https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112325
--- Comment #9 from Hongtao Liu <liuhongt at gcc dot gnu.org> --- The original case is a little different from the one in PR. It comes from ggml #include <stdint.h> #include <string.h> typedef uint16_t ggml_fp16_t; static float table_f32_f16[1 << 16]; inline static float ggml_lookup_fp16_to_fp32(ggml_fp16_t f) { uint16_t s; memcpy(&s, &f, sizeof(uint16_t)); return table_f32_f16[s]; } typedef struct { ggml_fp16_t d; ggml_fp16_t m; uint8_t qh[4]; uint8_t qs[32 / 2]; } block_q5_1; typedef struct { float d; float s; int8_t qs[32]; } block_q8_1; void ggml_vec_dot_q5_1_q8_1(const int n, float * restrict s, const void * restrict vx, const void * restrict vy) { const int qk = 32; const int nb = n / qk; const block_q5_1 * restrict x = vx; const block_q8_1 * restrict y = vy; float sumf = 0.0; for (int i = 0; i < nb; i++) { uint32_t qh; memcpy(&qh, x[i].qh, sizeof(qh)); int sumi = 0; for (int j = 0; j < qk/2; ++j) { const uint8_t xh_0 = ((qh >> (j + 0)) << 4) & 0x10; const uint8_t xh_1 = ((qh >> (j + 12)) ) & 0x10; const int32_t x0 = (x[i].qs[j] & 0xF) | xh_0; const int32_t x1 = (x[i].qs[j] >> 4) | xh_1; sumi += (x0 * y[i].qs[j]) + (x1 * y[i].qs[j + qk/2]); } sumf += (ggml_lookup_fp16_to_fp32(x[i].d)*y[i].d)*sumi + ggml_lookup_fp16_to_fp32(x[i].m)*y[i].s; } *s = sumf; }