diff options
Diffstat (limited to 'sysdeps/aarch64/strrchr.S')
| -rw-r--r-- | sysdeps/aarch64/strrchr.S | 205 |
1 files changed, 91 insertions, 114 deletions
diff --git a/sysdeps/aarch64/strrchr.S b/sysdeps/aarch64/strrchr.S index 94da08d351..a9b2bf47c2 100644 --- a/sysdeps/aarch64/strrchr.S +++ b/sysdeps/aarch64/strrchr.S @@ -24,142 +24,119 @@ * * ARMv8-a, AArch64 * Neon Available. + * MTE compatible. */ /* Arguments and results. */ #define srcin x0 #define chrin w1 - #define result x0 #define src x2 -#define tmp1 x3 -#define wtmp2 w4 -#define tmp3 x5 -#define src_match x6 -#define src_offset x7 -#define const_m1 x8 -#define tmp4 x9 -#define nul_match x10 -#define chr_match x11 +#define tmp x3 +#define wtmp w3 +#define synd x3 +#define shift x4 +#define src_match x4 +#define nul_match x5 +#define chr_match x6 #define vrepchr v0 -#define vdata1 v1 -#define vdata2 v2 -#define vhas_nul1 v3 -#define vhas_nul2 v4 -#define vhas_chr1 v5 -#define vhas_chr2 v6 -#define vrepmask_0 v7 -#define vrepmask_c v16 -#define vend1 v17 -#define vend2 v18 +#define vdata v1 +#define vhas_nul v2 +#define vhas_chr v3 +#define vrepmask v4 +#define vrepmask2 v5 +#define vend v5 +#define dend d5 /* Core algorithm. - For each 32-byte hunk we calculate a 64-bit syndrome value, with - two bits per byte (LSB is always in bits 0 and 1, for both big - and little-endian systems). For each tuple, bit 0 is set iff - the relevant byte matched the requested character; bit 1 is set - iff the relevant byte matched the NUL end of string (we trigger - off bit0 for the special case of looking for NUL). Since the bits - in the syndrome reflect exactly the order in which things occur - in the original string a count_trailing_zeros() operation will - identify exactly which byte is causing the termination, and why. */ + For each 16-byte chunk we calculate a 64-bit syndrome value, with + four bits per byte (LSB is always in bits 0 and 1, for both big + and little-endian systems). For each tuple, bits 0-1 are set if + the relevant byte matched the requested character; bits 2-3 are set + if the relevant byte matched the NUL end of string. */ ENTRY(strrchr) DELOUSE (0) - cbz x1, L(null_search) - /* Magic constant 0x40100401 to allow us to identify which lane - matches the requested byte. Magic constant 0x80200802 used - similarly for NUL termination. */ - mov wtmp2, #0x0401 - movk wtmp2, #0x4010, lsl #16 + bic src, srcin, 15 dup vrepchr.16b, chrin - bic src, srcin, #31 /* Work with aligned 32-byte hunks. */ - dup vrepmask_c.4s, wtmp2 - mov src_offset, #0 - ands tmp1, srcin, #31 - add vrepmask_0.4s, vrepmask_c.4s, vrepmask_c.4s /* equiv: lsl #1 */ - b.eq L(aligned) - - /* Input string is not 32-byte aligned. Rather than forcing - the padding bytes to a safe value, we calculate the syndrome - for all the bytes, but then mask off those bits of the - syndrome that are related to the padding. */ - ld1 {vdata1.16b, vdata2.16b}, [src], #32 - neg tmp1, tmp1 - cmeq vhas_nul1.16b, vdata1.16b, #0 - cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b - cmeq vhas_nul2.16b, vdata2.16b, #0 - cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b - and vhas_nul1.16b, vhas_nul1.16b, vrepmask_0.16b - and vhas_chr1.16b, vhas_chr1.16b, vrepmask_c.16b - and vhas_nul2.16b, vhas_nul2.16b, vrepmask_0.16b - and vhas_chr2.16b, vhas_chr2.16b, vrepmask_c.16b - addp vhas_nul1.16b, vhas_nul1.16b, vhas_nul2.16b // 256->128 - addp vhas_chr1.16b, vhas_chr1.16b, vhas_chr2.16b // 256->128 - addp vhas_nul1.16b, vhas_nul1.16b, vhas_nul1.16b // 128->64 - addp vhas_chr1.16b, vhas_chr1.16b, vhas_chr1.16b // 128->64 - mov nul_match, vhas_nul1.2d[0] - lsl tmp1, tmp1, #1 - mov const_m1, #~0 - mov chr_match, vhas_chr1.2d[0] - lsr tmp3, const_m1, tmp1 - - bic nul_match, nul_match, tmp3 // Mask padding bits. - bic chr_match, chr_match, tmp3 // Mask padding bits. - cbnz