[SPIRV] Expand RWBuffer load and store from HLSL

The code pattern that clang will generate for HLSL has changed from the
original plan. This allows the SPIR-V backend to generate code for the
current code generation.

It looks for patterns of the form:

```
%1 = @llvm.spv.resource.handlefrombinding
%2 = @llvm.spv.resource.getpointer(%1, index)
load/store %2
```

These three llvm-ir instruction are treated as a single unit that will

1. Generate or find the global variable identified by the call to
   `resource.handlefrombinding`.
2. Generate an OpLoad of the variable to get the handle to the image.
3. Generate an OpImageRead or OpImageWrite using that handle with the
   given index.

This will generate the OpLoad in the same BB as the read/write.

Note: Now that `resource.handlefrombinding` is not processed on its own,
many existing tests had to be removed. We do not have intrinsics that
are able to use handles to sampled images, input attachments, etc., so
we cannot generate the load of the handle. These tests are removed for
now, and will be added when those resource types are fully implemented.

Author: s-perron

llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp

@@ -264,7 +264,14 @@ bool expectIgnoredInIRTranslation(const Instruction *I) {
   const auto *II = dyn_cast<IntrinsicInst>(I);
   if (!II)
     return false;
-  return II->getIntrinsicID() == Intrinsic::invariant_start;
+  switch (II->getIntrinsicID()) {
+  case Intrinsic::invariant_start:
+  case Intrinsic::spv_resource_handlefrombinding:
+  case Intrinsic::spv_resource_getpointer:
+    return true;
+  default:
+    return false;
+  }
 }
 
 bool allowEmitFakeUse(const Value *Arg) {
@@ -725,6 +732,14 @@ Type *SPIRVEmitIntrinsics::deduceElementTypeHelper(
       if (Ty)
         break;
     }
+  } else if (auto *II = dyn_cast<IntrinsicInst>(I)) {
+    if (II->getIntrinsicID() == Intrinsic::spv_resource_getpointer) {
+      auto *ImageType = cast<TargetExtType>(II->getOperand(0)->getType());
+      assert(ImageType->getTargetExtName() == "spirv.Image");
+      Ty = ImageType->getTypeParameter(0);
+      // TODO: Need to look at the use to see if it needs to be a vector of the
+      // type.
+    }
   } else if (auto *CI = dyn_cast<CallInst>(I)) {
     static StringMap<unsigned> ResTypeByArg = {
         {"to_global", 0},

llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp

@@ -1114,9 +1114,12 @@ SPIRVGlobalRegistry::getSPIRVTypeForVReg(Register VReg,
   return nullptr;
 }
 
-SPIRVType *SPIRVGlobalRegistry::getResultType(Register VReg) {
-  MachineInstr *Instr = getVRegDef(CurMF->getRegInfo(), VReg);
-  return getSPIRVTypeForVReg(Instr->getOperand(1).getReg());
+SPIRVType *SPIRVGlobalRegistry::getResultType(Register VReg,
+                                              MachineFunction *MF) {
+  if (!MF)
+    MF = CurMF;
+  MachineInstr *Instr = getVRegDef(MF->getRegInfo(), VReg);
+  return getSPIRVTypeForVReg(Instr->getOperand(1).getReg(), MF);
 }
 
 SPIRVType *SPIRVGlobalRegistry::getOrCreateSPIRVType(

llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.h

@@ -377,7 +377,7 @@ class SPIRVGlobalRegistry {
                                  const MachineFunction *MF = nullptr) const;
 
   // Return the result type of the instruction defining the register.
-  SPIRVType *getResultType(Register VReg);
+  SPIRVType *getResultType(Register VReg, MachineFunction *MF = nullptr);
 
