[SPIR-V] Support 2 more instructions from SPV_INTEL_long_composites (#128190)

This change adds support for `OpSpecConstantCompositeContinuedINTEL` and
`OpCompositeConstructContinuedINTEL` instructions and continues work
done in #126545.

Specification:

https://github.khronos.org/SPIRV-Registry/extensions/INTEL/SPV_INTEL_long_composites.html

Author: vmaksimo

llvm/lib/Target/SPIRV/SPIRVBuiltins.cpp

@@ -2116,8 +2116,11 @@ static bool generateSelectInst(const SPIRV::IncomingCall *Call,
 static bool generateConstructInst(const SPIRV::IncomingCall *Call,
                                   MachineIRBuilder &MIRBuilder,
                                   SPIRVGlobalRegistry *GR) {
-  return buildOpFromWrapper(MIRBuilder, SPIRV::OpCompositeConstruct, Call,
-                            GR->getSPIRVTypeID(Call->ReturnType));
+  createContinuedInstructions(MIRBuilder, SPIRV::OpCompositeConstruct, 3,
+                              SPIRV::OpCompositeConstructContinuedINTEL,
+                              Call->Arguments, Call->ReturnRegister,
+                              GR->getSPIRVTypeID(Call->ReturnType));
+  return true;
 }
 
 static bool generateCoopMatrInst(const SPIRV::IncomingCall *Call,
@@ -2230,11 +2233,10 @@ static bool generateSpecConstantInst(const SPIRV::IncomingCall *Call,
     return true;
   }
   case SPIRV::OpSpecConstantComposite: {
-    auto MIB = MIRBuilder.buildInstr(Opcode)
-                   .addDef(Call->ReturnRegister)
-                   .addUse(GR->getSPIRVTypeID(Call->ReturnType));
-    for (unsigned i = 0; i < Call->Arguments.size(); i++)
-      MIB.addUse(Call->Arguments[i]);
+    createContinuedInstructions(MIRBuilder, Opcode, 3,
+                                SPIRV::OpSpecConstantCompositeContinuedINTEL,
+                                Call->Arguments, Call->ReturnRegister,
+                                GR->getSPIRVTypeID(Call->ReturnType));
     return true;
   }
   default:

llvm/lib/Target/SPIRV/SPIRVInstrInfo.cpp

@@ -55,6 +55,7 @@ bool SPIRVInstrInfo::isSpecConstantInstr(const MachineInstr &MI) const {
   case SPIRV::OpSpecConstantFalse:
   case SPIRV::OpSpecConstant:
   case SPIRV::OpSpecConstantComposite:
+  case SPIRV::OpSpecConstantCompositeContinuedINTEL:
   case SPIRV::OpSpecConstantOp:
     return true;
   default:

llvm/lib/Target/SPIRV/SPIRVUtils.cpp

@@ -800,4 +800,36 @@ bool isSpvIntrinsic(const Value *Arg) {
   return false;
 }
 
+// Function to create continued instructions for SPV_INTEL_long_composites
+// extension
+void createContinuedInstructions(MachineIRBuilder &MIRBuilder, unsigned Opcode,
+                                 unsigned MinWC, unsigned ContinuedOpcode,
+                                 ArrayRef<Register> Args,
+                                 Register ReturnRegister, Register TypeID) {
+  constexpr unsigned MaxWordCount = UINT16_MAX;
+  const size_t NumElements = Args.size();
+  size_t MaxNumElements = MaxWordCount - MinWC;
+  size_t SPIRVStructNumElements = NumElements;
+
+  if (NumElements > MaxNumElements) {
+    // Do adjustments for continued instructions which always had only one
+    // minumum word count.
+    SPIRVStructNumElements = MaxNumElements;
+    MaxNumElements = MaxWordCount - 1;
+  }
+
+  auto MIB =
+      MIRBuilder.buildInstr(Opcode).addDef(ReturnRegister).addUse(TypeID);
+
+  for (size_t I = 0; I < SPIRVStructNumElements; ++I)
+    MIB.addUse(Args[I]);
+
+  for (size_t I = SPIRVStructNumElements; I < NumElements;
+       I += MaxNumElements) {
+    auto MIB = MIRBuilder.buildInstr(ContinuedOpcode);
+    for (size_t J = I; J < std::min(I + MaxNumElements, NumElements); ++J)
+      MIB.addUse(Args[J]);
+  }
+}
+
 } // namespace llvm

llvm/lib/Target/SPIRV/SPIRVUtils.h

@@ -444,5 +444,10 @@ inline FPDecorationId demangledPostfixToDecorationId(const std::string &S) {
   return It == Mapping.end() ? FPDecorationId::NONE : It->second;
 }
 
+void createContinuedInstructions(MachineIRBuilder &MIRBuilder, unsigned Opcode,
+                                 unsigned MinWC, unsigned ContinuedOpcode,
+                                 ArrayRef<Register> Args,
+                                 Register ReturnRegister, Register TypeID);
+
 } // namespace llvm
 #endif // LLVM_LIB_TARGET_SPIRV_SPIRVUTILS_H