Fix performance regression on aarch64 with clang #1973

terrelln · 2020-01-24T01:31:34Z

This patch fixes a performance regression on aarch64 phones compiled with clang.

Only keep the special clang ordering of Huffman decompression on x86_64 and i386. It is neutral on armv7 and negative on aarch64.
Add a LIKELY() to the endSignal computation. There isn't a good reason for it other than clang on aarch64 needs it, and it doesn't hurt anyone else.
Add HINT_INLINE to ZSTD_overlapCopy8(). Without it -Oz will outline this function.

I've tested the performance of ./zstd -b1e1 enwik6 on the following devices.

Machine name	CPU	Clang version	Gcc version	Test command
Nexus 4	1.5 GHz quad-core Krait	9.0.8 (ndk-r21)	N/A	./zstd
Galaxy S6	Quad-core 2.1 GHz Cortex-A57 + Quad-core 1.5 GHz Cortex-A53	9.0.8 (ndk-r21)	N/A	./zstd
Macbook	2.4 GHz Intel Core i9	Apple 10.0.1	8.3.0	./zstd
Devserver	2.4 GHz 24 core Intel Skylake	3.4.2	6.2.1	taskset --cpu-list 0 ./zstd
Nickserv	3.6 GHz Intel i9-9900K (5.0 GHz turbo)	9.0.1	9.2.0	cset shield --exec -- ./zstd

The number listed is decompression speed in MB/s.

Machine	Arch	Compiler	zstd-1.4.3	zstd-1.4.4	dev	PR
Nexus 4	armv7	clang -Os	91.7	94.7	105.5	105.2
Galaxy S6	aarch64	clang -Os	254.3	288.3	261.6	293.5
Macbook	x86_64	clang -O3	925.2	1055.6	1182.0	1182.5
		gcc -O3	969.1	1205.2	1223.6	1229.5
Nickserv	x86_64	clang -O3	743.1	865.8	1064.9	1065.9
		gcc -O3	854.2	1017.2	1092.2	1089.5
	i386	clang -O3	535.0	587.6	597.6	597.8
		gcc -O3	511.8	611.9	624.7	622.7

Cyan4973 · 2020-01-24T02:06:08Z

Great work !

bimbashrestha · 2020-01-24T02:54:12Z

Awesome!!

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>

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>

…-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>

…-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> Signed-off-by: Forenche <prahul2003@gmail.com>

…-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>

…-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> Signed-off-by: Forenche <prahul2003@gmail.com>

…-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>

…-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> Signed-off-by: Forenche <prahul2003@gmail.com>

…-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> 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: 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> Signed-off-by: v4lkyr <valkyr23@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> 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>

…-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> Signed-off-by: fjrXTR <fajarslebew31@gmail.com>