On 9/11/2021 3:28 AM, Roger Sayle wrote:
This patch catches another place in the middle-end where it's possible
to preserve the SUBREG_PROMOTED_VAR_P annotation on a subreg to the
benefit of later RTL optimizations. This adds the same logic to
expr.c's convert_move as recently added to convert_modes.
On nvptx-none, the simple test program:
short foo (char c) { return c; }
currently generates three instructions:
mov.u32 %r23, %ar0;
cvt.u16.u32 %r24, %r23;
cvt.s32.s16 %value, %r24;
with this patch, we now generate just one:
mov.u32 %value, %ar0;
This patch should look familiar, it's almost identical to the recent patch
https://gcc.gnu.org/pipermail/gcc-patches/2021-August/578331.html but with
the fix https://gcc.gnu.org/pipermail/gcc-patches/2021-August/578519.html
[Apologies again for this breakage on affected (non-x86_64) targets; I hope
having that fixed within a few hours (before many folks even noticed a
problem) minimized the inconvenience].
This patch has been tested on x86_64-pc-linux-gnu with "make bootstrap"
and "make -k check" with no new failures, and on a cross-compiler to
nvptx-none, with no new failures in its testsuite. OK for mainline?
2021-09-11 Roger Sayle <ro...@nextmovesoftware.com>
gcc/ChangeLog
* expr.c (convert_move): Preserve SUBREG_PROMOTED_VAR_P when
creating a (wider) partial subreg from a SUBREG_PROMOTED_VAR_P
subreg.
OK
Jeff
