[Mesa-dev] [PATCH 2/2] i965: use a cast to silence a signed/unsigned comparison warning

[Paul Berry]

On 19 October 2011 12:58, Brian Paul <brianp at vmware.com> wrote:

> On 10/19/2011 01:53 PM, Paul Berry wrote:
>
>> On 18 October 2011 18:07, Brian Paul <brian.e.paul at gmail.com
>> <mailto:brian.e.paul at gmail.com**>> wrote:
>>
>>    From: Brian Paul <brianp at vmware.com <mailto:brianp at vmware.com>>
>>
>>
>>    ---
>>      .../drivers/dri/i965/brw_vec4_**reg_allocate.cpp     |    2 +-
>>      1 files changed, 1 insertions(+), 1 deletions(-)
>>
>>    diff --git a/src/mesa/drivers/dri/i965/**brw_vec4_reg_allocate.cpp
>>    b/src/mesa/drivers/dri/i965/**brw_vec4_reg_allocate.cpp
>>    index 1ace91f..6de7682 100644
>>    --- a/src/mesa/drivers/dri/i965/**brw_vec4_reg_allocate.cpp
>>    +++ b/src/mesa/drivers/dri/i965/**brw_vec4_reg_allocate.cpp
>>    @@ -217,7 +217,7 @@ vec4_visitor::reg_allocate()
>>           int reg = ra_get_node_reg(g, i);
>>
>>           hw_reg_mapping[i] = first_assigned_grf +
>>    brw->vs.ra_reg_to_grf[reg];
>>    -      prog_data->total_grf = MAX2(prog_data->total_grf,
>>    +      prog_data->total_grf = MAX2((int) prog_data->total_grf,
>>                                      hw_reg_mapping[i] +
>>    virtual_grf_sizes[i]);
>>
>> Since we're storing the result into an unsigned value, I'd prefer to
>> fix the warning by converting the second argument of MAX2 to GLuint
>> rather than converting the first argument of MAX2 to int.
>>
>
> I was wondering which way that should go.  The types in that expression
> are:
>
> GLuint total_grf;
> int hw_reg_mapping[];
>
> can hw_reg_mapping[] values be negative?
>
> -Brian
>
>
No, every element of hw_reg_mapping is a register number, and those go from
zero up.  It's possible that a better fix would be to make hw_reg_mapping[]
and and virtual_grf_sizes[] unsigned, but that might have more cascading
effects than you want to deal with.  Eric, do you have an opinion?

Aside: what compiler (and compiler options) are you using to see these
warnings?  I don't get them with GCC.
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