private static int GetConstOp(ref Operand baseOp)
{
Operation operation = GetAsgOpWithInst(baseOp, Instruction.Add);
if (operation == null)
{
return(0);
}
Operand src1 = operation.GetSource(0);
Operand src2 = operation.GetSource(1);
Operand constOp;
Operand otherOp;
if (src1.Kind == OperandKind.Constant && src2.Kind == OperandKind.LocalVariable)
{
constOp = src1;
otherOp = src2;
}
else if (src1.Kind == OperandKind.LocalVariable && src2.Kind == OperandKind.Constant)
{
constOp = src2;
otherOp = src1;
}
else
{
return(0);
}
// If we have addition by 64-bits constant, then we can't optimize it further,
// as we can't encode a 64-bits immediate on the memory operand.
if (CodeGenCommon.IsLongConst(constOp))
{
return(0);
}
baseOp = otherOp;
return(constOp.AsInt32());
}
private static void HandleConstantCopy(IntrusiveList <Node> nodes, Node node, Operation operation)
{
if (operation.SourcesCount == 0 || IsIntrinsic(operation.Instruction))
{
return;
}
Instruction inst = operation.Instruction;
Operand src1 = operation.GetSource(0);
Operand src2;
if (src1.Kind == OperandKind.Constant)
{
if (!src1.Type.IsInteger())
{
// Handle non-integer types (FP32, FP64 and V128).
// For instructions without an immediate operand, we do the following:
// - Insert a copy with the constant value (as integer) to a GPR.
// - Insert a copy from the GPR to a XMM register.
// - Replace the constant use with the XMM register.
src1 = AddXmmCopy(nodes, node, src1);
operation.SetSource(0, src1);
}
else if (!HasConstSrc1(inst))
{
// Handle integer types.
// Most ALU instructions accepts a 32-bits immediate on the second operand.
// We need to ensure the following:
// - If the constant is on operand 1, we need to move it.
// -- But first, we try to swap operand 1 and 2 if the instruction is commutative.
// -- Doing so may allow us to encode the constant as operand 2 and avoid a copy.
// - If the constant is on operand 2, we check if the instruction supports it,
// if not, we also add a copy. 64-bits constants are usually not supported.
if (IsCommutative(inst))
{
src2 = operation.GetSource(1);
Operand temp = src1;
src1 = src2;
src2 = temp;
operation.SetSource(0, src1);
operation.SetSource(1, src2);
}
if (src1.Kind == OperandKind.Constant)
{
src1 = AddCopy(nodes, node, src1);
operation.SetSource(0, src1);
}
}
}
if (operation.SourcesCount < 2)
{
return;
}
src2 = operation.GetSource(1);
if (src2.Kind == OperandKind.Constant)
{
if (!src2.Type.IsInteger())
{
src2 = AddXmmCopy(nodes, node, src2);
operation.SetSource(1, src2);
}
else if (!HasConstSrc2(inst) || CodeGenCommon.IsLongConst(src2))
{
src2 = AddCopy(nodes, node, src2);
operation.SetSource(1, src2);
}
}
}
public static void RunPass(ControlFlowGraph cfg)
{
for (BasicBlock block = cfg.Blocks.First; block != null; block = block.ListNext)
{
Node nextNode;
for (Node node = block.Operations.First; node != null; node = nextNode)
{
nextNode = node.ListNext;
if (!(node is Operation operation))
{
continue;
}
// Insert copies for constants that can't fit on a 32-bits immediate.
// Doing this early unblocks a few optimizations.
if (operation.Instruction == Instruction.Add)
{
Operand src1 = operation.GetSource(0);
Operand src2 = operation.GetSource(1);
if (src1.Kind == OperandKind.Constant && (src1.Relocatable || CodeGenCommon.IsLongConst(src1)))
{
Operand temp = Local(src1.Type);
Operation copyOp = Operation(Instruction.Copy, temp, src1);
block.Operations.AddBefore(operation, copyOp);
operation.SetSource(0, temp);
}
if (src2.Kind == OperandKind.Constant && (src2.Relocatable || CodeGenCommon.IsLongConst(src2)))
{
Operand temp = Local(src2.Type);
Operation copyOp = Operation(Instruction.Copy, temp, src2);
block.Operations.AddBefore(operation, copyOp);
operation.SetSource(1, temp);
}
}
// Try to fold something like:
// shl rbx, 2
// add rax, rbx
// add rax, 0xcafe
// mov rax, [rax]
// Into:
// mov rax, [rax+rbx*4+0xcafe]
if (IsMemoryLoadOrStore(operation.Instruction))
{
OperandType type;
if (operation.Destination != null)
{
type = operation.Destination.Type;
}
else
{
type = operation.GetSource(1).Type;
}
MemoryOperand memOp = GetMemoryOperandOrNull(operation.GetSource(0), type);
if (memOp != null)
{
operation.SetSource(0, memOp);
}
}
}
}
Optimizer.RemoveUnusedNodes(cfg);
}
public static void RunPass(ControlFlowGraph cfg)
{
var constants = new Dictionary <ulong, Operand>();
Operand GetConstantCopy(BasicBlock block, Operation operation, Operand source)
{
// If the constant has many uses, we also force a new constant mov to be added, in order
// to avoid overflow of the counts field (that is limited to 16 bits).
if (!constants.TryGetValue(source.Value, out var constant) || constant.UsesCount > MaxConstantUses)
{
constant = Local(source.Type);
Operation copyOp = Operation(Instruction.Copy, constant, source);
block.Operations.AddBefore(operation, copyOp);
constants[source.Value] = constant;
}
return(constant);
}
for (BasicBlock block = cfg.Blocks.First; block != null; block = block.ListNext)
{
constants.Clear();
Operation nextNode;
for (Operation node = block.Operations.First; node != default; node = nextNode)
{
nextNode = node.ListNext;
// Insert copies for constants that can't fit on a 32-bits immediate.
// Doing this early unblocks a few optimizations.
if (node.Instruction == Instruction.Add)
{
Operand src1 = node.GetSource(0);
Operand src2 = node.GetSource(1);
if (src1.Kind == OperandKind.Constant && (src1.Relocatable || CodeGenCommon.IsLongConst(src1)))
{
node.SetSource(0, GetConstantCopy(block, node, src1));
}
if (src2.Kind == OperandKind.Constant && (src2.Relocatable || CodeGenCommon.IsLongConst(src2)))
{
node.SetSource(1, GetConstantCopy(block, node, src2));
}
}
// Try to fold something like:
// shl rbx, 2
// add rax, rbx
// add rax, 0xcafe
// mov rax, [rax]
// Into:
// mov rax, [rax+rbx*4+0xcafe]
if (IsMemoryLoadOrStore(node.Instruction))
{
OperandType type;
if (node.Destination != default)
{
type = node.Destination.Type;
}
else
{
type = node.GetSource(1).Type;
}
Operand memOp = GetMemoryOperandOrNull(node.GetSource(0), type);
if (memOp != default)
{
node.SetSource(0, memOp);
}
}
}
}
Optimizer.RemoveUnusedNodes(cfg);
}