This patch adds support for the z13 architecture type. For compatibility
with GCC, a pair of options -mvx / -mno-vx can be used to selectively
enable/disable use of the vector facility.
When the vector facility is present, we default to the new vector ABI.
This is characterized by two major differences:
- Vector types are passed/returned in vector registers
(except for unnamed arguments of a variable-argument list function).
- Vector types are at most 8-byte aligned.
The reason for the choice of 8-byte vector alignment is that the hardware
is able to efficiently load vectors at 8-byte alignment, and the ABI only
guarantees 8-byte alignment of the stack pointer, so requiring any higher
alignment for vectors would require dynamic stack re-alignment code.
However, for compatibility with old code that may use vector types, when
*not* using the vector facility, the old alignment rules (vector types
are naturally aligned) remain in use.
These alignment rules are not only implemented at the C language level,
but also at the LLVM IR level. This is done by selecting a different
DataLayout string depending on whether the vector ABI is in effect or not.
Based on a patch by Richard Sandiford.
llvm-svn: 236531
Test cases must not check for symbolic variable names that are not
present in IR generated by no-assert builds.
Fixed by testing a more complete subset of the va_arg dataflow,
without relying on variable names.
llvm-svn: 233574
Running the GCC's inter-compiler ABI compatibility test suite uncovered
a couple of errors in clang's SystemZ ABI implementation. These all
affect only rare corner cases:
- Short vector types
GCC synthetic vector types defined with __attribute__ ((vector_size ...))
are always passed and returned by reference. (This is not documented in
the official ABI document, but is the de-facto ABI implemented by GCC.)
clang would do that only for vector sizes >= 16 bytes, but not for shorter
vector types.
- Float-like aggregates and empty bitfields
clang would consider any aggregate containing an empty bitfield as
first element to be a float-like aggregate. That's obviously wrong.
According to the ABI doc, the presence of an empty bitfield makes
an aggregate to be *not* float-like. However, due to a bug in GCC,
empty bitfields are ignored in C++; this patch changes clang to be
compatible with this "feature" of GCC.
- Float-like aggregates and va_arg
The va_arg implementation would mis-detect some aggregates as float-like
that aren't actually passed as such. This applies to aggregates that
have only a single element of type float or double, but using an aligned
attribute that increases the total struct size to more than 8 bytes.
This error occurred because the va_arg implement used to have an copy
of the float-like aggregate detection logic (i.e. it would call the
isFPArgumentType routine, but not perform the size check).
To simplify the logic, this patch removes the duplicated logic and
instead simply checks the (possibly coerced) LLVM argument type as
already determined by classifyArgumentType.
llvm-svn: 233543
Ulrich Weigand