   // Whether the given VReg has a SPIR-V type mapped to it yet.
   bool hasSPIRVTypeForVReg(Register VReg) const {

llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp

@@ -276,8 +276,9 @@ class SPIRVInstructionSelector : public InstructionSelector {
 
   bool selectReadImageIntrinsic(Register &ResVReg, const SPIRVType *ResType,
                                 MachineInstr &I) const;
-
   bool selectImageWriteIntrinsic(MachineInstr &I) const;
+  bool selectResourceGetPointer(Register &ResVReg, const SPIRVType *ResType,
+                                MachineInstr &I) const;
 
   // Utilities
   std::pair<Register, bool>
@@ -307,10 +308,15 @@ class SPIRVInstructionSelector : public InstructionSelector {
   SPIRVType *widenTypeToVec4(const SPIRVType *Type, MachineInstr &I) const;
   bool extractSubvector(Register &ResVReg, const SPIRVType *ResType,
                         Register &ReadReg, MachineInstr &InsertionPoint) const;
+  bool generateImageRead(Register &ResVReg, const SPIRVType *ResType,
+                         Register ImageReg, Register IdxReg, DebugLoc Loc,
+                         MachineInstr &Pos) const;
   bool BuildCOPY(Register DestReg, Register SrcReg, MachineInstr &I) const;
   bool loadVec3BuiltinInputID(SPIRV::BuiltIn::BuiltIn BuiltInValue,
                               Register ResVReg, const SPIRVType *ResType,
                               MachineInstr &I) const;
+  bool loadHandleBeforePosition(Register &HandleReg, const SPIRVType *ResType,
+                                GIntrinsic &HandleDef, MachineInstr &Pos) const;
 };
 
