From bb0cef6e9c97c09889a0a9af93d4d1e82549a812 Mon Sep 17 00:00:00 2001
From: Eric Christopher <echristo@gmail.com>
Date: Wed, 2 Sep 2015 00:12:02 +0000
Subject: [PATCH] Migrate the target attribute parsing code into an extension
 off of the main attribute and cache the results so we don't have to parse a
 single attribute more than once.

This reapplies r246596 with a fix for an uninitialized class member,
and a couple of cleanups and formatting changes.

llvm-svn: 246610
---
 clang/include/clang/Basic/Attr.td | 45 ++++++++++++++++++++++++++++++-
 clang/lib/CodeGen/CGCall.cpp      | 33 +++++------------------
 2 files changed, 50 insertions(+), 28 deletions(-)

diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 6f10ee62723d..8523ed92a710 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1315,9 +1315,52 @@ def Pascal : InheritableAttr {
 
 def Target : InheritableAttr {
   let Spellings = [GCC<"target">];
-  let Args = [StringArgument<"features">];
+  let Args = [StringArgument<"featuresStr">];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [TargetDocs];
+  let AdditionalMembers = [{
+    StringRef CPU;
+    std::vector<std::string> Features;
+    bool Parsed = false;
+    StringRef getCPU() {
+      if (!Parsed)
+        parse();
+      return CPU;
+    }
+    std::vector<std::string> &getFeatures() {
+      if (!Parsed)
+        parse();
+      return Features;
+    }
+    void parse() {
+      SmallVector<StringRef, 1> AttrFeatures;
+      getFeaturesStr().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="))
+          CPU = Feature.split("=").second.trim();
+        else if (Feature.startswith("no-"))
+          Features.push_back("-" + Feature.split("-").second.str());
+        else
+          Features.push_back("+" + Feature.str());
+      }
+      Parsed = true;
+    }
+  }];
 }
 
 def TransparentUnion : InheritableAttr {
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 270d9941ec8a..ed7bf60c024c 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1499,40 +1499,19 @@ void CodeGenModule::ConstructAttributeList(const CGFunctionInfo &FI,
     const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(TargetDecl);
     if (FD && FD->hasAttr<TargetAttr>()) {
       llvm::StringMap<bool> FeatureMap;
-      const auto *TD = FD->getAttr<TargetAttr>();
+      auto *TD = FD->getAttr<TargetAttr>();
 
       // Make a copy of the features as passed on the command line.
       std::vector<std::string> FnFeatures =
           getTarget().getTargetOpts().FeaturesAsWritten;
 
-      // Grab the target attribute string.
-      StringRef FeaturesStr = TD->getFeatures();
-      SmallVector<StringRef, 1> AttrFeatures;
-      FeaturesStr.split(AttrFeatures, ",");
+      std::vector<std::string> &AttrFeatures = TD->getFeatures();
+      std::copy(AttrFeatures.begin(), AttrFeatures.end(),
+                std::back_inserter(FnFeatures));
 
-      // 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();
+      if (TD->getCPU() != "")
+	TargetCPU = TD->getCPU();
 
-        // While we're here iterating check for a different target cpu.
-        if (Feature.startswith("arch="))
-          TargetCPU = Feature.split("=").second.trim();
-        else if (Feature.startswith("tune="))
-          // We don't support cpu tuning this way currently.
-          ;
-        else if (Feature.startswith("fpmath="))
-          // TODO: Support the fpmath option this way. It will require checking
-          // overall feature validity for the function with the rest of the
-          // attributes on the function.
-          ;
-        else if (Feature.startswith("no-"))
-          FnFeatures.push_back("-" + Feature.split("-").second.str());
-        else
-          FnFeatures.push_back("+" + Feature.str());
-      }
       // 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