[Bug tree-optimization/22312] reassoc does not handle (i+j)+(k+l) well

[dberlin at dberlin dot org]

------- Additional Comments From dberlin at gcc dot gnu dot org  2005-07-05 19:02 -------
Subject: Re:  New: reassoc does not handle
	(i+j)+(k+l) well

On Tue, 2005-07-05 at 18:33 +0000, pinskia at gcc dot gnu dot org wrote:
> take the following example:
> int f(int i, int j, int k, int l)
> {
>   int r1 = (i+j)+(k+l);
>   int r2 = (j+k)+(l+i);
>   return r1 == r2;
> }
> 
> This should return 1 all the time.  I found this while making testcases for reassoc working fp (well I just 
> change one little thing to make it work really).

We can't do a full top-down reassocation because update_stmt reorders
our operands so we lose information about which is the high ranked
operand, etc.
It's a pain in the ass to fix, but possible.

> 



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22312