We were assuming that vbtable indices were assigned in layout order in
our comparison, which is not the case. When a virtual method, such as
the destructor, appears in multiple vftables, the vftable that appears
first in object layout order is the one that points to the main
implementation of that method. The later vftables use thunks.
In this layout, we adjusted "this" in the main implementation by the
amount that is appropriate for 'B' instead of 'A', even though the main
implementation is found in D's vftable for A:
struct A {
virtual ~A() {}
};
struct B {
virtual ~B() {}
};
struct C : virtual B {};
struct D : virtual A, C {};
D's layout looks like:
0 D subobject (empty)
0 C base suboject
8 A base subobject
16 B base subobject
With this fix, we correctly adjust by -8 in D's deleting destructor
instead of -16.
Fixes PR36921.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@328723 91177308-0d34-0410-b5e6-96231b3b80d8
It is not needed after LLVM r327734. Now it will be easier to copy-paste
IR symbol names from Clang.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@327738 91177308-0d34-0410-b5e6-96231b3b80d8
The tests that failed on a windows host have been fixed.
Original message:
Start setting dso_local for COFF.
With this there are still some GVs where we don't set dso_local
because setGVProperties is never called. I intend to fix that in
followup commits. This is just the bare minimum to teach
shouldAssumeDSOLocal what it should do for COFF.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@325940 91177308-0d34-0410-b5e6-96231b3b80d8
With this there are still some GVs where we don't set dso_local
because setGVProperties is never called. I intend to fix that in
followup commits. This is just the bare minimum to teach
shouldAssumeDSOLocal what it should do for COFF.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@325915 91177308-0d34-0410-b5e6-96231b3b80d8
This change reduces the live range of the loaded function pointer,
resulting in a slight code size decrease (~10KB in clang), and also
improves the security of CFI for virtual calls by making it less
likely that the function pointer will be spilled, and ensuring that
it is not spilled across a function call boundary.
Fixes PR35353.
Differential Revision: https://reviews.llvm.org/D42725
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@324286 91177308-0d34-0410-b5e6-96231b3b80d8
When a function taking transparent union is declared as taking one of
union members earlier in the translation unit, clang would hit an
"Invalid cast" assertion during EmitFunctionProlog. This case
corresponds to function f1 in test/CodeGen/transparent-union-redecl.c.
We decided to cast i32 to union because after merging function
declarations function parameter type becomes int,
CGFunctionInfo::ArgInfo type matches with ABIArgInfo type, so we decide
it is a trivial case. But these types should also be castable to
parameter declaration type which is not the case here.
Now the fix is in converting from ABIArgInfo type to VarDecl type and using
argument demotion when necessary.
Additional tests in Sema/transparent-union.c capture current behavior and make
sure there are no regressions.
rdar://problem/34949329
Reviewers: rjmccall, rafael
Reviewed By: rjmccall
Subscribers: aemerson, cfe-commits, kristof.beyls, ahatanak
Differential Revision: https://reviews.llvm.org/D41311
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@323156 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Upstream LLVM is changing the the prototypes of the @llvm.memcpy/memmove/memset
intrinsics. This change updates the Clang tests for this change.
The @llvm.memcpy/memmove/memset intrinsics currently have an explicit argument
which is required to be a constant integer. It represents the alignment of the
dest (and source), and so must be the minimum of the actual alignment of the
two.
This change removes the alignment argument in favour of placing the alignment
attribute on the source and destination pointers of the memory intrinsic call.
For example, code which used to read:
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dest, i8* %src, i32 100, i32 4, i1 false)
will now read
call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 4 %dest, i8* align 4 %src, i32 100, i1 false)
At this time the source and destination alignments must be the same (Step 1).
Step 2 of the change, to be landed shortly, will relax that contraint and allow
the source and destination to have different alignments.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@322964 91177308-0d34-0410-b5e6-96231b3b80d8
When a function taking transparent union is declared as taking one of
union members earlier in the translation unit, clang would hit an
"Invalid cast" assertion during EmitFunctionProlog. This case
corresponds to function f1 in test/CodeGen/transparent-union-redecl.c.
