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invoke.texi (mpreferred-stack-boundary): Remove exception for -Os. 

2006-09-12  H.J. Lu  <hongjiu.lu@intel.com>

	* doc/invoke.texi (mpreferred-stack-boundary): Remove exception
	for -Os. Update __m128 alignment requirement.

From-SVN: r116917
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H.J. Lu 2006-09-13 05:59:30 +00:00 committed by H.J. Lu
parent 1cc8c7b292
commit 04df96dded
2 changed files with 8 additions and 5 deletions
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@ -1,3 +1,8 @@
2006-09-12 H.J. Lu <hongjiu.lu@intel.com>
* doc/invoke.texi (mpreferred-stack-boundary): Remove exception
for -Os. Update __m128 alignment requirement.
2006-09-13 Jan Hubicka <jh@suse.cz>
* cfganal.c (compute_dominance_frontiers_1): Don't be quadratic.

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gcc/doc/invoke.texi
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@ -9505,15 +9505,13 @@ applicable to individual functions.
@opindex mpreferred-stack-boundary
Attempt to keep the stack boundary aligned to a 2 raised to @var{num}
byte boundary. If @option{-mpreferred-stack-boundary} is not specified,
the default is 4 (16 bytes or 128 bits), except when optimizing for code
size (@option{-Os}), in which case the default is the minimum correct
alignment (4 bytes for x86, and 8 bytes for x86-64).
the default is 4 (16 bytes or 128 bits).
On Pentium and PentiumPro, @code{double} and @code{long double} values
should be aligned to an 8 byte boundary (see @option{-malign-double}) or
suffer significant run time performance penalties. On Pentium III, the
Streaming SIMD Extension (SSE) data type @code{__m128} suffers similar
penalties if it is not 16 byte aligned.
Streaming SIMD Extension (SSE) data type @code{__m128} may not work
properly if it is not 16 byte aligned.
To ensure proper alignment of this values on the stack, the stack boundary
must be as aligned as that required by any value stored on the stack.