From a446827249bdeb2f27e55a9f4942bd7425ecb0ff Mon Sep 17 00:00:00 2001
From: =?utf8?q?Juan=20Manuel=20MARTINEZ=20CAAMA=C3=91O?= <juamarti@amd.com>
Date: Mon, 5 Dec 2022 06:30:51 -0600
Subject: [PATCH] [NFC][Clang][Driver][AMDGPU] Avoid temporary copies of
 std::string by using Twine and StringRef

Reviewed By: tra

Differential Revision: https://reviews.llvm.org/D139023
---
 clang/lib/Driver/ToolChains/AMDGPU.cpp |  4 ++--
 clang/lib/Driver/ToolChains/HIPAMD.cpp | 12 ++++++------
 clang/lib/Driver/ToolChains/ROCm.h     | 11 +++++++----
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/AMDGPU.cpp b/clang/lib/Driver/ToolChains/AMDGPU.cpp
index f3ac7d2..ff77969 100644
--- a/clang/lib/Driver/ToolChains/AMDGPU.cpp
+++ b/clang/lib/Driver/ToolChains/AMDGPU.cpp
@@ -854,7 +854,7 @@ void ROCMToolChain::addClangTargetOptions(
   const StringRef GpuArch = getGPUArch(DriverArgs);
   auto Kind = llvm::AMDGPU::parseArchAMDGCN(GpuArch);
   const StringRef CanonArch = llvm::AMDGPU::getArchNameAMDGCN(Kind);
-  std::string LibDeviceFile = RocmInstallation.getLibDeviceFile(CanonArch);
+  StringRef LibDeviceFile = RocmInstallation.getLibDeviceFile(CanonArch);
   auto ABIVer = DeviceLibABIVersion::fromCodeObjectVersion(
       getAMDGPUCodeObjectVersion(getDriver(), DriverArgs));
   if (!RocmInstallation.checkCommonBitcodeLibs(CanonArch, LibDeviceFile,
@@ -946,7 +946,7 @@ ROCMToolChain::getCommonDeviceLibNames(const llvm::opt::ArgList &DriverArgs,
   auto Kind = llvm::AMDGPU::parseArchAMDGCN(GPUArch);
   const StringRef CanonArch = llvm::AMDGPU::getArchNameAMDGCN(Kind);
 
-  std::string LibDeviceFile = RocmInstallation.getLibDeviceFile(CanonArch);
+  StringRef LibDeviceFile = RocmInstallation.getLibDeviceFile(CanonArch);
   auto ABIVer = DeviceLibABIVersion::fromCodeObjectVersion(
       getAMDGPUCodeObjectVersion(getDriver(), DriverArgs));
   if (!RocmInstallation.checkCommonBitcodeLibs(CanonArch, LibDeviceFile,
diff --git a/clang/lib/Driver/ToolChains/HIPAMD.cpp b/clang/lib/Driver/ToolChains/HIPAMD.cpp
index c64421d..a555fe5 100644
--- a/clang/lib/Driver/ToolChains/HIPAMD.cpp
+++ b/clang/lib/Driver/ToolChains/HIPAMD.cpp
@@ -237,7 +237,7 @@ void HIPAMDToolChain::addClangTargetOptions(
       DriverArgs.getLastArgValue(options::OPT_gpu_max_threads_per_block_EQ);
   if (!MaxThreadsPerBlock.empty()) {
     std::string ArgStr =
-        std::string("--gpu-max-threads-per-block=") + MaxThreadsPerBlock.str();
+        (Twine("--gpu-max-threads-per-block=") + MaxThreadsPerBlock).str();
     CC1Args.push_back(DriverArgs.MakeArgStringRef(ArgStr));
   }
 
@@ -344,7 +344,7 @@ HIPAMDToolChain::getDeviceLibs(const llvm::opt::ArgList &DriverArgs) const {
   ArgStringList LibraryPaths;
 
   // Find in --hip-device-lib-path and HIP_LIBRARY_PATH.
-  for (auto Path : RocmInstallation.getRocmDeviceLibPathArg())
+  for (StringRef Path : RocmInstallation.getRocmDeviceLibPathArg())
     LibraryPaths.push_back(DriverArgs.MakeArgString(Path));
 
   addDirectoryList(DriverArgs, LibraryPaths, "", "HIP_DEVICE_LIB_PATH");
@@ -354,7 +354,7 @@ HIPAMDToolChain::getDeviceLibs(const llvm::opt::ArgList &DriverArgs) const {
   if (!BCLibArgs.empty()) {
     llvm::for_each(BCLibArgs, [&](StringRef BCName) {
       StringRef FullName;
-      for (std::string LibraryPath : LibraryPaths) {
+      for (StringRef LibraryPath : LibraryPaths) {
         SmallString<128> Path(LibraryPath);
         llvm::sys::path::append(Path, BCName);
         FullName = Path;
@@ -387,15 +387,15 @@ HIPAMDToolChain::getDeviceLibs(const llvm::opt::ArgList &DriverArgs) const {
         getDriver().Diag(DiagID);
         return {};
       } else
-        BCLibs.push_back({AsanRTL.str(), /*ShouldInternalize=*/false});
+        BCLibs.emplace_back(AsanRTL, /*ShouldInternalize=*/false);
     }
 
     // Add the HIP specific bitcode library.
     BCLibs.push_back(RocmInstallation.getHIPPath());
 
     // Add common device libraries like ocml etc.
-    for (auto N : getCommonDeviceLibNames(DriverArgs, GpuArch.str()))
-      BCLibs.push_back(StringRef(N));
+    for (StringRef N : getCommonDeviceLibNames(DriverArgs, GpuArch.str()))
+      BCLibs.emplace_back(N);
 
     // Add instrument lib.
     auto InstLib =
diff --git a/clang/lib/Driver/ToolChains/ROCm.h b/clang/lib/Driver/ToolChains/ROCm.h
index b16deec..600c8b3 100644
--- a/clang/lib/Driver/ToolChains/ROCm.h
+++ b/clang/lib/Driver/ToolChains/ROCm.h
@@ -252,8 +252,11 @@ public:
   }
 
   /// Get libdevice file for given architecture
-  std::string getLibDeviceFile(StringRef Gpu) const {
-    return LibDeviceMap.lookup(Gpu);
+  StringRef getLibDeviceFile(StringRef Gpu) const {
+    auto Loc = LibDeviceMap.find(Gpu);
+    if (Loc == LibDeviceMap.end())
+      return "";
+    return Loc->second;
   }
 
   void AddHIPIncludeArgs(const llvm::opt::ArgList &DriverArgs,
@@ -263,7 +266,7 @@ public:
   void detectHIPRuntime();
 
   /// Get the values for --rocm-device-lib-path arguments
-  std::vector<std::string> getRocmDeviceLibPathArg() const {
+  const ArrayRef<std::string> getRocmDeviceLibPathArg() const {
     return RocmDeviceLibPathArg;
   }
 
@@ -273,7 +276,7 @@ public:
   /// Get the value for --hip-version argument
   StringRef getHIPVersionArg() const { return HIPVersionArg; }
 
-  std::string getHIPVersion() const { return DetectedVersion; }
+  StringRef getHIPVersion() const { return DetectedVersion; }
 };
 
 } // end namespace driver
-- 
2.7.4