From 1f7228c040f614cde72ad0c48a819284f9ecd2f4 Mon Sep 17 00:00:00 2001 From: =?utf8?q?D=C3=A1vid=20Bolvansk=C3=BD?= Date: Mon, 23 Sep 2019 21:23:09 +0200 Subject: [PATCH] Use clz ^ 31 instead of 31 - clz; better codegen for GCC --- lib/common/bitstream.h | 2 +- lib/legacy/zstd_v01.c | 2 +- lib/legacy/zstd_v02.c | 2 +- lib/legacy/zstd_v03.c | 2 +- lib/legacy/zstd_v04.c | 2 +- lib/legacy/zstd_v05.c | 2 +- lib/legacy/zstd_v06.c | 2 +- lib/legacy/zstd_v07.c | 2 +- 8 files changed, 8 insertions(+), 8 deletions(-) diff --git a/lib/common/bitstream.h b/lib/common/bitstream.h index 306e019cc..1c294b80d 100644 --- a/lib/common/bitstream.h +++ b/lib/common/bitstream.h @@ -164,7 +164,7 @@ MEM_STATIC unsigned BIT_highbit32 (U32 val) _BitScanReverse ( &r, val ); return (unsigned) r; # elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */ - return 31 - __builtin_clz (val); + return __builtin_clz (val) ^ 31; # elif defined(__ICCARM__) /* IAR Intrinsic */ return 31 - __CLZ(val); # else /* Software version */ diff --git a/lib/legacy/zstd_v01.c b/lib/legacy/zstd_v01.c index ae8cba2a3..8112527f0 100644 --- a/lib/legacy/zstd_v01.c +++ b/lib/legacy/zstd_v01.c @@ -346,7 +346,7 @@ FORCE_INLINE unsigned FSE_highbit32 (U32 val) _BitScanReverse ( &r, val ); return (unsigned) r; # elif defined(__GNUC__) && (GCC_VERSION >= 304) /* GCC Intrinsic */ - return 31 - __builtin_clz (val); + return __builtin_clz (val) ^ 31; # else /* Software version */ static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 }; U32 v = val; diff --git a/lib/legacy/zstd_v02.c b/lib/legacy/zstd_v02.c index de0a4bd6b..c8783799b 100644 --- a/lib/legacy/zstd_v02.c +++ b/lib/legacy/zstd_v02.c @@ -353,7 +353,7 @@ MEM_STATIC unsigned BIT_highbit32 (U32 val) _BitScanReverse ( &r, val ); return (unsigned) r; # elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */ - return 31 - __builtin_clz (val); + return __builtin_clz (val) ^ 31; # else /* Software version */ static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 }; U32 v = val; diff --git a/lib/legacy/zstd_v03.c b/lib/legacy/zstd_v03.c index dbc83f1ee..162bd6302 100644 --- a/lib/legacy/zstd_v03.c +++ b/lib/legacy/zstd_v03.c @@ -356,7 +356,7 @@ MEM_STATIC unsigned BIT_highbit32 (U32 val) _BitScanReverse ( &r, val ); return (unsigned) r; # elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */ - return 31 - __builtin_clz (val); + return __builtin_clz (val) ^ 31; # else /* Software version */ static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 }; U32 v = val; diff --git a/lib/legacy/zstd_v04.c b/lib/legacy/zstd_v04.c index 201ce2b69..4dec30816 100644 --- a/lib/legacy/zstd_v04.c +++ b/lib/legacy/zstd_v04.c @@ -627,7 +627,7 @@ MEM_STATIC unsigned BIT_highbit32 (U32 val) _BitScanReverse ( &r, val ); return (unsigned) r; # elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */ - return 31 - __builtin_clz (val); + return __builtin_clz (val) ^ 31; # else /* Software version */ static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 }; U32 v = val; diff --git a/lib/legacy/zstd_v05.c b/lib/legacy/zstd_v05.c index e347b00dc..570e0ff86 100644 --- a/lib/legacy/zstd_v05.c +++ b/lib/legacy/zstd_v05.c @@ -756,7 +756,7 @@ MEM_STATIC unsigned BITv05_highbit32 (U32 val) _BitScanReverse ( &r, val ); return (unsigned) r; # elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */ - return 31 - __builtin_clz (val); + return __builtin_clz (val) ^ 31; # else /* Software version */ static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 }; U32 v = val; diff --git a/lib/legacy/zstd_v06.c b/lib/legacy/zstd_v06.c index f907a3a71..2a08e8dee 100644 --- a/lib/legacy/zstd_v06.c +++ b/lib/legacy/zstd_v06.c @@ -860,7 +860,7 @@ MEM_STATIC unsigned BITv06_highbit32 ( U32 val) _BitScanReverse ( &r, val ); return (unsigned) r; # elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */ - return 31 - __builtin_clz (val); + return __builtin_clz (val) ^ 31; # else /* Software version */ static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 }; U32 v = val; diff --git a/lib/legacy/zstd_v07.c b/lib/legacy/zstd_v07.c index a83ddc9a6..a2eeff808 100644 --- a/lib/legacy/zstd_v07.c +++ b/lib/legacy/zstd_v07.c @@ -530,7 +530,7 @@ MEM_STATIC unsigned BITv07_highbit32 (U32 val) _BitScanReverse ( &r, val ); return (unsigned) r; # elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */ - return 31 - __builtin_clz (val); + return __builtin_clz (val) ^ 31; # else /* Software version */ static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 }; U32 v = val; -- 2.47.2