Add support for the moveq instruction, which is both faster and smaller
(1/2 to 1/3 the size) than a move with immediate to register.
This change introduces the instruction, along with a set of
pseudoinstructions to handle immediate moves to a register that is
lowered post-RA.
Pseudos are used as moveq can only write to the full register, which
makes
matching i8 and i16 immediate loads difficult in tablegen. Furthermore,
selecting moveq before RA constrains that immediate to be moved into a
data
register, which may not be optimal.
The bulk of this change are fixes to existing tests, which cover the new
functionality sufficiently.
This patch refactors all the existing M68k arithmetic instructions
to use the new VarLenCodeEmitterGen infrastructure.
This patch is tested by the existing MC test cases.
Note that one of the codegen tests needed to be updated because the
ordering of two equivalent instructions were switched.
Differential Revision: https://reviews.llvm.org/D115234
Previously ADD & ADDA (as well as SUB & SUBA) instructions are mixed
together, which not only violated Motorola assembly's syntax but also
made asm parsing more difficult. This patch separates these two kinds of
instructions migrate rest of the tests from
test/CodeGen/M68k/Encoding/Arithmetic to test/MC/M68k/Arithmetic.
Note that we observed minor regressions on codegen quality: Sometimes
isel uses ADD instead of ADDA even the latter can lead to shorter
sequence of code. This issue implies that some isel patterns might need
to be updated.
And a small utilities -- extract-section.py -- that helps extracting
specific object file section and printing in textual format. This
utility is just a workaround for tests inside `Encoding`. Hopefully in
the future we can replace dependencies in those tests with existing tools
(e.g. llvm-readobj). Please refer to this bug for more context:
https://bugs.llvm.org/show_bug.cgi?id=49245
Note that since we don't have AsmParser for now, we are testing the MC
part using MIR as input and put those tests under the `Encoding` folder.
In the future when AsmParser (and disassembler) is finished, those tests
will be moved to `test/MC/M68k`.
Authors: myhsu, m4yers, glaubitz
Differential Revision: https://reviews.llvm.org/D88392
