[lld] r233088 - [Mips] Suppress "right shift by too large amount" warning

[David Blaikie]

On Tue, Mar 24, 2015 at 10:28 AM, Simon Atanasyan <simon at atanasyan.com>
wrote:

> On Tue, Mar 24, 2015 at 7:16 PM, David Blaikie <dblaikie at gmail.com> wrote:
> >
> > On Tue, Mar 24, 2015 at 8:49 AM, Simon Atanasyan <simon at atanasyan.com>
> > wrote:
> >>
> >> Author: atanasyan
> >> Date: Tue Mar 24 10:49:59 2015
> >> New Revision: 233088
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=233088&view=rev
> >> Log:
> >> [Mips] Suppress "right shift by too large amount" warning
> >>
> >> Visual C++ shows the "right shift by too large amount" warning if
> >> `MipsELFReference` is instantiated for 32-bit target and
> >> `Elf_Rel_Impl::getType`
> >> method has `unsigned char` return type. We can freely suppress the
> warning
> >> in
> >> that case because MIPS 32-bit ABI does not pack multiple relocation
> types
> >> into
> >> the single field `r_type` and the `MipsELFReference::_tag` should be
> >> always
> >> zero in that case.
> >
> >
> > Can we just disable the MSVC warning if it's wrong, then?
>
> I thought about an alternative solution - fix Elf_Rel_Impl::getType()
> method so all its variants have the same return type uint32_t. Any
> objections against this idea?
>

It still doesn't seem to improve anything - if getType() still only returns
a number 0-255, the shift still is a zero-ing action. Hiding it from the
compiler doesn't seem to change anything in the semantics of the operation
& just obscures things further... seems to me, at least.


>
> --
> Simon Atanasyan
>
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