[llvm] [NVPTX] Use v2.u64 to load/store 128-bit values (PR #136638)

[Artem Belevich via llvm-commits]

================
@@ -1168,60 +1168,54 @@ static bool isVectorElementTypeUpsized(EVT EltVT) {
 
 bool NVPTXDAGToDAGISel::tryLoadVector(SDNode *N) {
   MemSDNode *MemSD = cast<MemSDNode>(N);
-  EVT LoadedVT = MemSD->getMemoryVT();
-  if (!LoadedVT.isSimple())
+  const EVT MemEVT = MemSD->getMemoryVT();
+  if (!MemEVT.isSimple())
     return false;
+  const MVT MemVT = MemEVT.getSimpleVT();
 
   // Address Space Setting
   unsigned int CodeAddrSpace = getCodeAddrSpace(MemSD);
   if (canLowerToLDG(MemSD, *Subtarget, CodeAddrSpace, MF)) {
     return tryLDGLDU(N);
   }
 
+  EVT EltVT = N->getValueType(0);
   SDLoc DL(N);
   SDValue Chain = N->getOperand(0);
   auto [Ordering, Scope] = insertMemoryInstructionFence(DL, Chain, MemSD);
 
-  // Vector Setting
-  MVT SimpleVT = LoadedVT.getSimpleVT();
-
   // Type Setting: fromType + fromTypeWidth
   //
   // Sign   : ISD::SEXTLOAD
   // Unsign : ISD::ZEXTLOAD, ISD::NON_EXTLOAD or ISD::EXTLOAD and the
   //          type is integer
   // Float  : ISD::NON_EXTLOAD or ISD::EXTLOAD and the type is float
-  MVT ScalarVT = SimpleVT.getScalarType();
   // Read at least 8 bits (predicates are stored as 8-bit values)
-  unsigned FromTypeWidth = std::max(8U, (unsigned)ScalarVT.getSizeInBits());
-  unsigned int FromType;
   // The last operand holds the original LoadSDNode::getExtensionType() value
-  unsigned ExtensionType = cast<ConstantSDNode>(
-      N->getOperand(N->getNumOperands() - 1))->getZExtValue();
-  if (ExtensionType == ISD::SEXTLOAD)
-    FromType = NVPTX::PTXLdStInstCode::Signed;
-  else
-    FromType = getLdStRegType(ScalarVT);
+  const unsigned TotalWidth = MemVT.getSizeInBits();
+  unsigned ExtensionType = N->getConstantOperandVal(N->getNumOperands() - 1);
+  unsigned FromType = (ExtensionType == ISD::SEXTLOAD)
+                          ? NVPTX::PTXLdStInstCode::Signed
+                          : getLdStRegType(MemVT.getScalarType());
 
   unsigned VecType;
-
+  unsigned FromTypeWidth;
   switch (N->getOpcode()) {
   case NVPTXISD::LoadV2:
+    FromTypeWidth = TotalWidth / 2;
     VecType = NVPTX::PTXLdStInstCode::V2;
     break;
   case NVPTXISD::LoadV4:
+    FromTypeWidth = TotalWidth / 4;
     VecType = NVPTX::PTXLdStInstCode::V4;
     break;
   default:
     return false;
   }
 
-  EVT EltVT = N->getValueType(0);
-
   if (isVectorElementTypeUpsized(EltVT)) {
----------------
Artem-B wrote:

We should probably rename it to something more meaningful. `isSubVectorPackedInI32`?
Otherwise it's not clear why we're using i32 here without having to go and look at the implementation.

https://github.com/llvm/llvm-project/pull/136638