 } // end anonymous namespace
@@ -1018,6 +1024,25 @@ bool SPIRVInstructionSelector::selectLoad(Register ResVReg,
                                           MachineInstr &I) const {
   unsigned OpOffset = isa<GIntrinsic>(I) ? 1 : 0;
   Register Ptr = I.getOperand(1 + OpOffset).getReg();
+
+  auto *PtrDef = getVRegDef(*MRI, Ptr);
+  auto *IntPtrDef = dyn_cast<GIntrinsic>(PtrDef);
+  if (IntPtrDef &&
+      IntPtrDef->getIntrinsicID() == Intrinsic::spv_resource_getpointer) {
+    Register ImageReg = IntPtrDef->getOperand(2).getReg();
+    Register NewImageReg =
+        MRI->createVirtualRegister(MRI->getRegClass(ImageReg));
+    auto *ImageDef = cast<GIntrinsic>(getVRegDef(*MRI, ImageReg));
+    if (!loadHandleBeforePosition(NewImageReg, GR.getSPIRVTypeForVReg(ImageReg),
+                                  *ImageDef, I)) {
+      return false;
+    }
+
+    Register IdxReg = IntPtrDef->getOperand(3).getReg();
+    return generateImageRead(ResVReg, ResType, NewImageReg, IdxReg,
+                             I.getDebugLoc(), I);
+  }
+
   auto MIB = BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(SPIRV::OpLoad))
                  .addDef(ResVReg)
                  .addUse(GR.getSPIRVTypeID(ResType))
@@ -1037,6 +1062,29 @@ bool SPIRVInstructionSelector::selectStore(MachineInstr &I) const {
   unsigned OpOffset = isa<GIntrinsic>(I) ? 1 : 0;
   Register StoreVal = I.getOperand(0 + OpOffset).getReg();
   Register Ptr = I.getOperand(1 + OpOffset).getReg();
+
+  auto *PtrDef = getVRegDef(*MRI, Ptr);
+  auto *IntPtrDef = dyn_cast<GIntrinsic>(PtrDef);
+  if (IntPtrDef &&
+      IntPtrDef->getIntrinsicID() == Intrinsic::spv_resource_getpointer) {
+    Register ImageReg = IntPtrDef->getOperand(2).getReg();
+    Register NewImageReg =
+        MRI->createVirtualRegister(MRI->getRegClass(ImageReg));
+    auto *ImageDef = cast<GIntrinsic>(getVRegDef(*MRI, ImageReg));
+    if (!loadHandleBeforePosition(NewImageReg, GR.getSPIRVTypeForVReg(ImageReg),
+                                  *ImageDef, I)) {
+      return false;
+    }
+
+    Register IdxReg = IntPtrDef->getOperand(3).getReg();
+    return BuildMI(*I.getParent(), I, I.getDebugLoc(),
+                   TII.get(SPIRV::OpImageWrite))
+        .addUse(NewImageReg)
+        .addUse(IdxReg)
+        .addUse(StoreVal)
+        .constrainAllUses(TII, TRI, RBI);
+  }
+
   MachineBasicBlock &BB = *I.getParent();
   auto MIB = BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpStore))
                  .addUse(Ptr)
@@ -3007,6 +3055,9 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
   case Intrinsic::spv_resource_load_typedbuffer: {
     return selectReadImageIntrinsic(ResVReg, ResType, I);
   }
+  case Intrinsic::spv_resource_getpointer: {
+    return selectResourceGetPointer(ResVReg, ResType, I);
+  }
   case Intrinsic::spv_discard: {
     return selectDiscard(ResVReg, ResType, I);
   }
@@ -3024,27 +3075,7 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
 bool SPIRVInstructionSelector::selectHandleFromBinding(Register &ResVReg,
                                                        const SPIRVType *ResType,
                                                        MachineInstr &I) const {
-
-  uint32_t Set = foldImm(I.getOperand(2), MRI);
-  uint32_t Binding = foldImm(I.getOperand(3), MRI);
-  uint32_t ArraySize = foldImm(I.getOperand(4), MRI);
-  Register IndexReg = I.getOperand(5).getReg();
-  bool IsNonUniform = ArraySize > 1 && foldImm(I.getOperand(6), MRI);
-
-  MachineIRBuilder MIRBuilder(I);
-  Register VarReg = buildPointerToResource(ResType, Set, Binding, ArraySize,
-                                           IndexReg, IsNonUniform, MIRBuilder);
-
-  if (IsNonUniform)
-    buildOpDecorate(ResVReg, I, TII, SPIRV::Decoration::NonUniformEXT, {});
-
-  // TODO: For now we assume the resource is an image, which needs to be
-  // loaded to get the handle. That will not be true for storage buffers.
-  return BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(SPIRV::OpLoad))
-      .addDef(ResVReg)
-      .addUse(GR.getSPIRVTypeID(ResType))
-      .addUse(VarReg)
-      .constrainAllUses(TII, TRI, RBI);
+  return true;
 }
 
 bool SPIRVInstructionSelector::selectReadImageIntrinsic(
@@ -3057,42 +3088,75 @@ bool SPIRVInstructionSelector::selectReadImageIntrinsic(
   // We will do that when we can, but for now trying to move forward with other
   // issues.
   Register ImageReg = I.getOperand(2).getReg();
-  assert(MRI->getVRegDef(ImageReg)->getParent() == I.getParent() &&
-         "The image must be loaded in the same basic block as its use.");
+  auto *ImageDef = cast<GIntrinsic>(getVRegDef(*MRI, ImageReg));
+  Register NewImageReg = MRI->createVirtualRegister(MRI->getRegClass(ImageReg));
+  if (!loadHandleBeforePosition(NewImageReg, GR.getSPIRVTypeForVReg(ImageReg),
+                                *ImageDef, I)) {
+    return false;
+  }
+
+  Register IdxReg = I.getOperand(3).getReg();
+  DebugLoc Loc = I.getDebugLoc();
+  MachineInstr &Pos = I;
 
