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//==- CGObjCRuntime.cpp - Interface to Shared Objective-C Runtime Features ==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This abstract class defines the interface for Objective-C runtime-specific
// code generation. It provides some concrete helper methods for functionality
// shared between all (or most) of the Objective-C runtimes supported by clang.
//
//===----------------------------------------------------------------------===//
#include "CGObjCRuntime.h"
#include "CGRecordLayout.h"
#include "CodeGenModule.h"
#include "CodeGenFunction.h"
#include "CGCleanup.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/StmtObjC.h"
#include "llvm/Support/CallSite.h"
using namespace clang;
using namespace CodeGen;
static uint64_t LookupFieldBitOffset(CodeGen::CodeGenModule &CGM,
const ObjCInterfaceDecl *OID,
const ObjCImplementationDecl *ID,
const ObjCIvarDecl *Ivar) {
const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
// FIXME: We should eliminate the need to have ObjCImplementationDecl passed
// in here; it should never be necessary because that should be the lexical
// decl context for the ivar.
// If we know have an implementation (and the ivar is in it) then
// look up in the implementation layout.
const ASTRecordLayout *RL;
if (ID && declaresSameEntity(ID->getClassInterface(), Container))
RL = &CGM.getContext().getASTObjCImplementationLayout(ID);
else
RL = &CGM.getContext().getASTObjCInterfaceLayout(Container);
// Compute field index.
//
// FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
// implemented. This should be fixed to get the information from the layout
// directly.
unsigned Index = 0;
for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
IVD; IVD = IVD->getNextIvar()) {
if (Ivar == IVD)
break;
++Index;
}
assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
return RL->getFieldOffset(Index);
}
uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
const ObjCInterfaceDecl *OID,
const ObjCIvarDecl *Ivar) {
return LookupFieldBitOffset(CGM, OID, 0, Ivar) /
CGM.getContext().getCharWidth();
}
uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
const ObjCImplementationDecl *OID,
const ObjCIvarDecl *Ivar) {
return LookupFieldBitOffset(CGM, OID->getClassInterface(), OID, Ivar) /
CGM.getContext().getCharWidth();
}
LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
const ObjCInterfaceDecl *OID,
llvm::Value *BaseValue,
const ObjCIvarDecl *Ivar,
unsigned CVRQualifiers,
llvm::Value *Offset) {
// Compute (type*) ( (char *) BaseValue + Offset)
llvm::Type *I8Ptr = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
QualType IvarTy = Ivar->getType();
llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, I8Ptr);
V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");
V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
if (!Ivar->isBitField()) {
LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
LV.getQuals().addCVRQualifiers(CVRQualifiers);
return LV;
}
// We need to compute an access strategy for this bit-field. We are given the
// offset to the first byte in the bit-field, the sub-byte offset is taken
// from the original layout. We reuse the normal bit-field access strategy by
// treating this as an access to a struct where the bit-field is in byte 0,
// and adjust the containing type size as appropriate.
//
// FIXME: Note that currently we make a very conservative estimate of the
// alignment of the bit-field, because (a) it is not clear what guarantees the
// runtime makes us, and (b) we don't have a way to specify that the struct is
// at an alignment plus offset.
//
// Note, there is a subtle invariant here: we can only call this routine on
// non-synthesized ivars but we may be called for synthesized ivars. However,
// a synthesized ivar can never be a bit-field, so this is safe.
const ASTRecordLayout &RL =
CGF.CGM.getContext().getASTObjCInterfaceLayout(OID);
uint64_t TypeSizeInBits = CGF.CGM.getContext().toBits(RL.getSize());
uint64_t FieldBitOffset = LookupFieldBitOffset(CGF.CGM, OID, 0, Ivar);
uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
uint64_t ContainingTypeAlign = CGF.CGM.getContext().getTargetInfo().getCharAlign();
uint64_t ContainingTypeSize = TypeSizeInBits - (FieldBitOffset - BitOffset);
uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
// Allocate a new CGBitFieldInfo object to describe this access.
//
// FIXME: This is incredibly wasteful, these should be uniqued or part of some
// layout object. However, this is blocked on other cleanups to the
// Objective-C code, so for now we just live with allocating a bunch of these
// objects.
CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
ContainingTypeSize, ContainingTypeAlign));
return LValue::MakeBitfield(V, *Info,
IvarTy.withCVRQualifiers(CVRQualifiers));
}
namespace {
struct CatchHandler {
const VarDecl *Variable;
const Stmt *Body;
llvm::BasicBlock *Block;
llvm::Value *TypeInfo;
};
struct CallObjCEndCatch : EHScopeStack::Cleanup {
CallObjCEndCatch(bool MightThrow, llvm::Value *Fn) :
MightThrow(MightThrow), Fn(Fn) {}
bool MightThrow;
llvm::Value *Fn;
void Emit(CodeGenFunction &CGF, Flags flags) {
if (!MightThrow) {
CGF.Builder.CreateCall(Fn)->setDoesNotThrow();
return;
}
CGF.EmitCallOrInvoke(Fn);
}
};
}
void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
const ObjCAtTryStmt &S,
llvm::Constant *beginCatchFn,
llvm::Constant *endCatchFn,
llvm::Constant *exceptionRethrowFn) {
// Jump destination for falling out of catch bodies.
CodeGenFunction::JumpDest Cont;
if (S.getNumCatchStmts())
Cont = CGF.getJumpDestInCurrentScope("eh.cont");
CodeGenFunction::FinallyInfo FinallyInfo;
if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
FinallyInfo.enter(CGF, Finally->getFinallyBody(),
beginCatchFn, endCatchFn, exceptionRethrowFn);
SmallVector<CatchHandler, 8> Handlers;
// Enter the catch, if there is one.
if (S.getNumCatchStmts()) {
for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
Handlers.push_back(CatchHandler());
CatchHandler &Handler = Handlers.back();
Handler.Variable = CatchDecl;
Handler.Body = CatchStmt->getCatchBody();
Handler.Block = CGF.createBasicBlock("catch");
// @catch(...) always matches.
if (!CatchDecl) {
Handler.TypeInfo = 0; // catch-all
// Don't consider any other catches.
break;
}
Handler.TypeInfo = GetEHType(CatchDecl->getType());
}
EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
}
// Emit the try body.
CGF.EmitStmt(S.getTryBody());
// Leave the try.
if (S.getNumCatchStmts())
CGF.popCatchScope();
// Remember where we were.
CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
// Emit the handlers.
for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
CatchHandler &Handler = Handlers[I];
CGF.EmitBlock(Handler.Block);
llvm::Value *RawExn = CGF.getExceptionFromSlot();
// Enter the catch.
llvm::Value *Exn = RawExn;
if (beginCatchFn) {
Exn = CGF.Builder.CreateCall(beginCatchFn, RawExn, "exn.adjusted");
cast<llvm::CallInst>(Exn)->setDoesNotThrow();
}
CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
if (endCatchFn) {
// Add a cleanup to leave the catch.
bool EndCatchMightThrow = (Handler.Variable == 0);
CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
EndCatchMightThrow,
endCatchFn);
}
// Bind the catch parameter if it exists.
if (const VarDecl *CatchParam = Handler.Variable) {
llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
CGF.EmitAutoVarDecl(*CatchParam);
CGF.Builder.CreateStore(CastExn, CGF.GetAddrOfLocalVar(CatchParam));
}
CGF.ObjCEHValueStack.push_back(Exn);
CGF.EmitStmt(Handler.Body);
CGF.ObjCEHValueStack.pop_back();
// Leave any cleanups associated with the catch.
cleanups.ForceCleanup();
CGF.EmitBranchThroughCleanup(Cont);
}
// Go back to the try-statement fallthrough.
CGF.Builder.restoreIP(SavedIP);
// Pop out of the finally.
if (S.getFinallyStmt())
FinallyInfo.exit(CGF);
if (Cont.isValid())
CGF.EmitBlock(Cont.getBlock());
}
namespace {
struct CallSyncExit : EHScopeStack::Cleanup {
llvm::Value *SyncExitFn;
llvm::Value *SyncArg;
CallSyncExit(llvm::Value *SyncExitFn, llvm::Value *SyncArg)
: SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
CGF.Builder.CreateCall(SyncExitFn, SyncArg)->setDoesNotThrow();
}
};
}
void CGObjCRuntime::EmitAtSynchronizedStmt(CodeGenFunction &CGF,
const ObjCAtSynchronizedStmt &S,
llvm::Function *syncEnterFn,
llvm::Function *syncExitFn) {
CodeGenFunction::RunCleanupsScope cleanups(CGF);
// Evaluate the lock operand. This is guaranteed to dominate the
// ARC release and lock-release cleanups.
const Expr *lockExpr = S.getSynchExpr();
llvm::Value *lock;
if (CGF.getLangOptions().ObjCAutoRefCount) {
lock = CGF.EmitARCRetainScalarExpr(lockExpr);
lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
} else {
lock = CGF.EmitScalarExpr(lockExpr);
}
lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
// Acquire the lock.
CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
// Register an all-paths cleanup to release the lock.
CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
// Emit the body of the statement.
CGF.EmitStmt(S.getSynchBody());
}