Skip to content

RISC-V: Add RVV vectorized FindMatchLength optimization #233

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
zhanchangbao-sanechips wants to merge 1 commit into
base: main
Choose a base branch
from
Open

RISC-V: Add RVV vectorized FindMatchLength optimization #233

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
24 changes: 24 additions & 0 deletions snappy-internal.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -281,6 +281,30 @@ static inline std::pair<size_t, bool> FindMatchLength(const char* s1,
SNAPPY_PREFETCH(s1 + 64);
SNAPPY_PREFETCH(s2 + 64);

#if defined(__riscv) && SNAPPY_HAVE_RVV
// RISC-V Vector Extension (RVV) optimized version.
// Uses full hardware vector length without artificial 16-byte restriction.
// No scalar tail loop needed - RVV handles all lengths via vsetvl.
size_t len = s2_limit - s2;
const char* s1_current = s1 + matched;

for (size_t vl; len > 0; len -= vl, s1_current += vl, s2 += vl, matched += vl) {
vl = __riscv_vsetvl_e8m1(len);
vuint8m1_t v1 = __riscv_vle8_v_u8m1(reinterpret_cast<const uint8_t*>(s1_current), vl);
vuint8m1_t v2 = __riscv_vle8_v_u8m1(reinterpret_cast<const uint8_t*>(s2), vl);
long idx = __riscv_vfirst(__riscv_vmsne(v1, v2, vl), vl);
if (idx >= 0) {
matched += static_cast<size_t>(idx);
s2 += idx;
if (s2 <= s2_limit - 8) {
*data = UNALIGNED_LOAD64(s2);
}
return std::pair<size_t, bool>(matched, matched < 8);
}
}
return std::pair<size_t, bool>(matched, matched < 8);
#endif // defined(__riscv) && SNAPPY_HAVE_RVV

// Find out how long the match is. We loop over the data 64 bits at a
// time until we find a 64-bit block that doesn't match; then we find
// the first non-matching bit and use that to calculate the total
Expand Down