From 0526bf18952bc6c6877dcdc05731d34327396662 Mon Sep 17 00:00:00 2001
From: ReinUsesLisp <reinuseslisp@airmail.cc>
Date: Mon, 26 Aug 2019 22:09:12 -0300
Subject: shader_ir/warp: Implement SHFL

---
 src/video_core/renderer_opengl/gl_shader_cache.cpp |  3 +-
 .../renderer_opengl/gl_shader_decompiler.cpp       | 63 +++++++++++++++++++---
 2 files changed, 57 insertions(+), 9 deletions(-)

(limited to 'src/video_core/renderer_opengl')

diff --git a/src/video_core/renderer_opengl/gl_shader_cache.cpp b/src/video_core/renderer_opengl/gl_shader_cache.cpp
index 909ccb82c..0dbc4c02f 100644
--- a/src/video_core/renderer_opengl/gl_shader_cache.cpp
+++ b/src/video_core/renderer_opengl/gl_shader_cache.cpp
@@ -214,7 +214,8 @@ CachedProgram SpecializeShader(const std::string& code, const GLShader::ShaderEn
     std::string source = "#version 430 core\n"
                          "#extension GL_ARB_separate_shader_objects : enable\n"
                          "#extension GL_NV_gpu_shader5 : enable\n"
-                         "#extension GL_NV_shader_thread_group : enable\n";
+                         "#extension GL_NV_shader_thread_group : enable\n"
+                         "#extension GL_NV_shader_thread_shuffle : enable\n";
     if (entries.shader_viewport_layer_array) {
         source += "#extension GL_ARB_shader_viewport_layer_array : enable\n";
     }
diff --git a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
index 137b23740..6b31ba0f2 100644
--- a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
+++ b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
@@ -1934,8 +1934,7 @@ private:
     Expression BallotThread(Operation operation) {
         const std::string value = VisitOperand(operation, 0).AsBool();
         if (!device.HasWarpIntrinsics()) {
-            LOG_ERROR(Render_OpenGL,
-                      "Nvidia warp intrinsics are not available and its required by a shader");
+            LOG_ERROR(Render_OpenGL, "Nvidia vote intrinsics are required by this shader");
             // Stub on non-Nvidia devices by simulating all threads voting the same as the active
             // one.
             return {fmt::format("({} ? 0xFFFFFFFFU : 0U)", value), Type::Uint};
@@ -1946,8 +1945,7 @@ private:
     Expression Vote(Operation operation, const char* func) {
         const std::string value = VisitOperand(operation, 0).AsBool();
         if (!device.HasWarpIntrinsics()) {
-            LOG_ERROR(Render_OpenGL,
-                      "Nvidia vote intrinsics are not available and its required by a shader");
+            LOG_ERROR(Render_OpenGL, "Nvidia vote intrinsics are required by this shader");
             // Stub with a warp size of one.
             return {value, Type::Bool};
         }
@@ -1964,15 +1962,54 @@ private:
 
     Expression VoteEqual(Operation operation) {
         if (!device.HasWarpIntrinsics()) {
-            LOG_ERROR(Render_OpenGL,
-                      "Nvidia vote intrinsics are not available and its required by a shader");
-            // We must return true here since a stub for a theoretical warp size of 1 will always
-            // return an equal result for all its votes.
+            LOG_ERROR(Render_OpenGL, "Nvidia vote intrinsics are required by this shader");
+            // We must return true here since a stub for a theoretical warp size of 1.
+            // This will always return an equal result across all votes.
             return {"true", Type::Bool};
         }
         return Vote(operation, "allThreadsEqualNV");
     }
 
+    template <const std::string_view& func>
+    Expression Shuffle(Operation operation) {
+        const std::string value = VisitOperand(operation, 0).AsFloat();
+        if (!device.HasWarpIntrinsics()) {
+            LOG_ERROR(Render_OpenGL, "Nvidia shuffle intrinsics are required by this shader");
+            // On a "single-thread" device we are either on the same thread or out of bounds. Both
+            // cases return the passed value.
+            return {value, Type::Float};
+        }
+
+        const std::string index = VisitOperand(operation, 1).AsUint();
+        const std::string width = VisitOperand(operation, 2).AsUint();
+        return {fmt::format("{}({}, {}, {})", func, value, index, width), Type::Float};
+    }
+
+    template <const std::string_view& func>
+    Expression InRangeShuffle(Operation operation) {
+        const std::string index = VisitOperand(operation, 0).AsUint();
+        const std::string width = VisitOperand(operation, 1).AsUint();
+        if (!device.HasWarpIntrinsics()) {
+            // On a "single-thread" device we are only in bounds when the requested index is 0.
+            return {fmt::format("({} == 0U)", index), Type::Bool};
+        }
+
+        const std::string in_range = code.GenerateTemporary();
+        code.AddLine("bool {};", in_range);
+        code.AddLine("{}(0U, {}, {}, {});", func, index, width, in_range);
+        return {in_range, Type::Bool};
+    }
+
+    struct Func final {
+        Func() = delete;
+        ~Func() = delete;
+
+        static constexpr std::string_view ShuffleIndexed = "shuffleNV";
+        static constexpr std::string_view ShuffleUp = "shuffleUpNV";
+        static constexpr std::string_view ShuffleDown = "shuffleDownNV";
+        static constexpr std::string_view ShuffleButterfly = "shuffleXorNV";
+    };
+
     static constexpr std::array operation_decompilers = {
         &GLSLDecompiler::Assign,
 
@@ -2135,6 +2172,16 @@ private:
         &GLSLDecompiler::VoteAll,
         &GLSLDecompiler::VoteAny,
         &GLSLDecompiler::VoteEqual,
+
+        &GLSLDecompiler::Shuffle<Func::ShuffleIndexed>,
+        &GLSLDecompiler::Shuffle<Func::ShuffleUp>,
+        &GLSLDecompiler::Shuffle<Func::ShuffleDown>,
+        &GLSLDecompiler::Shuffle<Func::ShuffleButterfly>,
+
+        &GLSLDecompiler::InRangeShuffle<Func::ShuffleIndexed>,
+        &GLSLDecompiler::InRangeShuffle<Func::ShuffleUp>,
+        &GLSLDecompiler::InRangeShuffle<Func::ShuffleDown>,
+        &GLSLDecompiler::InRangeShuffle<Func::ShuffleButterfly>,
     };
     static_assert(operation_decompilers.size() == static_cast<std::size_t>(OperationCode::Amount));
 
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