llvm dev - Nov 2012 - [LLVMdev] fmac generation for cortex-a9

Hi all,


I've a .ll code that use double precision fmul/fadd or fmul/fsub. When I
compile it using llc -mcpu=cortex-a9 I couldn't get vmla/vmls generated even
using -fp-contract=fast, but when I use option -mtriple=armv7-eabi instead of
-mcpu=cortex-a9 fused mac are generated. Can someone explain me why  ?

Thanks for your answers
Seb
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On 8 November 2012 13:56, Sebastien DELDON-GNB <sebastien.deldon at
st.com> wrote:
> Hi all,
>
>
>
>
>
> I’ve a .ll code that use double precision fmul/fadd or fmul/fsub. When I
> compile it using llc –mcpu=cortex-a9 I couldn’t get vmla/vmls generated
even
> using –fp-contract=fast, but when I use option –mtriple=armv7-eabi instead
> of –mcpu=cortex-a9 fused mac are generated. Can someone explain me why  ?
>
Perhaps you need to use some attributes. -mattr=+vfp4
Check fusedMAC.ll from ARM codegen tests.


-- 
 Anitha

Hi Anitha,

Thanks for your answer but -mcpu=cortex-a9 -mattr=+vfp4 doesn' t enable
fused mac generation for me.
I would like just to understand why -mtriple=armv7-eabi enables it while
-mcpu=cortex-a9 seems to disable it ?

Seb
> -----Original Message-----
> From: Anitha Boyapati [mailto:anitha.boyapati at gmail.com]
> Sent: Thursday, November 08, 2012 10:22 AM
> To: Sebastien DELDON-GNB
> Cc: llvmdev at cs.uiuc.edu
> Subject: Re: [LLVMdev] fmac generation for cortex-a9
> 
> On 8 November 2012 13:56, Sebastien DELDON-GNB
> <sebastien.deldon at st.com> wrote:
> > Hi all,
> >
> >
> >
> >
> >
> > I've a .ll code that use double precision fmul/fadd or fmul/fsub.
When
> > I compile it using llc -mcpu=cortex-a9 I couldn't get vmla/vmls
> > generated even using -fp-contract=fast, but when I use option
> > -mtriple=armv7-eabi instead of -mcpu=cortex-a9 fused mac are
> generated. Can someone explain me why  ?
> >
> 
> Perhaps you need to use some attributes. -mattr=+vfp4 Check fusedMAC.ll
> from ARM codegen tests.
> 
> 
> --
>  Anitha