1 files changed, 346 insertions, 0 deletions
diff --git a/src/ARMeilleure/CodeGen/Optimizations/ConstantFolding.cs b/src/ARMeilleure/CodeGen/Optimizations/ConstantFolding.cs
new file mode 100644
index 00000000..c5a22a53
--- /dev/null
+++ b/src/ARMeilleure/CodeGen/Optimizations/ConstantFolding.cs
@@ -0,0 +1,346 @@
+using ARMeilleure.IntermediateRepresentation;
+using System;
+using static ARMeilleure.IntermediateRepresentation.Operand.Factory;
+
+namespace ARMeilleure.CodeGen.Optimizations
+{
+    static class ConstantFolding
+    {
+        public static void RunPass(Operation operation)
+        {
+            if (operation.Destination == default || operation.SourcesCount == 0)
+            {
+                return;
+            }
+
+            if (!AreAllSourcesConstant(operation))
+            {
+                return;
+            }
+
+            OperandType type = operation.Destination.Type;
+
+            switch (operation.Instruction)
+            {
+                case Instruction.Add:
+                    if (operation.GetSource(0).Relocatable ||
+                        operation.GetSource(1).Relocatable)
+                    {
+                        break;
+                    }
+
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => x + y);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => x + y);
+                    }
+                    break;
+
+                case Instruction.BitwiseAnd:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => x & y);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => x & y);
+                    }
+                    break;
+
+                case Instruction.BitwiseExclusiveOr:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => x ^ y);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => x ^ y);
+                    }
+                    break;
+
+                case Instruction.BitwiseNot:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateUnaryI32(operation, (x) => ~x);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateUnaryI64(operation, (x) => ~x);
+                    }
+                    break;
+
+                case Instruction.BitwiseOr:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => x | y);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => x | y);
+                    }
+                    break;
+
+                case Instruction.ConvertI64ToI32:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateUnaryI32(operation, (x) => x);
+                    }
+                    break;
+
+                case Instruction.Compare:
+                    if (type == OperandType.I32 &&
+                        operation.GetSource(0).Type == type &&
+                        operation.GetSource(1).Type == type)
+                    {
+                        switch ((Comparison)operation.GetSource(2).Value)
+                        {
+                            case Comparison.Equal:
+                                EvaluateBinaryI32(operation, (x, y) => x == y ? 1 : 0);
+                                break;
+                            case Comparison.NotEqual:
+                                EvaluateBinaryI32(operation, (x, y) => x != y ? 1 : 0);
+                                break;
+                            case Comparison.Greater:
+                                EvaluateBinaryI32(operation, (x, y) => x > y ? 1 : 0);
+                                break;
+                            case Comparison.LessOrEqual:
+                                EvaluateBinaryI32(operation, (x, y) => x <= y ? 1 : 0);
+                                break;
+                            case Comparison.GreaterUI:
+                                EvaluateBinaryI32(operation, (x, y) => (uint)x > (uint)y ? 1 : 0);
+                                break;
+                            case Comparison.LessOrEqualUI:
+                                EvaluateBinaryI32(operation, (x, y) => (uint)x <= (uint)y ? 1 : 0);
+                                break;
+                            case Comparison.GreaterOrEqual:
+                                EvaluateBinaryI32(operation, (x, y) => x >= y ? 1 : 0);
+                                break;
+                            case Comparison.Less:
+                                EvaluateBinaryI32(operation, (x, y) => x < y ? 1 : 0);
+                                break;
+                            case Comparison.GreaterOrEqualUI:
+                                EvaluateBinaryI32(operation, (x, y) => (uint)x >= (uint)y ? 1 : 0);
+                                break;
+                            case Comparison.LessUI:
+                                EvaluateBinaryI32(operation, (x, y) => (uint)x < (uint)y ? 1 : 0);
+                                break;
+                        }
+                    }
+                    break;
+
+                case Instruction.Copy:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateUnaryI32(operation, (x) => x);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateUnaryI64(operation, (x) => x);
+                    }
+                    break;
+
