[Clang][SVE] Change LLVM representation of ACLE tuple types to be struct based. (llvm#108008)

This implements our original design now that LLVM is comfortable with
structs and arrays of scalable vector types. All SVE ACLE intrinsics
already use struct types so the effect of this change is purely the
types used for alloca and function parameters.
    
There should be no C/C++ user visible change with this patch.

Author: paulwalker-arm

clang/include/clang/Basic/AArch64SVEACLETypes.def

@@ -46,9 +46,8 @@
 //
 //  - ElBits is the size of one element in bits.
 //
-//  - NF enumerates the number of sub-vectors.
-//    TODO: Tuple types are represented as a concatination of "NumEls x ElBits"
-//    vectors.  This will be changed to become a struct containing NF vectors.
+//  - NF enumerates the number of vectors whereby 1 implies a single vector,
+//    with other values implying a struct of NF "NumEls x NumEls" vectors.
 //
 //  - IsSigned is true for vectors of signed integer elements and
 //    for vectors of floating-point elements.

clang/lib/CodeGen/CGBuiltin.cpp

@@ -9990,31 +9990,6 @@ Value *CodeGenFunction::EmitSVEStructLoad(const SVETypeFlags &TypeFlags,
                                           SmallVectorImpl<Value*> &Ops,
                                           unsigned IntID) {
   llvm::ScalableVectorType *VTy = getSVEType(TypeFlags);
-
-  unsigned N;
-  switch (IntID) {
-  case Intrinsic::aarch64_sve_ld2_sret:
-  case Intrinsic::aarch64_sve_ld1_pn_x2:
-  case Intrinsic::aarch64_sve_ldnt1_pn_x2:
-  case Intrinsic::aarch64_sve_ld2q_sret:
-    N = 2;
-    break;
-  case Intrinsic::aarch64_sve_ld3_sret:
-  case Intrinsic::aarch64_sve_ld3q_sret:
-    N = 3;
-    break;
-  case Intrinsic::aarch64_sve_ld4_sret:
-  case Intrinsic::aarch64_sve_ld1_pn_x4:
-  case Intrinsic::aarch64_sve_ldnt1_pn_x4:
-  case Intrinsic::aarch64_sve_ld4q_sret:
-    N = 4;
-    break;
-  default:
-    llvm_unreachable("unknown intrinsic!");
-  }
-  auto RetTy = llvm::VectorType::get(VTy->getElementType(),
-                                     VTy->getElementCount() * N);
-
   Value *Predicate = EmitSVEPredicateCast(Ops[0], VTy);
   Value *BasePtr = Ops[1];
 
@@ -10023,15 +9998,7 @@ Value *CodeGenFunction::EmitSVEStructLoad(const SVETypeFlags &TypeFlags,
     BasePtr = Builder.CreateGEP(VTy, BasePtr, Ops[2]);
 
   Function *F = CGM.getIntrinsic(IntID, {VTy});
-  Value *Call = Builder.CreateCall(F, {Predicate, BasePtr});
-  unsigned MinElts = VTy->getMinNumElements();
-  Value *Ret = llvm::PoisonValue::get(RetTy);
-  for (unsigned I = 0; I < N; I++) {
-    Value *Idx = ConstantInt::get(CGM.Int64Ty, I * MinElts);
-    Value *SRet = Builder.CreateExtractValue(Call, I);
-    Ret = Builder.CreateInsertVector(RetTy, Ret, SRet, Idx);
-  }
-  return Ret;
+  return Builder.CreateCall(F, {Predicate, BasePtr});
 }
 
 Value *CodeGenFunction::EmitSVEStructStore(const SVETypeFlags &TypeFlags,
@@ -10304,6 +10271,19 @@ Value *CodeGenFunction::EmitSVEReinterpret(Value *Val, llvm::Type *Ty) {
   // view (when storing/reloading), whereas the svreinterpret builtin
   // implements bitwise equivalent cast from register point of view.
   // LLVM CodeGen for a bitcast must add an explicit REV for big-endian.
+
+  if (auto *StructTy = dyn_cast<StructType>(Ty)) {
+    Value *Tuple = llvm::PoisonValue::get(Ty);
+
+    for (unsigned I = 0; I < StructTy->getNumElements(); ++I) {
+      Value *In = Builder.CreateExtractValue(Val, I);
+      Value *Out = Builder.CreateBitCast(In, StructTy->getTypeAtIndex(I));
+      Tuple = Builder.CreateInsertValue(Tuple, Out, I);
+    }
+
+    return Tuple;
+  }
+
   return Builder.CreateBitCast(Val, Ty);
 }
 
@@ -10346,44 +10326,26 @@ CodeGenFunction::getSVEOverloadTypes(const SVETypeFlags &TypeFlags,
 }
 
 Value *CodeGenFunction::EmitSVETupleSetOrGet(const SVETypeFlags &TypeFlags,
-                                             llvm::Type *Ty,
                                              ArrayRef<Value *> Ops) {
   assert((TypeFlags.isTupleSet() || TypeFlags.isTupleGet()) &&
          "Expects TypleFlags.isTupleSet() or TypeFlags.isTupleGet()");
-
-  unsigned I = cast<ConstantInt>(Ops[1])->getSExtValue();
-  auto *SingleVecTy = dyn_cast<llvm::ScalableVectorType>(
-      TypeFlags.isTupleSet() ? Ops[2]->getType() : Ty);
-
-  if (!SingleVecTy)
-    return nullptr;
-
-  Value *Idx = ConstantInt::get(CGM.Int64Ty,
-                                I * SingleVecTy->getMinNumElements());
+  unsigned Idx = cast<ConstantInt>(Ops[1])->getZExtValue();
 
   if (TypeFlags.isTupleSet())
-    return Builder.CreateInsertVector(Ty, Ops[0], Ops[2], Idx);
-  return Builder.CreateExtractVector(Ty, Ops[0], Idx);
+    return Builder.CreateInsertValue(Ops[0], Ops[2], Idx);
+  return Builder.CreateExtractValue(Ops[0], Idx);
 }
 
