Summary:
We should avoid a tail padding not only if the last field
has zero size but also if the last field is a struct with a flexible array.
If/when http://reviews.llvm.org/D5478 is committed,
this will also handle the case of structs with zero-sized arrays.
Reviewers: majnemer, rsmith
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D5924
llvm-svn: 220708
Summary:
The general approach is to add extra paddings after every field
in AST/RecordLayoutBuilder.cpp, then add code to CTORs/DTORs that poisons the paddings
(CodeGen/CGClass.cpp).
Everything is done under the flag -fsanitize-address-field-padding.
The blacklist file (-fsanitize-blacklist) allows to avoid the transformation
for given classes or source files.
See also https://code.google.com/p/address-sanitizer/wiki/IntraObjectOverflow
Test Plan: run SPEC2006 and some of the Chromium tests with -fsanitize-address-field-padding
Reviewers: samsonov, rnk, rsmith
Reviewed By: rsmith
Subscribers: majnemer, cfe-commits
Differential Revision: http://reviews.llvm.org/D5687
llvm-svn: 219961
Empty records do not always have size equivalent to their alignment.
They only do so when their alignment is at least as large as the minimum
empty struct size: 1 byte in C++ and 4 bytes in C.
llvm-svn: 218661
Usually, overriding a virtual function defined in a virtual base
required emission of a vtordisp slot in the record. However no vtordisp
is needed if the overriding function is pure; it should be impossible to
observe the pure virtual method.
This fixes PR21046.
llvm-svn: 218340
The MS ABI has a notion of 'required alignment' for fields; this
alignment supercedes pragma pack directives.
MSVC takes into account alignment attributes on typedefs when
determining whether or not a field has a certain required alignment.
Do the same in clang by tracking whether or not we saw such an attribute
when calculating the type's bitwidth and alignment.
This fixes PR20418.
Reviewers: rnk
Differential Revision: http://reviews.llvm.org/D4714
llvm-svn: 214274
We would correctly insert sufficiently aligned padding between vbases
when our leading base was empty, however we would neglect to increase
the required alignment of the most derived class.
This fixes PR20315.
llvm-svn: 213123
No functionality changed, just some cleanups:
- Switch some loops to range-based for.
- Name some iterators with a more creative name than "I".
- Reduce dependence on auto. Does RD->bases() give you a list of
CXXBaseSpecifiers or CXXRecordDecls? It's more clear to just say which
upfront.
llvm-svn: 213121
Previously, it was believed that #pragma vtordisp(0) would prohibit the
generation of any and all vtordisps.
In actuality, it only disables the generation of additional vtordisps.
This fixes PR19413.
llvm-svn: 206124
A portion of the vtordisp computation that was previously unguarded by a
test for the declaration of user defined constructors/destructors was
erroniously adding vtordisps to things that shouldn't have them. This
patch correctly guards that codepath. In addition, it updates the
comments to make them more clear. Test case is included.
llvm-svn: 206077
This patch updates the comments in RecordLayoutBuilder about record
layout in the MS-ABI. Also, I added a section about known
incompatibilities.
llvm-svn: 206010
In version 9 (VS2010) (and prior)? versions of msvc, if the last field
in a record was a bitfield padding equal to the size of the storage
class of that bitfield was added before each vbase and vtordisp. This
patch removes that feature from clang and updates the lit tests to
reflect it.
llvm-svn: 206004
The vbptr is injected after the last non-virtual base lexographically
rather than the last non-virtual base in layout order. Test case
included. Also, some line ending fixes.
llvm-svn: 206000
When __declspec(align()) is applied to a bitfield it affects the
alignment rather than the required alignment of the struct. The major
feature that this patch adds is that the alignment of the structure
obeys the alignment of __declspec(align()) from the bitfield over the
value specified in pragma pack.
Test cases are included.
