[Statepoint] Sink logic about actual callee into GCStatepointInst

Sinking logic around actual callee from Statepoint to GCStatepointInst.  While doing so, adjust naming to be consistent about refering to "actual" callee and follow precedent on naming from CallBase otherwise.

Use the result to simplify one consumer.  This is mostly just to ensure the new code is exercised, but is also a helpful cleanup on it's own.

llvm/include/llvm/IR/Statepoint.h

@@ -115,6 +115,25 @@ public:
   uint64_t getFlags() const {
     return cast<ConstantInt>(getArgOperand(FlagsPos))->getZExtValue();
   }
+
+  /// Return the value actually being called or invoked.
+  Value *getActualCalledOperand() const {
+    return getArgOperand(CalledFunctionPos);
+  }
+
+  /// Returns the function called if this is a wrapping a direct call, and null
+  /// otherwise.
+  Function *getActualCalledFunction() const {
+    return dyn_cast_or_null<Function>(getActualCalledOperand());
+  }
+
+  /// Return the type of the value returned by the call underlying the
+  /// statepoint.
+  Type *getActualReturnType() const {
+    auto *CalleeTy =
+      cast<PointerType>(getActualCalledOperand()->getType())->getElementType();
+    return cast<FunctionType>(CalleeTy)->getReturnType();
+  }
 };
 
 /// A wrapper around a GC intrinsic call, this provides most of the actual
@@ -139,7 +158,6 @@ public:
   using arg_iterator = typename CallTy::const_op_iterator;
 
   enum {
-    CalledFunctionPos = GCStatepointInst::CalledFunctionPos,
     CallArgsBeginPos = GCStatepointInst::CallArgsBeginPos,
   };
 
@@ -162,22 +180,18 @@ public:
   uint64_t getID() const { return getCall()->getID(); }
   uint32_t getNumPatchBytes() const { return getCall()->getNumPatchBytes(); }
   int getNumCallArgs() const { return getCall()->getNumCallArgs(); }
-
-
-  /// Return the value actually being called or invoked.
   ValueTy *getCalledValue() const {
-    return getCall()->getArgOperand(CalledFunctionPos);
+    return getCall()->getActualCalledOperand();
+  }
+  Type *getActualReturnType() const { return getCall()->getActualReturnType(); }
+  FunTy *getCalledFunction() const {
+    return getCall()->getActualCalledFunction();
   }
 
+  
   // FIXME: Migrate users of this to `getCall` and remove it.
   InstructionTy *getInstruction() const { return getCall(); }
 
-  /// Return the function being called if this is a direct call, otherwise
-  /// return null (if it's an indirect call).
-  FunTy *getCalledFunction() const {
-    return dyn_cast<Function>(getCalledValue());
-  }
-
   /// Return the caller function for this statepoint.
   FunTy *getCaller() const { return getCall()->getCaller(); }
 
@@ -187,13 +201,6 @@ public:
     return getCall()->doesNotThrow() || (F ? F->doesNotThrow() : false);
   }
 
-  /// Return the type of the value returned by the call underlying the
-  /// statepoint.
-  Type *getActualReturnType() const {
-    auto *FTy = cast<FunctionType>(
-        cast<PointerType>(getCalledValue()->getType())->getElementType());
-    return FTy->getReturnType();
-  }
 
   size_t arg_size() const { return getNumCallArgs(); }
   arg_iterator arg_begin() const {

llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp

@@ -822,7 +822,7 @@ SelectionDAGBuilder::LowerStatepoint(const GCStatepointInst &I,
 #endif
 
   SDValue ActualCallee;
-  SDValue Callee = getValue(ISP.getCalledValue());
+  SDValue Callee = getValue(I.getActualCalledOperand());
 
   if (I.getNumPatchBytes() > 0) {
     // If we've been asked to emit a nop sequence instead of a call instruction
@@ -838,7 +838,7 @@ SelectionDAGBuilder::LowerStatepoint(const GCStatepointInst &I,
   StatepointLoweringInfo SI(DAG);
   populateCallLoweringInfo(SI.CLI, &I, GCStatepointInst::CallArgsBeginPos,
                            I.getNumCallArgs(), ActualCallee,
-                           ISP.getActualReturnType(), false /* IsPatchPoint */);
+                           I.getActualReturnType(), false /* IsPatchPoint */);
 
   // There may be duplication in the gc.relocate list; such as two copies of
   // each relocation on normal and exceptional path for an invoke.  We only
@@ -894,7 +894,7 @@ SelectionDAGBuilder::LowerStatepoint(const GCStatepointInst &I,
 
   // Export the result value if needed
   const GCResultInst *GCResult = ISP.getGCResult();
-  Type *RetTy = ISP.getActualReturnType();
+  Type *RetTy = I.getActualReturnType();
   if (!RetTy->isVoidTy() && GCResult) {
     if (GCResult->getParent() != I.getParent()) {
       // Result value will be used in a different basic block so we need to
@@ -979,10 +979,7 @@ void SelectionDAGBuilder::visitGCResult(const GCResultInst &CI) {
     // register because statepoint and actual call return types can be
     // different, and getValue() will use CopyFromReg of the wrong type,
     // which is always i32 in our case.
-    PointerType *CalleeType = cast<PointerType>(
-        ImmutableStatepoint(I).getCalledValue()->getType());
-    Type *RetTy =
-        cast<FunctionType>(CalleeType->getElementType())->getReturnType();
+    Type *RetTy = cast<GCStatepointInst>(I)->getActualReturnType();
     SDValue CopyFromReg = getCopyFromRegs(I, RetTy);
 
     assert(CopyFromReg.getNode());