Request reviews (S): 6896370: CTW fails share/vm/opto/matcher.cpp:1475 "duplicating node that's already been matched"

[Vladimir Kozlov]

Tom Rodriguez wrote:
> 
> On Nov 4, 2009, at 10:43 AM, Vladimir Kozlov wrote:
> 
>>
>> http://cr.openjdk.java.net/~kvn/6896370/webrev.00
>>
>> Fixed 6896370: CTW fails share/vm/opto/matcher.cpp:1475 "duplicating 
>> node that's already been matched"
>>
> I like this.  Which ones were missing?  There's also an oddity that 

LoadUB, LoadUI2L, LoadPLocked, LoadLLocked and all LoadStore nodes.

> !is_Store() && is_Mem() != is_Load() so you're now treating LoadStore 
> nodes as loads and mem_ops and they weren't previously.  Was that 
> intentional?  Calling set_shared on LoadStoreNodes is probably benign 

Yes, I did it intentionally since all Store[P|I|L]Conditional and
CompareAndSwap nodes have general memory with all address modes.

> but triggering the clone_shift_expressions logic for them probably 
> isn't.  Most cas style instructions don't support full address modes so 
> any cloning would be useless.

I disagree, according to x86 documents cas uses general memory:

CMPXCHG r/m32,r32    -    Compare EAX with r/m32. If equal, ZF is set and r32 is
                           loaded into r/m32. Else, clear ZF and load r/m32 into AL

Vladimir

> 
> tom
> 
>>
>> Reviewed by:
>>
>> Fix verified (y/n): y, test
>>
>> Other testing:
>> JPRT, CTW
>>
>