 Value *CodeGenFunction::EmitSVETupleCreate(const SVETypeFlags &TypeFlags,
-                                             llvm::Type *Ty,
-                                             ArrayRef<Value *> Ops) {
+                                           llvm::Type *Ty,
+                                           ArrayRef<Value *> Ops) {
   assert(TypeFlags.isTupleCreate() && "Expects TypleFlag isTupleCreate");
 
-  auto *SrcTy = dyn_cast<llvm::ScalableVectorType>(Ops[0]->getType());
-
-  if (!SrcTy)
-    return nullptr;
+  Value *Tuple = llvm::PoisonValue::get(Ty);
+  for (unsigned Idx = 0; Idx < Ops.size(); Idx++)
+    Tuple = Builder.CreateInsertValue(Tuple, Ops[Idx], Idx);
 
-  unsigned MinElts = SrcTy->getMinNumElements();
-  Value *Call = llvm::PoisonValue::get(Ty);
-  for (unsigned I = 0; I < Ops.size(); I++) {
-    Value *Idx = ConstantInt::get(CGM.Int64Ty, I * MinElts);
-    Call = Builder.CreateInsertVector(Ty, Call, Ops[I], Idx);
-  }
-
-  return Call;
+  return Tuple;
 }
 
 Value *CodeGenFunction::FormSVEBuiltinResult(Value *Call) {
@@ -10453,27 +10415,14 @@ void CodeGenFunction::GetAArch64SVEProcessedOperands(
       continue;
     }
 
-    if (IsTupleGetOrSet || !isa<ScalableVectorType>(Arg->getType())) {
-      Ops.push_back(Arg);
-      continue;
-    }
+    if (isa<StructType>(Arg->getType()) && !IsTupleGetOrSet) {
+      for (unsigned I = 0; I < Arg->getType()->getStructNumElements(); ++I)
+        Ops.push_back(Builder.CreateExtractValue(Arg, I));
 
-    auto *VTy = cast<ScalableVectorType>(Arg->getType());
-    unsigned MinElts = VTy->getMinNumElements();
-    bool IsPred = VTy->getElementType()->isIntegerTy(1);
-    unsigned N = (MinElts * VTy->getScalarSizeInBits()) / (IsPred ? 16 : 128);
-
-    if (N == 1) {
-      Ops.push_back(Arg);
       continue;
     }
 
-    for (unsigned I = 0; I < N; ++I) {
-      Value *Idx = ConstantInt::get(CGM.Int64Ty, (I * MinElts) / N);
-      auto *NewVTy =
-          ScalableVectorType::get(VTy->getElementType(), MinElts / N);
-      Ops.push_back(Builder.CreateExtractVector(NewVTy, Arg, Idx));
-    }
+    Ops.push_back(Arg);
   }
 }
 
@@ -10511,7 +10460,7 @@ Value *CodeGenFunction::EmitAArch64SVEBuiltinExpr(unsigned BuiltinID,
   else if (TypeFlags.isStructStore())
     return EmitSVEStructStore(TypeFlags, Ops, Builtin->LLVMIntrinsic);
   else if (TypeFlags.isTupleSet() || TypeFlags.isTupleGet())
-    return EmitSVETupleSetOrGet(TypeFlags, Ty, Ops);
+    return EmitSVETupleSetOrGet(TypeFlags, Ops);
   else if (TypeFlags.isTupleCreate())
     return EmitSVETupleCreate(TypeFlags, Ty, Ops);
   else if (TypeFlags.isUndef())

clang/lib/CodeGen/CodeGenFunction.h

@@ -4628,7 +4628,6 @@ class CodeGenFunction : public CodeGenTypeCache {
   llvm::ScalableVectorType *getSVEType(const SVETypeFlags &TypeFlags);
   llvm::ScalableVectorType *getSVEPredType(const SVETypeFlags &TypeFlags);
   llvm::Value *EmitSVETupleSetOrGet(const SVETypeFlags &TypeFlags,
-                                    llvm::Type *ReturnType,
                                     ArrayRef<llvm::Value *> Ops);
   llvm::Value *EmitSVETupleCreate(const SVETypeFlags &TypeFlags,
                                   llvm::Type *ReturnType,

clang/lib/CodeGen/CodeGenTypes.cpp

@@ -509,9 +509,20 @@ llvm::Type *CodeGenTypes::ConvertType(QualType T) {
       {
         ASTContext::BuiltinVectorTypeInfo Info =
             Context.getBuiltinVectorTypeInfo(cast<BuiltinType>(Ty));
-        return llvm::ScalableVectorType::get(ConvertType(Info.ElementType),
-                                             Info.EC.getKnownMinValue() *
-                                                 Info.NumVectors);
+        auto VTy =
+            llvm::VectorType::get(ConvertType(Info.ElementType), Info.EC);
+        switch (Info.NumVectors) {
+        default:
+          llvm_unreachable("Expected 1, 2, 3 or 4 vectors!");
+        case 1:
+          return VTy;
+        case 2:
+          return llvm::StructType::get(VTy, VTy);
+        case 3:
+          return llvm::StructType::get(VTy, VTy, VTy);
+        case 4:
+          return llvm::StructType::get(VTy, VTy, VTy, VTy);
+        }
       }
     case BuiltinType::SveCount:
       return llvm::TargetExtType::get(getLLVMContext(), "aarch64.svcount");