[SPIR-V] Fix illegal OpConstantComposite instruction with non-const constituents in SPIR-V Backend (#86352)

This PR fixes illegal use of OpConstantComposite with non-constant
constituents. The test attached to the PR is able now to satisfy
`spirv-val` check. Before the fix SPIR-V Backend produced for the
attached test case a pattern like
```
%a = OpVariable %_ptr_CrossWorkgroup_uint CrossWorkgroup %uint_123
%11 = OpConstantComposite %_struct_6 %a %a
```
so that `spirv-val` complained with
```
error: line 25: OpConstantComposite Constituent <id> '10[%a]' is not a constant or undef.
  %11 = OpConstantComposite %_struct_6 %a %a
```

Author: VyacheslavLevytskyy

llvm/lib/Target/SPIRV/SPIRVDuplicatesTracker.cpp

@@ -39,6 +39,7 @@ void SPIRVGeneralDuplicatesTracker::buildDepsGraph(
   prebuildReg2Entry(GT, Reg2Entry);
   prebuildReg2Entry(FT, Reg2Entry);
   prebuildReg2Entry(AT, Reg2Entry);
+  prebuildReg2Entry(MT, Reg2Entry);
   prebuildReg2Entry(ST, Reg2Entry);
 
   for (auto &Op2E : Reg2Entry) {

llvm/lib/Target/SPIRV/SPIRVDuplicatesTracker.h

@@ -262,6 +262,7 @@ class SPIRVGeneralDuplicatesTracker {
   SPIRVDuplicatesTracker<GlobalVariable> GT;
   SPIRVDuplicatesTracker<Function> FT;
   SPIRVDuplicatesTracker<Argument> AT;
+  SPIRVDuplicatesTracker<MachineInstr> MT;
   SPIRVDuplicatesTracker<SPIRV::SpecialTypeDescriptor> ST;
 
   // NOTE: using MOs instead of regs to get rid of MF dependency to be able
@@ -306,6 +307,10 @@ class SPIRVGeneralDuplicatesTracker {
     AT.add(Arg, MF, R);
   }
 
+  void add(const MachineInstr *MI, const MachineFunction *MF, Register R) {
+    MT.add(MI, MF, R);
+  }
+
   void add(const SPIRV::SpecialTypeDescriptor &TD, const MachineFunction *MF,
            Register R) {
     ST.add(TD, MF, R);
@@ -337,6 +342,10 @@ class SPIRVGeneralDuplicatesTracker {
     return AT.find(const_cast<Argument *>(Arg), MF);
   }
 
+  Register find(const MachineInstr *MI, const MachineFunction *MF) {
+    return MT.find(const_cast<MachineInstr *>(MI), MF);
+  }
+
   Register find(const SPIRV::SpecialTypeDescriptor &TD,
                 const MachineFunction *MF) {
     return ST.find(TD, MF);

llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp

@@ -123,6 +123,7 @@ SPIRVType *SPIRVGlobalRegistry::getOpTypeVector(uint32_t NumElems,
                                                 SPIRVType *ElemType,
                                                 MachineIRBuilder &MIRBuilder) {
   auto EleOpc = ElemType->getOpcode();
+  (void)EleOpc;
   assert((EleOpc == SPIRV::OpTypeInt || EleOpc == SPIRV::OpTypeFloat ||
           EleOpc == SPIRV::OpTypeBool) &&
          "Invalid vector element type");

llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.h

@@ -94,6 +94,14 @@ class SPIRVGlobalRegistry {
     DT.add(Arg, MF, R);
   }
 
+  void add(const MachineInstr *MI, MachineFunction *MF, Register R) {
+    DT.add(MI, MF, R);
+  }
+
+  Register find(const MachineInstr *MI, MachineFunction *MF) {
+    return DT.find(MI, MF);
+  }
+
   Register find(const Constant *C, MachineFunction *MF) {
     return DT.find(C, MF);
   }

llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp

@@ -231,6 +231,9 @@ class SPIRVInstructionSelector : public InstructionSelector {
   Register buildZerosVal(const SPIRVType *ResType, MachineInstr &I) const;
   Register buildOnesVal(bool AllOnes, const SPIRVType *ResType,
                         MachineInstr &I) const;
+
+  bool wrapIntoSpecConstantOp(MachineInstr &I,
+                              SmallVector<Register> &CompositeArgs) const;
 };
 
