Use the 'target-features' and 'target-cpu' attributes to reset the subtarget features.

If two functions require different features (e.g., `-mno-sse' vs. `-msse') then
we want to honor that, especially during LTO. We can do that by resetting the
subtarget's features depending upon the 'target-feature' attribute.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175314 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -354,6 +354,10 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
   TTI = getAnalysisIfAvailable<TargetTransformInfo>();
   GFI = Fn.hasGC() ? &getAnalysis<GCModuleInfo>().getFunctionInfo(Fn) : 0;
 
+  TargetSubtargetInfo &ST =
+    const_cast<TargetSubtargetInfo&>(TM.getSubtarget<TargetSubtargetInfo>());
+  ST.resetSubtargetFeatures(MF);
+
   DEBUG(dbgs() << "\n\n\n=== " << Fn.getName() << "\n");
 
   SplitCriticalSideEffectEdges(const_cast<Function&>(Fn), this);