Request for review (S): 7032388: guarantee(VM_Version::supports_cmov()) failed: illegal instruction on i586 after 6919934
christian.thalinger at oracle.com
Wed Mar 30 11:30:52 PDT 2011
I made two small changes that Paul suggested since #ifdefs are bad and cmovptr makes more sense in the context.
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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