Summary:
Subregister liveness tracking is not implemented for X86 backend, so
sometimes the whole super register is said to be live, when only a
subregister is really live. That might happen if the def and the use
are located in different MBBs, see added fixup-bw-isnt.mir test.
However, using knowledge of the specific instructions handled by the
bw-fixup-pass we can get more precise liveness information which this
change does.
Reviewers: MatzeB, DavidKreitzer, ab, andrew.w.kaylor, craig.topper
Reviewed By: craig.topper
Subscribers: n.bozhenov, myatsina, llvm-commits, hiraditya
Patch by Andrei Elovikov <andrei.elovikov@intel.com>
Differential Revision: https://reviews.llvm.org/D37559
llvm-svn: 313524
Ideally we'd be able to emit the SUBREG_TO_REG without the explicit register->register move, but we'd need to be sure the producing operation would select something that guaranteed the upper bits were already zeroed.
llvm-svn: 312450
In a future patch, I plan to teach isel to use a small vector move with implicit zeroing of the upper elements when it sees the (insert_subvector zero, X, 0) pattern.
llvm-svn: 312448
This patch adds support for including the avx512 mask register information in the mask/maskz versions of shuffle instruction comments.
This initial version just adds support for MOVDDUP/MOVSHDUP/MOVSLDUP to reduce the mass of test regenerations, other shuffle instructions can be added in due course.
Differential Revision: http://reviews.llvm.org/D21953
llvm-svn: 274459
Its not worth trying to write out tests for all the avx512f builtins yet, just adding tests for lowering of generic IR as we transition to it (shuffles mainly right now).
llvm-svn: 274434
Jina Nahias