Changes for version 0.22 - 2026-08-14
- Fixed a build failure on compilers older than GCC 4.3
- The SSE2 backend is no longer selected on x86_64 CPUs without SSSE3. It shuffles with pshufb, which is SSSE3, but the dispatcher tested only the SSE2 bit, so on a pre-SSSE3 x86_64 (K8, Prescott) the first classified chunk was an illegal instruction. Those CPUs now get the scalar backend, which is what the code always claimed happened.
- AVX2 selection now also requires OSXSAVE, an XCR0 that says the YMM state is saved across a context switch, and the BMI2 the backend's target attribute lets the compiler emit. An AVX2-capable CPU under a kernel that never enabled XSAVE was running vector code with a silently truncated register.
- No more "'hot' attribute directive ignored" warnings on GCC 4.2, which predates both attributes.
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