Luca, I'd rather use what the GLSL compiler provides since, as you say, the wider community cares about it. Although the GLSL if/loop emulation hasn't been tested on r300 yet, I think the r300 compiler will handle it just fine. However shader compilation should not fail if it hits an unsupported feature. Let's assume there is a GLSL shader which contains loops that cannot be emulated and a driver doesn't support loops, the shader should be sent to the driver anyway and be faked, or be emulated by a software fallback. See the comment from Ian here: <a href="https://bugs.freedesktop.org/show_bug.cgi?id=29439#c6">https://bugs.freedesktop.org/show_bug.cgi?id=29439#c6</a> NAK. Marek <div class="gmail_quote">On Mon, Sep 6, 2010 at 3:30 AM, Luca Barbieri <<a href="mailto:luca@luca-barbieri.com">luca@luca-barbieri.com</a>> wrote: <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">This purpose of this is so that loop/if emulation in the glsl compiler doesn't get enabled in the next change. Note that doing such emulation in driver-specific code is probably a bad idea, especially since the result won't be exposed to further generic optimizations, and the driver-specific code doesn't get improved by the wider community that cares about GLSL. Thus, it might be a good idea to revert this commit once/if r300g works well with the glsl compiler loop/if emulation, and possibly remove some of the emulation from the r300 compiler. The only part that makes sense to have in the driver is emulation of loops with an unknown number of iterations, since here the goal is to unroll as much as possible while staying in the instruction limits, and the glsl compiler cannot do this because it has no idea of how many instructions some IR will generate. --- src/gallium/drivers/r300/r300_screen.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/src/gallium/drivers/r300/r300_screen.c b/src/gallium/drivers/r300/r300_screen.c index 7f41ff0..8deb9d9 100644 --- a/src/gallium/drivers/r300/r300_screen.c +++ b/src/gallium/drivers/r300/r300_screen.c @@ -182,7 +182,7 @@ static int r300_get_shader_param(struct pipe_screen *pscreen, unsigned shader, e case PIPE_SHADER_CAP_MAX_TEX_INDIRECTIONS: return is_r500 ? 511 : 4; case PIPE_SHADER_CAP_MAX_CONTROL_FLOW_DEPTH: - return is_r500 ? 64 : 0; /* Actually unlimited on r500. */ + return is_r500 ? 64 : 1; /* Actually unlimited on r500. */ /* Fragment shader limits. */ case PIPE_SHADER_CAP_MAX_INPUTS: /* 2 colors + 8 texcoords are always supported @@ -216,7 +216,7 @@ static int r300_get_shader_param(struct pipe_screen *pscreen, unsigned shader, e case PIPE_SHADER_CAP_MAX_TEX_INDIRECTIONS: return 0; case PIPE_SHADER_CAP_MAX_CONTROL_FLOW_DEPTH: - return is_r500 ? 4 : 0; /* For loops; not sure about conditionals. */ + return is_r500 ? 4 : 1; /* For loops; not sure about conditionals. */ case PIPE_SHADER_CAP_MAX_INPUTS: return 16; case PIPE_SHADER_CAP_MAX_CONSTS: -- 1.7.0.4 _______________________________________________ mesa-dev mailing list <a href="mailto:mesa-dev@lists.freedesktop.org">mesa-dev@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/mesa-dev" target="_blank">http://lists.freedesktop.org/mailman/listinfo/mesa-dev</a> </blockquote></div>