1 files changed, 146 insertions, 0 deletions

diff --git a/src/shader_recompiler/ir_opt/constant_propagation_pass.cpp b/src/shader_recompiler/ir_opt/constant_propagation_pass.cpp
new file mode 100644
index 000000000..02f5b653d
--- /dev/null
+++ b/src/shader_recompiler/ir_opt/constant_propagation_pass.cpp
@@ -0,0 +1,146 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <algorithm>
+#include <type_traits>
+
+#include "common/bit_util.h"
+#include "shader_recompiler/exception.h"
+#include "shader_recompiler/frontend/ir/microinstruction.h"
+#include "shader_recompiler/ir_opt/passes.h"
+
+namespace Shader::Optimization {
+namespace {
+[[nodiscard]] u32 BitFieldUExtract(u32 base, u32 shift, u32 count) {
+    if (static_cast<size_t>(shift) + static_cast<size_t>(count) > Common::BitSize<u32>()) {
+        throw LogicError("Undefined result in BitFieldUExtract({}, {}, {})", base, shift, count);
+    }
+    return (base >> shift) & ((1U << count) - 1);
+}
+
+template <typename T>
+[[nodiscard]] T Arg(const IR::Value& value) {
+    if constexpr (std::is_same_v<T, bool>) {
+        return value.U1();
+    } else if constexpr (std::is_same_v<T, u32>) {
+        return value.U32();
+    } else if constexpr (std::is_same_v<T, u64>) {
+        return value.U64();
+    }
+}
+
+template <typename ImmFn>
+bool FoldCommutative(IR::Inst& inst, ImmFn&& imm_fn) {
+    const auto arg = [](const IR::Value& value) {
+        if constexpr (std::is_invocable_r_v<bool, ImmFn, bool, bool>) {
+            return value.U1();
+        } else if constexpr (std::is_invocable_r_v<u32, ImmFn, u32, u32>) {
+            return value.U32();
+        } else if constexpr (std::is_invocable_r_v<u64, ImmFn, u64, u64>) {
+            return value.U64();
+        }
+    };
+    const IR::Value lhs{inst.Arg(0)};
+    const IR::Value rhs{inst.Arg(1)};
+
+    const bool is_lhs_immediate{lhs.IsImmediate()};
+    const bool is_rhs_immediate{rhs.IsImmediate()};
+
+    if (is_lhs_immediate && is_rhs_immediate) {
+        const auto result{imm_fn(arg(lhs), arg(rhs))};
+        inst.ReplaceUsesWith(IR::Value{result});
+        return false;
+    }
+    if (is_lhs_immediate && !is_rhs_immediate) {
+        IR::Inst* const rhs_inst{rhs.InstRecursive()};
+        if (rhs_inst->Opcode() == inst.Opcode() && rhs_inst->Arg(1).IsImmediate()) {
+            const auto combined{imm_fn(arg(lhs), arg(rhs_inst->Arg(1)))};
+            inst.SetArg(0, rhs_inst->Arg(0));
+            inst.SetArg(1, IR::Value{combined});
+        } else {
+            // Normalize
+            inst.SetArg(0, rhs);
+            inst.SetArg(1, lhs);
+        }
+    }
+    if (!is_lhs_immediate && is_rhs_immediate) {
+        const IR::Inst* const lhs_inst{lhs.InstRecursive()};
+        if (lhs_inst->Opcode() == inst.Opcode() && lhs_inst->Arg(1).IsImmediate()) {
+            const auto combined{imm_fn(arg(rhs), arg(lhs_inst->Arg(1)))};
+            inst.SetArg(0, lhs_inst->Arg(0));
+            inst.SetArg(1, IR::Value{combined});
+        }
+    }
+    return true;
+}
+
+void FoldGetRegister(IR::Inst& inst) {
+    if (inst.Arg(0).Reg() == IR::Reg::RZ) {
+        inst.ReplaceUsesWith(IR::Value{u32{0}});
+    }
+}
+
+void FoldGetPred(IR::Inst& inst) {
+    if (inst.Arg(0).Pred() == IR::Pred::PT) {
+        inst.ReplaceUsesWith(IR::Value{true});
+    }
+}
+
+template <typename T>
+void FoldAdd(IR::Inst& inst) {
+    if (inst.HasAssociatedPseudoOperation()) {
+        return;
+    }
+    if (!FoldCommutative(inst, [](T a, T b) { return a + b; })) {
+        return;
+    }
+    const IR::Value rhs{inst.Arg(1)};
+    if (rhs.IsImmediate() && Arg<T>(rhs) == 0) {
+        inst.ReplaceUsesWith(inst.Arg(0));
+    }
+}
+
+void FoldLogicalAnd(IR::Inst& inst) {
+    if (!FoldCommutative(inst, [](bool a, bool b) { return a && b; })) {
+        return;
+    }
+    const IR::Value rhs{inst.Arg(1)};
+    if (rhs.IsImmediate()) {
+        if (rhs.U1()) {
+            inst.ReplaceUsesWith(inst.Arg(0));
+        } else {
+            inst.ReplaceUsesWith(IR::Value{false});
+        }
+    }
+}
+
+void ConstantPropagation(IR::Inst& inst) {
+    switch (inst.Opcode()) {
+    case IR::Opcode::GetRegister:
+        return FoldGetRegister(inst);
+    case IR::Opcode::GetPred:
+        return FoldGetPred(inst);
+    case IR::Opcode::IAdd32:
+        return FoldAdd<u32>(inst);
+    case IR::Opcode::IAdd64:
+        return FoldAdd<u64>(inst);
+    case IR::Opcode::BitFieldUExtract:
+        if (inst.AreAllArgsImmediates() && !inst.HasAssociatedPseudoOperation()) {
+            inst.ReplaceUsesWith(IR::Value{
+                BitFieldUExtract(inst.Arg(0).U32(), inst.Arg(1).U32(), inst.Arg(2).U32())});
+        }
+        break;
+    case IR::Opcode::LogicalAnd:
+        return FoldLogicalAnd(inst);
+    default:
+        break;
+    }
+}
+} // Anonymous namespace
+
+void ConstantPropagationPass(IR::Block& block) {
+    std::ranges::for_each(block, ConstantPropagation);
+}
+
+} // namespace Shader::Optimization