Coverage Report

Created: 2020-02-25 14:32

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/CodeGen/CGObjCRuntime.cpp
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//==- CGObjCRuntime.cpp - Interface to Shared Objective-C Runtime Features ==//
2
//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
8
//
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// This abstract class defines the interface for Objective-C runtime-specific
10
// code generation.  It provides some concrete helper methods for functionality
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// shared between all (or most) of the Objective-C runtimes supported by clang.
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//
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//===----------------------------------------------------------------------===//
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#include "CGObjCRuntime.h"
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#include "CGCleanup.h"
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#include "CGCXXABI.h"
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#include "CGRecordLayout.h"
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#include "CodeGenFunction.h"
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#include "CodeGenModule.h"
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#include "clang/AST/RecordLayout.h"
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#include "clang/AST/StmtObjC.h"
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#include "clang/CodeGen/CGFunctionInfo.h"
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#include "llvm/Support/SaveAndRestore.h"
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using namespace clang;
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using namespace CodeGen;
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uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
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                                              const ObjCInterfaceDecl *OID,
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463
                                              const ObjCIvarDecl *Ivar) {
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  return CGM.getContext().lookupFieldBitOffset(OID, nullptr, Ivar) /
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         CGM.getContext().getCharWidth();
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}
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uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
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                                              const ObjCImplementationDecl *OID,
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2.46k
                                              const ObjCIvarDecl *Ivar) {
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2.46k
  return CGM.getContext().lookupFieldBitOffset(OID->getClassInterface(), OID,
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2.46k
                                               Ivar) /
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2.46k
         CGM.getContext().getCharWidth();
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2.46k
}
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unsigned CGObjCRuntime::ComputeBitfieldBitOffset(
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    CodeGen::CodeGenModule &CGM,
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    const ObjCInterfaceDecl *ID,
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    const ObjCIvarDecl *Ivar) {
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  return CGM.getContext().lookupFieldBitOffset(ID, ID->getImplementation(),
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                                               Ivar);
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}
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LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
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                                               const ObjCInterfaceDecl *OID,
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                                               llvm::Value *BaseValue,
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                                               const ObjCIvarDecl *Ivar,
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                                               unsigned CVRQualifiers,
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2.19k
                                               llvm::Value *Offset) {
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2.19k
  // Compute (type*) ( (char *) BaseValue + Offset)
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2.19k
  QualType InterfaceTy{OID->getTypeForDecl(), 0};
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2.19k
  QualType ObjectPtrTy =
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2.19k
      CGF.CGM.getContext().getObjCObjectPointerType(InterfaceTy);
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2.19k
  QualType IvarTy =
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2.19k
      Ivar->getUsageType(ObjectPtrTy).withCVRQualifiers(CVRQualifiers);
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2.19k
  llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
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2.19k
  llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, CGF.Int8PtrTy);
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2.19k
  V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");
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2.19k
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2.19k
  if (!Ivar->isBitField()) {
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2.08k
    V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
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2.08k
    LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
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2.08k
    return LV;
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2.08k
  }
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115
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  // We need to compute an access strategy for this bit-field. We are given the
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  // offset to the first byte in the bit-field, the sub-byte offset is taken
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  // from the original layout. We reuse the normal bit-field access strategy by
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  // treating this as an access to a struct where the bit-field is in byte 0,
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  // and adjust the containing type size as appropriate.
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  //
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  // FIXME: Note that currently we make a very conservative estimate of the
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  // alignment of the bit-field, because (a) it is not clear what guarantees the
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  // runtime makes us, and (b) we don't have a way to specify that the struct is
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  // at an alignment plus offset.
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  //
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  // Note, there is a subtle invariant here: we can only call this routine on
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  // non-synthesized ivars but we may be called for synthesized ivars.  However,
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  // a synthesized ivar can never be a bit-field, so this is safe.
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  uint64_t FieldBitOffset =
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      CGF.CGM.getContext().lookupFieldBitOffset(OID, nullptr, Ivar);
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  uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
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  uint64_t AlignmentBits = CGF.CGM.getTarget().getCharAlign();
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  uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
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  CharUnits StorageSize = CGF.CGM.getContext().toCharUnitsFromBits(
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      llvm::alignTo(BitOffset + BitFieldSize, AlignmentBits));
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  CharUnits Alignment = CGF.CGM.getContext().toCharUnitsFromBits(AlignmentBits);
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  // Allocate a new CGBitFieldInfo object to describe this access.
