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using Ryujinx.Graphics.Shader.IntermediateRepresentation;
using static Ryujinx.Graphics.Shader.IntermediateRepresentation.OperandHelper;
namespace Ryujinx.Graphics.Shader.Translation.Optimizations
{
static class Simplification
{
private const int AllOnes = ~0;
public static void RunPass(Operation operation)
{
switch (operation.Inst)
{
case Instruction.Add:
TryEliminateBinaryOpCommutative(operation, 0);
break;
case Instruction.BitwiseAnd:
TryEliminateBitwiseAnd(operation);
break;
case Instruction.BitwiseExclusiveOr:
if (!TryEliminateXorSwap(operation))
{
TryEliminateBinaryOpCommutative(operation, 0);
}
break;
case Instruction.BitwiseOr:
TryEliminateBitwiseOr(operation);
break;
case Instruction.CompareNotEqual:
TryEliminateCompareNotEqual(operation);
break;
case Instruction.ConditionalSelect:
TryEliminateConditionalSelect(operation);
break;
case Instruction.Divide:
TryEliminateBinaryOpY(operation, 1);
break;
case Instruction.Multiply:
TryEliminateBinaryOpCommutative(operation, 1);
break;
case Instruction.ShiftLeft:
case Instruction.ShiftRightS32:
case Instruction.ShiftRightU32:
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))
{
operation.TurnIntoCopy(y);
}
else if (IsConstEqual(y, AllOnes))
{
operation.TurnIntoCopy(x);
}
else if (IsConstEqual(x, 0) || IsConstEqual(y, 0))
{
operation.TurnIntoCopy(Const(0));
}
}
private static bool TryEliminateXorSwap(Operation xCopyOp)
{
// Try to recognize XOR swap pattern:
// x = x ^ y
// y = x ^ y
// x = x ^ y
// Or, in SSA:
// x2 = x ^ y
// y2 = x2 ^ y
// x3 = x2 ^ y2
// Transform it into something more sane:
// temp = y
// y = x
// x = temp
// Note that because XOR is commutative, there are actually
// multiple possible combinations of this pattern, for
// simplicity this only catches one of them.
Operand x = xCopyOp.GetSource(0);
Operand y = xCopyOp.GetSource(1);
if (x.AsgOp is not Operation tCopyOp || tCopyOp.Inst != Instruction.BitwiseExclusiveOr ||
y.AsgOp is not Operation yCopyOp || yCopyOp.Inst != Instruction.BitwiseExclusiveOr)
{
return false;
}
if (tCopyOp == yCopyOp)
{
return false;
}
if (yCopyOp.GetSource(0) != x ||
yCopyOp.GetSource(1) != tCopyOp.GetSource(1) ||
x.UseOps.Count != 2)
{
return false;
}
x = tCopyOp.GetSource(0);
y = tCopyOp.GetSource(1);
tCopyOp.TurnIntoCopy(y); // Temp = Y
yCopyOp.TurnIntoCopy(x); // Y = X
xCopyOp.TurnIntoCopy(tCopyOp.Dest); // X = Temp
return true;
}
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) || IsConstEqual(y, AllOnes))
{
operation.TurnIntoCopy(Const(AllOnes));
}
}
private static void TryEliminateBinaryOpY(Operation operation, int comparand)
{
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (IsConstEqual(y, comparand))
{
operation.TurnIntoCopy(x);
}
}
private static void TryEliminateBinaryOpCommutative(Operation operation, int 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 TryEliminateCompareNotEqual(Operation operation)
{
// Comparison instruction returns 0 if the result is false, and -1 if true.
// Doing a not equal zero comparison on the result is redundant, so we can just copy the first result in this case.
Operand lhs = operation.GetSource(0);
Operand rhs = operation.GetSource(1);
if (lhs.Type == OperandType.Constant)
{
(lhs, rhs) = (rhs, lhs);
}
if (rhs.Type != OperandType.Constant || rhs.Value != 0)
{
return;
}
if (lhs.AsgOp is not Operation compareOp || !compareOp.Inst.IsComparison())
{
return;
}
operation.TurnIntoCopy(lhs);
}
private static void TryEliminateConditionalSelect(Operation operation)
{
Operand cond = operation.GetSource(0);
if (cond.Type != OperandType.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, int comparand)
{
if (operand.Type != OperandType.Constant)
{
return false;
}
return operand.Value == comparand;
}
}
}
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