We decided to cast i32 to union because after merging function
declarations function parameter type becomes int,
CGFunctionInfo::ArgInfo type matches with ABIArgInfo type, so we decide
it is a trivial case. But these types should also be castable to
parameter declaration type which is not the case here.
The fix is in checking for the trivial case if ABIArgInfo type matches with
parameter declaration type. It exposed inconsistency that we check
hasScalarEvaluationKind for different types in EmitParmDecl and
EmitFunctionProlog, and comment says they should match.
Additional tests in Sema/transparent-union.c capture current behavior and make
sure there are no regressions.
rdar://problem/34949329
Reviewers: rjmccall, rafael
Reviewed By: rjmccall
Subscribers: aemerson, cfe-commits, kristof.beyls
Differential Revision: https://reviews.llvm.org/D41311
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@321296 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The MS ABI convention is that the 'this' pointer on entry is the address
of the vfptr that was used to make the virtual method call. In other
words, the pointer on entry always points to the base subobject that
introduced the virtual method. Consider this hierarchy:
struct A { virtual void f() = 0; };
struct B { virtual void g() = 0; };
struct C : A, B {
void f() override;
void g() override;
};
On entry to C::g, [ER]CX will contain the address of C's B subobject,
and C::g will have to subtract sizeof(A) to recover a pointer to C.
Before this change, we applied this adjustment in the prologue and
stored the new value into the "this" local variable alloca used for
debug info. However, MSVC does not do this, presumably because it is
often profitable to fold the adjustment into later field accesses. This
creates a problem, because the debugger expects the variable to be
unadjusted. Unfortunately, CodeView doesn't have anything like DWARF
expressions for computing variables that aren't in the program anymore,
so we have to declare 'this' to be the unadjusted value if we want the
debugger to see the right value.
This has the side benefit that, in optimized builds, the 'this' pointer
will usually be available on function entry because it doesn't require
any adjustment.
Reviewers: hans
Subscribers: aprantl, cfe-commits
Differential Revision: https://reviews.llvm.org/D40109
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@318440 91177308-0d34-0410-b5e6-96231b3b80d8
They are a little bit of a special case in the mangling. They are always
mangled without taking into account their virtual-ness of the
destructor. They are also mangled to return void, unlike the actual
destructor.
This fixes PR31931.
Differential Revision: https://reviews.llvm.org/D29912
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@295010 91177308-0d34-0410-b5e6-96231b3b80d8
Move the logic for doing this from the ABI argument lowering into
EmitParmDecl, which runs for all parameters. Our codegen is slightly
suboptimal in this case, as we may leave behind a dead store after
optimization, but it's 32-bit inalloca, and this fixes the bug in a
robust way.
Fixes PR30293
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@280836 91177308-0d34-0410-b5e6-96231b3b80d8
Bases can be zero-initialized: the storage is zero-initialized before
the base constructor is run.
The MS ABI has a quirk where base VBPtrs are not installed by the
base constructor but by the most derived class. In particular, they are
installed before the base constructor is run.
The derived constructor must be careful to zero-initialize only the bits
of the class which haven't already been populated by virtual base
pointers.
While we correctly avoided this scenario, we didn't handle the case
where the base class has virtual bases which have virtual bases.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@269271 91177308-0d34-0410-b5e6-96231b3b80d8
If we are devirtualizing, then we want to compute the 'this' adjustment
of the devirtualized target, not the adjustment of the base's method
definition, which is usually zero.
Fixes PR27621
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@268418 91177308-0d34-0410-b5e6-96231b3b80d8
This is a follow on from a similar LLVM commit: r253511.
Note, this was reviewed (and more details are in) http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html
These intrinsics currently have an explicit alignment argument which is
required to be a constant integer. It represents the alignment of the
source and dest, and so must be the minimum of those.
This change allows source and dest to each have their own alignments
by using the alignment attribute on their arguments. The alignment
argument itself is removed.
The only code change to clang is hidden in CGBuilder.h which now passes
both dest and source alignment to IRBuilder, instead of taking the minimum of
dest and source alignments.
