From 6866378cf42c86d03f38616804e6714a932ab70b Mon Sep 17 00:00:00 2001 From: Ben Widawsky Date: Fri, 10 Apr 2015 10:04:55 -0700 Subject: [PATCH] i965/fs: Only emit FS_OPCODE_PLACEHOLDER_HALT if there are discards Based originally on a patch from Ken in May 2014 of the same title. Things changed enough that I didn't feel comfortable leaving his authorship. v2: Replace fp->UsesKill with wm_prog_data->uses_kill. Since Ken took the time to also explain the difference to me, here is his explanation for posterity: "fp->UsesKill indicates that a ARB_fragment_program shader uses the KIL instruction, or that a GLSL shader uses the "discard" insntruction (which are analogous). On Gen4-5, we sometimes have to simulate OpenGL's "Alpha Test" feature by emitting shader code that implicitly does a "discard" instruction. In the key setup, we do: /* key->alpha_test_func means simulating alpha testing via discards, * so the shader definitely kills pixels. */ prog_data.uses_kill = fp->program.UsesKill || key->alpha_test_func; Even though the shader may not technically contain a "discard", we need to act as if it does. I've also been trying to move the i965 state setup code to use brw_wm_prog_key for everything, rather than poking at core Mesa's gl_program/gl_fragment_program/gl_shader/gl_shader_program structures. --Ken" Signed-off-by: Ben Widawsky Reviewed-by: Matt Turner Reviewed-by: Kenneth Graunke --- src/mesa/drivers/dri/i965/brw_fs.cpp | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp index aea1ebb7dea..f04fb59f69f 100644 --- a/src/mesa/drivers/dri/i965/brw_fs.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp @@ -1699,6 +1699,8 @@ fs_visitor::emit_math(enum opcode opcode, fs_reg dst, fs_reg src0, fs_reg src1) void fs_visitor::emit_discard_jump() { + assert(((brw_wm_prog_data*) this->prog_data)->uses_kill); + /* For performance, after a discard, jump to the end of the * shader if all relevant channels have been discarded. */ @@ -3958,7 +3960,8 @@ fs_visitor::run_fs() if (failed) return false; - emit(FS_OPCODE_PLACEHOLDER_HALT); + if (wm_prog_data->uses_kill) + emit(FS_OPCODE_PLACEHOLDER_HALT); if (wm_key->alpha_test_func) emit_alpha_test(); -- 2.30.2