These instructions use a portion of the encodings for grevi and
gorci. The full encodings are only supported with Zbp. Note,
rev8 has a different encoding between rv32 and rv64.
Zbb is closer to being finalized that Zbp which has motivated
some decisions in this patch.
I'm treating rev8 and orc.b as separate instructions when
either Zbb or Zbp is enabled. This allows us to print to suggest
that either feature needs to be enabled to support these mnemonics.
I had tried to put HasStdExtZbbAndNotZbp on the Zbb instructions,
but that caused a diagnostic that said Zbp is required if neither
feature is enabled. We should really mention Zbb since its closer
to final.
This does require extra isel patterns for the different cases so
that bswap will always print as rev8 in assembly listing since
we can't use an InstAlias.
llvm-objdump disassembling should always pick the rev8 or orc.b
instructions. llvm-mc parsing and printing text will not convert
the grevi/gorci spellings to rev8/gorc.b. We could probably fix
this with a special case in processInstruction in the assembly
parser if it its important.
Reviewed By: asb, frasercrmck
Differential Revision: https://reviews.llvm.org/D94944
zext.h uses the same encoding as pack rd, rs, x0 in rv32 and
packw rd, rs, x0 in rv64. Encodings without x0 as the second source
are not valid in Zbb.
I've added two new instructions with these specific encodings with
predicates that enable them when either Zbb or Zbp is enabled.
The pack spelling will only be accepted with Zbp. The disassembler
will use the zext.h instruction when either feature is enabled.
Using the pack spelling will print as pack when llvm-mc is
emitting text. We could fix this with some custom code in
processInstruction if this is important, but I'm not sure it is.
Reviewed By: asb, frasercrmck
Differential Revision: https://reviews.llvm.org/D94818
This alias for andi x, 255 was recently added to the spec. If we
print it, code we output can't be compiled with -fno-integrated-as
unless the GNU assembler is also a version that supports alias.
Reviewed By: lenary
Differential Revision: https://reviews.llvm.org/D93826
This adds the instruction encoding and mnenomics for the proposed
RISC-V Bit Manipulation extension (version 0.92). It is implemented with
each category of instruction as its own target feature, with the 'b'
extension feature enabling all options. Since this extension is not yet
ratified, all target features are prefixed with 'experimental-' to note
their status.
Differential Revision: https://reviews.llvm.org/D65649
Craig Topper