On 2015/04/29 03:43:10, Benedikt Meurer wrote:
On 2015/04/27 07:57:51, titzer wrote:
>
https://codereview.chromium.org/1105693002/diff/1/src/heap/identity-map.h
> File src/heap/identity-map.h (right):
>
>
https://codereview.chromium.org/1105693002/diff/1/src/heap/identity-map.h#newcode68
> src/heap/identity-map.h:68: return static_cast<int>((raw_address >> 11)
^
> raw_address);
> On 2015/04/27 06:26:47, Sven Panne wrote:
> > On 2015/04/27 04:04:17, Benedikt Meurer wrote:
> > > Down casting to int looks wrong here. How about using uintptr_t
here? Or
> even
> > > better use size_t?
> >
> > Veto from the *San sheriff, too: This line is causing
implementation-defined
> > behavior...
>
> This is the computation of a hashcode from an address and is inherently
> implementation-dependent. This is not _undefined_ behavior.
I think you're talking about different implementation-defined behaviors:
There's
(a) the cast from a pointer to an integral type, which is _desired_
implementation-defined behavior, and (b) the down cast to int, which is
_undesired_ implementation-defined behavior. And I think Sven was only
talking
about (b).
We always mask the hash before going to search the table, so I think the
implementation-defined handling of the sign bit is a non-issue here.
https://codereview.chromium.org/1105693002/
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