[PATCH] add better support for Raspberry Pi board

[Karel Gardas]

On 01/25/13 09:38 PM, Simon Marlow wrote:
> This would improve things for RPi, but we shouldn't be guessing here.
> gcc has predefines for the appropriate features:
>
> #define __ARM_PCS_VFP 1
>
> indicates hard-float ABI, and
>
> #define __VFP_FP__ 1
>
> indicates VFP presences (2 or 3? I don't know)

The problem is that IIRC those defines are presented when you use 
appropriate GCC's command-line option. It does not tell anything about 
the target hardware itself. So that's why I'm just guessing in the 
patch. But honestly speaking do you think there is any other GHC user 
who would use GHC on ARMv6 and the hardware will be different than RPi? 
I think a chance for this is very low since otherwise everybody is using 
ARMv7 these days...

Anyway, if you don't like guessing, what about to add few configure 
options which will drive the generation of ARM related bits into 
settings file and keeping some good defaults like we use now? i.e. 
ARMv7+VFPv3+NEON or ARMv6+VFPv2 or ARMv5 alone?

Thanks!
Karel

>
> Cheers,
> Simon
>
> On 25/01/13 15:56, Karel Gardas wrote:
>> This patch adds support for Raspberry Pi board. The board is based
>> on Broadcom BCM2835, which includes ARM1176JZF-S CPU core. The core
>> is classical ARM11 so implementing ARMv6 ISA, but also provides VFPv2 FPU
>> unit. As this looks like fairly popular hardware, in this patch we assume
>> detected ARMv6 hardware to support VFPv2. Also as Raspberry Pi is very
>> commonly
>> used with hard-float ABI Linux distribution, the patch relaxes a
>> condition
>> of "hard-float support for ARMv7 only" to any general ARM core.
>> ---
>> aclocal.m4 | 2 +-
>> compiler/main/DriverPipeline.hs | 9 ++++++---
>> 2 files changed, 7 insertions(+), 4 deletions(-)
>>
>> diff --git a/aclocal.m4 b/aclocal.m4
>> index edbe389..b23568f 100644
>> --- a/aclocal.m4
>> +++ b/aclocal.m4
>> @@ -369,7 +369,7 @@ AC_DEFUN([GET_ARM_ISA],
>> [AC_DEFINE(arm_HOST_ARCH_PRE_ARMv7, 1, [ARM pre v7])
>> changequote(, )dnl
>> ARM_ISA=ARMv6
>> - ARM_ISA_EXT="[]"
>> + ARM_ISA_EXT="[VFPv2]"
>> changequote([, ])dnl
>> ],
>> [changequote(, )dnl
>> diff --git a/compiler/main/DriverPipeline.hs
>> b/compiler/main/DriverPipeline.hs
>> index c24bb51..81d0bc0 100644
>> --- a/compiler/main/DriverPipeline.hs
>> +++ b/compiler/main/DriverPipeline.hs
>> @@ -1454,14 +1454,17 @@ runPhase LlvmLlc input_fn dflags
>> else if (elem VFPv3D16 ext)
>> then ["-mattr=+v7,+vfp3,+d16"]
>> else []
>> + ArchARM ARMv6 ext _ -> if (elem VFPv2 ext)
>> + then ["-mattr=+v6,+vfp2"]
>> + else ["-mattr=+v6"]
>> _ -> []
>> -- On Ubuntu/Debian with ARM hard float ABI, LLVM's llc still
>> -- compiles into soft-float ABI. We need to explicitly set abi
>> -- to hard
>> abiOpts = case platformArch (targetPlatform dflags) of
>> - ArchARM ARMv7 _ HARD -> ["-float-abi=hard"]
>> - ArchARM ARMv7 _ _ -> []
>> - _ -> []
>> + ArchARM _ _ HARD -> ["-float-abi=hard"]
>> + ArchARM _ _ _ -> []
>> + _ -> []
>>
>> sseOpts | isSse4_2Enabled dflags = ["-mattr=+sse42"]
>> | isSse2Enabled dflags = ["-mattr=+sse2"]
>>
>
>