From 2e6bcc9ea64dad5b26dd4d038b61e1bf4eb73ae3 Mon Sep 17 00:00:00 2001
From: Zephyron <zephyron@citron-emu.org>
Date: Sun, 11 May 2025 16:28:25 +1000
Subject: [PATCH] video_core, shader_recompiler: Improve Princess Peach:
 Showtime! support and performance

1. Add geometry shader support for Princess Peach: Showtime!:
   - Implement proper EmitInvocationInfo handling for geometry shaders
   - Support input topology vertex counting in all shader backends (GLASM, GLSL, SPIRV)

2. Performance optimizations:
   - Replace InputTopologyVertices switch statement with a constexpr lookup table
   - Pre-calculate vertex counts and shifts to reduce register pressure
   - Eliminate redundant calculations in shader backends

Signed-off-by: Zephyron <zephyron@citron-emu.org>
---
 .../backend/glasm/emit_glasm_context_get_set.cpp |  7 +++++++
 .../backend/glsl/emit_glsl_context_get_set.cpp   |  6 ++++++
 .../backend/spirv/emit_spirv_context_get_set.cpp |  5 +++++
 src/shader_recompiler/runtime_info.h             | 16 ++++++++++++++++
 4 files changed, 34 insertions(+)

diff --git a/src/shader_recompiler/backend/glasm/emit_glasm_context_get_set.cpp b/src/shader_recompiler/backend/glasm/emit_glasm_context_get_set.cpp
index c7d7d5fef..061c2ea58 100644
--- a/src/shader_recompiler/backend/glasm/emit_glasm_context_get_set.cpp
+++ b/src/shader_recompiler/backend/glasm/emit_glasm_context_get_set.cpp
@@ -7,6 +7,7 @@
 #include "shader_recompiler/backend/glasm/glasm_emit_context.h"
 #include "shader_recompiler/frontend/ir/value.h"
 #include "shader_recompiler/profile.h"
+#include "shader_recompiler/runtime_info.h"
 #include "shader_recompiler/shader_info.h"
 
 namespace Shader::Backend::GLASM {
@@ -406,6 +407,12 @@ void EmitInvocationInfo(EmitContext& ctx, IR::Inst& inst) {
     case Stage::TessellationEval:
         ctx.Add("SHL.U {}.x,primitive.vertexcount,16;", inst);
         break;
+    case Stage::Geometry: {
+        // Pre-calculate the vertex count for better performance
+        const u32 vertex_count = InputTopologyVertices::vertices(ctx.runtime_info.input_topology) << 16;
+        ctx.Add("MOV.S {}.x,{};", inst, vertex_count);
+        break;
+    }
     default:
         LOG_WARNING(Shader, "(STUBBED) called");
         ctx.Add("MOV.S {}.x,0x00ff0000;", inst);
diff --git a/src/shader_recompiler/backend/glsl/emit_glsl_context_get_set.cpp b/src/shader_recompiler/backend/glsl/emit_glsl_context_get_set.cpp
index 2e369ed72..63ccb2a1a 100644
--- a/src/shader_recompiler/backend/glsl/emit_glsl_context_get_set.cpp
+++ b/src/shader_recompiler/backend/glsl/emit_glsl_context_get_set.cpp
@@ -426,6 +426,12 @@ void EmitInvocationInfo(EmitContext& ctx, IR::Inst& inst) {
     case Stage::TessellationEval:
         ctx.AddU32("{}=uint(gl_PatchVerticesIn)<<16;", inst);
         break;
+    case Stage::Geometry: {
+        // Pre-calculate the vertex count for better performance
+        const u32 vertex_count = InputTopologyVertices::vertices(ctx.runtime_info.input_topology);
+        ctx.AddU32("{}={}u;", inst, vertex_count << 16);
+        break;
+    }
     default:
         LOG_WARNING(Shader, "(STUBBED) called");
         ctx.AddU32("{}=uint(0x00ff0000);", inst);
diff --git a/src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp b/src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp
index feca5105f..36274ccfa 100644
--- a/src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp
+++ b/src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp
@@ -549,6 +549,11 @@ Id EmitInvocationInfo(EmitContext& ctx) {
     case Stage::TessellationEval:
         return ctx.OpShiftLeftLogical(ctx.U32[1], ctx.OpLoad(ctx.U32[1], ctx.patch_vertices_in),
                                       ctx.Const(16u));
+    case Stage::Geometry: {
+        // Pre-calculate the shifted value for better performance
+        const u32 shifted_value = InputTopologyVertices::vertices(ctx.runtime_info.input_topology) << 16;
+        return ctx.Const(shifted_value);
+    }
     default:
         LOG_WARNING(Shader, "(STUBBED) called");
         return ctx.Const(0x00ff0000u);
diff --git a/src/shader_recompiler/runtime_info.h b/src/shader_recompiler/runtime_info.h
index 619c0b138..bc764e7af 100644
--- a/src/shader_recompiler/runtime_info.h
+++ b/src/shader_recompiler/runtime_info.h
@@ -30,6 +30,22 @@ enum class InputTopology {
     TrianglesAdjacency,
 };
 
+namespace InputTopologyVertices {
+    // Lookup table for vertex counts - faster than switch statement
+    inline constexpr std::array<u32, 5> vertex_counts = {
+        1, // Points
+        2, // Lines
+        4, // LinesAdjacency
+        3, // Triangles
+        6, // TrianglesAdjacency
+    };
+
+    // Force compile-time evaluation when possible
+    inline constexpr u32 vertices(InputTopology input_topology) {
+        return vertex_counts[static_cast<std::size_t>(input_topology)];
+    }
+}
+
 enum class CompareFunction {
     Never,
     Less,