+  return generateImageRead(ResVReg, ResType, NewImageReg, IdxReg, Loc, Pos);
+}
+
+bool SPIRVInstructionSelector::generateImageRead(Register &ResVReg,
+                                                 const SPIRVType *ResType,
+                                                 Register ImageReg,
+                                                 Register IdxReg, DebugLoc Loc,
+                                                 MachineInstr &Pos) const {
   uint64_t ResultSize = GR.getScalarOrVectorComponentCount(ResType);
   if (ResultSize == 4) {
-    return BuildMI(*I.getParent(), I, I.getDebugLoc(),
-                   TII.get(SPIRV::OpImageRead))
+    return BuildMI(*Pos.getParent(), Pos, Loc, TII.get(SPIRV::OpImageRead))
         .addDef(ResVReg)
         .addUse(GR.getSPIRVTypeID(ResType))
         .addUse(ImageReg)
-        .addUse(I.getOperand(3).getReg())
+        .addUse(IdxReg)
         .constrainAllUses(TII, TRI, RBI);
   }
 
-  SPIRVType *ReadType = widenTypeToVec4(ResType, I);
+  SPIRVType *ReadType = widenTypeToVec4(ResType, Pos);
   Register ReadReg = MRI->createVirtualRegister(GR.getRegClass(ReadType));
   bool Succeed =
-      BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(SPIRV::OpImageRead))
+      BuildMI(*Pos.getParent(), Pos, Loc, TII.get(SPIRV::OpImageRead))
           .addDef(ReadReg)
           .addUse(GR.getSPIRVTypeID(ReadType))
           .addUse(ImageReg)
-          .addUse(I.getOperand(3).getReg())
+          .addUse(IdxReg)
           .constrainAllUses(TII, TRI, RBI);
   if (!Succeed)
     return false;
 
   if (ResultSize == 1) {
-    return BuildMI(*I.getParent(), I, I.getDebugLoc(),
+    return BuildMI(*Pos.getParent(), Pos, Loc,
                    TII.get(SPIRV::OpCompositeExtract))
         .addDef(ResVReg)
         .addUse(GR.getSPIRVTypeID(ResType))
         .addUse(ReadReg)
         .addImm(0)
         .constrainAllUses(TII, TRI, RBI);
   }
-  return extractSubvector(ResVReg, ResType, ReadReg, I);
+  return extractSubvector(ResVReg, ResType, ReadReg, Pos);
+}
+
+bool SPIRVInstructionSelector::selectResourceGetPointer(
+    Register &ResVReg, const SPIRVType *ResType, MachineInstr &I) const {
+#ifdef ASSERT
+  // For now, the operand is an image. This will change once we start handling
+  // more resource types.
+  Register ResourcePtr = I.getOperand(2).getReg();
+  SPIRVType *RegType = GR.getResultType(ResourcePtr);
+  assert(RegType->getOpcode() == SPIRV::OpTypeImage &&
+         "Can only handle texel buffers for now.");
+#endif
+
+  // For texel buffers, the index into the image is part of the OpImageRead or
+  // OpImageWrite instructions. So we will do nothing in this case. This
+  // intrinsic will be combined with the load or store when selecting the load
+  // or store.
+  return true;
 }
 
 bool SPIRVInstructionSelector::extractSubvector(
@@ -3144,15 +3208,20 @@ bool SPIRVInstructionSelector::selectImageWriteIntrinsic(
   // We will do that when we can, but for now trying to move forward with other
   // issues.
   Register ImageReg = I.getOperand(1).getReg();
-  assert(MRI->getVRegDef(ImageReg)->getParent() == I.getParent() &&
-         "The image must be loaded in the same basic block as its use.");
+  auto *ImageDef = cast<GIntrinsic>(getVRegDef(*MRI, ImageReg));
+  Register NewImageReg = MRI->createVirtualRegister(MRI->getRegClass(ImageReg));
+  if (!loadHandleBeforePosition(NewImageReg, GR.getSPIRVTypeForVReg(ImageReg),
+                                *ImageDef, I)) {
+    return false;
+  }
+
   Register CoordinateReg = I.getOperand(2).getReg();
   Register DataReg = I.getOperand(3).getReg();
   assert(GR.getResultType(DataReg)->getOpcode() == SPIRV::OpTypeVector);
   assert(GR.getScalarOrVectorComponentCount(GR.getResultType(DataReg)) == 4);
   return BuildMI(*I.getParent(), I, I.getDebugLoc(),
                  TII.get(SPIRV::OpImageWrite))
-      .addUse(ImageReg)
+      .addUse(NewImageReg)
       .addUse(CoordinateReg)
       .addUse(DataReg)
       .constrainAllUses(TII, TRI, RBI);
@@ -3677,6 +3746,36 @@ SPIRVType *SPIRVInstructionSelector::widenTypeToVec4(const SPIRVType *Type,
   return GR.getOrCreateSPIRVVectorType(ScalarType, 4, MIRBuilder);
 }
 
