[TableGen] Handle (outs variable_ops)

When `variable_ops` is specified in `InOperandList` of instruction,
it behaves as expected, i.e., does not count as operand.
So for `(ins variable_ops)` instruction description will have 0
operands.  However when used in OutOperandList it is counted as
operand. So `(outs variable_ops)` results in instruction with
one def.
This patch makes behavior of `variable_ops` in `out` list to match
that of `in` list.

Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D81095

diff --git a/llvm/utils/TableGen/CodeGenInstruction.cpp b/llvm/utils/TableGen/CodeGenInstruction.cpp
index b97193d..1df5902 100644 (file)
--- a/llvm/utils/TableGen/CodeGenInstruction.cpp
+++ b/llvm/utils/TableGen/CodeGenInstruction.cpp
@@ -56,6 +56,7 @@ CGIOperandList::CGIOperandList(Record *R) : TheDef(R) {
   std::set<std::string> OperandNames;
   unsigned e = InDI->getNumArgs() + OutDI->getNumArgs();
   OperandList.reserve(e);
+  bool VariadicOuts = false;
   for (unsigned i = 0; i != e; ++i){
     Init *ArgInit;
     StringRef ArgName;
@@ -109,6 +110,8 @@ CGIOperandList::CGIOperandList(Record *R) : TheDef(R) {
       else if (Rec->isSubClassOf("OptionalDefOperand"))
         hasOptionalDef = true;
     } else if (Rec->getName() == "variable_ops") {
+      if (i < NumDefs)
+        VariadicOuts = true;
       isVariadic = true;
       continue;
     } else if (Rec->isSubClassOf("RegisterClass")) {
@@ -137,6 +140,8 @@ CGIOperandList::CGIOperandList(Record *R) : TheDef(R) {
     MIOperandNo += NumOps;
   }
 
+  if (VariadicOuts)
+    --NumDefs;
 
   // Make sure the constraints list for each operand is large enough to hold
   // constraint info, even if none is present.