在 2025/5/21 15:46, Michael Niedermayer 写道:
On Wed, May 21, 2025 at 02:17:50PM +0800, Jiawei wrote:
This patch modifies the FFmpeg build system to remove the explicit disabling
of GCC's auto-vectorization feature.
Modern GCC versions (>= 10.0) have demonstrated stable auto-vectorization
capabilities through extensive optimizations in loop analysis and SIMD
code generation. The explicit -fno-tree-vectorize flag originally added
in commit 973859f (2009) to workaround early GCC vectorization instability
is no longer necessary.
Key improvements justifying this change:
1. Enhanced heuristics for loop vectorization cost models
2. Mature handling of alignment and memory access patterns
3. Robust fallback mechanisms for unsupported architectures
This change allows FFmpeg to benefit from automated SIMD optimizations
when built with -O3 optimization level, particularly improving
performance on x86_64 (AVX), ARM64 (SVE) and RISC-V(RVV) architectures.
[1]
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/973859f5230e77beea7bb59dc081870689d6d191
---
configure | 1 -
1 file changed, 1 deletion(-)
diff --git a/configure b/configure
index 3730b0524c..b9e95ce4ec 100755
--- a/configure
+++ b/configure
@@ -7656,7 +7656,6 @@ if enabled icc; then
disable aligned_stack
fi
elif enabled gcc; then
- check_optflags -fno-tree-vectorize
check_cflags -Werror=format-security
check_cflags -Werror=implicit-function-declaration
check_cflags -Werror=missing-prototypes
Your text speaks about this change being ok in a gcc version dependant
way
Your patch has no gcc version dependancy
If you claim that all issues where solved, please show the issues happening
in version v and no longer happening in w>v . Then it make sense to
change the flags for version w
Thx
[...]
Sorry I forgot about that, thanks for reminding me. Here still exist
many old version gcc user,
And I am not sure how will this impact them.
Maybe a later version gcc checking is good, like gcc 13-15, what you
think about it?
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