Something somewhere cut off the subject line: it should say Cortex-A57.
Sorry about that.
Kyrill
On 7/1/19 4:13 PM, Kyrill Tkachov wrote:
Hi all,
Some scheduling descriptions, like the Cortex-A57 one, are reused for
multiple -mcpu options.
Sometimes those other -mcpu cores support more architecture features
than the Armv8-A Cortex-A57.
For example, the Cortex-A75 and Cortex-A76 support Armv8.2-A as well as
the Dot Product instructions.
These Dot Product instructions have the neon_dot and neon_dot_q
scheduling type, but that type is not
handled in cortex-a57.md, since the Cortex-A57 itself doesn't need to
care about these instructions.
But if we just ignore the neon_dot(_q) type at scheduling we get really
terrible codegen when compiling
for -mcpu=cortex-a76, for example, because the scheduler just pools all
the UDOT instructions at the end
of the basic block, since it doesn't assume anything about their
behaviour.
This patch ameliorates the situation somewhat by telling the Cortex-A57
scheduling model to treat any
insn that doesn't get assigned a cortex_a57_neon_type but is actually a
is_neon_type instruction as
a simple neon_arith_basic instruction. This allows us to treat
post-Armv8-A SIMD instructions more sanely
without having to model each of them explicitly in cortex-a57.md.
Bootstrapped and tested on arm-none-linux-gnueabihf and
aarch64-none-linux-gnu.
Ok for trunk from an aarch64 perspective?
Thanks,
Kyrill
2019-01-07 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
* config/arm/cortex-a57.md (cortex_a57_neon_type): Use
neon_arith_basic
for is_neon_type instructions that have not already been categorized.
