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rjx-mirror/ARMeilleure/CodeGen/Optimizations/Simplification.cs
FICTURE7 f2a7b300c4
Fix type mismatch in BitwiseAnd simplification ()
* Fix type mismatch in `BitwiseAnd` simplification

`TryEliminateBitwiseAnd` would turn the `BitwiseAnd` operation into a
copy of the wrong type. E.g:

Before `Simplification`:
```llvm
i64 %0 = BitwiseAnd i64 0x0, %1
```

After `Simplication`:
```llvm
i64 %0 = Copy i32 0x0
```

Since the with the changes in , we iterate in reverse order and
`Simplication`, `ConstantFolding` does not indicate if it modified
the CFG, the second pass to "retype" the copy into the proper
destination type does not happen.

This also blocked copy propagation since its destination type did not
match with its source type. But in the cases I've seen, the
`PreAllocator` would insert a copy for the propagated constant, which
results in no diffs.

Since the copy remained as is, asserts are fired when generating it.

* Set PPTC version
2021-08-20 14:42:00 -03:00

183 lines
No EOL
5.8 KiB
C#

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)
{
switch (type)
{
case OperandType.I32: return ~0U;
case OperandType.I64: return ~0UL;
}
throw new ArgumentException("Invalid operand type \"" + type + "\".");
}
}
}