[Bug tree-optimization/15757] Convert "If (a >= b) X else if (b <= a) Y" into "if (a >= b) X".

[law at redhat dot com]

------- Additional Comments From law at redhat dot com  2004-06-05 20:22 -------
Subject: Re:  Convert "If (a >= b) X else if
	(b <= a) Y" into "if (a >= b) X".

On Tue, 2004-06-01 at 05:20, pinskia at gcc dot gnu dot org wrote:
> ------- Additional Comments From pinskia at gcc dot gnu dot org  2004-06-01 11:20 -------
> Confirmed.
> 
> Hmm, looks like jump threading needs a little improvement.
No.  More correctly, we do not canonicalize equivalent expressions.

What we're looking at is canonicalizing commutative operators and
conditionals so that given two SSA_NAMEs as operands, they will
be automatically ordered such that the lowest SSA_NAME_VERSION 
appears first.  Given an SSA_NAME and a constant, the SSA_NAME
should come first.

A prototype of this (of course) fixes this problem.  I'm still
evaluating that prototype.

jeff



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15757