From: Kenneth Graunke Date: Fri, 15 Mar 2013 21:48:24 +0000 (-0700) Subject: i965: Don't use texture swizzling to force alpha to 1.0 if unnecessary. X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=d86efc075ed84a8c45bfb71cee56dcd18858f727;p=mesa.git i965: Don't use texture swizzling to force alpha to 1.0 if unnecessary. Commit 33599433c7 began setting the texture swizzle mode to XYZ1 for RED, RG, and RGB textures in order to force alpha to 1.0 in case we actually stored the texture as RGBA. This had a unforseen performance implication: the shader precompile assumes that the texture swizzle mode will be XYZW for non-shadow sampler types. By setting it to XYZ1, this means every shader used with a RED, RG, or RGB texture has to be recompiled. This is a very common case. Unfortunately, there's no way to improve the precompile, since RGBA textures still need XYZW, and there's no way to know by looking at the shader source what texture formats might be used. However, we only need to smash alpha to 1.0 if the texture's memory format actually has alpha bits. If not, the sampler already returns 1.0 for us without any special swizzling. XRGB8888, for example, is a very common case where this occurs. This partially fixes a performance regression since commit 33599433c7. More work is required to fully fix it in all cases. This at least helps Warsow. NOTE: This is a candidate for the 9.1 branch. Reviewed-by: Carl Worth Signed-off-by: Kenneth Graunke --- diff --git a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c index 932e4728f27..7e4cc91c5f2 100644 --- a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c +++ b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c @@ -773,7 +773,8 @@ brw_get_texture_swizzle(const struct gl_context *ctx, case GL_RED: case GL_RG: case GL_RGB: - swizzles[3] = SWIZZLE_ONE; + if (_mesa_get_format_bits(img->TexFormat, GL_ALPHA_BITS) > 0) + swizzles[3] = SWIZZLE_ONE; break; }