1 files changed, 23 insertions, 8 deletions
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 3a8fb85..1c596b8 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -220,10 +220,19 @@ void InstrEmitter::CreateVirtualRegisters(SDNode *Node,
     unsigned VRBase = 0;
     const TargetRegisterClass *RC =
       TRI->getAllocatableClass(TII->getRegClass(II, i, TRI, *MF));
-    // If the register class is unknown for the given definition, then try to
-    // infer one from the value type.
-    if (!RC && i < NumResults)
-      RC = TLI->getRegClassFor(Node->getSimpleValueType(i));
+    // Always let the value type influence the used register class. The
+    // constraints on the instruction may be too lax to represent the value
+    // type correctly. For example, a 64-bit float (X86::FR64) can't live in
+    // the 32-bit float super-class (X86::FR32).
+    if (i < NumResults && TLI->isTypeLegal(Node->getSimpleValueType(i))) {
+      const TargetRegisterClass *VTRC =
+        TLI->getRegClassFor(Node->getSimpleValueType(i));
+      if (RC)
+        VTRC = TRI->getCommonSubClass(RC, VTRC);
+      if (VTRC)
+        RC = VTRC;
+    }
+
     if (II.OpInfo[i].isOptionalDef()) {
       // Optional def must be a physical register.
       unsigned NumResults = CountResults(Node);
@@ -731,10 +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);
   }