From 603c861532ed1a89254556ff84bbe121bd700765 Mon Sep 17 00:00:00 2001
From: Fernando Sahmkow <fsahmkow27@gmail.com>
Date: Sun, 5 Jan 2020 15:23:24 -0400
Subject: Shader_IR: Implement initial code for tracking indexed samplers.

---
 src/video_core/shader/track.cpp | 82 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)

(limited to 'src/video_core/shader/track.cpp')

diff --git a/src/video_core/shader/track.cpp b/src/video_core/shader/track.cpp
index 165c79330..69a677394 100644
--- a/src/video_core/shader/track.cpp
+++ b/src/video_core/shader/track.cpp
@@ -8,6 +8,7 @@
 
 #include "common/common_types.h"
 #include "video_core/shader/node.h"
+#include "video_core/shader/node_helper.h"
 #include "video_core/shader/shader_ir.h"
 
 namespace VideoCommon::Shader {
@@ -37,6 +38,87 @@ std::pair<Node, s64> FindOperation(const NodeBlock& code, s64 cursor,
 }
 } // Anonymous namespace
 
+std::optional<std::pair<Node, Node>> DecoupleIndirectRead(const OperationNode& operation) {
+    if (operation.GetCode() != OperationCode::UAdd) {
+        return std::nullopt;
+    }
+    Node gpr{};
+    Node offset{};
+    if (operation.GetOperandsCount() != 2) {
+        return std::nullopt;
+    }
+    for (std::size_t i = 0; i < operation.GetOperandsCount(); i++) {
+        Node operand = operation[i];
+        if (std::holds_alternative<ImmediateNode>(*operand)) {
+            offset = operation[i];
+        } else if (std::holds_alternative<GprNode>(*operand)) {
+            gpr = operation[i];
+        }
+    }
+    if (offset && gpr) {
+        return {std::make_pair(gpr, offset)};
+    }
+    return std::nullopt;
+}
+
+std::tuple<Node, TrackSampler> ShaderIR::TrackSampler(Node tracked, const NodeBlock& code,
+                                                      s64 cursor) const {
+    if (const auto cbuf = std::get_if<CbufNode>(&*tracked)) {
+        // Constant buffer found, test if it's an immediate
+        const auto offset = cbuf->GetOffset();
+        if (const auto immediate = std::get_if<ImmediateNode>(&*offset)) {
+            auto track =
+                MakeTrackSampler<BindlessSamplerNode>(cbuf->GetIndex(), immediate->GetValue());
+            return {tracked, track};
+        } else if (const auto operation = std::get_if<OperationNode>(&*offset)) {
+            auto bound_buffer = locker.ObtainBoundBuffer();
+            if (!bound_buffer) {
+                return {};
+            }
+            if (*bound_buffer != cbuf->GetIndex()) {
+                return {};
+            }
+            auto pair = DecoupleIndirectRead(*operation);
+            if (!pair) {
+                return {};
+            }
+            auto [gpr, base_offset] = *pair;
+            const auto offset_inm = std::get_if<ImmediateNode>(&*base_offset);
+            // TODO Implement Bindless Index custom variable
+            auto track =
+                MakeTrackSampler<ArraySamplerNode>(cbuf->GetIndex(), offset_inm->GetValue(), 0);
+            return {tracked, track};
+        }
+        return {};
+    }
+    if (const auto gpr = std::get_if<GprNode>(&*tracked)) {
+        if (gpr->GetIndex() == Tegra::Shader::Register::ZeroIndex) {
+            return {};
+        }
+        // Reduce the cursor in one to avoid infinite loops when the instruction sets the same
+        // register that it uses as operand
+        const auto [source, new_cursor] = TrackRegister(gpr, code, cursor - 1);
+        if (!source) {
+            return {};
+        }
+        return TrackSampler(source, code, new_cursor);
+    }
+    if (const auto operation = std::get_if<OperationNode>(&*tracked)) {
+        for (std::size_t i = operation->GetOperandsCount(); i > 0; --i) {
+            if (auto found = TrackSampler((*operation)[i - 1], code, cursor); std::get<0>(found)) {
+                // Cbuf found in operand.
+                return found;
+            }
+        }
+        return {};
+    }
+    if (const auto conditional = std::get_if<ConditionalNode>(&*tracked)) {
+        const auto& conditional_code = conditional->GetCode();
+        return TrackSampler(tracked, conditional_code, static_cast<s64>(conditional_code.size()));
+    }
+    return {};
+}
+
 std::tuple<Node, u32, u32> ShaderIR::TrackCbuf(Node tracked, const NodeBlock& code,
                                                s64 cursor) const {
     if (const auto cbuf = std::get_if<CbufNode>(&*tracked)) {
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