https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107892
--- Comment #1 from Eric Biggers <ebiggers3 at gmail dot com> --- The reproducer I gave in my first comment doesn't reproduce the bug on releases/gcc-11.1.0, so it must have regressed between then and trunk. I can do a bisection if needed. However, I actually still see the bug with gcc-11.1.0 on my original unminimized code at https://github.com/ebiggers/libdeflate/blob/fb0c43373f6fe600471457f4c021b8ad7e4bbabf/lib/x86/adler32_impl.h#L142. So maybe the reproducer I gave is not the best one. Here is a slightly different reproducer that reproduces the bug with both gcc-11.1.0 and trunk: #include <immintrin.h> __m256i __attribute__((target("avx2"))) f(const __m256i *p, size_t n) { __m256i a = _mm256_setzero_si256(); do { a = _mm256_add_epi32(a, *p++); } while (--n); return _mm256_madd_epi16(a, a); } The assembly of the loop has the unnecessary vmovdqa: 8: c5 f5 fe 07 vpaddd (%rdi),%ymm1,%ymm0 c: 48 83 c7 20 add $0x20,%rdi 10: c5 fd 6f c8 vmovdqa %ymm0,%ymm1 14: 48 83 ee 01 sub $0x1,%rsi 18: 75 ee jne 8 <f+0x8>
