Messages in this thread | | | Subject | Re: [PATCH] lib/zstd: Fix bitwise vs logical operators | From | Nathan Chancellor <> | Date | Mon, 16 Aug 2021 09:53:53 -0700 |
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On 8/16/2021 8:14 AM, David Sterba wrote: > You should CC Nick Terell for ZSTD patches, added.
Thanks for the info and adding him, I did not see an entry for lib/zstd/ in MAINTAINERS and there is no consistent person picking up patches according to git.
Cheers, Nathan
> On Sat, Aug 14, 2021 at 05:41:54PM -0700, Nathan Chancellor wrote: >> clang warns several times along the lines of: >> >> lib/zstd/compress.c:1043:7: warning: bitwise and of boolean expressions; did you mean logical and? [-Wbool-operation-and] >> if ((offset_1 > 0) & (ZSTD_read32(ip + 1 - offset_1) == ZSTD_read32(ip + 1))) { >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> && >> >> Bitwise ANDs do not short circuit, meaning that the ZSTD_read32 calls >> will be evaluated even if the first condition is not true. This is not >> always a problem but it is not a standard way to do conditionals so >> replace the bitwise ANDs with logical ones to fix the warning and make >> the code clearer. >> >> Signed-off-by: Nathan Chancellor <nathan@kernel.org> >> --- >> lib/zstd/compress.c | 16 ++++++++-------- >> 1 file changed, 8 insertions(+), 8 deletions(-) >> >> diff --git a/lib/zstd/compress.c b/lib/zstd/compress.c >> index b080264ed3ad..0e515d1d4237 100644 >> --- a/lib/zstd/compress.c >> +++ b/lib/zstd/compress.c >> @@ -1040,7 +1040,7 @@ void ZSTD_compressBlock_fast_generic(ZSTD_CCtx *cctx, const void *src, size_t sr >> const BYTE *match = base + matchIndex; >> hashTable[h] = curr; /* update hash table */ >> >> - if ((offset_1 > 0) & (ZSTD_read32(ip + 1 - offset_1) == ZSTD_read32(ip + 1))) { >> + if ((offset_1 > 0) && (ZSTD_read32(ip + 1 - offset_1) == ZSTD_read32(ip + 1))) { >> mLength = ZSTD_count(ip + 1 + 4, ip + 1 + 4 - offset_1, iend) + 4; >> ip++; >> ZSTD_storeSeq(seqStorePtr, ip - anchor, anchor, 0, mLength - MINMATCH); >> @@ -1072,7 +1072,7 @@ void ZSTD_compressBlock_fast_generic(ZSTD_CCtx *cctx, const void *src, size_t sr >> hashTable[ZSTD_hashPtr(base + curr + 2, hBits, mls)] = curr + 2; /* here because curr+2 could be > iend-8 */ >> hashTable[ZSTD_hashPtr(ip - 2, hBits, mls)] = (U32)(ip - 2 - base); >> /* check immediate repcode */ >> - while ((ip <= ilimit) && ((offset_2 > 0) & (ZSTD_read32(ip) == ZSTD_read32(ip - offset_2)))) { >> + while ((ip <= ilimit) && ((offset_2 > 0) && (ZSTD_read32(ip) == ZSTD_read32(ip - offset_2)))) { >> /* store sequence */ >> size_t const rLength = ZSTD_count(ip + 4, ip + 4 - offset_2, iend) + 4; >> { >> @@ -1291,7 +1291,7 @@ void ZSTD_compressBlock_doubleFast_generic(ZSTD_CCtx *cctx, const void *src, siz >> const BYTE *match = base + matchIndexS; >> hashLong[h2] = hashSmall[h] = curr; /* update hash tables */ >> >> - if ((offset_1 > 0) & (ZSTD_read32(ip + 1 - offset_1) == ZSTD_read32(ip + 1))) { /* note : by construction, offset_1 <= curr */ >> + if ((offset_1 > 0) && (ZSTD_read32(ip + 1 - offset_1) == ZSTD_read32(ip + 1))) { /* note : by construction, offset_1 <= curr */ >> mLength = ZSTD_count(ip + 1 + 4, ip + 1 + 4 - offset_1, iend) + 4; >> ip++; >> ZSTD_storeSeq(seqStorePtr, ip - anchor, anchor, 0, mLength - MINMATCH); >> @@ -1350,7 +1350,7 @@ void ZSTD_compressBlock_doubleFast_generic(ZSTD_CCtx *cctx, const void *src, siz >> hashLong[ZSTD_hashPtr(ip - 2, hBitsL, 8)] = hashSmall[ZSTD_hashPtr(ip - 2, hBitsS, mls)] = (U32)(ip - 2 - base); >> >> /* check immediate repcode */ >> - while ((ip <= ilimit) && ((offset_2 > 0) & (ZSTD_read32(ip) == ZSTD_read32(ip - offset_2)))) { >> + while ((ip <= ilimit) && ((offset_2 > 0) && (ZSTD_read32(ip) == ZSTD_read32(ip - offset_2)))) { >> /* store sequence */ >> size_t const rLength = ZSTD_count(ip + 4, ip + 4 - offset_2, iend) + 4; >> { >> @@ -1929,7 +1929,7 @@ void ZSTD_compressBlock_lazy_generic(ZSTD_CCtx *ctx, const void *src, size_t src >> const BYTE *start = ip + 1; >> >> /* check repCode */ >> - if ((offset_1 > 0) & (ZSTD_read32(ip + 1) == ZSTD_read32(ip + 1 - offset_1))) { >> + if ((offset_1 > 0) && (ZSTD_read32(ip + 1) == ZSTD_read32(ip + 1 - offset_1))) { >> /* repcode : we take it */ >> matchLength = ZSTD_count(ip + 1 + EQUAL_READ32, ip + 1 + EQUAL_READ32 - offset_1, iend) + EQUAL_READ32; >> if (depth == 0) >> @@ -1953,7 +1953,7 @@ void ZSTD_compressBlock_lazy_generic(ZSTD_CCtx *ctx, const void *src, size_t src >> if (depth >= 1) >> while (ip < ilimit) { >> ip++; >> - if ((offset) && ((offset_1 > 0) & (ZSTD_read32(ip) == ZSTD_read32(ip - offset_1)))) { >> + if ((offset) && ((offset_1 > 0) && (ZSTD_read32(ip) == ZSTD_read32(ip - offset_1)))) { >> size_t const mlRep = ZSTD_count(ip + EQUAL_READ32, ip + EQUAL_READ32 - offset_1, iend) + EQUAL_READ32; >> int const gain2 = (int)(mlRep * 3); >> int const gain1 = (int)(matchLength * 3 - ZSTD_highbit32((U32)offset + 1) + 1); >> @@ -1974,7 +1974,7 @@ void ZSTD_compressBlock_lazy_generic(ZSTD_CCtx *ctx, const void *src, size_t src >> /* let's find an even better one */ >> if ((depth == 2) && (ip < ilimit)) { >> ip++; >> - if ((offset) && ((offset_1 > 0) & (ZSTD_read32(ip) == ZSTD_read32(ip - offset_1)))) { >> + if ((offset) && ((offset_1 > 0) && (ZSTD_read32(ip) == ZSTD_read32(ip - offset_1)))) { >> size_t const ml2 = ZSTD_count(ip + EQUAL_READ32, ip + EQUAL_READ32 - offset_1, iend) + EQUAL_READ32; >> int const gain2 = (int)(ml2 * 4); >> int const gain1 = (int)(matchLength * 4 - ZSTD_highbit32((U32)offset + 1) + 1); >> @@ -2021,7 +2021,7 @@ void ZSTD_compressBlock_lazy_generic(ZSTD_CCtx *ctx, const void *src, size_t src >> } >> >> /* check immediate repcode */ >> - while ((ip <= ilimit) && ((offset_2 > 0) & (ZSTD_read32(ip) == ZSTD_read32(ip - offset_2)))) { >> + while ((ip <= ilimit) && ((offset_2 > 0) && (ZSTD_read32(ip) == ZSTD_read32(ip - offset_2)))) { >> /* store sequence */ >> matchLength = ZSTD_count(ip + EQUAL_READ32, ip + EQUAL_READ32 - offset_2, iend) + EQUAL_READ32; >> offset = offset_2; >> >> base-commit: ba31f97d43be41ca99ab72a6131d7c226306865f >> -- >> 2.33.0.rc2
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