From d8827b07b5c823903609e00b8f0e1c27fa34fb91 Mon Sep 17 00:00:00 2001 From: ReinUsesLisp Date: Thu, 23 May 2019 20:27:54 -0300 Subject: gl_shader_decompiler: Use an if based cbuf indexing for broken drivers The following code is broken on AMD's proprietary GLSL compiler: ```glsl uint idx = ...; vec4 values = ...; float some_value = values[idx & 3]; ``` It index the wrong components, to fix this the following pessimized code is emitted when that bug is present: ```glsl uint idx = ...; vec4 values = ...; float some_value; if ((idx & 3) == 0) some_value = values.x; if ((idx & 3) == 1) some_value = values.y; if ((idx & 3) == 2) some_value = values.z; if ((idx & 3) == 3) some_value = values.w; ``` --- .../renderer_opengl/gl_shader_decompiler.cpp | 23 +++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) (limited to 'src/video_core/renderer_opengl/gl_shader_decompiler.cpp') diff --git a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp index 6d4658c8b..4a40e4843 100644 --- a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp +++ b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp @@ -577,9 +577,26 @@ private: if (std::holds_alternative(*offset)) { // Indirect access const std::string final_offset = code.GenerateTemporary(); - code.AddLine("uint {} = (ftou({}) / 4);", final_offset, Visit(offset)); - return fmt::format("{}[{} / 4][{} % 4]", GetConstBuffer(cbuf->GetIndex()), - final_offset, final_offset); + code.AddLine("uint {} = ftou({}) >> 2;", final_offset, Visit(offset)); + + if (!device.HasComponentIndexingBug()) { + return fmt::format("{}[{} >> 2][{} & 3]", GetConstBuffer(cbuf->GetIndex()), + final_offset, final_offset); + } + + // AMD's proprietary GLSL compiler emits ill code for variable component access. + // To bypass this driver bug generate 4 ifs, one per each component. + const std::string pack = code.GenerateTemporary(); + code.AddLine("vec4 {} = {}[{} >> 2];", pack, GetConstBuffer(cbuf->GetIndex()), + final_offset); + + const std::string result = code.GenerateTemporary(); + code.AddLine("float {};", result); + for (u32 swizzle = 0; swizzle < 4; ++swizzle) { + code.AddLine("if (({} & 3) == {}) {} = {}{};", final_offset, swizzle, result, + pack, GetSwizzle(swizzle)); + } + return result; } UNREACHABLE_MSG("Unmanaged offset node type"); -- cgit v1.2.3