nul_match, L(tail) - -L(loop): - cmp chr_match, #0 - csel src_match, src, src_match, ne - csel src_offset, chr_match, src_offset, ne -L(aligned): - ld1 {vdata1.16b, vdata2.16b}, [src], #32 - cmeq vhas_nul1.16b, vdata1.16b, #0 - cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b - cmeq vhas_nul2.16b, vdata2.16b, #0 - cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b - addp vend1.16b, vhas_nul1.16b, vhas_nul2.16b // 256->128 - and vhas_chr1.16b, vhas_chr1.16b, vrepmask_c.16b - and vhas_chr2.16b, vhas_chr2.16b, vrepmask_c.16b - addp vhas_chr1.16b, vhas_chr1.16b, vhas_chr2.16b // 256->128 - addp vend1.16b, vend1.16b, vend1.16b // 128->64 - addp vhas_chr1.16b, vhas_chr1.16b, vhas_chr1.16b // 128->64 - mov nul_match, vend1.2d[0] - mov chr_match, vhas_chr1.2d[0] - cbz nul_match, L(loop) - - and vhas_nul1.16b, vhas_nul1.16b, vrepmask_0.16b - and vhas_nul2.16b, vhas_nul2.16b, vrepmask_0.16b - addp vhas_nul1.16b, vhas_nul1.16b, vhas_nul2.16b - addp vhas_nul1.16b, vhas_nul1.16b, vhas_nul1.16b - mov nul_match, vhas_nul1.2d[0] + mov wtmp, 0x3003 + dup vrepmask.8h, wtmp + tst srcin, 15 + beq L(loop1) + + ld1 {vdata.16b}, [src], 16 + cmeq vhas_nul.16b, vdata.16b, 0 + cmeq vhas_chr.16b, vdata.16b, vrepchr.16b + mov wtmp, 0xf00f + dup vrepmask2.8h, wtmp + bit vhas_nul.16b, vhas_chr.16b, vrepmask.16b + and vhas_nul.16b, vhas_nul.16b, vrepmask2.16b + addp vend.16b, vhas_nul.16b, vhas_nul.16b + lsl shift, srcin, 2 + fmov synd, dend + lsr synd, synd, shift + lsl synd, synd, shift + ands nul_match, synd, 0xcccccccccccccccc + bne L(tail) + cbnz synd, L(loop2) + + .p2align 5 +L(loop1): + ld1 {vdata.16b}, [src], 16 + cmeq vhas_chr.16b, vdata.16b, vrepchr.16b + cmhs vhas_nul.16b, vhas_chr.16b, vdata.16b + umaxp vend.16b, vhas_nul.16b, vhas_nul.16b + fmov synd, dend + cbz synd, L(loop1) + + cmeq vhas_nul.16b, vdata.16b, 0 + bit vhas_nul.16b, vhas_chr.16b, vrepmask.16b + bic vhas_nul.8h, 0x0f, lsl 8 + addp vend.16b, vhas_nul.16b, vhas_nul.16b + fmov synd, dend + ands nul_match, synd, 0xcccccccccccccccc + beq L(loop2) L(tail): - /* Work out exactly where the string ends. */ - sub tmp4, nul_match, #1 - eor tmp4, tmp4, nul_match - ands chr_match, chr_match, tmp4 - /* And pick the values corresponding to the last match. */ - csel src_match, src, src_match, ne - csel src_offset, chr_match, src_offset, ne - - /* Count down from the top of the syndrome to find the last match. */ - clz tmp3, src_offset - /* Src_match points beyond the word containing the match, so we can - simply subtract half the bit-offset into the syndrome. Because - we are counting down, we need to go back one more character. */ - add tmp3, tmp3, #2 - sub result, src_match, tmp3, lsr #1 - /* But if the syndrome shows no match was found, then return NULL. */ - cmp src_offset, #0 + sub nul_match, nul_match, 1 + and chr_match, synd, 0x3333333333333333 + ands chr_match, chr_match, nul_match + sub result, src, 1 + clz tmp, chr_match + sub result, result, tmp, lsr 2 csel result, result, xzr, ne + ret + .p2align 4 +L(loop2): + cmp synd, 0 + csel src_match, src, src_match, ne + csel chr_match, synd, chr_match, ne + ld1 {vdata.16b}, [src], 16 + cmeq vhas_nul.16b, vdata.16b, 0 + cmeq vhas_chr.16b, vdata.16b, vrepchr.16b + bit vhas_nul.16b, vhas_chr.16b, vrepmask.16b + umaxp vend.16b, vhas_nul.16b, vhas_nul.16b + fmov synd, dend + tst synd, 0xcccccccccccccccc + beq L(loop2) + + bic vhas_nul.8h, 0x0f, lsl 8 + addp vend.16b, vhas_nul.16b, vhas_nul.16b + fmov synd, dend + and nul_match, synd, 0xcccccccccccccccc + sub nul_match, nul_match, 1 + and tmp, synd, 0x3333333333333333 + ands tmp, tmp, nul_match + csel chr_match, tmp, chr_match, ne + csel src_match, src, src_match, ne + sub src_match, src_match, 1 + clz tmp, chr_match + sub result, src_match, tmp, lsr 2 ret -L(null_search): - b __strchrnul END(strrchr) weak_alias (strrchr, rindex) |