On 6/11/2024 12:57 PM, Michael Niedermayer wrote:
On Tue, Jun 11, 2024 at 12:38:37PM -0300, James Almer wrote:
On 6/11/2024 10:15 AM, Michael Niedermayer wrote:
On Fri, Jun 07, 2024 at 09:19:46PM +0300, Rémi Denis-Courmont wrote:
C code or compiler built-ins are preferable over inline assembler for
byte-swaps as it allows for better optimisations (e.g. instruction
scheduling) which would otherwise be impossible.
As with f64c2e710fa1a7b59753224e717f57c48462076f for x86 and Arm,
this removes the inline assembler on GCC (and Clang) since we now
require recent enough compiler versions (this indeed seems to work on
AArch64).
---
libavutil/aarch64/bswap.h | 56 ---------------------------------------
libavutil/avr32/bswap.h | 44 ------------------------------
libavutil/bswap.h | 8 +-----
libavutil/sh4/bswap.h | 48 ---------------------------------
As you are writing that this preferrable for better optimisations
Please provide benchmarks (for sh4, avr32)
This is a ridiculous request, considering nobody has such hardware at all.
Then I think its a ridiculous claim that this optimizes the code
I mean, at some point there was hardware and these optimisations did improve
speed.
This patch is not removing the code because its a rare (or dead) platform, it
removes
it with the claim that this would "allows for better optimisations"
Iam sorry but i do not see why asking for the claim in the commit message
to be backed up with facts being ridiculous
The claim in the commit message may be ridiculous
Compilers have come a long way since 20 years ago when this code was added.
See https://godbolt.org/z/jPose4rj3, where new GCC generates the same
code for sh4. And no inline assembly means instruction scheduling will
take these functions into account.
thx
[...]
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