[Stackmap] Materialize the jump address within the patchpoint noop slide.

This patch moves the jump address materialization inside the noop slide. This
enables patching of the materialization itself or its complete removal. This
patch also adds the ability to define scratch registers that can be used safely
by the code called from the patchpoint intrinsic. At least one scratch register
is required, because that one is used for the materialization of the jump
address. This patch depends on D2009.

Differential Revision: http://llvm-reviews.chandlerc.com/D2074

Reviewed by Andy

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194306 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/InstrEmitter.cpp

@@ -728,10 +728,14 @@ EmitMachineNode(SDNode *Node, bool IsClone, bool IsCloned,
   const MCInstrDesc &II = TII->get(Opc);
   unsigned NumResults = CountResults(Node);
   unsigned NumDefs = II.getNumDefs();
+  const uint16_t *ScratchRegs = NULL;
 
   // Handle PATCHPOINT specially and then use the generic code.
-  if (Opc == TargetOpcode::PATCHPOINT)
+  if (Opc == TargetOpcode::PATCHPOINT) {
+    unsigned CC = Node->getConstantOperandVal(4);
     NumDefs = NumResults;
+    ScratchRegs = TLI->getScratchRegisters((CallingConv::ID) CC);
+  }
 
   unsigned NumImpUses = 0;
   unsigned NodeOperands =
@@ -767,6 +771,12 @@ EmitMachineNode(SDNode *Node, bool IsClone, bool IsCloned,
     AddOperand(MIB, Node->getOperand(i), i-NumSkip+NumDefs, &II,
                VRBaseMap, /*IsDebug=*/false, IsClone, IsCloned);
 
+  // Add scratch registers as implicit def and early clobber
+  if (ScratchRegs)
+    for (unsigned i = 0; ScratchRegs[i]; ++i)
+      MIB.addReg(ScratchRegs[i], RegState::ImplicitDefine |
+                                 RegState::EarlyClobber);
+
   // Transfer all of the memory reference descriptions of this instruction.
   MIB.setMemRefs(cast<MachineSDNode>(Node)->memoperands_begin(),
                  cast<MachineSDNode>(Node)->memoperands_end());