diff options
| -rw-r--r-- | llvm/lib/Support/DJB.cpp | 35 |
1 files changed, 16 insertions, 19 deletions
diff --git a/llvm/lib/Support/DJB.cpp b/llvm/lib/Support/DJB.cpp index a20dfc08e35..b97e212aaaa 100644 --- a/llvm/lib/Support/DJB.cpp +++ b/llvm/lib/Support/DJB.cpp @@ -57,29 +57,26 @@ static UTF32 foldCharDwarf(UTF32 C) { return sys::unicode::foldCharSimple(C); } -static uint32_t caseFoldingDjbHashCharSlow(StringRef &Buffer, uint32_t H) { - UTF32 C = chopOneUTF32(Buffer); - - C = foldCharDwarf(C); - - std::array<UTF8, UNI_MAX_UTF8_BYTES_PER_CODE_POINT> Storage; - StringRef Folded = toUTF8(C, Storage); - return djbHash(Folded, H); +static Optional<uint32_t> fastCaseFoldingDjbHash(StringRef Buffer, uint32_t H) { + bool allASCII = true; + for (unsigned char C : Buffer) { + H = H * 33 + ('A' <= C && C <= 'Z' ? C - 'A' + 'a' : C); + allASCII &= C <= 0x7f; + } + if (allASCII) + return H; + return None; } uint32_t llvm::caseFoldingDjbHash(StringRef Buffer, uint32_t H) { + if (Optional<uint32_t> Result = fastCaseFoldingDjbHash(Buffer, H)) + return *Result; + + std::array<UTF8, UNI_MAX_UTF8_BYTES_PER_CODE_POINT> Storage; while (!Buffer.empty()) { - unsigned char C = Buffer.front(); - if (LLVM_LIKELY(C <= 0x7f)) { - // US-ASCII, encoded as one character in utf-8. - // This is by far the most common case, so handle this specially. - if (C >= 'A' && C <= 'Z') - C = 'a' + (C - 'A'); // fold uppercase into lowercase - H = (H << 5) + H + C; - Buffer = Buffer.drop_front(); - continue; - } - H = caseFoldingDjbHashCharSlow(Buffer, H); + UTF32 C = foldCharDwarf(chopOneUTF32(Buffer)); + StringRef Folded = toUTF8(C, Storage); + H = djbHash(Folded, H); } return H; } |
