Re: [Qemu-devel] [PATCH 03/14] cg3: remove unused width and height variables

[Richard Henderson]

On 04/05/2017 01:35 AM, Mark Cave-Ayland wrote:
> These aren't required since we can use the display width and height directly.
>
> Signed-off-by: Mark Cave-Ayland <address@hidden>
> ---
>  hw/display/cg3.c |   15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/hw/display/cg3.c b/hw/display/cg3.c
> index b42f60e..178a6dd 100644
> --- a/hw/display/cg3.c
> +++ b/hw/display/cg3.c
> @@ -93,14 +93,11 @@ static void cg3_update_display(void *opaque)
>      uint32_t *data;
>      uint32_t dval;
>      int x, y, y_start;
> -    unsigned int width, height;
>      ram_addr_t page, page_min, page_max;
>
>      if (surface_bits_per_pixel(surface) != 32) {
>          return;
>      }
> -    width = s->width;
> -    height = s->height;
>
>      y_start = -1;
>      page_min = -1;
> @@ -110,11 +107,11 @@ static void cg3_update_display(void *opaque)
>      data = (uint32_t *)surface_data(surface);
>
>      memory_region_sync_dirty_bitmap(&s->vram_mem);
> -    for (y = 0; y < height; y++) {
> +    for (y = 0; y < s->height; y++) {

I suspect the generated code is much worse, since the compiler can no longer 
tell that the loop bounds are constant.

You probably do want to keep width and height in local variables across this 
function.


r~