RFR 8222384 [lworld] Calling convention - C2 to C1 (floating point params)

[Ioi Lam]

Actually, please ignore this webrev.

I just realized that when shuffling the arguments, the stack may shrink 
(e.g., if a value argument has 2 int fields) or expand (e.g., if a value 
argument has 2 float fields). Also, there can be circular dependencies 
between the vmreg slots.  So I need to rewrite the whole thing to mirror 
unpack_value_args() :-(

Thanks
- Ioi


On 4/13/19 6:51 PM, Ioi Lam wrote:
> Hi Tobias,
>
> Thanks for the code review.
>
> On 4/12/19 5:38 AM, Tobias Hartmann wrote:
>> Hi Ioi,
>>
>> looks good to me. Little typo: "overwrite it now and and".
> Fixed
>
>> I wonder if you could use MacroAssembler::move_helper() to avoid code 
>> duplication?
> That's a good idea. I changed it as you suggested, and saved a bunch 
> of code!
>
> Here's the delta from my last webrev:
>
> http://cr.openjdk.java.net/~iklam/valhalla/8222384-c1-calling-convention-floats.v02-delta/ 
>
>
> Thanks
> - Ioi
>
>> Thanks,
>> Tobias
>>
>> On 12.04.19 06:58, Ioi Lam wrote:
>>> https://bugs.openjdk.java.net/browse/JDK-8222384
>>> http://cr.openjdk.java.net/~iklam/valhalla/8222384-c1-calling-convention-floats.v01/ 
>>>
>>>
>>> This changeset supports floating point parameters (x64 only, i.e., 
>>> XMM registers). I also fixed an
>>> issue wheresome registers may be trashed before their contents are 
>>> shuffled. Here's an example (see
>>> the rdx register).
>>>
>>>
>>> C2 passes outgoing parameters as:
>>>
>>>    # {method} {0x00007fb8593f8420} 'test' '(IQFloatTriplet;I)I' in 
>>> 'Test'
>>>    # parm0:    rsi       = int
>>>    # parm1:    xmm0      = float
>>>    # parm2:    xmm1      = float
>>>    # parm3:    xmm2      = float
>>>    # parm4:    rdx       = int
>>>
>>>
>>> C1 expects incoming parameters as:
>>>
>>>    # parm0:    rsi       = int
>>>    # parm1:    rdx:rdx   = 'FloatTriplet'
>>>    # parm2:    rcx       = int
>>>
>>> shuffling code:
>>>
>>>       20: mov    0x10(%rax),%r11d  ;r11 = buffered FloatTriplet obj
>>>       24: shl    $0x3,%r11
>>>       28: vmovss %xmm0,0x10(%r11)
>>>       34: vmovss %xmm1,0x14(%r11)
>>>       40: vmovss %xmm2,0x18(%r11)
>>>       46: push   %r11              ; can't write to rdx yet -> save it
>>>       48: mov    %rdx,%rcx         ; rdx is now shuffled
>>>       51: pop    %rdx              ; now update rdx
>>>
>>> Thanks
>>> - Ioi
>