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Re: Value range propagation pass in 4.0.1 RC1 (or not)


On Tue, Jun 07, 2005 at 11:41:34AM +0300, nkavv@physics.auth.gr wrote:
> Dear Diego,
> 
> is the newest version of your pass (including the June 01 modifications at
> gcc-patches) applicable to all statements in a basic block and not only to the
> conditionals?
> 
You'll have to be more specific.  What do you mean by "applicable
to all statements"?  VRP is mostly used to fold predicates whose
ranges can be computed at compile time, but single-valued ranges
are replaced in non-predicates:

if (a == 4)
  return a + 2;

-->

if (a == 4)
  return 6;

> I mean, i saw the gcc-4.0.0 release version (VRP in tree-ssa-dom.c). In this
> version two things happen:
> 
> a. -fdump-tree-vrp not applicable
>
Correct.  This is a 4.1 switch.

> b. VRP applied only to variables in conditional statements
> 
You'll need to give me an example.  Alternately, why don't you
try a CVS snapshot post Jun03?


Diego.


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