Revert the two changes to thread CodeGenOptions into the TargetInfo allocation
and to fix the layering violation by moving CodeGenOptions into Basic.
Code Generation is arguably not particularly "basic". This addresses Richard's
post-commit review comments. This change purely does the mechanical revert and
will be followed up with an alternate approach to thread the desired information
into TargetInfo.
llvm-svn: 265806
This is a mechanical move of CodeGenOptions from libFrontend to libBasic. This
fixes the layering violation introduced earlier by threading CodeGenOptions into
TargetInfo. It should also fix the modules based self-hosting builds. NFC.
llvm-svn: 265702
We got this right for Itanium but not MSVC because CGRecordLayoutBuilder
was checking if the base's size was zero when it should have been
checking the non-virtual size.
This fixes PR21040.
llvm-svn: 251036
tools/clang/test/CodeGen/packed-nest-unpacked.c contains this test:
struct XBitfield {
unsigned b1 : 10;
unsigned b2 : 12;
unsigned b3 : 10;
};
struct YBitfield {
char x;
struct XBitfield y;
} __attribute((packed));
struct YBitfield gbitfield;
unsigned test7() {
// CHECK: @test7
// CHECK: load i32, i32* getelementptr inbounds (%struct.YBitfield, %struct.YBitfield* @gbitfield, i32 0, i32 1, i32 0), align 4
return gbitfield.y.b2;
}
The "align 4" is actually wrong. Accessing all of "gbitfield.y" as a single
i32 is of course possible, but that still doesn't make it 4-byte aligned as
it remains packed at offset 1 in the surrounding gbitfield object.
This alignment was changed by commit r169489, which also introduced changes
to bitfield access code in CGExpr.cpp. Code before that change used to take
into account *both* the alignment of the field to be accessed within the
current struct, *and* the alignment of that outer struct itself; this logic
was removed by the above commit.
Neglecting to consider both values can cause incorrect code to be generated
(I've seen an unaligned access crash on SystemZ due to this bug).
In order to always use the best known alignment value, this patch removes
the CGBitFieldInfo::StorageAlignment member and replaces it with a
StorageOffset member specifying the offset from the start of the surrounding
struct to the bitfield's underlying storage. This offset can then be combined
with the best-known alignment for a bitfield access lvalue to determine the
alignment to use when accessing the bitfield's storage.
Differential Revision: http://reviews.llvm.org/D11034
llvm-svn: 241916
The patch is generated using this command:
$ tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
-checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
work/llvm/tools/clang
To reduce churn, not touching namespaces spanning less than 10 lines.
llvm-svn: 240270
The first named data member is the field used to default initialize the
union. An IndirectFieldDecl can introduce the first named data member
of a union.
llvm-svn: 238649
Types can be classified as being zero-initializable or
non-zero-initializable. We used to classify array types by giving them
the classification of their base element type. However, incomplete
array types are never initialized directly and thus are always
zero-initializable.
llvm-svn: 238256
Fixes rdar://20621065.
A more elegant fix would preclude this case by defining the
rules such that zero-size classes are always formally empty.
I believe the only extensions which create zero-size classes
right now are flexible arrays and zero-length arrays; it's
not abstractly unreasonable to say that those don't count
as members for the purposes of emptiness, just as zero-width
bitfields don't count. But that's an ABI-affecting change
and requires further discussion; in the meantime, let's not
assert / miscompile.
llvm-svn: 235815
Unions are initialized with the default initialization of their first
named member. If that member is not zero initialized, then we should
prefer that member's type. Otherwise, we might try to make an otherwise
unsuitable type (like an array) which we cannot easily initialize with a
pointer to member.
llvm-svn: 219781
Clang uses two types to talk about a C++ class, the
NonVirtualBaseLLVMType and the LLVMType. Previously, we would allow one
of these to be packed and the other not.
This is problematic. If both don't agree on a common subset of fields,
then routines like getLLVMFieldNo will point to the wrong field. Solve
this by copying the 'packed'-ness of the complete type to the
non-virtual subobject. For this to work, we need to take into account
the non-virtual subobject's size and alignment when we are computing the
layout of the complete object.
This fixes PR21089.
llvm-svn: 218577
It fits better with LLVM's memory model to try to do this in the
backend. Specifically, narrowing wide loads in the backends should be
relatively straightforward and is generally valuable, whereas widening
loads tends to be very constrained.
Discussion here:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140811/112581.html
This reverts commit r215614.
llvm-svn: 215648
Currently when laying out bitfields that don't need any padding, we
represent them as a wide enough int to contain all of the bits. This
can be hard on the backend since we'll do things like represent stores
to a few bits as loading an i144, masking it with a large constant,
and storing it back.
This turns up in less pathological cases where we load and mask 64 bit
word on a 32 bit platform when we actually only need to access 32 bits.
This leads to bad code being generated in most of our 32 bit backends.
In practice, there are often natural breaks in bitfields, and it's a
fairly simple and effective heuristic to split these fields into legal
integer sized chunks when it will be equivalent (ie, it won't force us
to add any extra padding).
llvm-svn: 215614
Prior to this patch, CGRecordLower assumed that virtual bases could not
be placed before the nvsize of an object. This isn't true in Itanium
mode, virtual bases are placed at dsize rather than vnsize and in the
case of zero sized non-virtual bases nvsize can be larger than dsize.
This patch fixes CGRecordLowering to avoid an assert and to clip
bitfields properly in this case. A test case is included.
llvm-svn: 207280
Saleem Abdulrasool
Yaron Keren
Rui Ueyama
David Majnemer
Ulrich Weigand
Alexander Kornienko
John McCall
Aaron Ballman
Justin Bogner
Craig Topper
Warren Hunt
Richard Smith