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| author | Kyrylo Tkachov <kyrylo.tkachov@arm.com> | 2014-08-04 10:06:28 +0000 |
|---|---|---|
| committer | Kyrylo Tkachov <ktkachov@gcc.gnu.org> | 2014-08-04 10:06:28 +0000 |
| commit | e7a45277aa2ed5b30f96ac55bf9c1de47cb36f95 (patch) | |
| tree | d43087527edd7bf3ca97c48b0e11cf87bcc14945 /gcc/doc | |
| parent | 97334291c223eea459531b1c0691da465387b6a2 (diff) | |
| download | gcc-e7a45277aa2ed5b30f96ac55bf9c1de47cb36f95.zip gcc-e7a45277aa2ed5b30f96ac55bf9c1de47cb36f95.tar.gz gcc-e7a45277aa2ed5b30f96ac55bf9c1de47cb36f95.tar.bz2 | |
[doc] Document clrsb optab and fix some inconsistencies.
* doc/md.texi (clrsb): Document.
(clz): Change reference to x into operand 1.
(ctz): Likewise.
(popcount): Likewise.
Co-Authored-By: James Greenhalgh <james.greenhalgh@arm.com>
From-SVN: r213557
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/md.texi | 22 |
1 files changed, 15 insertions, 7 deletions
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index fde67d7..dd78611 100644 --- a/gcc/doc/md.texi +++ b/gcc/doc/md.texi @@ -5316,10 +5316,18 @@ generating the instruction. The @code{ffs} built-in function of C always uses the mode which corresponds to the C data type @code{int}. +@cindex @code{clrsb@var{m}2} instruction pattern +@item @samp{clrsb@var{m}2} +Count leading redundant sign bits. +Store into operand 0 the number of redundant sign bits in operand 1, starting +at the most significant bit position. +A redundant sign bit is defined as any sign bit after the first. As such, +this count will be one less than the count of leading sign bits. + @cindex @code{clz@var{m}2} instruction pattern @item @samp{clz@var{m}2} -Store into operand 0 the number of leading 0-bits in @var{x}, starting -at the most significant bit position. If @var{x} is 0, the +Store into operand 0 the number of leading 0-bits in operand 1, starting +at the most significant bit position. If operand 1 is 0, the @code{CLZ_DEFINED_VALUE_AT_ZERO} (@pxref{Misc}) macro defines if the result is undefined or has a useful value. @var{m} is the mode of operand 0; operand 1's mode is @@ -5328,8 +5336,8 @@ operand to that mode before generating the instruction. @cindex @code{ctz@var{m}2} instruction pattern @item @samp{ctz@var{m}2} -Store into operand 0 the number of trailing 0-bits in @var{x}, starting -at the least significant bit position. If @var{x} is 0, the +Store into operand 0 the number of trailing 0-bits in operand 1, starting +at the least significant bit position. If operand 1 is 0, the @code{CTZ_DEFINED_VALUE_AT_ZERO} (@pxref{Misc}) macro defines if the result is undefined or has a useful value. @var{m} is the mode of operand 0; operand 1's mode is @@ -5338,15 +5346,15 @@ operand to that mode before generating the instruction. @cindex @code{popcount@var{m}2} instruction pattern @item @samp{popcount@var{m}2} -Store into operand 0 the number of 1-bits in @var{x}. @var{m} is the +Store into operand 0 the number of 1-bits in operand 1. @var{m} is the mode of operand 0; operand 1's mode is specified by the instruction pattern, and the compiler will convert the operand to that mode before generating the instruction. @cindex @code{parity@var{m}2} instruction pattern @item @samp{parity@var{m}2} -Store into operand 0 the parity of @var{x}, i.e.@: the number of 1-bits -in @var{x} modulo 2. @var{m} is the mode of operand 0; operand 1's mode +Store into operand 0 the parity of operand 1, i.e.@: the number of 1-bits +in operand 1 modulo 2. @var{m} is the mode of operand 0; operand 1's mode is specified by the instruction pattern, and the compiler will convert the operand to that mode before generating the instruction. |