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

[Berg, Michael C]

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
>