llvm dev - Jan 2020 - [RFC] Print FP constant assembly in hexadecimal form instead of decimal

Hi:

When debugging some floating point assembly, we found it is inconvenient to
read the decimal constants in assembly.

In hex form many FP numbers are immediately recognizable, their exponents
are more obvious etc.
We normally use hex form in debugger or LLVM IR,
not sure what is the reason that we want to use decimal in assembly?

The form change won't change precision or affecting rounding, I think most
assembler should support hex form too?

Appreciate your feedback and comments if there is anything that we should
consider before changing the default behavior.

FYI. This is a patch https://reviews.llvm.org/D73566 that show the change
and affected in tree testcases.
Reviews and comments are highly appreciated, thank you!



Best,

Jinsong Ji (纪金松), PhD.

XL/LLVM on Power Compiler Development
E-mail: jji at us.ibm.com
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On Tue, Jan 28, 2020 at 11:05 AM Jinsong Ji via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
> Hi:
>
> When debugging some floating point assembly, we found it is inconvenient to
read the decimal constants in assembly.
>
> In hex form many FP numbers are immediately recognizable, their exponents
are more obvious etc.
> We normally use hex form in debugger or LLVM IR,
> not sure what is the reason that we want to use decimal in assembly?
This seems like a really good idea!

Jacob

Seems reasonable to me, but we should make sure that various assemblers out
there support this.
I think it would make sense to try this out on some number of platforms
before proceeding. Perhaps a few Linux distros, AIX, Windows, MacOS,
FreeBSD. And of course, to make sure that LLVM's own llvm-mc understands it
:) (but I suspect this is in the mentioned patch which I haven't looked at
yet).

On Tue, Jan 28, 2020 at 4:33 PM Jacob Lifshay via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> On Tue, Jan 28, 2020 at 11:05 AM Jinsong Ji via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> >
> > Hi:
> >
> > When debugging some floating point assembly, we found it is
inconvenient
> to read the decimal constants in assembly.
> >
> > In hex form many FP numbers are immediately recognizable, their
> exponents are more obvious etc.
> > We normally use hex form in debugger or LLVM IR,
> > not sure what is the reason that we want to use decimal in assembly?
>
> This seems like a really good idea!
>
> Jacob
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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