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();
}
}
private static bool CollapseArrayReferences(NodeBlock block)
{
bool changed = false;
for (NodeList.reverse_iterator iter = block.nodes.rbegin(); iter.more(); iter.next())
{
DNode node = iter.node;
if (node.type == NodeType.Store || node.type == NodeType.Load)
{
if (node.getOperand(0).type != NodeType.ArrayRef && IsArray(node.getOperand(0).typeSet))
{
DConstant index0 = new DConstant(0);
DArrayRef aref0 = new DArrayRef(node.getOperand(0), index0, 0);
block.nodes.insertBefore(node, index0);
block.nodes.insertBefore(node, aref0);
node.replaceOperand(0, aref0);
continue;
}
}
if (node.type != NodeType.Binary)
{
continue;
}
DBinary binary = (DBinary)node;
if (binary.spop != SPOpcode.add)
{
continue;
}
if (binary.lhs.type == NodeType.LocalRef)
{
//Debug.Assert(true);
}
// Check for an array index.
DNode abase = GuessArrayBase(binary.lhs, binary.rhs);
if (abase == null)
{
continue;
}
DNode index = (abase == binary.lhs) ? binary.rhs : binary.lhs;
if (!IsReallyLikelyArrayCompute(binary, abase))
{
continue;
}
// Multi-dimensional arrays are indexed like:
// x[y] => x + x[y]
//
// We recognize this and just remove the add, ignoring the
// underlying representation of the array.
if (index.type == NodeType.Load && index.getOperand(0) == abase)
{
node.replaceAllUsesWith(index);
node.removeFromUseChains();
block.nodes.remove(iter);
changed = true;
continue;
}
// Otherwise, create a new array reference.
DArrayRef aref = new DArrayRef(abase, index);
iter.node.replaceAllUsesWith(aref);
iter.node.removeFromUseChains();
block.nodes.remove(iter);
block.nodes.insertBefore(iter.node, aref);
changed = true;
}
return(changed);
}