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  //
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  // FIXME: This is incredibly wasteful, these should be uniqued or part of some
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  // layout object. However, this is blocked on other cleanups to the
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  // Objective-C code, so for now we just live with allocating a bunch of these
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  // objects.
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  CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
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    CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
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                             CGF.CGM.getContext().toBits(StorageSize),
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                             CharUnits::fromQuantity(0)));
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  Address Addr(V, Alignment);
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  Addr = CGF.Builder.CreateElementBitCast(Addr,
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                                   llvm::Type::getIntNTy(CGF.getLLVMContext(),
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                                                         Info->StorageSize));
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  return LValue::MakeBitfield(Addr, *Info, IvarTy,
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                              LValueBaseInfo(AlignmentSource::Decl),
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                              TBAAAccessInfo());
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}
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namespace {
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  struct CatchHandler {
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    const VarDecl *Variable;
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    const Stmt *Body;
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    llvm::BasicBlock *Block;
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    llvm::Constant *TypeInfo;
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    /// Flags used to differentiate cleanups and catchalls in Windows SEH
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    unsigned Flags;
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  };
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  struct CallObjCEndCatch final : EHScopeStack::Cleanup {
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    CallObjCEndCatch(bool MightThrow, llvm::FunctionCallee Fn)
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        : MightThrow(MightThrow), Fn(Fn) {}
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    bool MightThrow;
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    llvm::FunctionCallee Fn;
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    void Emit(CodeGenFunction &CGF, Flags flags) override {
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      if (MightThrow)
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        CGF.EmitRuntimeCallOrInvoke(Fn);
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      else
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        CGF.EmitNounwindRuntimeCall(Fn);
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    }
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  };
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}
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void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
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                                     const ObjCAtTryStmt &S,
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                                     llvm::FunctionCallee beginCatchFn,
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                                     llvm::FunctionCallee endCatchFn,
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                                     llvm::FunctionCallee exceptionRethrowFn) {
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  // Jump destination for falling out of catch bodies.
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  CodeGenFunction::JumpDest Cont;
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  if (S.getNumCatchStmts())
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    Cont = CGF.getJumpDestInCurrentScope("eh.cont");
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  bool useFunclets = EHPersonality::get(CGF).usesFuncletPads();
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  CodeGenFunction::FinallyInfo FinallyInfo;
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  if (!useFunclets)
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    if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
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      FinallyInfo.enter(CGF, Finally->getFinallyBody(),
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                        beginCatchFn, endCatchFn, exceptionRethrowFn);
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  SmallVector<CatchHandler, 8> Handlers;
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  // Enter the catch, if there is one.
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  if (S.getNumCatchStmts()) {
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    for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; 
++I182
) {
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      const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
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      const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
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      Handlers.push_back(CatchHandler());
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      CatchHandler &Handler = Handlers.back();
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      Handler.Variable = CatchDecl;
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      Handler.Body = CatchStmt->getCatchBody();
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      Handler.Block = CGF.createBasicBlock("catch");
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      Handler.Flags = 0;
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      // @catch(...) always matches.
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      if (!CatchDecl) {
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        auto catchAll = getCatchAllTypeInfo();
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        Handler.TypeInfo = catchAll.RTTI;
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        Handler.Flags = catchAll.Flags;
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        // Don't consider any other catches.
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        break;
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      }
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      Handler.TypeInfo = GetEHType(CatchDecl->getType());
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    }
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    EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
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403
    for (unsigned I = 0, E = Handlers.size(); I != E; 
++I224
)
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      Catch->setHandler(I, { Handlers[I].TypeInfo, Handlers[I].Flags }, Handlers[I].Block);
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  }
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193
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  if (useFunclets)
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    if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt()) {
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        CodeGenFunction HelperCGF(CGM, /*suppressNewContext=*/true);
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        if (!CGF.CurSEHParent)
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            CGF.CurSEHParent = cast<NamedDecl>(CGF.CurFuncDecl);
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        // Outline the finally block.
