From bac8c2d44147395e31c4d5a2247be1b449139272 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Sat, 24 Sep 2016 23:13:17 +1000
Subject: [PATCH] Vulkan: Work around indexed fragment output bug on AMD
 drivers

---
 Source/Core/VideoCommon/DriverDetails.cpp  |  2 ++
 Source/Core/VideoCommon/DriverDetails.h    |  8 ++++++++
 Source/Core/VideoCommon/PixelShaderGen.cpp | 12 ++++++++++--
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/Source/Core/VideoCommon/DriverDetails.cpp b/Source/Core/VideoCommon/DriverDetails.cpp
index cf167f7d8d..645360d791 100644
--- a/Source/Core/VideoCommon/DriverDetails.cpp
+++ b/Source/Core/VideoCommon/DriverDetails.cpp
@@ -84,6 +84,8 @@ static BugInfo m_known_bugs[] = {
      -1.0, true},
     {API_OPENGL, OS_ALL, VENDOR_MESA, DRIVER_I965, Family::UNKNOWN, BUG_BROKENCLIPDISTANCE, -1.0,
      -1.0, true},
+    {API_VULKAN, OS_ALL, VENDOR_ATI, DRIVER_ATI, Family::UNKNOWN,
+     BUG_BROKEN_FRAGMENT_SHADER_INDEX_DECORATION, -1.0, -1.0, true},
 };
 
 static std::map<Bug, BugInfo> m_bugs;
diff --git a/Source/Core/VideoCommon/DriverDetails.h b/Source/Core/VideoCommon/DriverDetails.h
index 86a365d578..ebf38886be 100644
--- a/Source/Core/VideoCommon/DriverDetails.h
+++ b/Source/Core/VideoCommon/DriverDetails.h
@@ -222,6 +222,14 @@ enum Bug
   // the geometry shader. Current workaround is to make sure the geometry shader always consumes
   // the gl_ClipDistance inputs from the vertex shader.
   BUG_BROKENCLIPDISTANCE,
+
+  // Bug: Dual-source outputs from fragment shaders are broken on AMD Vulkan drivers
+  // Started Version: -1
+  // Ended Version: -1
+  // Fragment shaders that specify dual-source outputs, via layout(location = 0, index = ...) cause
+  // the driver to fail to create graphics pipelines. The workaround for this is to specify the
+  // index as a MRT location instead, or omit the binding completely.
+  BUG_BROKEN_FRAGMENT_SHADER_INDEX_DECORATION,
 };
 
 // Initializes our internal vendor, device family, and driver version
diff --git a/Source/Core/VideoCommon/PixelShaderGen.cpp b/Source/Core/VideoCommon/PixelShaderGen.cpp
index 4038d9329c..e4227e8280 100644
--- a/Source/Core/VideoCommon/PixelShaderGen.cpp
+++ b/Source/Core/VideoCommon/PixelShaderGen.cpp
@@ -517,8 +517,16 @@ ShaderCode GeneratePixelShaderCode(DSTALPHA_MODE dstAlphaMode, APIType ApiType,
   {
     if (dstAlphaMode == DSTALPHA_DUAL_SOURCE_BLEND)
     {
-      out.Write("FRAGMENT_OUTPUT_LOCATION_INDEXED(0, 0) out vec4 ocol0;\n");
-      out.Write("FRAGMENT_OUTPUT_LOCATION_INDEXED(0, 1) out vec4 ocol1;\n");
+      if (DriverDetails::HasBug(DriverDetails::BUG_BROKEN_FRAGMENT_SHADER_INDEX_DECORATION))
+      {
+        out.Write("FRAGMENT_OUTPUT_LOCATION(0) out vec4 ocol0;\n");
+        out.Write("FRAGMENT_OUTPUT_LOCATION(1) out vec4 ocol1;\n");
+      }
+      else
+      {
+        out.Write("FRAGMENT_OUTPUT_LOCATION_INDEXED(0, 0) out vec4 ocol0;\n");
+        out.Write("FRAGMENT_OUTPUT_LOCATION_INDEXED(0, 1) out vec4 ocol1;\n");
+      }
     }
     else
     {