Convert attribute 'target' parsing from a 'pair' to a 'struct' to make further improvements easier

[erichkeane]

Summary

The attribute 'target' parse function previously returned a pair. Convert this to a 'pair' in order to add more functionality, and improve usability.

[echristo]

LGTM.

include/clang/Basic/Attr.td

 }
 
 def Target : InheritableAttr {
   let Spellings = [GCC<"target">];
   let Args = [StringArgument<"featuresStr">];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [TargetDocs];
   let AdditionalMembers = [{
-    typedef std::pair<std::vector<std::string>, StringRef> ParsedTargetAttr;
+    struct ParsedTargetAttr {
+      std::vector<std::string> Features;
+      StringRef Architecture;
+      bool DuplicateArchitecture = false;
+    };
     ParsedTargetAttr parse() const {
+      return parse(getFeaturesStr());
+    }
+    static ParsedTargetAttr parse(StringRef Features) {
       ParsedTargetAttr Ret;
       SmallVector<StringRef, 1> AttrFeatures;
-      getFeaturesStr().split(AttrFeatures, ",");
+      Features.split(AttrFeatures, ",");
 
       // Grab the various features and prepend a "+" to turn on the feature to
       // the backend and add them to our existing set of features.
       for (auto &Feature : AttrFeatures) {
         // Go ahead and trim whitespace rather than either erroring or
         // accepting it weirdly.
         Feature = Feature.trim();
 
         // We don't support cpu tuning this way currently.
         // TODO: Support the fpmath option. It will require checking
         // overall feature validity for the function with the rest of the
         // attributes on the function.
         if (Feature.startswith("fpmath=") || Feature.startswith("tune="))
     continue;
 
         // While we're here iterating check for a different target cpu.
-        if (Feature.startswith("arch="))
-          Ret.second = Feature.split("=").second.trim();
-        else if (Feature.startswith("no-"))
-          Ret.first.push_back("-" + Feature.split("-").second.str());
+        if (Feature.startswith("arch=")) {
+          if (!Ret.Architecture.empty())
+            Ret.DuplicateArchitecture = true;
+          else
+            Ret.Architecture = Feature.split("=").second.trim();
+        } else if (Feature.startswith("no-"))
+          Ret.Features.push_back("-" + Feature.split("-").second.str());
         else
-          Ret.first.push_back("+" + Feature.str());
+          Ret.Features.push_back("+" + Feature.str());
       }
       return Ret;
     }
   }];
 }
 
 def TransparentUnion : InheritableAttr {
   let Spellings = [GCC<"transparent_union">];

lib/CodeGen/CGCall.cpp

if (FD && FD->hasAttr<TargetAttr>()) {
         Features.push_back((it->second ? "+" : "-") + it->first().str());
 
       // Now add the target-cpu and target-features to the function.
       // While we populated the feature map above, we still need to
       // get and parse the target attribute so we can get the cpu for
       // the function.
       const auto *TD = FD->getAttr<TargetAttr>();
       TargetAttr::ParsedTargetAttr ParsedAttr = TD->parse();
-      if (ParsedAttr.second != "")
-        TargetCPU = ParsedAttr.second;
+      if (ParsedAttr.Architecture != "")
+        TargetCPU = ParsedAttr.Architecture;
       if (TargetCPU != "")
         FuncAttrs.addAttribute("target-cpu", TargetCPU);
       if (!Features.empty()) {
         std::sort(Features.begin(), Features.end());
         FuncAttrs.addAttribute(
             "target-features",
             llvm::join(Features.begin(), Features.end(), ","));
       }

lib/CodeGen/CodeGenModule.cpp

void CodeGenModule::getFunctionFeatureMap(llvm::StringMap<bool> &FeatureMap,
                                           const FunctionDecl *FD) {
   StringRef TargetCPU = Target.getTargetOpts().CPU;
   if (const auto *TD = FD->getAttr<TargetAttr>()) {
     // If we have a TargetAttr build up the feature map based on that.
     TargetAttr::ParsedTargetAttr ParsedAttr = TD->parse();
 
     // Make a copy of the features as passed on the command line into the
     // beginning of the additional features from the function to override.
-    ParsedAttr.first.insert(ParsedAttr.first.begin(),
+    ParsedAttr.Features.insert(ParsedAttr.Features.begin(),
                             Target.getTargetOpts().FeaturesAsWritten.begin(),
                             Target.getTargetOpts().FeaturesAsWritten.end());
 
-    if (ParsedAttr.second != "")
-      TargetCPU = ParsedAttr.second;
+    if (ParsedAttr.Architecture != "")
+      TargetCPU = ParsedAttr.Architecture ;
 
     // Now populate the feature map, first with the TargetCPU which is either
     // the default or a new one from the target attribute string. Then we'll use
     // the passed in features (FeaturesAsWritten) along with the new ones from
     // the attribute.
-    Target.initFeatureMap(FeatureMap, getDiags(), TargetCPU, ParsedAttr.first);
+    Target.initFeatureMap(FeatureMap, getDiags(), TargetCPU,
+                          ParsedAttr.Features);
   } else {
     Target.initFeatureMap(FeatureMap, getDiags(), TargetCPU,
                           Target.getTargetOpts().Features);
   }
 }
 
 llvm::SanitizerStatReport &CodeGenModule::getSanStats() {
   if (!SanStats)