When passing a type with large alignment byval, we were specifying the type's
alignment rather than the alignment that the backend is actually capable of
producing (ABIAlign).
This would be OK (if odd) assuming the backend dealt with it prooperly,
unfortunately it doesn't and trying to pass types with "byval align 16" can
cause it to set fp incorrectly and trash the stack during the prologue. I'll be
fixing that in a separate patch, but Clang should still be emitting IR that's
as close to its intent as possible.
rdar://20059039
llvm-svn: 231706
The backend should now be able to handle all AAPCS rules based on argument
type, which means Clang no longer has to duplicate the register-counting logic
and the CodeGen can be significantly simplified.
llvm-svn: 230349
Now that LLVM can count the registers needed to implement AAPCS rules, we don't
need to duplicate that logic here. This means we can drop the explicit padding
and also use more natural types in many cases (e.g. "struct { float arr[3]; }"
used to end up as "[2 x double]" to avoid holes on the stack.
The one wrinkle is that AAPCS va_arg was also using the register counting
machinery. But the local replacement isn't too bad.
llvm-svn: 222904
Homogeneous aggregates on AAPCS_VFP ARM need to be passed *without* being
flattened (e.g. [2 x float] rather than "float, float") for various weird ABI
reasons. However, this isn't the case for anything else; further, we know at
the ABIArgInfo::getDirect callsites whether this flattening is allowed.
So, we can get more unified ARM code, with a simpler Clang, by just using that
knowledge directly.
llvm-svn: 221559
r211898 introduced a regression where a large struct, which would
normally be passed ByVal, was causing padding to be inserted to
prevent the backend from using some GPRs, in order to follow the
AAPCS. However, the type of the argument was not being set correctly,
so the backend cannot align 8-byte aligned struct types on the stack.
The fix is to not insert the padding arguments when the argument is
being passed ByVal.
llvm-svn: 213359
This is a fix to the code in clang which inserts padding arguments to
ensure that the ARM backend can emit AAPCS-VFP compliant code. This code
needs to track the number of registers which have been allocated in order
to do this. When passing a very large struct (>64 bytes) by value, clang
emits IR which takes a pointer to the struct, but the backend converts this
back to passing the struct in registers and on the stack. The bug was that
this was being considered by clang to only use one register, meaning that
there were situations in which padding arguments were incorrectly emitted
by clang.
llvm-svn: 211898
When we were padding a struct to avoid splitting it between registers and
the stack, we were throwing away the type which the argument should be coerced
to.
llvm-svn: 209122
This is the clang counterpart to 208413, which ensures that Homogeneous
Floating-point Aggregates are passed in consecutive registers on ARM.
llvm-svn: 208417
In cases where a struct must, according to the AAPCS, not be split between
general purpose and floating point registers, we use
ABIArgInfo::getExpandWithPadding to add the padding arguments. However,
ExpandWithPadding does not work if the struct contains bitfields, so we
instead must use ABIArgInfo::getDirect.
llvm-svn: 208185
This adds Clang support for the ARM64 backend. There are definitely
still some rough edges, so please bring up any issues you see with
this patch.
As with the LLVM commit though, we think it'll be more useful for
merging with AArch64 from within the tree.
llvm-svn: 205100
When a struct has bitfields overlapping with other members
(as required by the AAPCS), clang uses a packed struct to
represent this. If such a struct is large enough for clang to
pass it as a byval pointer (>64 bytes), we need to set the
alignment of the argument to match the original type.
llvm-svn: 203660
According to the AAPCS, we can split structs between GPRs and the stack,
except for when an argument has already been allocated on the stack. This
can occur when a large number of floating-point arguments fill up the VFP
registers, and are alllocated on the stack before the general-purpose argument
registers are full.
llvm-svn: 201137
Arguments and return values must always be marshalled as for the base
AAPCS when the callee is a variadic function.
Patch by Oliver Stannard!
llvm-svn: 200307
Lots of tests are using an explicit target triple w/o first checking that the
target is actually available. Add a REQUIRES clause to a bunch of them. This should
hopefully unbreak bots which don't configure w/ all targets enabled.
llvm-svn: 159949
A homogeneous aggregate is an aggregate data structure where after flattening
any nesting there are 1 to 4 elements of the same base type that is either a
float, double, or Neon vector. All Neon vectors of the same size, either 64
or 128 bits, are treated as equivalent for this purpose. When using the
AAPCS-VFP ABI, check for homogeneous aggregates and pass them as arguments by
expanding them into a sequence of their base types. This requires extending
the existing support for expanded arguments to handle not only structs, but
also constant arrays and complex types.
llvm-svn: 136767
Tim Northover