diff options
Diffstat (limited to 'lib')
-rw-r--r-- | lib/CodeGen/CGObjCMac.cpp | 45 |
1 files changed, 24 insertions, 21 deletions
diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp index f397c56b6d..54d0ff21ea 100644 --- a/lib/CodeGen/CGObjCMac.cpp +++ b/lib/CodeGen/CGObjCMac.cpp @@ -113,11 +113,27 @@ LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF, return LV; } - // We need to compute the bit offset for the bit-field, the offset is to the - // byte. 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. - uint64_t BitOffset = LookupFieldBitOffset(CGF.CGM, OID, 0, Ivar) % 8; + // 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 = RL.getSize(); + uint64_t FieldBitOffset = LookupFieldBitOffset(CGF.CGM, OID, 0, Ivar); + uint64_t BitOffset = FieldBitOffset % 8; + uint64_t ContainingTypeAlign = 8; + uint64_t ContainingTypeSize = TypeSizeInBits - (FieldBitOffset - BitOffset); uint64_t BitFieldSize = Ivar->getBitWidth()->EvaluateAsInt(CGF.getContext()).getZExtValue(); @@ -127,23 +143,10 @@ LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF, // 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)); - // We always construct a single, possibly unaligned, access for this case. - CGBitFieldInfo::AccessInfo AI; - AI.FieldIndex = 0; - AI.FieldByteOffset = 0; - AI.FieldBitStart = BitOffset; - AI.AccessWidth = CGF.CGM.getContext().getTypeSize(IvarTy); - AI.AccessAlignment = 0; - AI.TargetBitOffset = 0; - AI.TargetBitWidth = BitFieldSize; - - CGBitFieldInfo *Info = - new (CGF.CGM.getContext()) CGBitFieldInfo(BitFieldSize, 1, &AI, - IvarTy->isSignedIntegerType()); - - // FIXME: We need to set a very conservative alignment on this, or make sure - // that the runtime is doing the right thing. return LValue::MakeBitfield(V, *Info, IvarTy.getCVRQualifiers() | CVRQualifiers); } |