我试图从内存加载一个u16数组，并找到小于某个数字的第一个元素，在M1 mac上尽可能快。我一直在查看 neon 指令，但我无法找到一个好的方法来完成它。有比较向量指令，但是它们留给你的是全1或全0元素的向量，你怎么把它放到一个通用寄存器中呢？有没有一种方法可以通过测试向量指令来打破循环呢？
kh212irz1#
// int32_t searchArrayU16(uint16_t *pArray, uint16_t threshold, uint32_t len); // assert(len & 127 == 0); // assert(len >= 128); .arch armv8-a .global searchArrayU16 .text pArray0 .req x0 thresh .req w1 len .req x2 stride .req x3 pArray1 .req x4 count .req w5 val0 .req x6 val0w .req w6 val1 .req x7 val1w .req w7 .balign 64 .func searchArrayU16: adr x15, 2f dup v0.8h, thresh ld1r {v1.2d}, [x15] mov stride, #128 add pArray1, pArray0, #64 mov count, #0 b 1f .balign 8 2: .byte 1, 2, 4, 8, 16, 32, 64, 128 .balign 64 1: ld1 {v16.8h-v19.8h}, [pArray0], stride ld1 {v20.8h-v23.8h}, [pArray1], stride ld1 {v24.8h-v27.8h}, [pArray0], stride ld1 {v28.8h-v31.8h}, [pArray1], stride cmhi v16.8h, v0.8h, v16.8h cmhi v17.8h, v0.8h, v17.8h cmhi v18.8h, v0.8h, v18.8h cmhi v19.8h, v0.8h, v19.8h cmhi v20.8h, v0.8h, v20.8h cmhi v21.8h, v0.8h, v21.8h cmhi v22.8h, v0.8h, v22.8h cmhi v23.8h, v0.8h, v23.8h cmhi v24.8h, v0.8h, v24.8h cmhi v25.8h, v0.8h, v25.8h cmhi v26.8h, v0.8h, v26.8h cmhi v27.8h, v0.8h, v27.8h cmhi v28.8h, v0.8h, v28.8h cmhi v29.8h, v0.8h, v29.8h cmhi v30.8h, v0.8h, v30.8h cmhi v31.8h, v0.8h, v31.8h uzp1 v16.16b, v16.16b, v17.16b uzp1 v18.16b, v18.16b, v19.16b uzp1 v20.16b, v20.16b, v21.16b uzp1 v22.16b, v22.16b, v23.16b uzp1 v24.16b, v24.16b, v25.16b uzp1 v26.16b, v26.16b, v27.16b uzp1 v28.16b, v28.16b, v29.16b uzp1 v30.16b, v30.16b, v31.16b and v16.16b, v16.16b, v1.16b and v18.16b, v18.16b, v1.16b and v20.16b, v20.16b, v1.16b and v22.16b, v22.16b, v1.16b and v24.16b, v24.16b, v1.16b and v26.16b, v26.16b, v1.16b and v28.16b, v28.16b, v1.16b and v30.16b, v30.16b, v1.16b addp v16.16b, v16.16b, v18.16b addp v20.16b, v20.16b, v22.16b addp v24.16b, v24.16b, v26.16b addp v28.16b, v28.16b, v30.16b addp v16.16b, v16.16b, v20.16b addp v24.16b, v24.16b, v28.16b add count, count, #128 addp v16.16b, v16.16b, v24.16b // total pipeline stall here mov val0, v16.d[0] mov val1, v16.d[1] orr x15, val0, val1 cbnz x15, 1f // found a match!!! cmp len, count, uxtw b.hi 1b .balign 16 mov w0, #-1 // no match found ret .balign 16 1: rbit val0, val0 rbit val1, val1 cmp val0, #0 sub w0, count, #128 sub w1, count, #64 clz val0, val0 clz val1, val1 add w0, w0, val0w add w1, w1, val1w csel w0, w0, w1, ne ret .endfunc .end
给你。当没有找到匹配时，它返回-1。它应该可以在所有armv8-a或更高版本的内核上运行。
armv8-a
1条答案
按热度按时间kh212irz1#
给你。当没有找到匹配时，它返回-1。
它应该可以在所有
armv8-a或更高版本的内核上运行。