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| author | Wilco Dijkstra <wdijkstr@arm.com> | 2017-10-30 18:46:02 +0000 |
|---|---|---|
| committer | Wilco Dijkstra <wilco@gcc.gnu.org> | 2017-10-30 18:46:02 +0000 |
| commit | b832b29f6578d3171e41d084b7a8432a24c5bf62 (patch) | |
| tree | bc8021aa242ff8a5c91571f998c0664543be9467 /gcc/gcc.c | |
| parent | 0d1cf53834bdcbe23c20c872036754c028caaa06 (diff) | |
| download | gcc-b832b29f6578d3171e41d084b7a8432a24c5bf62.zip gcc-b832b29f6578d3171e41d084b7a8432a24c5bf62.tar.gz gcc-b832b29f6578d3171e41d084b7a8432a24c5bf62.tar.bz2 | |
Remove DImode expansions for 1-bit shifts
A left shift of 1 can always be done using an add, so slightly adjust rtx
cost for DImode left shift by 1 so that adddi3 is preferred in all cases,
and the arm_ashldi3_1bit is redundant.
DImode right shifts of 1 are rarely used (6 in total in the GCC binary),
so there is little benefit of the arm_ashrdi3_1bit and arm_lshrdi3_1bit
patterns. The generated code is better and faster without these shifts
as it allows early expansion, optimization and better register allocation.
gcc/
* config/arm/arm.md (ashldi3): Remove shift by 1 expansion.
(arm_ashldi3_1bit): Remove pattern.
(ashrdi3): Remove shift by 1 expansion.
(arm_ashrdi3_1bit): Remove pattern.
(lshrdi3): Remove shift by 1 expansion.
(arm_lshrdi3_1bit): Remove pattern.
* config/arm/arm.c (arm_rtx_costs_internal): Slightly increase
cost of ashldi3 by 1.
* config/arm/neon.md (ashldi3_neon): Remove shift by 1 expansion.
(<shift>di3_neon): Likewise.
From-SVN: r254237
Diffstat (limited to 'gcc/gcc.c')
0 files changed, 0 insertions, 0 deletions