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        const Stmt *FinallyBlock = Finally->getFinallyBody();
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        HelperCGF.startOutlinedSEHHelper(CGF, /*isFilter*/false, FinallyBlock);
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        // Emit the original filter expression, convert to i32, and return.
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        HelperCGF.EmitStmt(FinallyBlock);
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0
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        HelperCGF.FinishFunction(FinallyBlock->getEndLoc());
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0
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        llvm::Function *FinallyFunc = HelperCGF.CurFn;
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0
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0
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        // Push a cleanup for __finally blocks.
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        CGF.pushSEHCleanup(NormalAndEHCleanup, FinallyFunc);
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    }
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  // Emit the try body.
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  CGF.EmitStmt(S.getTryBody());
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183
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  // Leave the try.
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  if (S.getNumCatchStmts())
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    CGF.popCatchScope();
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183
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  // Remember where we were.
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  CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
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183
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  // Emit the handlers.
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  for (unsigned I = 0, E = Handlers.size(); I != E; 
++I224
) {
227
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    CatchHandler &Handler = Handlers[I];
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    CGF.EmitBlock(Handler.Block);
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    llvm::CatchPadInst *CPI = nullptr;
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    SaveAndRestore<llvm::Instruction *> RestoreCurrentFuncletPad(CGF.CurrentFuncletPad);
232
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    if (useFunclets)
233
23
      if ((CPI = dyn_cast_or_null<llvm::CatchPadInst>(Handler.Block->getFirstNonPHI()))) {
234
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        CGF.CurrentFuncletPad = CPI;
235
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        CPI->setOperand(2, CGF.getExceptionSlot().getPointer());
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      }
237
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    llvm::Value *RawExn = CGF.getExceptionFromSlot();
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224
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    // Enter the catch.
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    llvm::Value *Exn = RawExn;
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    if (beginCatchFn)
242
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      Exn = CGF.EmitNounwindRuntimeCall(beginCatchFn, RawExn, "exn.adjusted");
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224
244
224
    CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
245
224
246
224
    if (endCatchFn) {
247
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      // Add a cleanup to leave the catch.
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174
      bool EndCatchMightThrow = (Handler.Variable == nullptr);
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174
250
174
      CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
251
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                                                EndCatchMightThrow,
252
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                                                endCatchFn);
253
174
    }
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224
255
224
    // Bind the catch parameter if it exists.
256
224
    if (const VarDecl *CatchParam = Handler.Variable) {
257
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      llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
258
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      llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
259
182
260
182
      CGF.EmitAutoVarDecl(*CatchParam);
261
182
      EmitInitOfCatchParam(CGF, CastExn, CatchParam);
262
182
    }
263
224
    if (CPI)
264
14
        CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
265
224
266
224
    CGF.ObjCEHValueStack.push_back(Exn);
267
224
    CGF.EmitStmt(Handler.Body);
268
224
    CGF.ObjCEHValueStack.pop_back();
269
224
270
224
    // Leave any cleanups associated with the catch.
271
224
    cleanups.ForceCleanup();
272
224
273
224
    CGF.EmitBranchThroughCleanup(Cont);
274
224
  }
275
183
276
183
  // Go back to the try-statement fallthrough.
277
183
  CGF.Builder.restoreIP(SavedIP);
278
183
279
183
  // Pop out of the finally.
