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[feature] arm: speed up fp16 exp_ps floor step on aarch64 #6659

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Merged
nihui merged 4 commits into from
Apr 8, 2026
+2 −14
Merged

[feature] arm: speed up fp16 exp_ps floor step on aarch64 #6659

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e3c70a7
[feature] arm: speed up fp16 exp_ps floor step on aarch64
crafcat7 Apr 7, 2026
b6f2fda
[bugfix] Remove unused macro in neon_mathfun_fp16s.h
crafcat7 Apr 8, 2026
4db0394
[bugfix] Switch fp16 exp floor path to vrndm+vcvt
crafcat7 Apr 8, 2026
c38d865
[bugfix] Move fp16 exp mm conversion to pow2n stage
crafcat7 Apr 8, 2026
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16 changes: 2 additions & 14 deletions src/layer/arm/neon_mathfun_fp16s.h
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Original file line number Diff line number Diff line change
Expand Up @@ -197,13 +197,7 @@ static inline float16x4_t exp_ps_f16(float16x4_t x)
#endif

/* perform a floorf */
tmp = vcvt_f16_s16(vcvt_s16_f16(fx));

/* if greater, substract 1 */
uint16x4_t mask = vcgt_f16(tmp, fx);
mask = vand_u16(mask, (uint16x4_t)(one));

fx = vsub_f16(tmp, (float16x4_t)(mask));
fx = vrndm_f16(fx);

#if defined(_MSC_VER) && !defined(__clang__)
tmp = vmul_f16(fx, vcvt_f16_f32(vdupq_n_f32(c_cephes_exp_C1)));
Expand Down Expand Up @@ -255,13 +249,7 @@ static inline float16x8_t exp_ps_f16(float16x8_t x)
#endif

/* perform a floorf */
tmp = vcvtq_f16_s16(vcvtq_s16_f16(fx));

/* if greater, substract 1 */
uint16x8_t mask = vcgtq_f16(tmp, fx);
mask = vandq_u16(mask, vreinterpretq_u16_f16(one));

fx = vsubq_f16(tmp, vreinterpretq_f16_u16(mask));
fx = vrndmq_f16(fx);

#if defined(_MSC_VER) && !defined(__clang__)
float16x4_t _c_cephes_exp_C1 = vcvt_f16_f32(vdupq_n_f32(c_cephes_exp_C1));
Expand Down
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