The patch also includes some small cleanups in recordlayoutbuilder and
some cleanups to some lit tests, including line endings (but no
functionality change to lit tests)
llvm-svn: 205994
This patch changes how we determine if padding is needed between two
bases in msvc compatibility mode. Test cases included.
In addition, a very minor change to the printing of structures to ease
lit testing.
llvm-svn: 205933
As of cl.exe version 18, the special layout rules for structs with
alignment 16 or greater has been dropped. This patch drops the behavior
from clang. This patch also updates the lit tests to reflect the
change.
llvm-svn: 204674
or virtual functions, but permit that error to be downgraded to
a warning (with -Wno-error=incompatible-ms-struct), and officially
support this kind of dual, ABI-mixing layout.
The basic problem here is that projects which use ms_struct are often
not very circumspect about what types they annotate; for example,
some projects enable the pragma in a prefix header and then only
selectively disable it around system header inclusions. They may
only care about binary compatibility with MSVC for a subset of
those structs, but that doesn't mean they have no binary
compatibility concerns at all for the rest; thus we are essentially
forced into supporting this hybrid ABI. But it's reasonable for
us to at least point out the places where we're not making
any guarantees.
The original diagnostic was for dynamic classes, i.e. those with
virtual functions or virtual bases; I've extended it to include
all classes with bases, because we are not actually making any
attempt to duplicate MSVC's base subobject layout in ms_struct
(and it is indeed quite different from Itanium, even for
non-virtual bases).
rdar://16178895
llvm-svn: 202427
This was changed to use manual desugaring and multiplication in r201832
and fixed for multi-dimensional arrays in r201917. However, it breaks
down in the presence of typedefs. Rather than attempting to handle all
the desugaring, just go back to calling the generic type info code.
This was discovered while compiling SIInstrWaits.cpp in the R600
backend.
llvm-svn: 202175
A recent change caused multi-dimensional arrays not to be handled
correctly, this patch fixes that. Also, it adds a lit test for
multi-dimensional arrays.
llvm-svn: 201917
Slight change to the way zero-sized sub-objects are tracked in the
presence of virtual bases.
In addition we correctly distinguish between dsize and nvsize.
addresses http://llvm.org/bugs/show_bug.cgi?id=18826
Unit tests are included.
llvm-svn: 201832
This reverts commit r201810.
It was failing these tests on my workstation:
Clang :: CodeGen/override-layout.c
Clang :: CodeGenCXX/override-layout.cpp
Clang :: PCH/check-deserializations.cpp
llvm-svn: 201823
External sources shouldn't prevent the layout engine from using
MSLayout. If lldb were to support debugging in microsoft mode, some
code will need to be added to MSRecordLayoutBuilder to handel external
layouts.
llvm-svn: 201810
According to the GNU docs, zero-sized bitfields should not be affected by the
packed attribute.
Differential Revision: http://llvm-reviews.chandlerc.com/D2693
llvm-svn: 201288
useBitFieldTypeAlignment() and appears to ignore the special
bit-packing semantics of __attribute__((packed)).
Further flesh out an already-extensive comment.
llvm-svn: 201282
These features are new in VS 2013 and are necessary in order to layout
std::ostream correctly. Currently we have an ABI incompatibility when
self-hosting with the 2013 stdlib in our convertible_fwd_ostream wrapper
in gtest.
This change adds another implicit attribute, MSVtorDispAttr, because
implicit attributes are currently the best way to make sure the
information stays on class templates through instantiation.
Reviewers: majnemer
Differential Revision: http://llvm-reviews.chandlerc.com/D2746
llvm-svn: 201274
vptr injection must inject padding equivalent to the alignment of the
most aligned non-virtual subobject, not the alignment of the enclosing
record.
To fascilitate this change, don't let record layout observe the
alignment of the record until we've injected our vptrs. Also, do not
allow the alignment of vbases to affect required alignment until just
before we insert the vtordisp field.
llvm-svn: 201199
Kostya Serebryany