[llvm-dev] [GlobalISel] G_LOAD/G_STORE i64/f64 handling

[Francois Pichet via llvm-dev]

On Mon, Jul 3, 2017 at 4:28 PM, Friedman, Eli via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> On 7/2/2017 3:50 AM, Breger, Igor via llvm-dev wrote:
>
> Hi all,
>
> I am working on enabling X86 using  GLobalIsel framework.
>
> I have 32bit platform + float/double  configuration
> (-mtriple=i386-linux-gnu -mattr=+sse2 )
>
>                load i64, i64* %p1                   -   illegal, require
> narrowScalar action
>
>                load double, double * %p1   -    legal
>
>
>
> What is the best approach to Legalize this case ? Should I mark
> G_LOAD/G_STORE s64 as Custom?
>
>
>
>
> In the world of GlobalISel, i64 and double are both s64, so "load i64" and
> "load double" are the same operation; if one is Legal, both are Legal.
> This should just work, barring any bugs.
>
> The resulting code will probably be low-quality because there isn't any
> good way to lower the resulting transfers between SSE and integer
> registers, but you can put off dealing with that for now.
>
>
Ok but for 32-bit target, will GlobalISel handle the splitting of
i64/double on 2 32-bit registers automatically like the SelectionDAG is
currently doing?
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