+bool SPIRVInstructionSelector::loadHandleBeforePosition(
+    Register &HandleReg, const SPIRVType *ResType, GIntrinsic &HandleDef,
+    MachineInstr &Pos) const {
+
+  assert(HandleDef.getIntrinsicID() ==
+         Intrinsic::spv_resource_handlefrombinding);
+  uint32_t Set = foldImm(HandleDef.getOperand(2), MRI);
+  uint32_t Binding = foldImm(HandleDef.getOperand(3), MRI);
+  uint32_t ArraySize = foldImm(HandleDef.getOperand(4), MRI);
+  Register IndexReg = HandleDef.getOperand(5).getReg();
+  bool IsNonUniform = ArraySize > 1 && foldImm(HandleDef.getOperand(6), MRI);
+
+  MachineIRBuilder MIRBuilder(HandleDef);
+  Register VarReg = buildPointerToResource(ResType, Set, Binding, ArraySize,
+                                           IndexReg, IsNonUniform, MIRBuilder);
+
+  if (IsNonUniform)
+    buildOpDecorate(HandleReg, HandleDef, TII, SPIRV::Decoration::NonUniformEXT,
+                    {});
+
+  // TODO: For now we assume the resource is an image, which needs to be
+  // loaded to get the handle. That will not be true for storage buffers.
+  return BuildMI(*Pos.getParent(), Pos, HandleDef.getDebugLoc(),
+                 TII.get(SPIRV::OpLoad))
+      .addDef(HandleReg)
+      .addUse(GR.getSPIRVTypeID(ResType))
+      .addUse(VarReg)
+      .constrainAllUses(TII, TRI, RBI);
+}
+
 namespace llvm {
 InstructionSelector *
 createSPIRVInstructionSelector(const SPIRVTargetMachine &TM,

llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp

@@ -1696,14 +1696,16 @@ void addInstrRequirements(const MachineInstr &MI,
     break;
   case SPIRV::OpImageRead: {
     Register ImageReg = MI.getOperand(2).getReg();
-    SPIRVType *TypeDef = ST.getSPIRVGlobalRegistry()->getResultType(ImageReg);
+    SPIRVType *TypeDef = ST.getSPIRVGlobalRegistry()->getResultType(
+        ImageReg, const_cast<MachineFunction *>(MI.getMF()));
     if (isImageTypeWithUnknownFormat(TypeDef))
       Reqs.addCapability(SPIRV::Capability::StorageImageReadWithoutFormat);
     break;
   }
   case SPIRV::OpImageWrite: {
     Register ImageReg = MI.getOperand(0).getReg();
-    SPIRVType *TypeDef = ST.getSPIRVGlobalRegistry()->getResultType(ImageReg);
+    SPIRVType *TypeDef = ST.getSPIRVGlobalRegistry()->getResultType(
+        ImageReg, const_cast<MachineFunction *>(MI.getMF()));
     if (isImageTypeWithUnknownFormat(TypeDef))
       Reqs.addCapability(SPIRV::Capability::StorageImageWriteWithoutFormat);
     break;