[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

llvm/include/llvm/CodeGen/FastISel.h

@@ -76,6 +76,8 @@ public:
     unsigned ResultReg;
     unsigned NumResultRegs;
 
+    bool IsPatchPoint;
+
     SmallVector<Value *, 16> OutVals;
     SmallVector<ISD::ArgFlagsTy, 16> OutFlags;
     SmallVector<unsigned, 16> OutRegs;
@@ -87,7 +89,7 @@ public:
           IsInReg(false), DoesNotReturn(false), IsReturnValueUsed(true),
           IsTailCall(false), NumFixedArgs(-1), CallConv(CallingConv::C),
           Callee(nullptr), SymName(nullptr), CS(nullptr), Call(nullptr),
-          ResultReg(0), NumResultRegs(0) {}
+          ResultReg(0), NumResultRegs(0), IsPatchPoint(false) {}
 
     CallLoweringInfo &setCallee(Type *ResultTy, FunctionType *FuncTy,
                                 const Value *Target, ArgListTy &&ArgsList,
@@ -162,6 +164,11 @@ public:
       return *this;
     }
 
+    CallLoweringInfo &setIsPatchPoint(bool Value = true) {
+      IsPatchPoint = Value;
+      return *this;
+    }
+
     ArgListTy &getArgs() { return Args; }
 
     void clearOuts() {

llvm/include/llvm/Target/TargetLowering.h

@@ -2299,6 +2299,7 @@ public:
     SelectionDAG &DAG;
     SDLoc DL;
     ImmutableCallSite *CS;
+    bool IsPatchPoint;
     SmallVector<ISD::OutputArg, 32> Outs;
     SmallVector<SDValue, 32> OutVals;
     SmallVector<ISD::InputArg, 32> Ins;
@@ -2307,7 +2308,7 @@ public:
       : RetTy(nullptr), RetSExt(false), RetZExt(false), IsVarArg(false),
         IsInReg(false), DoesNotReturn(false), IsReturnValueUsed(true),
         IsTailCall(false), NumFixedArgs(-1), CallConv(CallingConv::C),
-        DAG(DAG), CS(nullptr) {}
+        DAG(DAG), CS(nullptr), IsPatchPoint(false) {}
 
     CallLoweringInfo &setDebugLoc(SDLoc dl) {
       DL = dl;
@@ -2389,6 +2390,11 @@ public:
       return *this;
     }
 
+    CallLoweringInfo &setIsPatchPoint(bool Value = true) {
+      IsPatchPoint = Value;
+      return *this;
+    }
+
     ArgListTy &getArgs() {
       return Args;
     }

llvm/lib/CodeGen/SelectionDAG/FastISel.cpp

@@ -728,6 +728,7 @@ bool FastISel::selectPatchpoint(const CallInst *I) {
   // For AnyRegCC the arguments are lowered later on manually.
   unsigned NumCallArgs = IsAnyRegCC ? 0 : NumArgs;
   CallLoweringInfo CLI;
+  CLI.setIsPatchPoint();
   if (!lowerCallOperands(I, NumMetaOpers, NumCallArgs, Callee, IsAnyRegCC, CLI))
     return false;
 

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -7023,7 +7023,8 @@ std::pair<SDValue, SDValue>
 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 @@ SelectionDAGBuilder::lowerCallOperands(ImmutableCallSite CS, unsigned ArgIdx,
   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 @@ void SelectionDAGBuilder::visitPatchpoint(ImmutableCallSite CS,
   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))

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h

@@ -653,7 +653,8 @@ public:
           unsigned NumArgs,
           SDValue Callee,
           bool UseVoidTy = false,
-          MachineBasicBlock *LandingPad = nullptr);
+          MachineBasicBlock *LandingPad = nullptr,
+          bool IsPatchPoint = false);
 
   /// UpdateSplitBlock - When an MBB was split during scheduling, update the
   /// references that need to refer to the last resulting block.