accelerate %s -nodefaultlibs -target arm64-apple-ios8.0.0 -### 2>&1 | FileCheck --check-prefix=CHECK-LINK-NODEFAULTLIBS %s
// CHECK-LINK-NODEFAULTLIBS-NOT: "-framework" "Accelerate"


/* Verify that the correct vector library is passed to LTO flags. */

// RUN: %clang -### --target=x86_64-unknown-linux-gnu -fveclib=LIBMVEC -flto %s 2>&1 | FileCheck -check-prefix CHECK-LTO-LIBMVEC %s
// CHECK-LTO-LIBMVEC: "-plugin-opt=-vector-library=LIBMVEC-X86"

// RUN: %clang -### --target=powerpc64-unknown-linux-gnu -fveclib=MASSV -flto %s 2>&1 | FileCheck -check-prefix CHECK-LTO-MASSV %s
// CHECK-LTO-MASSV: "-plugin-opt=-vector-library=MASSV"

// RUN: %clang -### --target=x86_64-unknown-linux-gnu -fveclib=SVML -flto %s 2>&1 | FileCheck -check-prefix CHECK-LTO-SVML %s
// CHECK-LTO-SVML: "-plugin-opt=-vector-library=SVML"

// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=SLEEF -flto %s 2>&1 | FileCheck -check-prefix CHECK-LTO-SLEEF %s
// CHECK-LTO-SLEEF: "-plugin-opt=-vector-library=sleefgnuabi"

// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL -flto %s 2>&1 | FileCheck -check-prefix CHECK-LTO-ARMPL %s
// CHECK-LTO-ARMPL: "-plugin-opt=-vector-library=ArmPL"