[NVPTX] Improve lowering of v4i8 (#67866)

Make v4i8 a legal type and plumb through lowering of relevant instructions.

Author: Artem-B

llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXInstPrinter.cpp

@@ -309,3 +309,34 @@ void NVPTXInstPrinter::printProtoIdent(const MCInst *MI, int OpNum,
   const MCSymbol &Sym = cast<MCSymbolRefExpr>(Expr)->getSymbol();
   O << Sym.getName();
 }
+
+void NVPTXInstPrinter::printPrmtMode(const MCInst *MI, int OpNum,
+                                     raw_ostream &O, const char *Modifier) {
+  const MCOperand &MO = MI->getOperand(OpNum);
+  int64_t Imm = MO.getImm();
+
+  switch (Imm) {
+  default:
+    return;
+  case NVPTX::PTXPrmtMode::NONE:
+    break;
+  case NVPTX::PTXPrmtMode::F4E:
+    O << ".f4e";
+    break;
+  case NVPTX::PTXPrmtMode::B4E:
+    O << ".b4e";
+    break;
+  case NVPTX::PTXPrmtMode::RC8:
+    O << ".rc8";
+    break;
+  case NVPTX::PTXPrmtMode::ECL:
+    O << ".ecl";
+    break;
+  case NVPTX::PTXPrmtMode::ECR:
+    O << ".ecr";
+    break;
+  case NVPTX::PTXPrmtMode::RC16:
+    O << ".rc16";
+    break;
+  }
+}

llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXInstPrinter.h

@@ -47,6 +47,8 @@ class NVPTXInstPrinter : public MCInstPrinter {
                        raw_ostream &O, const char *Modifier = nullptr);
   void printProtoIdent(const MCInst *MI, int OpNum,
                        raw_ostream &O, const char *Modifier = nullptr);
+  void printPrmtMode(const MCInst *MI, int OpNum, raw_ostream &O,
+                     const char *Modifier = nullptr);
 };
 
 }

llvm/lib/Target/NVPTX/NVPTX.h

@@ -181,6 +181,18 @@ enum CmpMode {
   FTZ_FLAG = 0x100
 };
 }
+
+namespace PTXPrmtMode {
+enum PrmtMode {
+  NONE,
+  F4E,
+  B4E,
+  RC8,
+  ECL,
+  ECR,
+  RC16,
+};
+}
 }
 void initializeNVPTXDAGToDAGISelPass(PassRegistry &);
 } // namespace llvm

llvm/lib/Target/NVPTX/NVPTXISelDAGToDAG.cpp

@@ -14,6 +14,7 @@
 #include "MCTargetDesc/NVPTXBaseInfo.h"
 #include "NVPTXUtilities.h"
 #include "llvm/Analysis/ValueTracking.h"
+#include "llvm/CodeGen/ISDOpcodes.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicsNVPTX.h"
@@ -829,6 +830,7 @@ pickOpcodeForVT(MVT::SimpleValueType VT, unsigned Opcode_i8,
   case MVT::v2f16:
   case MVT::v2bf16:
   case MVT::v2i16:
+  case MVT::v4i8:
     return Opcode_i32;
   case MVT::f32:
     return Opcode_f32;
@@ -910,7 +912,8 @@ bool NVPTXDAGToDAGISel::tryLoad(SDNode *N) {
   // Vector Setting
   unsigned vecType = NVPTX::PTXLdStInstCode::Scalar;
   if (SimpleVT.isVector()) {
-    assert(Isv2x16VT(LoadedVT) && "Unexpected vector type");
+    assert((Isv2x16VT(LoadedVT) || LoadedVT == MVT::v4i8) &&
+           "Unexpected vector type");
     // v2f16/v2bf16/v2i16 is loaded using ld.b32
     fromTypeWidth = 32;
   }
@@ -1254,19 +1257,23 @@ bool NVPTXDAGToDAGISel::tryLDGLDU(SDNode *N) {
   SDLoc DL(N);
   SDNode *LD;
   SDValue Base, Offset, Addr;
+  EVT OrigType = N->getValueType(0);
 
   EVT EltVT = Mem->getMemoryVT();
   unsigned NumElts = 1;
   if (EltVT.isVector()) {
     NumElts = EltVT.getVectorNumElements();
     EltVT = EltVT.getVectorElementType();
     // vectors of 16bits type are loaded/stored as multiples of v2x16 elements.
-    if ((EltVT == MVT::f16 && N->getValueType(0) == MVT::v2f16) ||
-        (EltVT == MVT::bf16 && N->getValueType(0) == MVT::v2bf16) ||
-        (EltVT == MVT::i16 && N->getValueType(0) == MVT::v2i16)) {
+    if ((EltVT == MVT::f16 && OrigType == MVT::v2f16) ||
+        (EltVT == MVT::bf16 && OrigType == MVT::v2bf16) ||
+        (EltVT == MVT::i16 && OrigType == MVT::v2i16)) {
       assert(NumElts % 2 == 0 && "Vector must have even number of elements");
-      EltVT = N->getValueType(0);
+      EltVT = OrigType;
       NumElts /= 2;
+    } else if (OrigType == MVT::v4i8) {
+      EltVT = OrigType;
+      NumElts = 1;
     }
   }
 
@@ -1601,7 +1608,6 @@ bool NVPTXDAGToDAGISel::tryLDGLDU(SDNode *N) {
   // concept of sign-/zero-extension, so emulate it here by adding an explicit
   // CVT instruction. Ptxas should clean up any redundancies here.
 
-  EVT OrigType = N->getValueType(0);
   LoadSDNode *LdNode = dyn_cast<LoadSDNode>(N);
 
   if (OrigType != EltVT &&
@@ -1679,7 +1685,8 @@ bool NVPTXDAGToDAGISel::tryStore(SDNode *N) {
   MVT ScalarVT = SimpleVT.getScalarType();
   unsigned toTypeWidth = ScalarVT.getSizeInBits();
   if (SimpleVT.isVector()) {
-    assert(Isv2x16VT(StoreVT) && "Unexpected vector type");
+    assert((Isv2x16VT(StoreVT) || StoreVT == MVT::v4i8) &&
+           "Unexpected vector type");
     // v2x16 is stored using st.b32
     toTypeWidth = 32;
   }