[FFmpeg-devel] gcc: Remove auto-vectorization limitation.

[Jiawei <jiawei@iscas.ac.cn>]

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
-- 
2.43.0

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