+                case Instruction.Divide:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => y != 0 ? x / y : 0);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => y != 0 ? x / y : 0);
+                    }
+                    break;
+
+                case Instruction.DivideUI:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => y != 0 ? (int)((uint)x / (uint)y) : 0);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => y != 0 ? (long)((ulong)x / (ulong)y) : 0);
+                    }
+                    break;
+
+                 case Instruction.Multiply:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => x * y);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => x * y);
+                    }
+                    break;
+
+                case Instruction.Negate:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateUnaryI32(operation, (x) => -x);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateUnaryI64(operation, (x) => -x);
+                    }
+                    break;
+
+                case Instruction.ShiftLeft:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => x << y);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => x << (int)y);
+                    }
+                    break;
+
+                case Instruction.ShiftRightSI:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => x >> y);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => x >> (int)y);
+                    }
+                    break;
+
+                case Instruction.ShiftRightUI:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => (int)((uint)x >> y));
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => (long)((ulong)x >> (int)y));
+                    }
+                    break;
+
+                case Instruction.SignExtend16:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateUnaryI32(operation, (x) => (short)x);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateUnaryI64(operation, (x) => (short)x);
+                    }
+                    break;
+
+                case Instruction.SignExtend32:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateUnaryI32(operation, (x) => x);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateUnaryI64(operation, (x) => (int)x);
+                    }
+                    break;
+
+                case Instruction.SignExtend8:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateUnaryI32(operation, (x) => (sbyte)x);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateUnaryI64(operation, (x) => (sbyte)x);
+                    }
+                    break;
+
+                case Instruction.ZeroExtend16:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateUnaryI32(operation, (x) => (ushort)x);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateUnaryI64(operation, (x) => (ushort)x);
+                    }
+                    break;
+
+                case Instruction.ZeroExtend32:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateUnaryI32(operation, (x) => x);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateUnaryI64(operation, (x) => (uint)x);
+                    }
+                    break;
+
+                case Instruction.ZeroExtend8:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateUnaryI32(operation, (x) => (byte)x);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateUnaryI64(operation, (x) => (byte)x);
+                    }
+                    break;
+
+                case Instruction.Subtract:
+                    if (type == OperandType.I32)
+                    {
+                        EvaluateBinaryI32(operation, (x, y) => x - y);
+                    }
+                    else if (type == OperandType.I64)
+                    {
+                        EvaluateBinaryI64(operation, (x, y) => x - y);
+                    }
+                    break;
+            }
+        }
+
+        private static bool AreAllSourcesConstant(Operation operation)
+        {
+            for (int index = 0; index < operation.SourcesCount; index++)
+            {
+                Operand srcOp = operation.GetSource(index);
+
+                if (srcOp.Kind != OperandKind.Constant)
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
+        private static void EvaluateUnaryI32(Operation operation, Func<int, int> op)
+        {
+            int x = operation.GetSource(0).AsInt32();
+
+            operation.TurnIntoCopy(Const(op(x)));
+        }
+
+        private static void EvaluateUnaryI64(Operation operation, Func<long, long> op)
+        {
+            long x = operation.GetSource(0).AsInt64();
+
+            operation.TurnIntoCopy(Const(op(x)));
+        }
+
+        private static void EvaluateBinaryI32(Operation operation, Func<int, int, int> op)
+        {
+            int x = operation.GetSource(0).AsInt32();
+            int y = operation.GetSource(1).AsInt32();
+
+            operation.TurnIntoCopy(Const(op(x, y)));
+        }
+
+        private static void EvaluateBinaryI64(Operation operation, Func<long, long, long> op)
+        {
+            long x = operation.GetSource(0).AsInt64();
+            long y = operation.GetSource(1).AsInt64();
+
+            operation.TurnIntoCopy(Const(op(x, y)));
+        }
+    }
+}
+\ No newline at end of file