Minor fixes when accesing CallInst operands

Summary: Fix minor issues found while adding support for emitting textual function names when calling non-callables.

Reviewed By: tmikov, avp

Differential Revision: D40617534

fbshipit-source-id: 02b8782159d4f30f10fc875f47a947fd822e9f57

include/hermes/IR/Instrs.h

@@ -699,6 +699,10 @@ class CallInst : public Instruction {
   CallInst(const CallInst &) = delete;
   void operator=(const CallInst &) = delete;
 
+  // Forces the code to use the appropriate getters instead of relying on
+  // hard-coded offsets when accessing the arguments.
+  using Instruction::getOperand;
+
  public:
   enum { CalleeIdx, ThisIdx };
 
@@ -721,7 +725,7 @@ class CallInst : public Instruction {
   }
 
   unsigned getNumArguments() const {
-    return getNumOperands() - 1;
+    return getNumOperands() - ThisIdx;
   }
 
   explicit CallInst(

lib/BCGen/HBC/Passes.cpp

@@ -811,7 +811,7 @@ bool SpillRegisters::requiresShortOperand(Instruction *I, int op) {
     case ValueKind::CallBuiltinInstKind:
     case ValueKind::HBCConstructInstKind:
     case ValueKind::HBCCallDirectInstKind:
-      return op == 0;
+      return op == CallInst::CalleeIdx;
     default:
       return true;
   }

lib/Optimizer/Scalar/FuncSigOpts.cpp

@@ -149,11 +149,11 @@ static bool performFSO(Function *F, std::vector<Function *> &worklist) {
 
   // Replace all unused arguments with undef.
   for (auto &arg : unusedParams) {
-    auto *prevArg = arg.first->getOperand(arg.second + 1);
+    auto *prevArg = arg.first->getArgument(arg.second);
     if (!llvh::isa<Literal>(prevArg))
       toRedo.insert(arg.first->getParent()->getParent());
 
-    arg.first->setOperand(undef, arg.second + 1);
+    arg.first->setArgument(undef, arg.second);
     NumArgsOpt++;
   }
 

lib/Utils/Dumper.cpp

@@ -99,7 +99,7 @@ void IRPrinter::printTypeLabel(Type T) {
 
 void IRPrinter::printValueLabel(Instruction *I, Value *V, unsigned opIndex) {
   auto &ctx = I->getContext();
-  if (isa<CallBuiltinInst>(I) && opIndex == 0) {
+  if (isa<CallBuiltinInst>(I) && opIndex == CallInst::CalleeIdx) {
     os << "["
        << getBuiltinMethodName(cast<CallBuiltinInst>(I)->getBuiltinIndex())
        << "]";