[NFC] Extract out a helper function for SimplifyCall(CS, Q)

This simplifies code, but the real motivation is that it lets me clean up some downstream code.

llvm-svn: 321466

llvm/include/llvm/Analysis/InstructionSimplify.h

@@ -197,6 +197,9 @@ Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
 Value *SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
                        FastMathFlags FMF, const SimplifyQuery &Q);
 
+/// Given a callsite, fold the result or return null.
+Value *SimplifyCall(ImmutableCallSite CS, const SimplifyQuery &Q);
+
 /// Given a function and iterators over arguments, fold the result or return
 /// null.
 Value *SimplifyCall(ImmutableCallSite CS, Value *V, User::op_iterator ArgBegin,

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -4617,6 +4617,12 @@ Value *llvm::SimplifyCall(ImmutableCallSite CS, Value *V,
   return ::SimplifyCall(CS, V, Args.begin(), Args.end(), Q, RecursionLimit);
 }
 
+Value *llvm::SimplifyCall(ImmutableCallSite ICS, const SimplifyQuery &Q) {
+  CallSite CS(const_cast<Instruction*>(ICS.getInstruction()));
+  return ::SimplifyCall(CS, CS.getCalledValue(), CS.arg_begin(), CS.arg_end(),
+                        Q, RecursionLimit);
+}
+
 /// See if we can compute a simplified version of this instruction.
 /// If not, this returns null.
 
@@ -4751,8 +4757,7 @@ Value *llvm::SimplifyInstruction(Instruction *I, const SimplifyQuery &SQ,
     break;
   case Instruction::Call: {
     CallSite CS(cast<CallInst>(I));
-    Result = SimplifyCall(CS, CS.getCalledValue(), CS.arg_begin(), CS.arg_end(),
-                          Q);
+    Result = SimplifyCall(CS, Q);
     break;
   }
 #define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc:

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -1802,9 +1802,7 @@ Instruction *InstCombiner::visitVACopyInst(VACopyInst &I) {
 /// instructions. For normal calls, it allows visitCallSite to do the heavy
 /// lifting.
 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
-  auto Args = CI.arg_operands();
-  if (Value *V = SimplifyCall(&CI, CI.getCalledValue(), Args.begin(),
-                              Args.end(), SQ.getWithInstruction(&CI)))
+  if (Value *V = SimplifyCall(&CI, SQ.getWithInstruction(&CI)))
     return replaceInstUsesWith(CI, V);
 
   if (isFreeCall(&CI, &TLI))