From b3340cd32acf5935891f19833de0cfc500a93e0b Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Wed, 20 Jan 2016 17:33:14 -0800 Subject: [PATCH] i965: Implement a drirc workaround for broken dual color blending. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit OpenGL's dual color blending feature was specified so that an implementation could support both multiple render targets (MRT) and dual source blending. Fragment shader outputs specify both "location" (the render target number) and "index" (either color 0 or 1). I believe DirectX only has the notion of "location" - if using dual color blending, location 0 or 1 will specify the operands. If not, then location means the render target index. The two features can't be used together. As such, some applications mistakenly try to use and in a shader used for dual color blending with a single render target, rather than the correct and . In particular, Unigine Heaven 4.0 and Valley 1.0 suffer from this bug. Unigine is aware of the problem, and quickly developed a fix, but has not bothered to change the download link on their website to a working copy in over a year. People were still using the broken version and complaining. We tried working around this by disabling dual color blending, but that apparently hurts performance, and people were once again unhappy. On i965, dual source blending is achieved by using different framebuffer write messages than normal rendering. So, we have to compile different code for the two cases. We're not being pedantic: we actually have to know in order to function. Normally, dual source blending is detectable in the shader: if a shader has an output with index = 1, then it's meant for blending, not MRT. With the broken inputs, they're indistinguishable, so we can only tell by looking at the current GL state. This patch implements a new drirc workaround: export dual_color_blend_by_location=true which makes the i965 driver detect when OpenGL state is configured for dual source blending, and recompile the fragment shader to use the right messages. In that case, we allow either location = 1 or index = 1 to specify the second source for the blending equations. It also re-enables GL_ARB_blend_func_extended for Unigine. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92233 Signed-off-by: Kenneth Graunke Reviewed-by: Marek Olšák Reviewed-by: Iago Toral Quiroga Reviewed-by: Ian Romanick Acked-by: Ilia Mirkin --- src/mesa/drivers/dri/common/drirc | 16 ++++++++-------- src/mesa/drivers/dri/common/xmlpool/t_options.h | 5 +++++ src/mesa/drivers/dri/i965/brw_compiler.h | 1 + src/mesa/drivers/dri/i965/brw_context.c | 3 +++ src/mesa/drivers/dri/i965/brw_context.h | 1 + src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 6 +++++- src/mesa/drivers/dri/i965/brw_wm.c | 4 ++++ src/mesa/drivers/dri/i965/intel_screen.c | 1 + 8 files changed, 28 insertions(+), 9 deletions(-) diff --git a/src/mesa/drivers/dri/common/drirc b/src/mesa/drivers/dri/common/drirc index e1874c3f1dc..183a1dcabe8 100644 --- a/src/mesa/drivers/dri/common/drirc +++ b/src/mesa/drivers/dri/common/drirc @@ -37,26 +37,26 @@ TODO: document the other workarounds. diff --git a/src/mesa/drivers/dri/common/xmlpool/t_options.h b/src/mesa/drivers/dri/common/xmlpool/t_options.h index 4e5a7217ee2..55e926b239e 100644 --- a/src/mesa/drivers/dri/common/xmlpool/t_options.h +++ b/src/mesa/drivers/dri/common/xmlpool/t_options.h @@ -90,6 +90,11 @@ DRI_CONF_OPT_BEGIN_B(disable_blend_func_extended, def) \ DRI_CONF_DESC(en,gettext("Disable dual source blending")) \ DRI_CONF_OPT_END +#define DRI_CONF_DUAL_COLOR_BLEND_BY_LOCATION(def) \ +DRI_CONF_OPT_BEGIN_B(dual_color_blend_by_location, def) \ + DRI_CONF_DESC(en,gettext("Identify dual color blending sources by location rather than index")) \ +DRI_CONF_OPT_END + #define DRI_CONF_DISABLE_GLSL_LINE_CONTINUATIONS(def) \ DRI_CONF_OPT_BEGIN_B(disable_glsl_line_continuations, def) \ DRI_CONF_DESC(en,gettext("Disable backslash-based line continuations in GLSL source")) \ diff --git a/src/mesa/drivers/dri/i965/brw_compiler.h b/src/mesa/drivers/dri/i965/brw_compiler.h index 224ddb14ed1..748ffe58b0c 100644 --- a/src/mesa/drivers/dri/i965/brw_compiler.h +++ b/src/mesa/drivers/dri/i965/brw_compiler.h @@ -246,6 +246,7 @@ struct brw_wm_prog_key { bool compute_sample_id:1; unsigned line_aa:2; bool high_quality_derivatives:1; + bool force_dual_color_blend:1; uint16_t drawable_height; uint64_t input_slots_valid; diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c index 9ba33396d36..1032e5a8175 100644 --- a/src/mesa/drivers/dri/i965/brw_context.c +++ b/src/mesa/drivers/dri/i965/brw_context.c @@ -750,6 +750,9 @@ brw_process_driconf_options(struct brw_context *brw) ctx->Const.AllowGLSLExtensionDirectiveMidShader = driQueryOptionb(options, "allow_glsl_extension_directive_midshader"); + + brw->dual_color_blend_by_location = + driQueryOptionb(options, "dual_color_blend_by_location"); } GLboolean diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h index 2a29dfe5eec..55d6723eab7 100644 --- a/src/mesa/drivers/dri/i965/brw_context.h +++ b/src/mesa/drivers/dri/i965/brw_context.h @@ -836,6 +836,7 @@ struct brw_context bool always_flush_cache; bool disable_throttling; bool precompile; + bool dual_color_blend_by_location; driOptionCache optionCache; /** @} */ diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp index d7bcc1c5374..f9df2a4e3b6 100644 --- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp @@ -130,7 +130,11 @@ fs_visitor::nir_setup_outputs() break; } case MESA_SHADER_FRAGMENT: - if (var->data.index > 0) { + if (key->force_dual_color_blend && + var->data.location == FRAG_RESULT_DATA1) { + this->dual_src_output = reg; + this->do_dual_src = true; + } else if (var->data.index > 0) { assert(var->data.location == FRAG_RESULT_DATA0); assert(var->data.index == 1); this->dual_src_output = reg; diff --git a/src/mesa/drivers/dri/i965/brw_wm.c b/src/mesa/drivers/dri/i965/brw_wm.c index 39d644ea63a..78846dc3790 100644 --- a/src/mesa/drivers/dri/i965/brw_wm.c +++ b/src/mesa/drivers/dri/i965/brw_wm.c @@ -515,6 +515,10 @@ brw_wm_populate_key(struct brw_context *brw, struct brw_wm_prog_key *key) /* _NEW_BUFFERS */ key->nr_color_regions = ctx->DrawBuffer->_NumColorDrawBuffers; + /* _NEW_COLOR */ + key->force_dual_color_blend = brw->dual_color_blend_by_location && + (ctx->Color.BlendEnabled & 1) && ctx->Color.Blend[0]._UsesDualSrc; + /* _NEW_MULTISAMPLE, _NEW_COLOR, _NEW_BUFFERS */ key->replicate_alpha = ctx->DrawBuffer->_NumColorDrawBuffers > 1 && (ctx->Multisample.SampleAlphaToCoverage || ctx->Color.AlphaEnabled); diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c index e1e1e62d26a..bca783aea86 100644 --- a/src/mesa/drivers/dri/i965/intel_screen.c +++ b/src/mesa/drivers/dri/i965/intel_screen.c @@ -79,6 +79,7 @@ DRI_CONF_BEGIN DRI_CONF_FORCE_GLSL_EXTENSIONS_WARN("false") DRI_CONF_DISABLE_GLSL_LINE_CONTINUATIONS("false") DRI_CONF_DISABLE_BLEND_FUNC_EXTENDED("false") + DRI_CONF_DUAL_COLOR_BLEND_BY_LOCATION("false") DRI_CONF_ALLOW_GLSL_EXTENSION_DIRECTIVE_MIDSHADER("false") DRI_CONF_OPT_BEGIN_B(shader_precompile, "true") -- 2.30.2