Request for review (S): 7032388: guarantee(VM_Version::supports_cmov()) failed: illegal instruction on i586 after 6919934
vladimir.kozlov at oracle.com
Wed Mar 30 11:36:06 PDT 2011
Christian Thalinger wrote:
> I made two small changes that Paul suggested since #ifdefs are bad and cmovptr makes more sense in the context.
> -- Christian
> On Mar 30, 2011, at 5:40 PM, Paul Hohensee wrote:
>> Couple of small comments.
>> In assembler_x86.cpp, I'd removed the #ifdef _LP64 and have supports_cmov
>> be the condition that determines whether or not to emit the cmov. Every 64-bit
>> chip supports cmov, so supports_cmov will return true on every 64-bit platform.
>> In templateTable_x86_32.cpp, you use cmov, which you've made an alias for
>> cmovptr in assembler_x86.hpp. I'd get use cmovptr directly here instead,
>> esp. since cmpptr is used just before it.
>> On 3/30/11 8:46 AM, Christian Thalinger wrote:
>>> 7032388: guarantee(VM_Version::supports_cmov()) failed: illegal instruction on i586 after 6919934
>>> Summary: 6919934 added some unguarded cmov instructions which hit a guarantee on older hardware.
>>> 6919934 added some unguarded cmov instructions which hit a guarantee
>>> on older hardware (pre-i686).
>>> The fix is to either guard the added cmov instructions with a
>>> supports_cmov() or let the cmov instruction decide itself if the
>>> hardware supports cmov and if not use a branch-mov idiom. I chose the
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