Re: [Bug testsuite/26344] New: [4.2 Regression] three testsuite failures in gcc.dg/tree-ssa/

[Jeffrey A Law <law at redhat dot com>]

On Fri, 2006-02-17 at 18:21 +0000, pinskia at gcc dot gnu dot org wrote:
> FAIL: gcc.dg/tree-ssa/20030730-1.c scan-tree-dump-times if  0
> FAIL: gcc.dg/tree-ssa/20030730-2.c scan-tree-dump-times if  0
> FAIL: gcc.dg/tree-ssa/20030807-2.c scan-tree-dump-times if  0
Last week's patch fixed 20030730-1.c and 2000730-2.c.  This patch
fixes 20030807-2.c.

The existing VRP code never visits statements with virtual operands.
In general, that's a good thing -- fewer statements to visit means
less work and assignments with virtual operands are highly unlikely
to produce useful ranges.

However, there is one exception, when the RHS is a call to a
built-in function.  In that case we may be able to determine
non-null ranges (builtin-alloca) and in some cases we can 
determine non-negative ranges.

This patch allows VRP to visit assignments with virtual operands
in this one case (RHS is a call to a built-in function).  Once
that's done the existing machinery will automatically discover
ranges created by calls to these special built-in functions.

Bootstrapped and regression tested on i686-pc-linux-gnu.

Attachment: PPP
Description: Text document