Make stackmap machineinstrs clobber the scratch regs too.

Patchpoints already did this. Doing it for stackmaps is a convenience
for the runtime in the event that it needs to scratch register to
patch or perform a runtime call thunk.

Unlike patchpoints, we just assume the AnyRegCC calling
convention. This is the only language and target independent calling
convention specific to stackmaps so makes sense.  Although the calling
convention is not currently used to select the scratch registers.

llvm-svn: 202943

1 files changed, 10 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 856ef34a2ad..1c596b8c42e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -740,10 +740,16 @@ EmitMachineNode(SDNode *Node, bool IsClone, bool IsCloned,
   unsigned NumDefs = II.getNumDefs();
   const uint16_t *ScratchRegs = NULL;
 
-  // Handle PATCHPOINT specially and then use the generic code.
-  if (Opc == TargetOpcode::PATCHPOINT) {
-    unsigned CC = Node->getConstantOperandVal(PatchPointOpers::CCPos);
-    NumDefs = NumResults;
+  // Handle STACKMAP and PATCHPOINT specially and then use the generic code.
+  if (Opc == TargetOpcode::STACKMAP || Opc == TargetOpcode::PATCHPOINT) {
+    // Stackmaps do not have arguments and do not preserve their calling
+    // convention. However, to simplify runtime support, they clobber the same
+    // scratch registers as AnyRegCC.
+    unsigned CC = CallingConv::AnyReg;
+    if (Opc == TargetOpcode::PATCHPOINT) {
+      CC = Node->getConstantOperandVal(PatchPointOpers::CCPos);
+      NumDefs = NumResults;
+    }
     ScratchRegs = TLI->getScratchRegisters((CallingConv::ID) CC);
   }