void WhileStmt::copyShare(const WhileStmt& ref,
SymbolMap* mapRef,
bool internal)
{
SymbolMap localMap;
SymbolMap* map = (mapRef != 0) ? mapRef : &localMap;
Expr* condExpr = ref.condExprGet();
astloc = ref.astloc;
blockTag = ref.blockTag;
mBreakLabel = ref.mBreakLabel;
mContinueLabel = ref.mContinueLabel;
mOrderIndependent = ref.mOrderIndependent;
if (condExpr != 0)
mCondExpr = condExpr->copy(map, true);
for_alist(expr, ref.body)
insertAtTail(expr->copy(map, true));
if (internal == false)
update_symbols(this, map);
}
/*
* Attempts to replace iteration over simple anonymous ranges with calls to
* direct iterators that take low, high and stride as arguments. This is to
* avoid the cost of constructing ranges, and if the stride is known at compile
* time, provide a more optimized iterator that uses "<, <=, >, or >=" as the
* relational operator.
*
* This is only meant to replace anonymous range iteration for "simple" ranges.
* Simple means it's a range of the form "low..high", "low..high by stride", or
* "low..#count". Anything more complex is ignored with the thinking that this
* should optimize the most common range iterators, but it could be expanded to
* handle more cases.
*
* An alternative is to update scalar replacement of aggregates to work on
* ranges, which should be able to achieve similar results as this optimization
* while handling all ranges, including non-anonymous ranges.
*
* This function will optimize things like:
* - "for i in 1..10"
* - "for i in 1..10+1"
* - "var lo=1, hi=10;for i in lo..hi"
* - "for i in 1..10 by 2"
* - "for i in 1..#10"
* - "for (i, j) in zip(1..10 by 2, 1..10 by -2)"
* - "for (i, j) in zip(A, 1..10 by 2)" // will optimize range iter still
* - "coforall i in 1..10 by 2" // works for coforalls as well
*
* Will not optimize ranges like:
* - "for in in (1..)" // doesn't handle unbounded ranges
* - "for i in 1..10 by 2 by 2" // doesn't handle more than one by operator
* - "for i in 1..10 align 2" // doesn't handle align operator
* - "for i in (1..10)#2" // doesn't handle bounded counted ranges
* - "for i in 1..#10 by 2" // doesn't handle strided and counted ranges
* - "var r = 1..10"; for i in r" // not an anonymous range
* - "forall i in 1..10" // doesn't get applied to foralls
*
* Note that this function is pretty fragile because it relies on names of
* functions/iterators as well as the arguments and order of those
* functions/iterators but there's not really a way around it this early in
* compilation. If the iterator can't be replaced, it is left unchanged.
*/
static void tryToReplaceWithDirectRangeIterator(Expr* iteratorExpr)
{
if (CallExpr* call = toCallExpr(iteratorExpr))
{
CallExpr* range = NULL;
Expr* stride = NULL;
Expr* count = NULL;
// grab the stride if we have a strided range
if (call->isNamed("chpl_by"))
{
range = toCallExpr(call->get(1)->copy());
stride = toExpr(call->get(2)->copy());
}
// or grab the count if we have a counted range and set unit stride
else if (call->isNamed("#"))
{
range = toCallExpr(call->get(1)->copy());
count = toExpr(call->get(2)->copy());
stride = new SymExpr(new_IntSymbol(1));
}
// or assume the call is the range (checked below) and set unit stride
else
{
range = call;
stride = new SymExpr(new_IntSymbol(1));
}
//
// see if we're looking at a range builder. The builder is iteratable since
// range has these() iterators
//
// replace fully bounded (and possibly strided range) with a direct range
// iter. e.g. replace:
//
// `low..high by stride`
//
// with:
//
// `chpl_direct_range_iter(low, high, stride)`
if (range && range->isNamed("chpl_build_bounded_range"))
{
// replace the range construction with a direct range iterator
Expr* low = range->get(1)->copy();
Expr* high = range->get(2)->copy();
iteratorExpr->replace(new CallExpr("chpl_direct_range_iter", low, high, stride));
}
// replace a counted, low bounded range with unit stride with an equivalent
// direct range iter. e.g. replace:
//
// `low..#count` (which is equivalent to `low..low+count-1`)
//
// with:
//
// `chpl_direct_range_iter(low, low+count-1, 1)`
else if (count && range && range->isNamed("chpl_build_low_bounded_range"))
{
Expr* low = range->get(1)->copy();
Expr* high = new CallExpr("-", new CallExpr("+", low->copy(), count), new_IntSymbol(1));
iteratorExpr->replace(new CallExpr("chpl_direct_range_iter", low, high, stride));
}
}
}
BlockStmt* ForLoop::buildForLoop(Expr* indices,
Expr* iteratorExpr,
BlockStmt* body,
bool coforall,
bool zippered)
{
VarSymbol* index = newTemp("_indexOfInterest");
VarSymbol* iterator = newTemp("_iterator");
CallExpr* iterInit = 0;
CallExpr* iterMove = 0;
ForLoop* loop = new ForLoop(index, iterator, body, zippered);
LabelSymbol* continueLabel = new LabelSymbol("_continueLabel");
LabelSymbol* breakLabel = new LabelSymbol("_breakLabel");
BlockStmt* retval = new BlockStmt();
iterator->addFlag(FLAG_EXPR_TEMP);
// Unzippered loop, treat all objects (including tuples) the same
if (zippered == false) {
iterInit = new CallExpr(PRIM_MOVE, iterator, new CallExpr("_getIterator", iteratorExpr));
// try to optimize anonymous range iteration
tryToReplaceWithDirectRangeIterator(iteratorExpr);
}
// Zippered loop: Expand args to a tuple with an iterator for each element.
