[HIP] use GetProgramPath for executable discovery

This change replaces the manual building of executable paths
using llvm::sys::path::append with GetProgramPath.
This enables adding other paths in case executables reside
in different directories and makes the code easier to read.

Differential Revision: https://reviews.llvm.org/D72903

(cherry picked from commit 24d7a09)

clang/lib/Driver/ToolChains/HIP.cpp

@@ -105,9 +105,8 @@ const char *AMDGCN::Linker::constructLLVMLinkCommand(
   CmdArgs.push_back("-o");
   auto OutputFileName = getOutputFileName(C, OutputFilePrefix, "-linked", "bc");
   CmdArgs.push_back(OutputFileName);
-  SmallString<128> ExecPath(C.getDriver().Dir);
-  llvm::sys::path::append(ExecPath, "llvm-link");
-  const char *Exec = Args.MakeArgString(ExecPath);
+  const char *Exec =
+      Args.MakeArgString(getToolChain().GetProgramPath("llvm-link"));
   C.addCommand(std::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
   return OutputFileName;
 }
@@ -133,9 +132,8 @@ const char *AMDGCN::Linker::constructOptCommand(
   auto OutputFileName =
       getOutputFileName(C, OutputFilePrefix, "-optimized", "bc");
   OptArgs.push_back(OutputFileName);
-  SmallString<128> OptPath(C.getDriver().Dir);
-  llvm::sys::path::append(OptPath, "opt");
-  const char *OptExec = Args.MakeArgString(OptPath);
+  const char *OptExec =
+      Args.MakeArgString(getToolChain().GetProgramPath("opt"));
   C.addCommand(std::make_unique<Command>(JA, *this, OptExec, OptArgs, Inputs));
   return OutputFileName;
 }
@@ -180,9 +178,7 @@ const char *AMDGCN::Linker::constructLlcCommand(
   auto LlcOutputFile =
       getOutputFileName(C, OutputFilePrefix, "", OutputIsAsm ? "s" : "o");
   LlcArgs.push_back(LlcOutputFile);
-  SmallString<128> LlcPath(C.getDriver().Dir);
-  llvm::sys::path::append(LlcPath, "llc");
-  const char *Llc = Args.MakeArgString(LlcPath);
+  const char *Llc = Args.MakeArgString(getToolChain().GetProgramPath("llc"));
   C.addCommand(std::make_unique<Command>(JA, *this, Llc, LlcArgs, Inputs));
   return LlcOutputFile;
 }
@@ -196,9 +192,7 @@ void AMDGCN::Linker::constructLldCommand(Compilation &C, const JobAction &JA,
   // The output from ld.lld is an HSA code object file.
   ArgStringList LldArgs{
       "-flavor", "gnu", "-shared", "-o", Output.getFilename(), InputFileName};
-  SmallString<128> LldPath(C.getDriver().Dir);
-  llvm::sys::path::append(LldPath, "lld");
-  const char *Lld = Args.MakeArgString(LldPath);
+  const char *Lld = Args.MakeArgString(getToolChain().GetProgramPath("lld"));
   C.addCommand(std::make_unique<Command>(JA, *this, Lld, LldArgs, Inputs));
 }
 
@@ -230,9 +224,8 @@ void AMDGCN::constructHIPFatbinCommand(Compilation &C, const JobAction &JA,
       Args.MakeArgString(std::string("-outputs=").append(OutputFileName));
   BundlerArgs.push_back(BundlerOutputArg);
 
-  SmallString<128> BundlerPath(C.getDriver().Dir);
-  llvm::sys::path::append(BundlerPath, "clang-offload-bundler");
-  const char *Bundler = Args.MakeArgString(BundlerPath);
+  const char *Bundler = Args.MakeArgString(
+      T.getToolChain().GetProgramPath("clang-offload-bundler"));
   C.addCommand(std::make_unique<Command>(JA, T, Bundler, BundlerArgs, Inputs));
 }