[LLVM][TableGen] Support type casts of nodes with multiple results

Currently, type casts can only be used to pattern match for intrinsics with a single overloaded return value. For instance:
```
def int_foo : Intrinsic<[llvm_anyint_ty], []>;
def : Pat<(i32 (int_foo)), ...>;
```

This patch extends type casts to support matching intrinsics with multiple overloaded return values. As an example, the following defines a pattern that matches only if the overloaded intrinsic call returns an `i16` for the first result and an `i32` for the second result:
```
def int_bar : Intrinsic<[llvm_anyint_ty, llvm_anyint_ty], []>;
def : Pat<([i16, i32] (int_bar)), ...>;
```

Author: stephenchouca

llvm/lib/TableGen/TGParser.cpp

@@ -2844,11 +2844,13 @@ Init *TGParser::ParseSimpleValue(Record *CurRec, RecTy *ItemType,
 
     return ListInit::get(Vals, DeducedEltTy);
   }
-  case tgtok::l_paren: {         // Value ::= '(' IDValue DagArgList ')'
+  case tgtok::l_paren: {       // Value ::= '(' IDValue DagArgList ')'
+                               // Value ::= '(' '[' ValueList ']' DagArgList ')'
     Lex.Lex();   // eat the '('
     if (Lex.getCode() != tgtok::Id && Lex.getCode() != tgtok::XCast &&
-        Lex.getCode() != tgtok::question && Lex.getCode() != tgtok::XGetDagOp) {
-      TokError("expected identifier in dag init");
+        Lex.getCode() != tgtok::question && Lex.getCode() != tgtok::XGetDagOp &&
+        Lex.getCode() != tgtok::l_square) {
+      TokError("expected identifier or list of value types in dag init");
       return nullptr;
     }
 

llvm/test/TableGen/GlobalISelEmitter-multiple-type-casts.td

@@ -0,0 +1,29 @@
+// RUN: llvm-tblgen -gen-global-isel -optimize-match-table=false -warn-on-skipped-patterns -I %p/../../include -I %p/Common %s -o - < %s | FileCheck %s
+
+include "llvm/Target/Target.td"
+include "GlobalISelEmitterCommon.td"
+
+def REG : Register<"REG">;
+def GPR : RegisterClass<"MyTarget", [i16, i32], 32, (add REG)>;
+
+def int_foo : Intrinsic<[llvm_anyint_ty, llvm_anyint_ty], []>;
+
+def INSTR_FOO_I16_I32 : Instruction {
+  let OutOperandList = (outs GPR:$a, GPR:$b);
+  let InOperandList = (ins);
+}
+
+def INSTR_FOO_I32_I16 : Instruction {
+  let OutOperandList = (outs GPR:$a, GPR:$b);
+  let InOperandList = (ins);
+}
+
+// CHECK: GIM_RootCheckType, /*Op*/0, /*Type*/GILLT_s16
+// CHECK: GIM_RootCheckType, /*Op*/1, /*Type*/GILLT_s32
+// CHECK: GIR_BuildRootMI, /*Opcode*/GIMT_Encode2(::INSTR_FOO_I16_I32)
+def : Pat<([i16, i32] (int_foo)), ([i16, i32] (INSTR_FOO_I16_I32))>;
+
+// CHECK: GIM_RootCheckType, /*Op*/0, /*Type*/GILLT_s32
+// CHECK: GIM_RootCheckType, /*Op*/1, /*Type*/GILLT_s16
+// CHECK: GIR_BuildRootMI, /*Opcode*/GIMT_Encode2(::INSTR_FOO_I32_I16)
+def : Pat<([i32, i16] (int_foo)), ([i32, i16] (INSTR_FOO_I32_I16))>;

