Request for reviews (XS): 7123926: Some CTW test crash: !_control.contains(ctrl)

[Vladimir Kozlov]

I looked again on my changes and, I think, the lines with push_int();continue; should be also under (arg->outcnt() == 1) 
condition. If we don't remove call to Integer.toString() - use its result. Otherwise we have to generate conversion from 
int to String by hand for each use (see int_getChars()). As result Integer.toString() code will not be folded by later 
optimizations for the case I showed in previous mail. I need to do more testing for this and will resend webrev later.

 > I'm a little bit worried about this part after seeing your fix for 7181658. Do you think it's safe to use uncast()

It was another Vladimir (Ivanov) who fixed 7181658 :-)

 > this way, or should we use eqv_uncast() for comparison at the use sites of StringConcat::argument_uncast()?

I think using uncast() in argument_uncast() is safe, it is used only in related code. The first time argument_uncast() 
is called to find a Proj node from SB.toString() call. Then that Proj node passed to merge() method as 'arg'. And in the 
merge() method argument_uncast() is called second time to compare with that passed 'arg'.

Thanks,
Vladimir

On 7/5/12 8:23 PM, Krystal Mok wrote:
> Comments inline:
>
> On Fri, Jul 6, 2012 at 10:38 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com <mailto:vladimir.kozlov at oracle.com>> wrote:
>
>     Thank you, Kris
>
>
>     Krystal Mok wrote:
>
>         Hi Vladimir,
>
>         foo(Integer intobj) {
>            String intstr = intobj.toString();
>            String str = intstr + ", " + intstr;
>
>         What should be the desired behavior for the case above?
>         Is it all right to skip all Integer.toString() calls, and let later optimizations handle it?
>
>
>     You have only one toString() call. And it will be kept because it is referenced by debug info which is copied from
>     SB constructor to new char[] constructor (AllocateArray node). It is needed for deoptimization since the bytecode
>     will be executed after that call.
>
> I see. So that's what you meant in the original "Keep case". That makes sense.
>
>     The next code is the case when Integer.toString() will be eliminated by later optimizations:
>
>        StringBuilder sb = new StringBuilder();
>        String intstr = intobj.toString();
>        String str = sb.append(intstr).append(__intstr).toString();
>
>     I also applied your uncast() suggestion in argument_uncast() method.
>
> I'm a little bit worried about this part after seeing your fix for 7181658. Do you think it's safe to use uncast() this
> way, or should we use eqv_uncast() for comparison at the use sites of StringConcat::argument_uncast()?
>
> Thanks,
> Kris
>
>     And I fixed typos.
>
>     Thanks,
>     Vladimir
>
>
>         And, two typos:
>
>         541               // chain. It's node could be eliminated only if it's result
>
>         It's -> Its. Other occurrences of "it's" should also be replaced with "its".
>
>         543               // An other limitation: it should be used only once because
>
>         An other -> Another.
>
>         - Kris
>
>         On Fri, Jul 6, 2012 at 4:37 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com <mailto:vladimir.kozlov at oracle.com>
>         <mailto:vladimir.kozlov at __oracle.com <mailto:vladimir.kozlov at oracle.com>>> wrote:
>
>              Vladimir Kozlov wrote:
>
>         http://cr.openjdk.java.net/~____kvn/7123926/webrev <http://cr.openjdk.java.net/~__kvn/7123926/webrev>
>
>         <http://cr.openjdk.java.net/~__kvn/7123926/webrev <http://cr.openjdk.java.net/~kvn/7123926/webrev>>
>
>                  7123926: Some CTW test crash: !_control.contains(ctrl)
>
>                  Don't try to eliminate Integer::toString() call node during
>                  String concatenation optimization if it's result has several uses.
>
>                  Eliminate case:
>                    foo (Integer intob) {
>                      String str = "int: " + intobj;
>
>                  Keep case:
>                    foo (Integer intob) {
>                      String intstr = intobj.toString();
>                      String str = "int: " + intobj; // second use is in SB
>                  allocation
>
>
>              Sorry, it should be: "int: " + intstr;
>
>              Vladimir
>
>
>                  debug info
>
>                  Tested with failed test.
>
>                  Thanks,
>                  Vladimir
>
>
>