280
183
  if (!useFunclets && 
S.getFinallyStmt()168
)
281
10
    FinallyInfo.exit(CGF);
282
183
283
183
  if (Cont.isValid())
284
179
    CGF.EmitBlock(Cont.getBlock());
285
183
}
286
287
void CGObjCRuntime::EmitInitOfCatchParam(CodeGenFunction &CGF,
288
                                         llvm::Value *exn,
289
207
                                         const VarDecl *paramDecl) {
290
207
291
207
  Address paramAddr = CGF.GetAddrOfLocalVar(paramDecl);
292
207
293
207
  switch (paramDecl->getType().getQualifiers().getObjCLifetime()) {
294
6
  case Qualifiers::OCL_Strong:
295
6
    exn = CGF.EmitARCRetainNonBlock(exn);
296
6
    LLVM_FALLTHROUGH;
297
6
298
205
  case Qualifiers::OCL_None:
299
205
  case Qualifiers::OCL_ExplicitNone:
300
205
  case Qualifiers::OCL_Autoreleasing:
301
205
    CGF.Builder.CreateStore(exn, paramAddr);
302
205
    return;
303
205
304
205
  case Qualifiers::OCL_Weak:
305
2
    CGF.EmitARCInitWeak(paramAddr, exn);
306
2
    return;
307
0
  }
308
0
  llvm_unreachable("invalid ownership qualifier");
309
0
}
310
311
namespace {
312
  struct CallSyncExit final : EHScopeStack::Cleanup {
313
    llvm::FunctionCallee SyncExitFn;
314
    llvm::Value *SyncArg;
315
    CallSyncExit(llvm::FunctionCallee SyncExitFn, llvm::Value *SyncArg)
316
7
        : SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
317
318
7
    void Emit(CodeGenFunction &CGF, Flags flags) override {
319
7
      CGF.EmitNounwindRuntimeCall(SyncExitFn, SyncArg);
320
7
    }
321
  };
322
}
323
324
void CGObjCRuntime::EmitAtSynchronizedStmt(CodeGenFunction &CGF,
325
                                           const ObjCAtSynchronizedStmt &S,
326
                                           llvm::FunctionCallee syncEnterFn,
327
7
                                           llvm::FunctionCallee syncExitFn) {
328
7
  CodeGenFunction::RunCleanupsScope cleanups(CGF);
329
7
330
7
  // Evaluate the lock operand.  This is guaranteed to dominate the
331
7
  // ARC release and lock-release cleanups.
332
7
  const Expr *lockExpr = S.getSynchExpr();
333
7
  llvm::Value *lock;
334
7
  if (CGF.getLangOpts().ObjCAutoRefCount) {
335
4
    lock = CGF.EmitARCRetainScalarExpr(lockExpr);
336
4
    lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
337
4
  } else {
338
3
    lock = CGF.EmitScalarExpr(lockExpr);
339
3
  }
340
7
  lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
341
7
342
7
  // Acquire the lock.
343
7
  CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
344
7
345
7
  // Register an all-paths cleanup to release the lock.
346
7
  CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
347
7
348
7
  // Emit the body of the statement.
349
7
  CGF.EmitStmt(S.getSynchBody());
350
7
}
351
352
/// Compute the pointer-to-function type to which a message send
353
/// should be casted in order to correctly call the given method
354
/// with the given arguments.
355
///
356
/// \param method - may be null
357
/// \param resultType - the result type to use if there's no method
358
/// \param callArgs - the actual arguments, including implicit ones
359
CGObjCRuntime::MessageSendInfo
360
CGObjCRuntime::getMessageSendInfo(const ObjCMethodDecl *method,
361
                                  QualType resultType,
362
12.3k
                                  CallArgList &callArgs) {
363
12.3k
  // If there's a method, use information from that.
364
12.3k
  if (method) {
365
11.5k
    const CGFunctionInfo &signature =
366
11.5k
      CGM.getTypes().arrangeObjCMessageSendSignature(method, callArgs[0].Ty);
367
11.5k
368
11.5k
    llvm::PointerType *signatureType =
369
11.5k
      CGM.getTypes().GetFunctionType(signature)->getPointerTo();
370
11.5k
371
11.5k
    const CGFunctionInfo &signatureForCall =
372
11.5k
      CGM.getTypes().arrangeCall(signature, callArgs);
373
11.5k
374
11.5k
    return MessageSendInfo(signatureForCall, signatureType);
375
11.5k
  }
376
757
377
757
  // There's no method;  just use a default CC.
378
757
  const CGFunctionInfo &argsInfo =
379
757
    CGM.getTypes().arrangeUnprototypedObjCMessageSend(resultType, callArgs);
380
757
381
757
  // Derive the signature to call from that.
382
757
  llvm::PointerType *signatureType =
383
757
    CGM.getTypes().GetFunctionType(argsInfo)->getPointerTo();
384
757
  return MessageSendInfo(argsInfo, signatureType);
385
757
}