On Fri, Jan 6, 2012 at 7:17 PM, Eric Botcazou <ebotca...@adacore.com> wrote: >> > OK, I see. Then the only way out I can think of is to stop going up the >> > chain of COMPONENT_REFs as soon as the offset becomes negative. >> >> Yeah, that sounds like a better solution. > > PR ada/51775 shows that this pessimizes though because if you have an > enclosing > sub-component at offset 0 on the LHS and not on the RHS, and you're using the > model of the LHS for the RHS, you'll build a convoluted (but correct) MEM on > the RHS, and this is apparently enough to thwart FRE/PRE and the likes in some > simple cases: > > t$F$i2_9 = MEM[(struct pack9__r2 *)y_1(D)].F.i2; > D.2233_3 = y_1(D)->i2; > > The compiler doesn't see that D.2233_3 == t$F$i2_9. Additionally using the > type trick would help, at least for PR ada/51775 and I guess in most cases. > > Thoughts?
Can you get me a testcase that I can compile? This should be fixed in FRE. Thanks, Richard. > -- > Eric Botcazou
