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https://github.com/ikawrakow/ik_llama.cpp.git
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Andrew MoryakovandGitHub
418d60a909
The IQK quantized GEMM kernels (ggml/src/iqk/iqk_gemm_*.cpp) are gated by HAVE_FANCY_SIMD in iqk_config.h, which requires five AVX-512 macros to be defined: __AVX512F__, __AVX512VNNI__, __AVX512VL__, __AVX512BW__, __AVX512DQ__. If they are not defined, the AVX-512 quantized matmul path is skipped silently — no build warning, no runtime symptom, just lower performance than the hardware can deliver. Surprises users on Windows/MSVC where -march=native semantics are not propagated. Adds a docs/build.md section that documents: - Which macros gate which path (HAVE_FANCY_SIMD for quant GEMM, __AVX512F__ alone for f16/f32, __AVX512BF16__ for bf16, __AVXVNNI__ for AVX2+VNNI-only CPUs). - Linux/GCC: GGML_NATIVE=ON (default) handles this automatically on Zen4 / Sapphire Rapids; just verify with objdump. - Windows/MSVC and cross-compile: explicit GGML_ARCH_FLAGS with -D__AVX512* defines is required. - Note on Zen4 implementing AVX-512 as 256-bit double-pumped. Documentation only — no code changes, no behavioural changes, no new CMake options introduced.