Ignore PhiNodes when mapping sample profile data

[david2050]

Summary

Like branch instructions, phi nodes frequently do not have debug information related to the block they are in and so they should be ignored.

[wmi]

LGTM.

llvm/trunk/lib/Transforms/IPO/SampleProfile.cpp

ErrorOr<uint64_t> SampleProfileLoader::getInstWeight(const Instruction &Inst) {
   const DebugLoc &DLoc = Inst.getDebugLoc();
   if (!DLoc)
     return std::error_code();
 
   const FunctionSamples *FS = findFunctionSamples(Inst);
   if (!FS)
     return std::error_code();
 
-  // Ignore all intrinsics and branch instructions.
-  // Branch instruction usually contains debug info from sources outside of
+  // Ignore all intrinsics, phinodes and branch instructions.
+  // Branch and phinodes instruction usually contains debug info from sources outside of
   // the residing basic block, thus we ignore them during annotation.
-  if (isa<BranchInst>(Inst) || isa<IntrinsicInst>(Inst))
+  if (isa<BranchInst>(Inst) || isa<IntrinsicInst>(Inst) || isa<PHINode>(Inst))
     return std::error_code();
 
   // If a direct call/invoke instruction is inlined in profile
   // (findCalleeFunctionSamples returns non-empty result), but not inlined here,
   // it means that the inlined callsite has no sample, thus the call
   // instruction should have 0 count.
   if ((isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) &&
       !ImmutableCallSite(&Inst).isIndirectCall() &&