public static void CoalesceLoadsAndDeclarations(NodeGraph graph)
{
for (int i = 0; i < graph.numBlocks; i++)
{
NodeBlock block = graph[i];
for (NodeList.iterator iter = block.nodes.begin(); iter.more();)
{
DNode node = iter.node;
if (node.type == NodeType.DeclareLocal)
{
// Peephole next = store(this, expr)
DDeclareLocal local = (DDeclareLocal)node;
if (node.next.type == NodeType.Store)
{
DStore store = (DStore)node.next;
if (store.getOperand(0) == local)
{
local.replaceOperand(0, store.getOperand(1));
store.removeFromUseChains();
iter.next();
block.nodes.remove(iter);
continue;
}
}
}
iter.next();
}
}
}
private static void CoalesceLoadStores(NodeBlock block)
{
for (NodeList.reverse_iterator riter = block.nodes.rbegin(); riter.more(); riter.next())
{
if (riter.node.type != NodeType.Store)
{
continue;
}
DStore store = (DStore)riter.node;
DNode coalesce = null;
if (store.rhs.type == NodeType.Binary)
{
DBinary rhs = (DBinary)store.rhs;
if (rhs.lhs.type == NodeType.Load)
{
DLoad load = (DLoad)rhs.lhs;
if (load.from == store.lhs)
{
coalesce = rhs.rhs;
}
else if (load.from.type == NodeType.ArrayRef &&
store.lhs.type == NodeType.Load)
{
DArrayRef aref = (DArrayRef)load.from;
load = (DLoad)store.lhs;
if (aref.abase == load &&
aref.index.type == NodeType.Constant &&
((DConstant)aref.index).value == 0)
{
coalesce = rhs.rhs;
store.replaceOperand(0, aref);
}
}
}
if (coalesce != null)
{
store.makeStoreOp(rhs.spop);
}
}
else if (store.rhs.type == NodeType.Load &&
store.rhs.getOperand(0) == store.lhs)
{
// AWFUL PATTERN MATCHING AHEAD.
// This *looks* like a dead store, but there is probably
// something in between the load and store that changes
// the reference. We assume this has to be an incdec.
if (store.prev.type == NodeType.IncDec &&
store.prev.getOperand(0) == store.rhs)
{
// This detects a weird case in ucp.smx:
// v0 = ArrayRef
// v1 = Load(v0)
// -- Dec(v1)
// -- Store(v0, v1)
// This appears to be:
// *ref = (--*ref)
// But, this should suffice:
// --*ref
store.removeFromUseChains();
block.nodes.remove(riter);
//Debug.Assert(riter.node.type == NodeType.IncDec);
riter.node.replaceOperand(0, riter.node.getOperand(0).getOperand(0));
}
}
if (coalesce != null)
{
store.replaceOperand(1, coalesce);
}
}
}
