Two days old build breakage on i386.

[Johan Tibell]

I fixed the x86 issue and re-commited my work as
4ee4ab01c1d97845aecb7707ad2f9a80933e7a49.

On Fri, Jun 27, 2014 at 1:27 PM, Simon Marlow <marlowsd at gmail.com> wrote:
> On 27/06/2014 12:23, Johan Tibell wrote:
>>
>> On Fri, Jun 27, 2014 at 1:14 PM, Simon Marlow <marlowsd at gmail.com> wrote:
>>>
>>> The problem is that this instruction requires three separate registers,
>>> but
>>> cmpxchgl already reads and writes %eax leaving only two free registers
>>> (%ecx
>>> and %edx).
>>>
>>> You'll need to arrange to not use the complicated addressing modes with
>>> cmpxchg on i386, and keep the number of free regs required <= 2.
>>
>>
>> Where's the best place to arrange for that? If I switch from using
>> getAmode to computing the address into a temp register in StgCmmPrim
>> will that ensure that the address is simple, or could some
>> optimization replace my temp register computation with a complex
>> address again?
>
>
> There aren't any optimisations that happen on the instructions after
> codegen, and if there were, they would have to respect the same rule. So
> using a register is the right thing, yes.
>
> Cheers,
> Simon
>