[Mono-list] 32-bit vs 64-bit Performance Discrepency
justin.holewinski at gmail.com
Wed Oct 26 20:12:40 EDT 2011
On Wed, Oct 26, 2011 at 7:37 PM, Rodrigo Kumpera <kumpera at gmail.com> wrote:
> On Wed, Oct 26, 2011 at 9:06 PM, Justin Holewinski <
> justin.holewinski at gmail.com> wrote:
>> On Wed, Oct 26, 2011 at 6:15 PM, Rodrigo Kumpera <kumpera at gmail.com>wrote:
>>> The CLR demands that all floating point calculations to be conducted with
>>> double precision.
>> Where in the spec does it state this? Everything I've read allows for
>> both 32-bit and 64-bit representations, with the only restriction being that
>> arithmetic must be performed with enough precision for the expression type.
>> And if 64-bit arithmetic is required, why is 32-bit used in the 32-bit
>> Mono VM, and in the .NET VM?
> 32bits mono uses 64bits precision for both float and double types.
> AFAICT, .net uses 64bits precision on all cases.
I'm getting code like the following on .NET 4.0 x64:
00000099 mov rcx,qword ptr [rsp+000000D8h]
000000a1 mov rax,qword ptr [rsp+30h]
000000a6 movss xmm0,dword ptr [rsp+28h]
000000ac mulss xmm0,dword ptr [rcx+rax*4+10h]
000000b2 movss dword ptr [rsp+38h],xmm0
Is there any way to force Mono to use 32-bit arithmetic for floats?
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