[Target] Cache the command line derived feature map in TargetOptions.

We can use this to remove some calls to initFeatureMap from Sema
and CodeGen when a function doesn't have a target attribute.

This reduces compile time of the linux kernel where this map
is needed to diagnose some inline assembly constraints based
on whether sse, avx, or avx512 is enabled.

Differential Revision: https://reviews.llvm.org/D85807

Author: topperc

clang/include/clang/Basic/TargetOptions.h

@@ -54,6 +54,10 @@ class TargetOptions {
   /// be a list of strings starting with by '+' or '-'.
   std::vector<std::string> Features;
 
+  /// The map of which features have been enabled disabled based on the command
+  /// line.
+  llvm::StringMap<bool> FeatureMap;
+
   /// Supported OpenCL extensions and optional core features.
   OpenCLOptions SupportedOpenCLOptions;
 

clang/lib/AST/ASTContext.cpp

@@ -11186,8 +11186,7 @@ void ASTContext::getFunctionFeatureMap(llvm::StringMap<bool> &FeatureMap,
     std::vector<std::string> Features(FeaturesTmp.begin(), FeaturesTmp.end());
     Target->initFeatureMap(FeatureMap, getDiagnostics(), TargetCPU, Features);
   } else {
-    Target->initFeatureMap(FeatureMap, getDiagnostics(), TargetCPU,
-                           Target->getTargetOpts().Features);
+    FeatureMap = Target->getTargetOpts().FeatureMap;
   }
 }
 

clang/lib/Basic/Targets.cpp

@@ -666,14 +666,13 @@ TargetInfo::CreateTargetInfo(DiagnosticsEngine &Diags,
 
   // Compute the default target features, we need the target to handle this
   // because features may have dependencies on one another.
-  llvm::StringMap<bool> Features;
-  if (!Target->initFeatureMap(Features, Diags, Opts->CPU,
+  if (!Target->initFeatureMap(Opts->FeatureMap, Diags, Opts->CPU,
                               Opts->FeaturesAsWritten))
     return nullptr;
 
   // Add the features to the compile options.
   Opts->Features.clear();
-  for (const auto &F : Features)
+  for (const auto &F : Opts->FeatureMap)
     Opts->Features.push_back((F.getValue() ? "+" : "-") + F.getKey().str());
   // Sort here, so we handle the features in a predictable order. (This matters
   // when we're dealing with features that overlap.)

clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp

@@ -4948,11 +4948,7 @@ bool CGOpenMPRuntimeGPU::hasAllocateAttributeForGlobalVar(const VarDecl *VD,
 static CudaArch getCudaArch(CodeGenModule &CGM) {
   if (!CGM.getTarget().hasFeature("ptx"))
     return CudaArch::UNKNOWN;
-  llvm::StringMap<bool> Features;
-  CGM.getTarget().initFeatureMap(Features, CGM.getDiags(),
-                                 CGM.getTarget().getTargetOpts().CPU,
-                                 CGM.getTarget().getTargetOpts().Features);
-  for (const auto &Feature : Features) {
+  for (const auto &Feature : CGM.getTarget().getTargetOpts().FeatureMap) {
     if (Feature.getValue()) {
       CudaArch Arch = StringToCudaArch(Feature.getKey());
       if (Arch != CudaArch::UNKNOWN)