Add a WASM SIMD128 SAXPY/DAXPY kernel - #5984
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kernel/wasm/KERNEL is included after KERNEL.WASM128_GENERIC and unconditionally pointed S/D AXPY at RISC-V scalar axpy.c, so the x86_64 V_SIMD sources listed in the target file never ran. Add kernel/wasm/axpy.c for both precisions. Unit-stride y += da * x uses eight independent v128 lanes (32 floats / 16 doubles) with IEEE mul+add; remainder is one vector then scalar. Skip relaxed madd: AXPY is checked to machine epsilon, and putting it in the generic V_SIMD path previously slowed Level 1. Non-unit stride stays scalar (no WASM gather); inc==0 uses that path so y[0] += n * da * x[0]. Guard SAXPYKERNEL/DAXPYKERNEL with ifndef in KERNEL so the target file wins. CAXPY/ZAXPY stay RISC-V scalar. On n=512..8192 vs the RISC-V champion, SAXPY is about 1.4–3.0x and DAXPY about 1.4–2.2x. test.sh is green. Signed-off-by: Julien Jerphanion <git@jjerphan.xyz>
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Summary
Follow-up to #5983 / #5680 / #4023: replace the RISC-V scalar SAXPY/DAXPY kernels used by
WASM128_GENERICwith a WASM SIMD128 unit-stride kernel.kernel/wasm/KERNELis included afterKERNEL.WASM128_GENERICand previously overwrote S/D AXPY withkernel/riscv64/axpy.c, so thex86_64V_SIMD sources listed in the target file never ran.kernel/wasm/axpy.c. Unit-stridey += da * xis eight independentv128lanes (32 floats / 16 doubles) with IEEE mul+add; remainder is one vector then scalar.V_SIMDpath previously slowed Level 1. Non-unit stride stays scalar (no WASM gather);inc == 0uses that path soy[0] += n * da * x[0].SAXPYKERNEL/DAXPYKERNELinKERNELare wrapped inifndefso the target file wins (same include-order fix as TRMM in Add a 4x4 WASM SIMD128 GEMM microkernel #5983). CAXPY/ZAXPY stay RISC-V scalar.Benchmarks
Node / Emscripten,
TARGET=WASM128_GENERIC,USE_THREAD=0,COMMON_OPT=-O2. Same machine, 5 warmup + 10 timed samples (median). Speedup > 1 means this branch is faster thandevelop.Geomean vs
develop: SAXPY 1.63x, DAXPY 1.53x.Test plan
utestunder node (includingsaxpy/daxpyinc==0; 106/106)ctestL1 (x{s,d,c,z}cblat1) under node, including SAXPY/DAXPY