Reviewed by Hal Finkel.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@253512 91177308-0d34-0410-b5e6-96231b3b80d8
Certain CXXConstructExpr nodes require zero-initialization before a
constructor is called. We had a bug in the case where the constructor
is called on a virtual base: we zero-initialized the base's vbptr field.
A complementary bug is present in MSVC where no zero-initialization
occurs for the subobject at all.
This fixes PR25370.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@251783 91177308-0d34-0410-b5e6-96231b3b80d8
Introduce an Address type to bundle a pointer value with an
alignment. Introduce APIs on CGBuilderTy to work with Address
values. Change core APIs on CGF/CGM to traffic in Address where
appropriate. Require alignments to be non-zero. Update a ton
of code to compute and propagate alignment information.
As part of this, I've promoted CGBuiltin's EmitPointerWithAlignment
helper function to CGF and made use of it in a number of places in
the expression emitter.
The end result is that we should now be significantly more correct
when performing operations on objects that are locally known to
be under-aligned. Since alignment is not reliably tracked in the
type system, there are inherent limits to this, but at least we
are no longer confused by standard operations like derived-to-base
conversions and array-to-pointer decay. I've also fixed a large
number of bugs where we were applying the complete-object alignment
to a pointer instead of the non-virtual alignment, although most of
these were hidden by the very conservative approach we took with
member alignment.
Also, because IRGen now reliably asserts on zero alignments, we
should no longer be subject to an absurd but frustrating recurring
bug where an incomplete type would report a zero alignment and then
we'd naively do a alignmentAtOffset on it and emit code using an
alignment equal to the largest power-of-two factor of the offset.
We should also now be emitting much more aggressive alignment
attributes in the presence of over-alignment. In particular,
field access now uses alignmentAtOffset instead of min.
Several times in this patch, I had to change the existing
code-generation pattern in order to more effectively use
the Address APIs. For the most part, this seems to be a strict
improvement, like doing pointer arithmetic with GEPs instead of
ptrtoint. That said, I've tried very hard to not change semantics,
but it is likely that I've failed in a few places, for which I
apologize.
ABIArgInfo now always carries the assumed alignment of indirect and
indirect byval arguments. In order to cut down on what was already
a dauntingly large patch, I changed the code to never set align
attributes in the IR on non-byval indirect arguments. That is,
we still generate code which assumes that indirect arguments have
the given alignment, but we don't express this information to the
backend except where it's semantically required (i.e. on byvals).
This is likely a minor regression for those targets that did provide
this information, but it'll be trivial to add it back in a later
patch.
I partially punted on applying this work to CGBuiltin. Please
do not add more uses of the CreateDefaultAligned{Load,Store}
APIs; they will be going away eventually.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@246985 91177308-0d34-0410-b5e6-96231b3b80d8
We currently use i32 (...)** as the type of the vptr field in the LLVM
struct type. LLVM's GlobalOpt prefers any bitcasts to be on the side of
the data being stored rather than on the pointer being stored to.
Reviewers: majnemer
Differential Revision: http://reviews.llvm.org/D5916
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@223267 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The Itanium ABI approach of using offset-to-top isn't possible with the
MS ABI, it doesn't have that kind of information lying around.
Instead, we do the following:
- Call the virtual deleting destructor with the "don't delete the object
flag" set. The virtual deleting destructor will return a pointer to
'this' adjusted to the most derived class.
- Call the global delete using the adjusted 'this' pointer.
Reviewers: rnk
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D5996
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@220993 91177308-0d34-0410-b5e6-96231b3b80d8
This eliminates some i8* GEPs and makes the IR that clang emits a bit
more canonical. More work is needed for vftables, but that isn't a clear
win so I plan to send it for review.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@220398 91177308-0d34-0410-b5e6-96231b3b80d8
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
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199250 91177308-0d34-0410-b5e6-96231b3b80d8
Fixes PR18435, where we generated a base ctor instead of a complete
ctor, and so failed to construct virtual bases when constructing the
complete object.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199160 91177308-0d34-0410-b5e6-96231b3b80d8
Reid Kleckner