Empty structs in C differ from those in C++.
- C++ requires that empty types have size 1; alignment requirements may
increase the size of the struct.
- The C implementation doesn't let empty structs have a size under 4
bytes. Again, alignment requirements may increase the struct's size.
Add a test to stress these differences.
llvm-svn: 218963
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
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
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
For namespaces, this is consistent with mangling and GCC's debug info
behavior. For structs, GCC uses <anonymous struct> but we prefer
consistency between all anonymous entities but don't want to confuse
them with template arguments, etc, so we'll just go with parens in all
cases.
llvm-svn: 205398
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
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
Some lines intended to be used for testing x86_64 ABI compatibility were
not firing because lines were annotated with the wrong FileCheck prefix:
X64 vs 64
llvm-svn: 201454
Some lines intended to be used for testing x86_64 ABI compatibility were
not firing because lines were annotated with the wrong FileCheck prefix:
X64 vs C64
llvm-svn: 201453
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
Some lines intended to be used for testing x86_64 ABI compatibility were
not firing because lines were annotated with the wrong FileCheck prefix:
X64 vs x64
N.B. Changes beyond just changing x64 to X64 were made, presumably
because other parts of the layout engine have changed. I've verified
the changes to make sure that MSVC creates a compatible layout.
llvm-svn: 200670
With this change, we give different results for __alignof than MSVC, but
our record layout is compatible.
Some data member pointers also now have a size that is not a multiple of
their alignment.
Fixes PR18618.
Reviewers: majnemer
Differential Revision: http://llvm-reviews.chandlerc.com/D2669
llvm-svn: 200585
This makes the C++ ABI depend entirely on the target: MS ABI for -win32 triples,
Itanium otherwise. It's no longer possible to do weird combinations.
To be able to run a test with a specific ABI without constraining it to a
specific triple, new substitutions are added to lit: %itanium_abi_triple and
%ms_abi_triple can be used to get the current target triple adjusted to the
desired ABI. For example, if the test suite is running with the i686-pc-win32
target, %itanium_abi_triple will expand to i686-pc-mingw32.
Differential Revision: http://llvm-reviews.chandlerc.com/D2545
llvm-svn: 199250
This patch makes a small behavioral change to the interaction between
pack and alignment. Specifically it makes __declspec(align()) on a
field change that field's alignment without respect to pack but the
alignment change to the record alignment as a whole still obeys pack.
llvm-svn: 199172
This patch moves the check for pragma pack until after the application
of __declspec align to before pragma pack. This causes observable
changes in the use of tail padding for bases. A test case is included.
llvm-svn: 199154
The MS-ABI tracks a bit that asserts that the first sub-object is zero
sized. This bit is used to add padding between objects if there's the
potential for zero sized objects to alias. The bit is still true even
if the zero sized base is lead by a VFPtr. This patch makes clang mimic
that behavior.
llvm-svn: 199132
This patch more cleanly seperates the concepts of Preferred Alignment
and Required Alignment. Most notable that changes to Required Alignment
do *not* impact preferred alignment until late in struct layout. This
is observable when using pragma pack and non-virtual bases and the use
of tail padding when laying them out.
Test cases included.
llvm-svn: 198988
The presence of a VBPtr suppresses the presence of zero sized
sub-objects in the non-virtual portion of the object in the context of
determining if two base objects need alias-avoidance padding placed
between them.
Test cases included.
llvm-svn: 198975
__declspec(align), when applied to bitfields affects their perferred
alignment instead of their required alignment. We don't know why.
Also, #pragma pack(n) turns packing *off* if n is greater than the
pointer size. This is now observable because of the impact of
declspec(align) on bitfields.
llvm-svn: 198907
This patch refactors microsoft record layout to be more "natural". The
most dominant change is that vbptrs and vfptrs are injected after the
fact. This simplifies the implementation and the math for the offest
for the first base/field after the vbptr.
llvm-svn: 198818
With pragma pack, the layout engine would produce vfptrs that were
packed width rather than pointer width. This patch addresses the issue
and adds a test case.
llvm-svn: 198059
The alignment impact of the virtual bases apperas to be applied in
order, rather than up front. This patch adds the new behavior and
provides a test case.
llvm-svn: 197639
This refactor addresses bugzilla bug 18167 and simplifies the code at
the same time. Also I add a test case for the bug. Also I make a
non-functional change to the basic layout lit tests to make them more
reliable (using CHECK-NEXT instead of CHECK).
llvm-svn: 197183
Prior to this patch, the alignment imposed by virtual bases only
included direct virtual bases. This patch fixes it to look at all
virtual bases.
llvm-svn: 196997
In order to address latent bugs that were easier to expose in 64-bit
mode, we move the application of __declspec(align) to before the layout
of vbases rather than after.
llvm-svn: 196861
MS-ABI adds padding before *every* vbase if the last field in a record
is a bit-field. This changes clangs behavior to match. I also fix some
windows-style line endings in the test file.
Differential Revision: http://llvm-reviews.chandlerc.com/D2277
llvm-svn: 196605
Adds padding between bases or virtual bases in an attempt to avoid
aliasing of zero-sized sub-objects. The approach used by the ABI adds
two more bits of state. Detailed comments are in the code. Test cases
included.
Differential Revision: http://llvm-reviews.chandlerc.com/D2258
llvm-svn: 196602
Evgeny Astigeevich