FreeChainXenon/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

rtl.texi (COMPARE): Clarify documentation and reference section on comparisons.

Browse source 
* rtl.texi (COMPARE): Clarify documentation and reference section
	on comparisons.

From-SVN: r40681
This commit is contained in:
Richard Kenner 2001-03-21 01:14:20 +00:00 • committed by Richard Kenner
parent ddd705d182
commit e26b89960c
2 changed files with 19 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
gcc/ChangeLog
View file

@ -1,3 +1,8 @@
Tue Mar 20 20:15:06 2001 Richard Kenner <kenner@vlsi1.ultra.nyu.edu>
* rtl.texi (COMPARE): Clarify documentation and reference section
on comparisons.
2001-03-20 Stan Shebs <shebs@apple.com> 2001-03-20 Stan Shebs <shebs@apple.com>
* objc/objc-act.c (get_static_reference): Use NULL_TREE. * objc/objc-act.c (get_static_reference): Use NULL_TREE.

22
gcc/rtl.texi
View file

@ -1412,15 +1412,21 @@ of comparison. The result is computed without overflow, as if with
infinite precision. infinite precision.
Of course, machines can't really subtract with infinite precision. Of course, machines can't really subtract with infinite precision.
However, they can pretend to do so when only the sign of the However, they can pretend to do so when only the sign of the result will
result will be used, which is the case when the result is stored be used, which is the case when the result is stored in the condition
in the condition code. And that is the only way this kind of expression code. And that is the @emph{only} way this kind of expression may
may validly be used: as a value to be stored in the condition codes. validly be used: as a value to be stored in the condition codes, either
@code{(cc0)} or a register. @xref{Comparisons}.
The mode @var{m} is not related to the modes of @var{x} and @var{y}, The mode @var{m} is not related to the modes of @var{x} and @var{y}, but
but instead is the mode of the condition code value. If @code{(cc0)} instead is the mode of the condition code value. If @code{(cc0)} is
is used, it is @code{VOIDmode}. Otherwise it is some mode in class used, it is @code{VOIDmode}. Otherwise it is some mode in class
@code{MODE_CC}, often @code{CCmode}. @xref{Condition Code}. @code{MODE_CC}, often @code{CCmode}. @xref{Condition Code}. If @var{m}
is @code{VOIDmode} or @code{CCmode}, the operation returns sufficient
information (in an unspecified format) so that any comparison operator
can be applied to the result of the @code{COMPARE} operation. For other
modes in class @code{MODE_CC}, the operation only returns a subset of
this information.
Normally, @var{x} and @var{y} must have the same mode. Otherwise, Normally, @var{x} and @var{y} must have the same mode. Otherwise,
@code{compare} is valid only if the mode of @var{x} is in class @code{compare} is valid only if the mode of @var{x} is in class