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381 lines
14 KiB
381 lines
14 KiB
//==- CGObjCRuntime.cpp - Interface to Shared Objective-C Runtime Features ==//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This abstract class defines the interface for Objective-C runtime-specific
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// 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 "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/IR/CallSite.h"
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using namespace clang;
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using namespace CodeGen;
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static uint64_t LookupFieldBitOffset(CodeGen::CodeGenModule &CGM,
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const ObjCInterfaceDecl *OID,
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const ObjCImplementationDecl *ID,
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const ObjCIvarDecl *Ivar) {
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const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
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// FIXME: We should eliminate the need to have ObjCImplementationDecl passed
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// in here; it should never be necessary because that should be the lexical
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// decl context for the ivar.
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// If we know have an implementation (and the ivar is in it) then
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// look up in the implementation layout.
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const ASTRecordLayout *RL;
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if (ID && declaresSameEntity(ID->getClassInterface(), Container))
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RL = &CGM.getContext().getASTObjCImplementationLayout(ID);
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else
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RL = &CGM.getContext().getASTObjCInterfaceLayout(Container);
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// Compute field index.
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//
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// FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
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// implemented. This should be fixed to get the information from the layout
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// directly.
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unsigned Index = 0;
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for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
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IVD; IVD = IVD->getNextIvar()) {
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if (Ivar == IVD)
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break;
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++Index;
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}
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assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
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return RL->getFieldOffset(Index);
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}
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uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
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const ObjCInterfaceDecl *OID,
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const ObjCIvarDecl *Ivar) {
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return LookupFieldBitOffset(CGM, 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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const ObjCIvarDecl *Ivar) {
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return LookupFieldBitOffset(CGM, OID->getClassInterface(), OID, Ivar) /
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CGM.getContext().getCharWidth();
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}
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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 LookupFieldBitOffset(CGM, ID, ID->getImplementation(), 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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llvm::Value *Offset) {
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// Compute (type*) ( (char *) BaseValue + Offset)
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QualType IvarTy = Ivar->getType();
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llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
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llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, CGF.Int8PtrTy);
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V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");
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if (!Ivar->isBitField()) {
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V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
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LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
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LV.getQuals().addCVRQualifiers(CVRQualifiers);
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return LV;
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}
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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 = LookupFieldBitOffset(CGF.CGM, 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,
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IvarTy.withCVRQualifiers(CVRQualifiers),
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AlignmentSource::Decl);
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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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};
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struct CallObjCEndCatch final : EHScopeStack::Cleanup {
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CallObjCEndCatch(bool MightThrow, llvm::Value *Fn) :
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MightThrow(MightThrow), Fn(Fn) {}
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bool MightThrow;
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llvm::Value *Fn;
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void Emit(CodeGenFunction &CGF, Flags flags) override {
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if (!MightThrow) {
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CGF.Builder.CreateCall(Fn)->setDoesNotThrow();
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return;
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}
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CGF.EmitRuntimeCallOrInvoke(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::Constant *beginCatchFn,
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llvm::Constant *endCatchFn,
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llvm::Constant *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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CodeGenFunction::FinallyInfo FinallyInfo;
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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; ++I) {
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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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// @catch(...) always matches.
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if (!CatchDecl) {
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Handler.TypeInfo = nullptr; // catch-all
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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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for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
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Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
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}
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// Emit the try body.
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CGF.EmitStmt(S.getTryBody());
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// Leave the try.
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if (S.getNumCatchStmts())
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CGF.popCatchScope();
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// Remember where we were.
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CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
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// Emit the handlers.
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for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
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CatchHandler &Handler = Handlers[I];
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CGF.EmitBlock(Handler.Block);
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llvm::Value *RawExn = CGF.getExceptionFromSlot();
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// Enter the catch.
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llvm::Value *Exn = RawExn;
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if (beginCatchFn) {
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Exn = CGF.Builder.CreateCall(beginCatchFn, RawExn, "exn.adjusted");
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cast<llvm::CallInst>(Exn)->setDoesNotThrow();
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}
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CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
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if (endCatchFn) {
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// Add a cleanup to leave the catch.
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bool EndCatchMightThrow = (Handler.Variable == nullptr);
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CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
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EndCatchMightThrow,
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endCatchFn);
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}
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// Bind the catch parameter if it exists.
