[GVNSink] Add unary FNeg support to GVNSink pass

[dmgreen]

Looks good to me.

llvm/trunk/lib/Transforms/Scalar/GVNSink.cpp

uint32_t lookupOrAdd(Value *V) {
     case Instruction::Load:
       exp = createMemoryExpr(cast<LoadInst>(I));
       break;
     case Instruction::Store:
       exp = createMemoryExpr(cast<StoreInst>(I));
       break;
     case Instruction::Call:
     case Instruction::Invoke:
+    case Instruction::FNeg:
     case Instruction::Add:
     case Instruction::FAdd:
     case Instruction::Sub:
     case Instruction::FSub:
     case Instruction::Mul:
     case Instruction::FMul:
     case Instruction::UDiv:
     case Instruction::SDiv:

llvm/trunk/test/Transforms/GVNSink/fpmath.ll

 ; RUN: opt -S < %s -gvn-sink | FileCheck %s
 
 ; CHECK-LABEL: sink
-; CHECK: fneg
+; CHECK-NOT: fneg
 ; CHECK: = phi
+; CHECK: fneg
 define float @sink(float %a, float %b, i1 %cmp) {
 entry:
   br i1 %cmp, label %if.then, label %if.else
 
 if.then:
   %sub = fsub float %a, %b
   %neg0 = fneg float %sub
   br label %if.end