[Hexagon] Use GetLinkerPath method instead of hard-coded linker name.

[sidneym]

Summary

Use GetLinkerPath method instead of hard-coding linker name.

Change should allow -fuse-ld to work on the Hexagon target.

[davezarzycki]

A bisect revealed this change as the source of test failures on my Red Hat Fedora 28 Linux box. How was/is this tested?

Command Output (stderr):

/home/dave/s/lc/tools/clang/test/Driver/linux-ld.c:882:19: error: CHECK-HEXAGON: expected string not found in input
// CHECK-HEXAGON: "{{.*}}hexagon-link{{(.exe)?}}"

^

<stdin>:1:1: note: scanning from here
clang version 8.0.0 (https://git.llvm.org/git/clang.git efe41bf98e6011bb413a5056f0025a4509de860d) (https://git.llvm.org/git/llvm.git 638941f488dd9d1b1b9d49913240fdc2beec56a0)
^
<stdin>:2:3: note: possible intended match here
Target: hexagon-unknown-linux-gnu

^

---

Testing Time: 43.34s

---

Failing Tests (2):

  Clang :: Driver/hexagon-toolchain-elf.c
  Clang :: Driver/linux-ld.c

Expected Passes    : 34506
Expected Failures  : 82
Unsupported Tests  : 8838
Unexpected Failures: 2

FAILED: CMakeFiles/check-all

[sidneym]

Seems like the test cases do not consider the possibility of CLANG_DEFAULT_LINKER being set. If CLANG_DEFAULT_LINKER was set to "hexagon-link" these tests would probably pass.

I'm checking this out now.

[sidneym]

I updated the tests: https://reviews.llvm.org/D53219

lib/Driver/ToolChains/Hexagon.h

void addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
                              llvm::opt::ArgStringList &CC1Args,
                              Action::OffloadKind DeviceOffloadKind) const override;
   void
   AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                             llvm::opt::ArgStringList &CC1Args) const override;
   void addLibStdCxxIncludePaths(
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override;
+
+  const char *getDefaultLinker() const override { return "hexagon-link"; }
+
   CXXStdlibType GetCXXStdlibType(const llvm::opt::ArgList &Args) const override;
 
   StringRef GetGCCLibAndIncVersion() const { return GCCLibAndIncVersion.Text; }
   bool IsIntegratedAssemblerDefault() const override {
     return true;
   }
 
   std::string getHexagonTargetDir(

lib/Driver/ToolChains/Hexagon.cpp

void hexagon::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                                    const ArgList &Args,
                                    const char *LinkingOutput) const {
   auto &HTC = static_cast<const toolchains::HexagonToolChain&>(getToolChain());
 
   ArgStringList CmdArgs;
   constructHexagonLinkArgs(C, JA, HTC, Output, Inputs, Args, CmdArgs,
                            LinkingOutput);
 
-  std::string Linker = HTC.GetProgramPath("hexagon-link");
-  C.addCommand(llvm::make_unique<Command>(JA, *this, Args.MakeArgString(Linker),
-                                          CmdArgs, Inputs));
+  const char *Exec = Args.MakeArgString(HTC.GetLinkerPath());
+  C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
 }
 // Hexagon tools end.
 
 /// Hexagon Toolchain
 
 std::string HexagonToolChain::getHexagonTargetDir(
       const std::string &InstalledDir,
       const SmallVectorImpl<std::string> &PrefixDirs) const {