[StackMaps] Mark in CallLoweringInfo when lowering a patchpoint

While, generally speaking, the process of lowering arguments for a patchpoint
is the same as lowering a regular indirect call, on some targets it may not be
exactly the same. Targets may not, for example, want to add additional register
dependencies that apply only to making cross-DSO calls through linker stubs,
may not want to load additional registers out of function descriptors, and may
not want to add additional side-effect-causing instructions that cannot be
removed later with the call itself being generated.

The PowerPC target will use this in a future commit (for all of the reasons
stated above).

llvm-svn: 225806
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 068a5c4..151bc72 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7023,7 +7023,8 @@
 SelectionDAGBuilder::lowerCallOperands(ImmutableCallSite CS, unsigned ArgIdx,
                                        unsigned NumArgs, SDValue Callee,
                                        bool UseVoidTy,
-                                       MachineBasicBlock *LandingPad) {
+                                       MachineBasicBlock *LandingPad,
+                                       bool IsPatchPoint) {
   TargetLowering::ArgListTy Args;
   Args.reserve(NumArgs);
 
@@ -7046,7 +7047,7 @@
   TargetLowering::CallLoweringInfo CLI(DAG);
   CLI.setDebugLoc(getCurSDLoc()).setChain(getRoot())
     .setCallee(CS.getCallingConv(), retTy, Callee, std::move(Args), NumArgs)
-    .setDiscardResult(CS->use_empty());
+    .setDiscardResult(CS->use_empty()).setIsPatchPoint(IsPatchPoint);
 
   return lowerInvokable(CLI, LandingPad);
 }
@@ -7178,7 +7179,7 @@
   unsigned NumCallArgs = IsAnyRegCC ? 0 : NumArgs;
   std::pair<SDValue, SDValue> Result =
     lowerCallOperands(CS, NumMetaOpers, NumCallArgs, Callee, IsAnyRegCC,
-                      LandingPad);
+                      LandingPad, true);
 
   SDNode *CallEnd = Result.second.getNode();
   if (HasDef && (CallEnd->getOpcode() == ISD::CopyFromReg))