Request for reviews (S): 6910664: C2: java/util/Arrays/ fails with DeoptimizeALot flag

Tom Rodriguez Thomas.Rodriguez at Sun.COM
Fri Feb 19 09:11:35 PST 2010

I was wrong about C1, it already handles this correctly.  It uses float_in_dbl for fpu registers and normal for xmm.


On Feb 19, 2010, at 8:46 AM, Vladimir Kozlov wrote:

> Thank you, Tom
> Yes, you are right, I did not thought that I can use Location::normal.
> Then the comment in the .ad files is wrong.
> I can fix C1 also if you point me the place.
> Thanks,
> Vladimir
> Tom Rodriguez wrote:
>> I'm not sure that's the right fix.  The whole point of float_in_dbl is to deal with x86 FPU registers so converting it into some platform dependent thing based on UseSSE doesn't seem right.  I think Matcher::float_in_double should be false if UseSSE >= 1 in and should always be false in  In that case it will use Location::normal instead which will do:
>>      // Just copy all other bits straight through
>>      union { intptr_t p; jint ji;} value;
>>      value.p = (intptr_t) CONST64(0xDEADDEAFDEADDEAF);
>>      value.ji = *(jint*)value_addr;
>>      return new StackValue(value.p);
>> which is equivalent to your new create_float_stack_value logic.
>> How did we go for so long with this being broken?  It's totally wrong on 64 bit.  C1 has the same problem too.
>> tom
>> On Feb 18, 2010, at 7:08 PM, Vladimir Kozlov wrote:
>>> Fixed 6910664: C2: java/util/Arrays/ fails with DeoptimizeALot flag
>>> Problem:
>>> The test has several java float locals and use XMM registers in debug info.
>>> But the code which restore these values during deoptimization was not
>>> updated for XMM registers usage. It assumes that float values were converted
>>> to double on stack as it was before SSE hardware when FPU was used.
>>> Solution:
>>> Add platform specific method to get float stack value from compiled frame.
>>> Reviewed by:
>>> Fix verified (y/n): y, test with -XX:UseSSE=0|1|2
>>> Other testing:
>>> JPRT

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