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invoke.texi (i386 and x86-64 Options): Clarify -msahf option.

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* doc/invoke.texi (i386 and x86-64 Options): Clarify -msahf option.

From-SVN: r122910
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Uros Bizjak 2007-03-14 08:47:32 +01:00 committed by Uros Bizjak
parent e31657e812
commit 8c5fd59f94
2 changed files with 10 additions and 5 deletions
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gcc/ChangeLog
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@ -1,3 +1,7 @@
2007-03-14 Uros Bizjak <ubizjak@gmail.com>
* doc/invoke.texi (i386 and x86-64 Options): Clarify -msahf option.
2007-03-13 Seongbae Park <seongbae.park@gmail.com>
PR tree-optimization/30590

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gcc/doc/invoke.texi
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@ -10091,11 +10091,12 @@ atomic built-in functions: see @ref{Atomic Builtins} for details.
@item -msahf
@opindex -msahf
This option will enable GCC to use SAHF instruction in generated code. Early
Intel CPUs with Intel 64 lacked LAHF and SAHF instructions supported by AMD64
until introduction of Pentium 4 G1 step in December 2005. LAHF and SAHF are
load and store instructions, respectively, for certain status flags. These
instructions are used for virtualization and floating-point condition handling.
This option will enable GCC to use SAHF instruction in generated 64-bit code.
Early Intel CPUs with Intel 64 lacked LAHF and SAHF instructions supported
by AMD64 until introduction of Pentium 4 G1 step in December 2005. LAHF and
SAHF are load and store instructions, respectively, for certain status flags.
In 64-bit mode, SAHF instruction is used to optimize @code{fmod}, @code{drem}
or @code{remainder} built-in functions: see @ref{Other Builtins} for details.
@item -mpush-args
@itemx -mno-push-args