[AMDGPU] More radical feature initialization refactoring

Factoring in flang, just have a single fillAMDGPUFeatureMap
function doing it all as an external interface and returing
an error.

Author: rampitec

clang/lib/Basic/Targets/AMDGPU.cpp

@@ -201,8 +201,7 @@ bool AMDGPUTargetInfo::initFeatureMap(
   if (!TargetInfo::initFeatureMap(Features, Diags, CPU, FeatureVec))
     return false;
 
-  // TODO: Should move this logic into TargetParser
-  auto HasError = insertWaveSizeFeature(CPU, getTriple(), Features);
+  auto HasError = fillAMDGPUFeatureMap(CPU, getTriple(), Features);
   switch (HasError.first) {
   default:
     break;

flang/lib/Frontend/CompilerInstance.cpp

@@ -253,18 +253,15 @@ getExplicitAndImplicitAMDGPUTargetFeatures(clang::DiagnosticsEngine &diags,
                                            const TargetOptions &targetOpts,
                                            const llvm::Triple triple) {
   llvm::StringRef cpu = targetOpts.cpu;
-  llvm::StringMap<bool> implicitFeaturesMap;
-  // Get the set of implicit target features
-  llvm::AMDGPU::fillAMDGPUFeatureMap(cpu, triple, implicitFeaturesMap);
+  llvm::StringMap<bool> FeaturesMap;
 
   // Add target features specified by the user
   for (auto &userFeature : targetOpts.featuresAsWritten) {
     std::string userKeyString = userFeature.substr(1);
-    implicitFeaturesMap[userKeyString] = (userFeature[0] == '+');
+    FeaturesMap[userKeyString] = (userFeature[0] == '+');
   }
 
-  auto HasError =
-      llvm::AMDGPU::insertWaveSizeFeature(cpu, triple, implicitFeaturesMap);
+  auto HasError = llvm::AMDGPU::fillAMDGPUFeatureMap(cpu, triple, FeaturesMap);
   if (HasError.first) {
     unsigned diagID = diags.getCustomDiagID(clang::DiagnosticsEngine::Error,
                                             "Unsupported feature ID: %0");
@@ -273,9 +270,9 @@ getExplicitAndImplicitAMDGPUTargetFeatures(clang::DiagnosticsEngine &diags,
   }
 
   llvm::SmallVector<std::string> featuresVec;
-  for (auto &implicitFeatureItem : implicitFeaturesMap) {
-    featuresVec.push_back((llvm::Twine(implicitFeatureItem.second ? "+" : "-") +
-                           implicitFeatureItem.first().str())
+  for (auto &FeatureItem : FeaturesMap) {
+    featuresVec.push_back((llvm::Twine(FeatureItem.second ? "+" : "-") +
+                           FeatureItem.first().str())
                               .str());
   }
   llvm::sort(featuresVec);

llvm/include/llvm/TargetParser/TargetParser.h

@@ -183,15 +183,11 @@ LLVM_ABI void fillValidArchListR600(SmallVectorImpl<StringRef> &Values);
 
 LLVM_ABI IsaVersion getIsaVersion(StringRef GPU);
 
-/// Fills Features map with default values for given target GPU
-LLVM_ABI void fillAMDGPUFeatureMap(StringRef GPU, const Triple &T,
-                                   StringMap<bool> &Features);
-
-/// Inserts wave size feature for given GPU into features map
+/// Fills Features map with default values for given target GPU.
+/// \p Features contains overriding target features and this function returns
+/// default target features with entries overridden by \p Features.
 LLVM_ABI std::pair<FeatureError, StringRef>
-insertWaveSizeFeature(StringRef GPU, const Triple &T,
-                      StringMap<bool> &Features);
-
+fillAMDGPUFeatureMap(StringRef GPU, const Triple &T, StringMap<bool> &Features);
 } // namespace AMDGPU
 
 struct BasicSubtargetFeatureKV {