[Mesa-dev] [PATCH 06/40] glsl: add helper to convert pointers to uint64_t

[Bas Nieuwenhuizen]

On Sat, Feb 11, 2017, at 13:03, Timothy Arceri wrote:
> 
> 
> On 10/02/17 21:43, Nicolai Hähnle wrote:
> > On 07.02.2017 04:42, Timothy Arceri wrote:
> >> From: Timothy Arceri <timothy.arceri at collabora.com>
> >>
> >> This will be used to store all pointers in the cache as 64bit ints
> >> allowing us to avoid issues when a 32bit program reads a cached
> >> shader that was created by a 64bit application.
> >> ---
> >>  src/compiler/glsl/shader_cache.h | 10 ++++++++++
> >>  1 file changed, 10 insertions(+)
> >>
> >> diff --git a/src/compiler/glsl/shader_cache.h 
> >> b/src/compiler/glsl/shader_cache.h
> >> index 8bd0a3c..1596c33 100644
> >> --- a/src/compiler/glsl/shader_cache.h
> >> +++ b/src/compiler/glsl/shader_cache.h
> >> @@ -27,6 +27,16 @@
> >>
> >>  #include "util/disk_cache.h"
> >>
> >> +static uint64_t inline
> >> +ptr_to_uint64_t(void *ptr)
> >> +{
> >> +   uint64_t ptr_int = (uint64_t) ptr;
> >> +#if __i386__
> >> +   ptr_int &= 0xFFFFFFFF;
> >> +#endif
> >
> > Is the bit-wise and here really necessary?
> Yes. See [1] for an example and the standard and gcc quotes.
> 
> [1] 
> http://stackoverflow.com/questions/25039796/cast-from-32-bit-address-to-64-bit-integer-yields-unexpected-results
> 

Would using (uint64_t)(uintptr_t) not work? You first cast using the ptr
size and then cast using an unisgned cast to 64 bits. And that avoids
having some conditional there.

> >
> > Nicolai
> >
> >> +   return ptr_int;
> >> +}
> >> +
> >>  void
> >>  shader_cache_write_program_metadata(struct gl_context *ctx,
> >>                                      struct gl_shader_program *prog);
> >>
> >
> 
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/mesa-dev