llvm/test/TableGen/dag-isel-multiple-type-casts.td

@@ -0,0 +1,34 @@
+// RUN: llvm-tblgen -gen-dag-isel -I %p/../../include %s | FileCheck %s
+
+include "llvm/Target/Target.td"
+
+def TestTargetInstrInfo : InstrInfo;
+
+def TestTarget : Target {
+  let InstructionSet = TestTargetInstrInfo;
+}
+
+def REG : Register<"REG">;
+def GPR : RegisterClass<"TestTarget", [i16, i32], 32, (add REG)>;
+
+def int_foo : Intrinsic<[llvm_anyint_ty, llvm_anyint_ty], []>;
+
+def INSTR_FOO_I16_I32 : Instruction {
+  let OutOperandList = (outs GPR:$a, GPR:$b);
+  let InOperandList = (ins);
+}
+
+def INSTR_FOO_I32_I16 : Instruction {
+  let OutOperandList = (outs GPR:$a, GPR:$b);
+  let InOperandList = (ins);
+}
+
+// CHECK: 7*/  OPC_SwitchType {{.*}}, 10, /*MVT::i16*/6
+// CHECK:       OPC_CheckTypeRes, 1, /*MVT::i32*/7
+// CHECK:       OPC_MorphNodeTo2Chain, TARGET_VAL(::INSTR_FOO_I16_I32)
+def : Pat<([i16, i32] (int_foo)), ([i16, i32] (INSTR_FOO_I16_I32))>;
+
+// CHECK: 20*/ /*SwitchType*/ {{.*}} /*MVT::i32*/7
+// CHECK:       OPC_CheckTypeRes, 1, /*MVT::i16*/6
+// CHECK:       OPC_MorphNodeTo2Chain, TARGET_VAL(::INSTR_FOO_I32_I16)
+def : Pat<([i32, i16] (int_foo)), ([i32, i16] (INSTR_FOO_I32_I16))>;

llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp

@@ -2896,6 +2896,35 @@ TreePatternNodePtr TreePattern::ParseTreePattern(Init *TheInit,
     error("Pattern has unexpected init kind!");
     return nullptr;
   }
+
+  auto ParseCastOperand = [this](DagInit *Dag, StringRef OpName) {
+    if (Dag->getNumArgs() != 1)
+      error("Type cast only takes one operand!");
+
+    if (!OpName.empty())
+      error("Type cast should not have a name!");
+
+    return ParseTreePattern(Dag->getArg(0), Dag->getArgNameStr(0));
+  };
+
+  if (ListInit *LI = dyn_cast<ListInit>(Dag->getOperator())) {
+    // If the operator is a list (of value types), then this must be "type cast"
+    // of a leaf node with multiple results.
+    TreePatternNodePtr New = ParseCastOperand(Dag, OpName);
+
+    unsigned NumTypes = New->getNumTypes();
+    if (NumTypes != LI->size())
+      error("Invalid number of type casts!");
+
+    // Apply the type casts.
+    const CodeGenHwModes &CGH = getDAGPatterns().getTargetInfo().getHwModes();
+    for (unsigned i = 0; i < NumTypes; ++i)
+      New->UpdateNodeType(
+          i, getValueTypeByHwMode(LI->getElementAsRecord(i), CGH), *this);
+
+    return New;
+  }
+
   DefInit *OpDef = dyn_cast<DefInit>(Dag->getOperator());
   if (!OpDef) {
     error("Pattern has unexpected operator type!");
@@ -2906,20 +2935,15 @@ TreePatternNodePtr TreePattern::ParseTreePattern(Init *TheInit,
   if (Operator->isSubClassOf("ValueType")) {
     // If the operator is a ValueType, then this must be "type cast" of a leaf
     // node.
-    if (Dag->getNumArgs() != 1)
-      error("Type cast only takes one operand!");
+    TreePatternNodePtr New = ParseCastOperand(Dag, OpName);
 
-    TreePatternNodePtr New =
-        ParseTreePattern(Dag->getArg(0), Dag->getArgNameStr(0));
+    if (New->getNumTypes() != 1)
+      error("ValueType cast can only have one type!");
 
     // Apply the type cast.
-    if (New->getNumTypes() != 1)
-      error("Type cast can only have one type!");
     const CodeGenHwModes &CGH = getDAGPatterns().getTargetInfo().getHwModes();
     New->UpdateNodeType(0, getValueTypeByHwMode(Operator, CGH), *this);
 
-    if (!OpName.empty())
-      error("ValueType cast should not have a name!");
     return New;
   }