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Keep start and stop symbols linked through clang (Linux) #8214

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Keep start and stop symbols linked through clang (Linux) #8214

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2 changes: 1 addition & 1 deletion clang/lib/Driver/ToolChain.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -836,7 +836,7 @@ std::string ToolChain::GetLinkerPath(bool *LinkerIsLLD) const {
if (llvm::sys::fs::can_execute(UseLinker))
return std::string(UseLinker);
} else {
llvm::SmallString<8> LinkerName;
llvm::SmallString<8> LinkerName = {};
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This seems unnecessary? Would be nice to stay as close to upstream as possible.

if (Triple.isOSDarwin())
LinkerName.append("ld64.");
else
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11 changes: 10 additions & 1 deletion clang/lib/Driver/ToolChains/Gnu.cpp
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Expand Up @@ -677,8 +677,17 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
}

Args.AddAllArgs(CmdArgs, options::OPT_T);
bool useLLD = false;
const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath(&useLLD));
if (useLLD) {
Comment on lines +680 to +682
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Why not if (Args.hasArg(options::OPT_fuse_ld_EQ) && Args.getLastArgValue(options::OPT_fuse_ld_EQ).ends_with_insensitive("lld"))?

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Yeah, mainly to support when someone isn't passing --fuse-ld=lld. It should still catch it if clang was configured to use lld by default. We're already calling GetLinkerPath, which is also conveniently supposed to detect when the linker is lld either through clang being configured to use lld by default, --fuse-ld=lld, or --ld-path=<filepath>/ld.lld.

/// Workaround for https://reviews.llvm.org/D96914 breaking Swift.
/// Newer LLD versions change symbols, resulting in incorrect locations
/// for the type metadata tables. Forcing `-z nostart-stop-gc` on LLD so
/// that it does not munge the symbols.
CmdArgs.push_back("-z");
CmdArgs.push_back("nostart-stop-gc");
}

const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath());
C.addCommand(std::make_unique<Command>(JA, *this,
ResponseFileSupport::AtFileCurCP(),
Exec, CmdArgs, Inputs, Output));
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