-Wbitwise-instead-of-logical in lib/zstd/decompress/huf_decompress.c #1486

nickdesaulniers · 2021-10-21T17:02:13Z

our build of ppc44x_defconfig is printing:

Warning: /builds/linux/lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical]
                        (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished)
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/builds/linux/lib/zstd/decompress/../common/compiler.h:127:38: note: expanded from macro 'LIKELY'
#define LIKELY(x) (__builtin_expect((x), 1))
                                    ~^~
/builds/linux/lib/zstd/decompress/huf_decompress.c:890:25: note: cast one or both operands to int to silence this warning
Warning: /builds/linux/lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical]
                        (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished)
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/builds/linux/lib/zstd/decompress/../common/compiler.h:127:38: note: expanded from macro 'LIKELY'
#define LIKELY(x) (__builtin_expect((x), 1))
                                     ^
/builds/linux/lib/zstd/decompress/huf_decompress.c:890:25: note: cast one or both operands to int to silence this warning
Warning: /builds/linux/lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical]
                        (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished)
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/builds/linux/lib/zstd/decompress/../common/compiler.h:127:38: note: expanded from macro 'LIKELY'
#define LIKELY(x) (__builtin_expect((x), 1))
                                     ^

The text was updated successfully, but these errors were encountered:

nathanchance · 2021-10-21T20:24:23Z

Patch submitted: https://lore.kernel.org/r/20211021202353.2356400-1-nathan@kernel.org/

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com>

Credit to Nathan Chancellor for the bug fix and Nick Desaulniers for the bug report. Link: ClangBuiltLinux/linux#1486 Link: https://lore.kernel.org/all/20211021202353.2356400-1-nathan@kernel.org/

nathanchance · 2021-11-05T21:17:23Z

Patch accepted: terrelln@8e211b8

Credit to Nathan Chancellor for the bug fix and Nick Desaulniers for the bug report. Link: ClangBuiltLinux/linux#1486 Link: https://lore.kernel.org/all/20211021202353.2356400-1-nathan@kernel.org/

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com>

nathanchance · 2021-11-16T20:07:08Z

Fixed: https://git.kernel.org/linus/0a8ea235837cc39f27c45689930aa97ae91d5953

…-logical A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com> [cyberknight777: backport to 4.14] Signed-off-by: Cyber Knight <cyberknight755@gmail.com>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: LibXZR <i@xzr.moe>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: Marco Zanin <mrczn.bb@gmail.com>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Change-Id: I01e90578367ab5c420be0b817c5148722b936be8 Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: Divyanshu-Modi <divyan.m05@gmail.com> Signed-off-by: Divyanshu-Modi <divyan.m05@gmail.com> (cherry picked from commit 71f3b54) Signed-off-by: TogoFire <togofire@mailfence.com>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: Marco Zanin <mrczn.bb@gmail.com>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com> Change-Id: Id8e0b8bdb4c7816de99d07687cd468e23374c239

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com> Change-Id: Id5a9b6074b9c99834b5ef7af20d2e615b9cec926

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com>

A new warning in clang warns that there is an instance where boolean expressions are being used with bitwise operators instead of logical ones: lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical] (BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ zstd does this frequently to help with performance, as logical operators have branches whereas bitwise ones do not. To fix this warning in other cases, the expressions were placed on separate lines with the '&=' operator; however, this particular instance was moved away from that so that it could be surrounded by LIKELY, which is a macro for __builtin_expect(), to help with a performance regression, according to upstream zstd pull #1973. Aside from switching to logical operators, which is likely undesirable in this instance, or disabling the warning outright, the solution is casting one of the expressions to an integer type to make it clear to clang that the author knows what they are doing. Add a cast to U32 to silence the warning. The first U32 cast is to silence an instance of -Wshorten-64-to-32 because __builtin_expect() returns long so it cannot be moved. Link: ClangBuiltLinux/linux#1486 Link: facebook/zstd#1973 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: LibXZR <i@xzr.moe>

nickdesaulniers added [ARCH] powerpc This bug impacts ARCH=powerpc [BUG] linux-next This is an issue only seen in linux-next -Wbitwise-instead-of-logical labels Oct 21, 2021

nathanchance removed the [ARCH] powerpc This bug impacts ARCH=powerpc label Oct 21, 2021

nathanchance self-assigned this Oct 21, 2021

nathanchance added [PATCH] Accepted A submitted patch has been accepted upstream [PATCH] Submitted A patch has been submitted for review and removed [PATCH] Accepted A submitted patch has been accepted upstream labels Oct 21, 2021

terrelln mentioned this issue Nov 5, 2021

Backport zstd patch from LKML facebook/zstd#2849

Merged

nathanchance added [PATCH] Accepted A submitted patch has been accepted upstream and removed [PATCH] Submitted A patch has been submitted for review labels Nov 5, 2021

nathanchance closed this as completed Nov 16, 2021

nathanchance added [FIXED][LINUX] development cycle This bug was only present and fixed in a -next or -rc cycle and removed [PATCH] Accepted A submitted patch has been accepted upstream labels Nov 16, 2021

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-Wbitwise-instead-of-logical in lib/zstd/decompress/huf_decompress.c #1486

-Wbitwise-instead-of-logical in lib/zstd/decompress/huf_decompress.c #1486

nickdesaulniers commented Oct 21, 2021

nathanchance commented Oct 21, 2021

nathanchance commented Nov 5, 2021

nathanchance commented Nov 16, 2021

-Wbitwise-instead-of-logical in lib/zstd/decompress/huf_decompress.c #1486

-Wbitwise-instead-of-logical in lib/zstd/decompress/huf_decompress.c #1486

Comments

nickdesaulniers commented Oct 21, 2021

nathanchance commented Oct 21, 2021

nathanchance commented Nov 5, 2021

nathanchance commented Nov 16, 2021