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if (const VarDecl *CatchParam = Handler.Variable) {
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llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
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llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
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CGF.EmitAutoVarDecl(*CatchParam);
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EmitInitOfCatchParam(CGF, CastExn, CatchParam);
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}
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CGF.ObjCEHValueStack.push_back(Exn);
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CGF.EmitStmt(Handler.Body);
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CGF.ObjCEHValueStack.pop_back();
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// Leave any cleanups associated with the catch.
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cleanups.ForceCleanup();
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CGF.EmitBranchThroughCleanup(Cont);
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}
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// Go back to the try-statement fallthrough.
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CGF.Builder.restoreIP(SavedIP);
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// Pop out of the finally.
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if (S.getFinallyStmt())
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FinallyInfo.exit(CGF);
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if (Cont.isValid())
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CGF.EmitBlock(Cont.getBlock());
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}
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void CGObjCRuntime::EmitInitOfCatchParam(CodeGenFunction &CGF,
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llvm::Value *exn,
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const VarDecl *paramDecl) {
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Address paramAddr = CGF.GetAddrOfLocalVar(paramDecl);
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switch (paramDecl->getType().getQualifiers().getObjCLifetime()) {
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case Qualifiers::OCL_Strong:
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exn = CGF.EmitARCRetainNonBlock(exn);
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// fallthrough
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case Qualifiers::OCL_None:
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case Qualifiers::OCL_ExplicitNone:
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case Qualifiers::OCL_Autoreleasing:
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CGF.Builder.CreateStore(exn, paramAddr);
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return;
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case Qualifiers::OCL_Weak:
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CGF.EmitARCInitWeak(paramAddr, exn);
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return;
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}
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llvm_unreachable("invalid ownership qualifier");
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}
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namespace {
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struct CallSyncExit final : EHScopeStack::Cleanup {
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llvm::Value *SyncExitFn;
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llvm::Value *SyncArg;
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CallSyncExit(llvm::Value *SyncExitFn, llvm::Value *SyncArg)
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: SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
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void Emit(CodeGenFunction &CGF, Flags flags) override {
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CGF.Builder.CreateCall(SyncExitFn, SyncArg)->setDoesNotThrow();
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}
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};
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}
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void CGObjCRuntime::EmitAtSynchronizedStmt(CodeGenFunction &CGF,
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const ObjCAtSynchronizedStmt &S,
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llvm::Function *syncEnterFn,
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llvm::Function *syncExitFn) {
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CodeGenFunction::RunCleanupsScope cleanups(CGF);
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// Evaluate the lock operand. This is guaranteed to dominate the
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// ARC release and lock-release cleanups.
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const Expr *lockExpr = S.getSynchExpr();
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llvm::Value *lock;
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if (CGF.getLangOpts().ObjCAutoRefCount) {
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lock = CGF.EmitARCRetainScalarExpr(lockExpr);
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lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
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} else {
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lock = CGF.EmitScalarExpr(lockExpr);
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}
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lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
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// Acquire the lock.
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CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
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// Register an all-paths cleanup to release the lock.
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CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
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// Emit the body of the statement.
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CGF.EmitStmt(S.getSynchBody());
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}
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/// Compute the pointer-to-function type to which a message send
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/// should be casted in order to correctly call the given method
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/// with the given arguments.
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///
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/// \param method - may be null
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/// \param resultType - the result type to use if there's no method
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/// \param callArgs - the actual arguments, including implicit ones
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CGObjCRuntime::MessageSendInfo
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CGObjCRuntime::getMessageSendInfo(const ObjCMethodDecl *method,
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QualType resultType,
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CallArgList &callArgs) {
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// If there's a method, use information from that.
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if (method) {
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const CGFunctionInfo &signature =
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CGM.getTypes().arrangeObjCMessageSendSignature(method, callArgs[0].Ty);
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llvm::PointerType *signatureType =
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CGM.getTypes().GetFunctionType(signature)->getPointerTo();
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const CGFunctionInfo &signatureForCall =
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CGM.getTypes().arrangeCall(signature, callArgs);
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return MessageSendInfo(signatureForCall, signatureType);
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}
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// There's no method; just use a default CC.
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const CGFunctionInfo &argsInfo =
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CGM.getTypes().arrangeUnprototypedObjCMessageSend(resultType, callArgs);
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// Derive the signature to call from that.
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llvm::PointerType *signatureType =
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CGM.getTypes().GetFunctionType(argsInfo)->getPointerTo();
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return MessageSendInfo(argsInfo, signatureType);
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}
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