From c50ad56bf59169bd0fc808ebecfb4a69376f10df Mon Sep 17 00:00:00 2001
From: Fernando Sahmkow <fsahmkow27@gmail.com>
Date: Sun, 31 Oct 2021 17:46:46 +0100
Subject: ShaderCache: Order Phi Arguments from farthest away to nearest.

---
 src/shader_recompiler/frontend/ir/basic_block.h            | 14 ++++++++++++++
 src/shader_recompiler/frontend/ir/microinstruction.cpp     | 11 +++++++++++
 src/shader_recompiler/frontend/ir/value.h                  |  3 +++
 .../frontend/maxwell/translate_program.cpp                 |  2 ++
 src/shader_recompiler/ir_opt/ssa_rewrite_pass.cpp          |  7 +++++++
 5 files changed, 37 insertions(+)

(limited to 'src/shader_recompiler')

diff --git a/src/shader_recompiler/frontend/ir/basic_block.h b/src/shader_recompiler/frontend/ir/basic_block.h
index 7e134b4c7..9ce1ed07e 100644
--- a/src/shader_recompiler/frontend/ir/basic_block.h
+++ b/src/shader_recompiler/frontend/ir/basic_block.h
@@ -152,6 +152,17 @@ public:
         return instructions.crend();
     }
 
+    // Set the order of the block, it can be set pre order, the user decides
+    void SetOrder(u32 new_order) {
+        order = new_order;
+    }
+
+    // Get the order of the block.
+    // The higher, the closer is the block to the end.
+    [[nodiscard]] u32 GetOrder() const {
+        return order;
+    }
+
 private:
     /// Memory pool for instruction list
     ObjectPool<Inst>* inst_pool;
@@ -171,6 +182,9 @@ private:
 
     /// Intrusively stored host definition of this block.
     u32 definition{};
+
+    /// Order of the block.
+    u32 order{};
 };
 
 using BlockList = std::vector<Block*>;
diff --git a/src/shader_recompiler/frontend/ir/microinstruction.cpp b/src/shader_recompiler/frontend/ir/microinstruction.cpp
index 3dfa5a880..e563b4022 100644
--- a/src/shader_recompiler/frontend/ir/microinstruction.cpp
+++ b/src/shader_recompiler/frontend/ir/microinstruction.cpp
@@ -6,6 +6,7 @@
 #include <memory>
 
 #include "shader_recompiler/exception.h"
+#include "shader_recompiler/frontend/ir/basic_block.h"
 #include "shader_recompiler/frontend/ir/type.h"
 #include "shader_recompiler/frontend/ir/value.h"
 
@@ -291,6 +292,16 @@ void Inst::AddPhiOperand(Block* predecessor, const Value& value) {
     phi_args.emplace_back(predecessor, value);
 }
 
+void Inst::OrderPhiArgs() {
+    if (op != Opcode::Phi) {
+        throw LogicError("{} is not a Phi instruction", op);
+    }
+    std::sort(phi_args.begin(), phi_args.end(),
+              [](const std::pair<Block*, Value>& a, const std::pair<Block*, Value>& b) {
+                  return a.first->GetOrder() < b.first->GetOrder();
+              });
+}
+
 void Inst::Invalidate() {
     ClearArgs();
     ReplaceOpcode(Opcode::Void);
diff --git a/src/shader_recompiler/frontend/ir/value.h b/src/shader_recompiler/frontend/ir/value.h
index 334bb47aa..6c9ef6bdd 100644
--- a/src/shader_recompiler/frontend/ir/value.h
+++ b/src/shader_recompiler/frontend/ir/value.h
@@ -182,6 +182,9 @@ public:
     /// Add phi operand to a phi instruction.
     void AddPhiOperand(Block* predecessor, const Value& value);
 
+    /// Orders the Phi arguments from farthest away to nearest.
+    void OrderPhiArgs();
+
     void Invalidate();
     void ClearArgs();
 
diff --git a/src/shader_recompiler/frontend/maxwell/translate_program.cpp b/src/shader_recompiler/frontend/maxwell/translate_program.cpp
index 012d55357..2fc542f0e 100644
--- a/src/shader_recompiler/frontend/maxwell/translate_program.cpp
+++ b/src/shader_recompiler/frontend/maxwell/translate_program.cpp
@@ -27,9 +27,11 @@ IR::BlockList GenerateBlocks(const IR::AbstractSyntaxList& syntax_list) {
     }
     IR::BlockList blocks;
     blocks.reserve(num_syntax_blocks);
+    u32 order_index{};
     for (const auto& node : syntax_list) {
         if (node.type == IR::AbstractSyntaxNode::Type::Block) {
             blocks.push_back(node.data.block);
+            blocks.back()->SetOrder(order_index++);
         }
     }
     return blocks;
diff --git a/src/shader_recompiler/ir_opt/ssa_rewrite_pass.cpp b/src/shader_recompiler/ir_opt/ssa_rewrite_pass.cpp
index 53145fb5e..5545f8197 100644
--- a/src/shader_recompiler/ir_opt/ssa_rewrite_pass.cpp
+++ b/src/shader_recompiler/ir_opt/ssa_rewrite_pass.cpp
@@ -378,6 +378,13 @@ void SsaRewritePass(IR::Program& program) {
     for (auto block = program.post_order_blocks.rbegin(); block != end; ++block) {
         VisitBlock(pass, *block);
     }
+    for (auto block = program.post_order_blocks.rbegin(); block != end; ++block) {
+        for (IR::Inst& inst : (*block)->Instructions()) {
+            if (inst.GetOpcode() == IR::Opcode::Phi) {
+                inst.OrderPhiArgs();
+            }
+        }
+    }
 }
 
 } // namespace Shader::Optimization
-- 
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