[9] RFR(S): 8178033: C1 crashes with -XX:UseAVX = 3: "not a mov [reg+offs], reg instruction"

[Tobias Hartmann]

Thanks Vladimir and Michael!

Here's the new webrev:
http://cr.openjdk.java.net/~thartmann/8178033/webrev.01/

Best regards,
Tobias

On 04.04.2017 18:31, Berg, Michael C wrote:
> I agree to both, for the use of supports_evex() under 0x62 in locate_operand() and in instruction_start() with the new code or at least alternatively UseAVX > 2.
> 
> Regards,
> Michael
> 
> -----Original Message-----
> From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com] 
> Sent: Tuesday, April 04, 2017 9:19 AM
> To: hotspot-compiler-dev at openjdk.java.net
> Cc: Berg, Michael C <michael.c.berg at intel.com>
> Subject: Re: [9] RFR(S): 8178033: C1 crashes with -XX:UseAVX = 3: "not a mov [reg+offs], reg instruction"
> 
> I think it is better to use VM_Version::supports_evex() in assert. May be change similar assert in Assembler::locate_operand() too.
> Note, assembler instructions VM_Version::supports_evex() check too.
> 
> CCing to Michael to review this change.
> 
> Thanks,
> Vladimir
> 
> On 4/4/17 3:38 AM, Tobias Hartmann wrote:
>> Hi,
>>
>> please review the following patch:
>> https://bugs.openjdk.java.net/browse/JDK-8178033
>> http://cr.openjdk.java.net/~thartmann/8178033/webrev.00/
>>
>> JDK-8076276 [1] added support for AVX512 but NativeMovRegMem::instruction_start() was not updated to recognize/skip the 4-bytes prefix for EVEX instructions. As a result, C1 crashes in NativeMovRegMem::verify() because the instruction_address() points to the EVEX prefix (0x62) which is not a valid MovRegMem instruction.
>>
>> Similar to the VEX prefixes, we should skip the corresponding number of bytes such that the instruction address points to the prefixed opcode (see also 'case 0x62' in Assembler::locate_operand()).
>>
>> Tested with replay compilation and RBT (running).
>>
>> Thanks,
>> Tobias
>>
>> [1] https://bugs.openjdk.java.net/browse/JDK-8076276
>>