public override void visit(DPhi phi)
{
// Convert a phi into a move on each incoming edge. Declare the
// temporary name in the dominator.
var idom = graph_[phi.block.lir.idom.id];
var name = new DTempName(graph_.tempName());
idom.prepend(name);
for (var i = 0; i < phi.numOperands; i++)
{
var input = phi.getOperand(i);
var store = new DStore(name, input);
var pred = graph_[phi.block.lir.getPredecessor(i).id];
pred.prepend(store);
}
phi.replaceAllUsesWith(name);
}
private void renameBlock(NodeBlock block)
{
for (NodeList.iterator iter = block.nodes.begin(); iter.more();)
{
DNode node = iter.node;
switch (node.type)
{
case NodeType.TempName:
case NodeType.Jump:
case NodeType.JumpCondition:
case NodeType.Store:
case NodeType.Return:
case NodeType.IncDec:
case NodeType.DeclareStatic:
case NodeType.Switch:
{
iter.next();
continue;
}
case NodeType.DeclareLocal:
{
DDeclareLocal decl = (DDeclareLocal)node;
if (decl.var == null)
{
if (decl.uses.Count <= 1)
{
// This was probably just a stack temporary.
if (decl.uses.Count == 1)
{
DUse use = decl.uses.First.Value;
use.node.replaceOperand(use.index, decl.value);
}
block.nodes.remove(iter);
continue;
}
DTempName name = new DTempName(graph_.tempName());
node.replaceAllUsesWith(name);
name.init(decl.value);
block.nodes.replace(iter, name);
}
iter.next();
continue;
}
case NodeType.SysReq:
case NodeType.Call:
{
// Calls are statements or expressions, so we can't
// remove them if they have no uses.
if (node.uses.Count <= 1)
{
if (node.uses.Count == 1)
{
block.nodes.remove(iter);
}
else
{
iter.next();
}
continue;
}
break;
}
case NodeType.Constant:
{
// Constants can be deeply copied.
block.nodes.remove(iter);
continue;
}
default:
{
if (node.uses.Count <= 1)
{
// This node has one or zero uses, so instead of
// renaming it, we remove it from the instruction
// stream. This way the source printer will deep-
// print it instead of using its 'SSA' name.
block.nodes.remove(iter);
continue;
}
break;
}
}
// If we've reached here, the expression has more than one use
// and we have to wrap it in some kind of name, lest we
// duplicate it in the expression tree which may be illegal.
DTempName replacement = new DTempName(graph_.tempName());
node.replaceAllUsesWith(replacement);
replacement.init(node);
block.nodes.replace(iter, replacement);
iter.next();
}
}