[clang][NFC] Extract the EmitAssemblyHelper::TargetTriple member

Few times in different methods of the EmitAssemblyHelper class the following
code snippet is used to get the TargetTriple and then use it's single method
to check some conditions:

TargetTriple(TheModule->getTargetTriple())

The parsing of a target triple string is not a trivial operation and it takes
time to repeat the parsing many times in different methods of the class and
even numerous times in one method just to call a getter
(llvm::Triple(TheModule->getTargetTriple()).getVendor()), for example.
The patch extracts the TargetTriple member of the EmitAssemblyHelper class to
parse the triple only once in the class' constructor.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D122587

clang/lib/CodeGen/BackendUtil.cpp

@@ -118,6 +118,8 @@ class EmitAssemblyHelper {
 
   std::unique_ptr<raw_pwrite_stream> OS;
 
+  Triple TargetTriple;
+
   TargetIRAnalysis getTargetIRAnalysis() const {
     if (TM)
       return TM->getTargetIRAnalysis();
@@ -170,7 +172,8 @@ public:
                      const LangOptions &LOpts, Module *M)
       : Diags(_Diags), HSOpts(HeaderSearchOpts), CodeGenOpts(CGOpts),
         TargetOpts(TOpts), LangOpts(LOpts), TheModule(M),
-        CodeGenerationTime("codegen", "Code Generation Time") {}
+        CodeGenerationTime("codegen", "Code Generation Time"),
+        TargetTriple(TheModule->getTargetTriple()) {}
 
   ~EmitAssemblyHelper() {
     if (CodeGenOpts.DisableFree)
@@ -695,7 +698,6 @@ void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
   // manually (and not via PMBuilder), since some passes (eg. InstrProfiling)
   // are inserted before PMBuilder ones - they'd get the default-constructed
   // TLI with an unknown target otherwise.
-  Triple TargetTriple(TheModule->getTargetTriple());
   std::unique_ptr<TargetLibraryInfoImpl> TLII(
       createTLII(TargetTriple, CodeGenOpts));
 
@@ -965,7 +967,6 @@ bool EmitAssemblyHelper::AddEmitPasses(legacy::PassManager &CodeGenPasses,
                                        raw_pwrite_stream &OS,
                                        raw_pwrite_stream *DwoOS) {
   // Add LibraryInfo.
-  llvm::Triple TargetTriple(TheModule->getTargetTriple());
   std::unique_ptr<TargetLibraryInfoImpl> TLII(
       createTLII(TargetTriple, CodeGenOpts));
   CodeGenPasses.add(new TargetLibraryInfoWrapperPass(*TLII));
@@ -1054,10 +1055,8 @@ void EmitAssemblyHelper::EmitAssemblyWithLegacyPassManager(
       // Emit a module summary by default for Regular LTO except for ld64
       // targets
       bool EmitLTOSummary =
-          (CodeGenOpts.PrepareForLTO &&
-           !CodeGenOpts.DisableLLVMPasses &&
-           llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
-               llvm::Triple::Apple);
+          (CodeGenOpts.PrepareForLTO && !CodeGenOpts.DisableLLVMPasses &&
+           TargetTriple.getVendor() != llvm::Triple::Apple);
       if (EmitLTOSummary) {
         if (!TheModule->getModuleFlag("ThinLTO"))
           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
@@ -1338,7 +1337,6 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
 
   // Register the target library analysis directly and give it a customized
   // preset TLI.
-  Triple TargetTriple(TheModule->getTargetTriple());
   std::unique_ptr<TargetLibraryInfoImpl> TLII(
       createTLII(TargetTriple, CodeGenOpts));
   FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
@@ -1474,8 +1472,7 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
       // targets
       bool EmitLTOSummary =
           (CodeGenOpts.PrepareForLTO && !CodeGenOpts.DisableLLVMPasses &&
-           llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
-               llvm::Triple::Apple);
+           TargetTriple.getVendor() != llvm::Triple::Apple);
       if (EmitLTOSummary) {
         if (!TheModule->getModuleFlag("ThinLTO"))
           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));