From 485c21eac3adbc29258da09a16cc8067aaa9b366 Mon Sep 17 00:00:00 2001
From: ReinUsesLisp <reinuseslisp@airmail.cc>
Date: Thu, 19 Dec 2019 01:43:29 -0300
Subject: [PATCH] vk_shader_decompiler: Normalize output fragment attachments

Some games write from fragment shaders to an unexistant framebuffer
attachment or they don't write to one when it exists in the framebuffer.
Fix this by skipping writes or adding zeroes.
---
 .../renderer_vulkan/vk_shader_decompiler.cpp  | 21 ++++++++-----------
 .../renderer_vulkan/vk_shader_decompiler.h    |  3 +++
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/src/video_core/renderer_vulkan/vk_shader_decompiler.cpp b/src/video_core/renderer_vulkan/vk_shader_decompiler.cpp
index 93e2704b4d..c84f9e4beb 100644
--- a/src/video_core/renderer_vulkan/vk_shader_decompiler.cpp
+++ b/src/video_core/renderer_vulkan/vk_shader_decompiler.cpp
@@ -543,7 +543,7 @@ private:
         }
 
         for (u32 rt = 0; rt < static_cast<u32>(frag_colors.size()); ++rt) {
-            if (!IsRenderTargetUsed(rt)) {
+            if (!specialization.enabled_rendertargets[rt]) {
                 continue;
             }
 
@@ -1868,12 +1868,18 @@ private:
             // rendertargets/components are skipped in the register assignment.
             u32 current_reg = 0;
             for (u32 rt = 0; rt < Maxwell::NumRenderTargets; ++rt) {
+                if (!specialization.enabled_rendertargets[rt]) {
+                    // Skip rendertargets that are not enabled
+                    continue;
+                }
                 // TODO(Subv): Figure out how dual-source blending is configured in the Switch.
                 for (u32 component = 0; component < 4; ++component) {
+                    const Id pointer = AccessElement(t_out_float, frag_colors.at(rt), component);
                     if (header.ps.IsColorComponentOutputEnabled(rt, component)) {
-                        OpStore(AccessElement(t_out_float, frag_colors.at(rt), component),
-                                SafeGetRegister(current_reg));
+                        OpStore(pointer, SafeGetRegister(current_reg));
                         ++current_reg;
+                    } else {
+                        OpStore(pointer, component == 3 ? v_float_one : v_float_zero);
                     }
                 }
             }
@@ -2003,15 +2009,6 @@ private:
         return DeclareBuiltIn(builtin, spv::StorageClass::Input, type, std::move(name));
     }
 
-    bool IsRenderTargetUsed(u32 rt) const {
-        for (u32 component = 0; component < 4; ++component) {
-            if (header.ps.IsColorComponentOutputEnabled(rt, component)) {
-                return true;
-            }
-        }
-        return false;
-    }
-
     template <typename... Args>
     Id AccessElement(Id pointer_type, Id composite, Args... elements_) {
         std::vector<Id> members;
diff --git a/src/video_core/renderer_vulkan/vk_shader_decompiler.h b/src/video_core/renderer_vulkan/vk_shader_decompiler.h
index 2b01321b6d..415801b6c5 100644
--- a/src/video_core/renderer_vulkan/vk_shader_decompiler.h
+++ b/src/video_core/renderer_vulkan/vk_shader_decompiler.h
@@ -101,6 +101,9 @@ struct Specialization final {
         Maxwell::TessellationSpacing spacing{};
         bool clockwise{};
     } tessellation;
+
+    // Fragment specific
+    std::bitset<8> enabled_rendertargets;
 };
 // Old gcc versions don't consider this trivially copyable.
 // static_assert(std::is_trivially_copyable_v<Specialization>);