SystemZ.cpp

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//===- SystemZ.cpp --------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include "ABIInfoImpl.h"
#include "TargetInfo.h"
#include "clang/Basic/Builtins.h"
#include "llvm/IR/IntrinsicsS390.h"
 
using namespace clang;
using namespace clang::CodeGen;
 
//===----------------------------------------------------------------------===//
// SystemZ ABI Implementation
//===----------------------------------------------------------------------===//
 
namespace {
 
class SystemZABIInfo : public ABIInfo {
  bool HasVector;
  bool IsSoftFloatABI;
 
public:
  SystemZABIInfo(CodeGenTypes &CGT, bool HV, bool SF)
      : ABIInfo(CGT), HasVector(HV), IsSoftFloatABI(SF) {}
 
  bool isPromotableIntegerTypeForABI(QualType Ty) const;
  bool isCompoundType(QualType Ty) const;
  bool isVectorArgumentType(QualType Ty) const;
  bool isFPArgumentType(QualType Ty) const;
  QualType GetSingleElementType(QualType Ty) const;
 
  ABIArgInfo classifyReturnType(QualType RetTy) const;
  ABIArgInfo classifyArgumentType(QualType ArgTy) const;
 
  void computeInfo(CGFunctionInfo &FI) const override;
  RValue EmitVAArg(CodeGenFunction &CGF, Address VAListAddr, QualType Ty,
                   AggValueSlot Slot) const override;
};
 
class SystemZTargetCodeGenInfo : public TargetCodeGenInfo {
  ASTContext &Ctx;
 
  // These are used for speeding up the search for a visible vector ABI.
  mutable bool HasVisibleVecABIFlag = false;
  mutable std::set<const Type *> SeenTypes;
 
  // Returns true (the first time) if Ty is, or is found to include, a vector
  // type that exposes the vector ABI. This is any vector >=16 bytes which
  // with vector support are aligned to only 8 bytes. When IsParam is true,
  // the type belongs to a value as passed between functions. If it is a
  // vector <=16 bytes it will be passed in a vector register (if supported).
  bool isVectorTypeBased(const Type *Ty, bool IsParam) const;
 
public:
  SystemZTargetCodeGenInfo(CodeGenTypes &CGT, bool HasVector, bool SoftFloatABI)
      : TargetCodeGenInfo(
            std::make_unique<SystemZABIInfo>(CGT, HasVector, SoftFloatABI)),
            Ctx(CGT.getContext()) {
    SwiftInfo =
        std::make_unique<SwiftABIInfo>(CGT, /*SwiftErrorInRegister=*/false);
  }
 
  // The vector ABI is different when the vector facility is present and when
  // a module e.g. defines an externally visible vector variable, a flag
  // indicating a visible vector ABI is added. Eventually this will result in
  // a GNU attribute indicating the vector ABI of the module.  Ty is the type
  // of a variable or function parameter that is globally visible.
  void handleExternallyVisibleObjABI(const Type *Ty, CodeGen::CodeGenModule &M,
                                     bool IsParam) const {
    if (!HasVisibleVecABIFlag && isVectorTypeBased(Ty, IsParam)) {
      M.getModule().addModuleFlag(llvm::Module::Warning,
                                  "s390x-visible-vector-ABI", 1);
      HasVisibleVecABIFlag = true;
    }
  }
 
  void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
                           CodeGen::CodeGenModule &M) const override {
    if (!D)
      return;
 
    // Check if the vector ABI becomes visible by an externally visible
    // variable or function.
    if (const auto *VD = dyn_cast<VarDecl>(D)) {
      if (VD->isExternallyVisible())
        handleExternallyVisibleObjABI(VD->getType().getTypePtr(), M,
                                      /*IsParam*/false);
    }
    else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
      if (FD->isExternallyVisible())
        handleExternallyVisibleObjABI(FD->getType().getTypePtr(), M,
                                      /*IsParam*/false);
    }
  }
 
  llvm::Value *testFPKind(llvm::Value *V, unsigned BuiltinID,
                          CGBuilderTy &Builder,
                          CodeGenModule &CGM) const override {
    assert(V->getType()->isFloatingPointTy() && "V should have an FP type.");
    // Only use TDC in constrained FP mode.
    if (!Builder.getIsFPConstrained())
      return nullptr;
 
    llvm::Type *Ty = V->getType();
    if (Ty->isFloatTy() || Ty->isDoubleTy() || Ty->isFP128Ty()) {
      llvm::Module &M = CGM.getModule();
      auto &Ctx = M.getContext();
      llvm::Function *TDCFunc = llvm::Intrinsic::getOrInsertDeclaration(
          &M, llvm::Intrinsic::s390_tdc, Ty);
      unsigned TDCBits = 0;
      switch (BuiltinID) {
      case Builtin::BI__builtin_isnan:
        TDCBits = 0xf;
        break;
      case Builtin::BIfinite:
      case Builtin::BI__finite:
      case Builtin::BIfinitef:
      case Builtin::BI__finitef:
      case Builtin::BIfinitel:
      case Builtin::BI__finitel:
      case Builtin::BI__builtin_isfinite:
        TDCBits = 0xfc0;
        break;
      case Builtin::BI__builtin_isinf:
        TDCBits = 0x30;
        break;
      default:
        break;
      }
      if (TDCBits)
        return Builder.CreateCall(
            TDCFunc,
            {V, llvm::ConstantInt::get(llvm::Type::getInt64Ty(Ctx), TDCBits)});
    }
    return nullptr;
  }
};
}
 
bool SystemZABIInfo::isPromotableIntegerTypeForABI(QualType Ty) const {
  // Treat an enum type as its underlying type.
  if (const EnumType *EnumTy = Ty->getAs<EnumType>())
    Ty = EnumTy->getDecl()->getIntegerType();
 
  // Promotable integer types are required to be promoted by the ABI.
  if (ABIInfo::isPromotableIntegerTypeForABI(Ty))
    return true;
 
  if (const auto *EIT = Ty->getAs<BitIntType>())
    if (EIT->getNumBits() < 64)
      return true;
 
  // 32-bit values must also be promoted.
  if (const