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using ARMeilleure.IntermediateRepresentation;
using System;
using static ARMeilleure.IntermediateRepresentation.Operand.Factory;
namespace ARMeilleure.CodeGen.Optimizations
{
static class Simplification
{
public static void RunPass(Operation operation)
{
switch (operation.Instruction)
{
case Instruction.Add:
if (operation.GetSource(0).Relocatable ||
operation.GetSource(1).Relocatable)
{
break;
}
TryEliminateBinaryOpComutative(operation, 0);
break;
case Instruction.BitwiseAnd:
TryEliminateBitwiseAnd(operation);
break;
case Instruction.BitwiseOr:
TryEliminateBitwiseOr(operation);
break;
case Instruction.BitwiseExclusiveOr:
TryEliminateBitwiseExclusiveOr(operation);
break;
case Instruction.ConditionalSelect:
TryEliminateConditionalSelect(operation);
break;
case Instruction.Divide:
TryEliminateBinaryOpY(operation, 1);
break;
case Instruction.Multiply:
TryEliminateBinaryOpComutative(operation, 1);
break;
case Instruction.ShiftLeft:
case Instruction.ShiftRightSI:
case Instruction.ShiftRightUI:
case Instruction.Subtract:
TryEliminateBinaryOpY(operation, 0);
break;
}
}
private static void TryEliminateBitwiseAnd(Operation operation)
{
// Try to recognize and optimize those 3 patterns (in order):
// x & 0xFFFFFFFF == x, 0xFFFFFFFF & y == y,
// x & 0x00000000 == 0x00000000, 0x00000000 & y == 0x00000000
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (IsConstEqual(x, AllOnes(x.Type)))
{
operation.TurnIntoCopy(y);
}
else if (IsConstEqual(y, AllOnes(y.Type)))
{
operation.TurnIntoCopy(x);
}
else if (IsConstEqual(x, 0) || IsConstEqual(y, 0))
{
operation.TurnIntoCopy(Const(x.Type, 0));
}
}
private static void TryEliminateBitwiseOr(Operation operation)
{
// Try to recognize and optimize those 3 patterns (in order):
// x | 0x00000000 == x, 0x00000000 | y == y,
// x | 0xFFFFFFFF == 0xFFFFFFFF, 0xFFFFFFFF | y == 0xFFFFFFFF
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (IsConstEqual(x, 0))
{
operation.TurnIntoCopy(y);
}
else if (IsConstEqual(y, 0))
{
operation.TurnIntoCopy(x);
}
else if (IsConstEqual(x, AllOnes(x.Type)) || IsConstEqual(y, AllOnes(y.Type)))
{
operation.TurnIntoCopy(Const(AllOnes(x.Type)));
}
}
private static void TryEliminateBitwiseExclusiveOr(Operation operation)
{
// Try to recognize and optimize those 2 patterns (in order):
// x ^ y == 0x00000000 when x == y
// 0x00000000 ^ y == y, x ^ 0x00000000 == x
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (x == y && x.Type.IsInteger())
{
operation.TurnIntoCopy(Const(x.Type, 0));
}
else
{
TryEliminateBinaryOpComutative(operation, 0);
}
}
private static void TryEliminateBinaryOpY(Operation operation, ulong comparand)
{
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (IsConstEqual(y, comparand))
{
operation.TurnIntoCopy(x);
}
}
private static void TryEliminateBinaryOpComutative(Operation operation, ulong comparand)
{
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (IsConstEqual(x, comparand))
{
operation.TurnIntoCopy(y);
}
else if (IsConstEqual(y, comparand))
{
operation.TurnIntoCopy(x);
}
}
private static void TryEliminateConditionalSelect(Operation operation)
{
Operand cond = operation.GetSource(0);
if (cond.Kind != OperandKind.Constant)
{
return;
}
// The condition is constant, we can turn it into a copy, and select
// the source based on the condition value.
int srcIndex = cond.Value != 0 ? 1 : 2;
Operand source = operation.GetSource(srcIndex);
operation.TurnIntoCopy(source);
}
private static bool IsConstEqual(Operand operand, ulong comparand)
{
if (operand.Kind != OperandKind.Constant || !operand.Type.IsInteger())
{
return false;
}
return operand.Value == comparand;
}
private static ulong AllOnes(OperandType type)
{
return type switch
{
OperandType.I32 => ~0U,
OperandType.I64 => ~0UL,
_ => throw new ArgumentException("Invalid operand type \"" + type + "\"."),
};
}
}
}
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