Request for review (S): 7032388: guarantee(VM_Version::supports_cmov()) failed: illegal instruction on i586 after 6919934

[Christian Thalinger]

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.
> 
> Paul
> 
> On 3/30/11 8:46 AM, Christian Thalinger wrote:
>> http://cr.openjdk.java.net/~twisti/7032388/
>> 
>> 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.
>> Reviewed-by:
>> 
>> 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
>> latter.
>> 
>> src/cpu/x86/vm/assembler_x86.cpp
>> src/cpu/x86/vm/assembler_x86.hpp
>> src/cpu/x86/vm/c1_LIRAssembler_x86.cpp
>> src/cpu/x86/vm/c1_Runtime1_x86.cpp
>> src/cpu/x86/vm/templateTable_x86_32.cpp