 } // end anonymous namespace
@@ -1249,6 +1252,24 @@ static unsigned getArrayComponentCount(MachineRegisterInfo *MRI,
   return N;
 }
 
+// Return true if the type represents a constant register
+static bool isConstReg(MachineRegisterInfo *MRI, SPIRVType *OpDef) {
+  if (OpDef->getOpcode() == SPIRV::ASSIGN_TYPE &&
+      OpDef->getOperand(1).isReg()) {
+    if (SPIRVType *RefDef = MRI->getVRegDef(OpDef->getOperand(1).getReg()))
+      OpDef = RefDef;
+  }
+  return OpDef->getOpcode() == TargetOpcode::G_CONSTANT ||
+         OpDef->getOpcode() == TargetOpcode::G_FCONSTANT;
+}
+
+// Return true if the virtual register represents a constant
+static bool isConstReg(MachineRegisterInfo *MRI, Register OpReg) {
+  if (SPIRVType *OpDef = MRI->getVRegDef(OpReg))
+    return isConstReg(MRI, OpDef);
+  return false;
+}
+
 bool SPIRVInstructionSelector::selectSplatVector(Register ResVReg,
                                                  const SPIRVType *ResType,
                                                  MachineInstr &I) const {
@@ -1266,16 +1287,7 @@ bool SPIRVInstructionSelector::selectSplatVector(Register ResVReg,
 
   // check if we may construct a constant vector
   Register OpReg = I.getOperand(OpIdx).getReg();
-  bool IsConst = false;
-  if (SPIRVType *OpDef = MRI->getVRegDef(OpReg)) {
-    if (OpDef->getOpcode() == SPIRV::ASSIGN_TYPE &&
-        OpDef->getOperand(1).isReg()) {
-      if (SPIRVType *RefDef = MRI->getVRegDef(OpDef->getOperand(1).getReg()))
-        OpDef = RefDef;
-    }
-    IsConst = OpDef->getOpcode() == TargetOpcode::G_CONSTANT ||
-              OpDef->getOpcode() == TargetOpcode::G_FCONSTANT;
-  }
+  bool IsConst = isConstReg(MRI, OpReg);
 
   if (!IsConst && N < 2)
     report_fatal_error(
@@ -1628,6 +1640,48 @@ bool SPIRVInstructionSelector::selectGEP(Register ResVReg,
   return Res.constrainAllUses(TII, TRI, RBI);
 }
 
