From f1aed86177591ef2ad8520b61fde9cc3d7c5fb2f Mon Sep 17 00:00:00 2001
From: Billy Laws <blaws05@gmail.com>
Date: Sun, 8 Jan 2023 19:22:45 +0000
Subject: [PATCH] Add a workaround for split-mapping shaders

Some games split shaders across multiple mappings and *also* miss the end header, so read a suitably large amount and hope that's enough for now.
---
 .../gpu/interconnect/common/shader_cache.cpp  | 19 +++++++++++++++++--
 .../gpu/interconnect/common/shader_cache.h    |  1 +
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/app/src/main/cpp/skyline/gpu/interconnect/common/shader_cache.cpp b/app/src/main/cpp/skyline/gpu/interconnect/common/shader_cache.cpp
index 743caaf6..55bb336d 100644
--- a/app/src/main/cpp/skyline/gpu/interconnect/common/shader_cache.cpp
+++ b/app/src/main/cpp/skyline/gpu/interconnect/common/shader_cache.cpp
@@ -73,6 +73,7 @@ namespace skyline::gpu::interconnect {
         span<u8> blockMappingMirror{blockMapping.data() - mirrorBlock.data() + entry->mirror.data(), blockMapping.size()};
 
         ShaderBinary binary{};
+        auto shaderSubmapping{blockMappingMirror.subspan(blockOffset)};
         // If nothing was in the cache then do a full shader parse
         binary.binary = [](span<u8> mapping) {
             // We attempt to find the shader size by looking for "BRA $" (Infinite Loop) which is used as padding at the end of the shader
@@ -87,8 +88,22 @@ namespace skyline::gpu::interconnect {
                     return span{shaderInstructions.begin(), it}.cast<u8>();
             }
 
-            return mapping;
-        }(blockMappingMirror.subspan(blockOffset));
+            return span<u8>{};
+        }(shaderSubmapping);
+
+        if (!binary.binary.valid()) {
+            static constexpr size_t FallbackSize{0x10000}; //!< Fallback shader size for when we can't detect it with the BRA $ pattern
+            if (shaderSubmapping.size() > FallbackSize) {
+                binary.binary = shaderSubmapping;
+            } else {
+                // If the shader is split across multiple mappings then read into an internal vector to store the binary
+                size_t storageOffset{splitBinaryStorage.size()};
+                splitBinaryStorage.resize(storageOffset + FallbackSize);
+                auto shaderStorage{span{splitBinaryStorage}.subspan(storageOffset, FallbackSize)};
+                ctx.channelCtx.asCtx->gmmu.Read(shaderStorage, programBase + programOffset);
+                binary.binary = shaderStorage;
+            }
+        }
 
         binary.baseOffset = programOffset;
 
diff --git a/app/src/main/cpp/skyline/gpu/interconnect/common/shader_cache.h b/app/src/main/cpp/skyline/gpu/interconnect/common/shader_cache.h
index 9c9fa77c..a832af16 100644
--- a/app/src/main/cpp/skyline/gpu/interconnect/common/shader_cache.h
+++ b/app/src/main/cpp/skyline/gpu/interconnect/common/shader_cache.h
@@ -35,6 +35,7 @@ namespace skyline::gpu::interconnect {
         span<u8> mirrorBlock{}; //!< Guest mapped memory block corresponding to `entry`
         u64 lastProgramBase{};
         u32 lastProgramOffset{};
+        std::vector<u8> splitBinaryStorage;
 
       public:
         /**