+// Maybe wrap a value into OpSpecConstantOp
+bool SPIRVInstructionSelector::wrapIntoSpecConstantOp(
+    MachineInstr &I, SmallVector<Register> &CompositeArgs) const {
+  bool Result = true;
+  unsigned Lim = I.getNumExplicitOperands();
+  for (unsigned i = I.getNumExplicitDefs() + 1; i < Lim; ++i) {
+    Register OpReg = I.getOperand(i).getReg();
+    SPIRVType *OpDefine = MRI->getVRegDef(OpReg);
+    SPIRVType *OpType = GR.getSPIRVTypeForVReg(OpReg);
+    if (!OpDefine || !OpType || isConstReg(MRI, OpDefine) ||
+        OpDefine->getOpcode() == TargetOpcode::G_ADDRSPACE_CAST) {
+      // The case of G_ADDRSPACE_CAST inside spv_const_composite() is processed
+      // by selectAddrSpaceCast()
+      CompositeArgs.push_back(OpReg);
+      continue;
+    }
+    MachineFunction *MF = I.getMF();
+    Register WrapReg = GR.find(OpDefine, MF);
+    if (WrapReg.isValid()) {
+      CompositeArgs.push_back(WrapReg);
+      continue;
+    }
+    // Create a new register for the wrapper
+    WrapReg = MRI->createVirtualRegister(&SPIRV::IDRegClass);
+    GR.add(OpDefine, MF, WrapReg);
+    CompositeArgs.push_back(WrapReg);
+    // Decorate the wrapper register and generate a new instruction
+    MRI->setType(WrapReg, LLT::pointer(0, 32));
+    GR.assignSPIRVTypeToVReg(OpType, WrapReg, *MF);
+    MachineBasicBlock &BB = *I.getParent();
+    Result = BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpSpecConstantOp))
+                 .addDef(WrapReg)
+                 .addUse(GR.getSPIRVTypeID(OpType))
+                 .addImm(static_cast<uint32_t>(SPIRV::Opcode::Bitcast))
+                 .addUse(OpReg)
+                 .constrainAllUses(TII, TRI, RBI);
+    if (!Result)
+      break;
+  }
+  return Result;
+}
+
 bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
                                                const SPIRVType *ResType,
                                                MachineInstr &I) const {
@@ -1666,17 +1720,21 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
   case Intrinsic::spv_const_composite: {
     // If no values are attached, the composite is null constant.
     bool IsNull = I.getNumExplicitDefs() + 1 == I.getNumExplicitOperands();
-    unsigned Opcode =
-        IsNull ? SPIRV::OpConstantNull : SPIRV::OpConstantComposite;
+    // Select a proper instruction.
+    unsigned Opcode = SPIRV::OpConstantNull;
+    SmallVector<Register> CompositeArgs;
+    if (!IsNull) {
+      Opcode = SPIRV::OpConstantComposite;
+      if (!wrapIntoSpecConstantOp(I, CompositeArgs))
+        return false;
+    }
     auto MIB = BuildMI(BB, I, I.getDebugLoc(), TII.get(Opcode))
                    .addDef(ResVReg)
                    .addUse(GR.getSPIRVTypeID(ResType));
     // skip type MD node we already used when generated assign.type for this
     if (!IsNull) {
-      for (unsigned i = I.getNumExplicitDefs() + 1;
-           i < I.getNumExplicitOperands(); ++i) {
-        MIB.addUse(I.getOperand(i).getReg());
-      }
+      for (Register OpReg : CompositeArgs)
+        MIB.addUse(OpReg);
     }
     return MIB.constrainAllUses(TII, TRI, RBI);
   }

llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp

@@ -543,6 +543,7 @@ static void processSwitches(MachineFunction &MF, SPIRVGlobalRegistry *GR,
       Register Dst = ICMP->getOperand(0).getReg();
       MachineOperand &PredOp = ICMP->getOperand(1);
       const auto CC = static_cast<CmpInst::Predicate>(PredOp.getPredicate());
+      (void)CC;
       assert((CC == CmpInst::ICMP_EQ || CC == CmpInst::ICMP_ULE) &&
              MRI.hasOneUse(Dst) && MRI.hasOneDef(CompareReg));
       uint64_t Value = getIConstVal(ICMP->getOperand(3).getReg(), &MRI);

llvm/lib/Target/SPIRV/SPIRVSymbolicOperands.td

@@ -1611,3 +1611,4 @@ multiclass OpcodeOperand<bits<32> value> {
 // TODO: implement other mnemonics.
 defm InBoundsPtrAccessChain : OpcodeOperand<70>;
 defm PtrCastToGeneric : OpcodeOperand<121>;
+defm Bitcast : OpcodeOperand<124>;

llvm/test/CodeGen/SPIRV/pointers/struct-opaque-pointers.ll

@@ -1,5 +1,5 @@
 ; RUN: llc -O0 -mtriple=spirv32-unknown-unknown %s -o - | FileCheck %s
-; TODO: %if spirv-tools %{ llc -O0 -mtriple=spirv32-unknown-unknown %s -o - -filetype=obj | spirv-val %}
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv32-unknown-unknown %s -o - -filetype=obj | spirv-val %}
 
 ; CHECK: %[[TyInt8:.*]] = OpTypeInt 8 0
 ; CHECK: %[[TyInt8Ptr:.*]] = OpTypePointer {{[a-zA-Z]+}} %[[TyInt8]]