else {
CallExpr* zipExpr = toCallExpr(iteratorExpr);
if (zipExpr && zipExpr->isPrimitive(PRIM_ZIP)) {
// The PRIM_ZIP indicates this is a new-style zip() AST.
// Expand arguments to a tuple with appropriate iterators for each value.
//
// Specifically, change:
// zip(a, b, c, ...)
// into the tuple:
// (_getIterator(a), _getIterator(b), _getIterator(c), ...)
//
// (ultimately, we will probably want to make this style of
// rewrite into a utility function for the other get*Zip
// functions as we convert parallel loops over to use PRIM_ZIP).
//
zipExpr->primitive = NULL; // remove the primitive
// If there's just one argument...
if (zipExpr->argList.length == 1) {
Expr* zipArg = zipExpr->argList.only();
CallExpr* zipArgCall = toCallExpr(zipArg);
// ...and it is a tuple expansion '(...t)' then remove the
// tuple expansion primitive and simply pass the tuple itself
// to _getIteratorZip(). This will not require any more
// tuples than the user introduced themselves.
//
if (zipArgCall && zipArgCall->isPrimitive(PRIM_TUPLE_EXPAND)) {
zipExpr->baseExpr = new UnresolvedSymExpr("_getIteratorZip");
Expr* tupleArg = zipArgCall->argList.only();
tupleArg->remove();
zipArgCall->replace(tupleArg);
} else {
// ...otherwise, make the expression into a _getIterator()
// call
zipExpr->baseExpr = new UnresolvedSymExpr("_getIterator");
// try to optimize anonymous range iteration
tryToReplaceWithDirectRangeIterator(zipArg);
}
} else {
//
// Otherwise, if there's more than one argument, build up the
// tuple by applying _getIterator() to each element.
//
zipExpr->baseExpr = new UnresolvedSymExpr("_build_tuple");
Expr* arg = zipExpr->argList.first();
while (arg) {
Expr* next = arg->next;
Expr* argCopy = arg->copy();
arg->replace(new CallExpr("_getIterator", argCopy));
// try to optimize anonymous range iteration
tryToReplaceWithDirectRangeIterator(argCopy);
arg = next;
}
}
iterInit = new CallExpr(PRIM_MOVE, iterator, zipExpr);
assert(zipExpr == iteratorExpr);
} else {
//
// This is an old-style zippered loop so handle it in the old style
//
iterInit = new CallExpr(PRIM_MOVE, iterator,
new CallExpr("_getIteratorZip", iteratorExpr));
// try to optimize anonymous range iteration
if (CallExpr* call = toCallExpr(iteratorExpr))
if (call->isNamed("_build_tuple"))
for_actuals(actual, call)
tryToReplaceWithDirectRangeIterator(actual);
}
}
index->addFlag(FLAG_INDEX_OF_INTEREST);
iterMove = new CallExpr(PRIM_MOVE, index, new CallExpr("iteratorIndex", iterator));
if (indices == 0)
indices = new UnresolvedSymExpr("chpl__elidedIdx");
checkIndices(indices);
destructureIndices(loop, indices, new SymExpr(index), coforall);
if (coforall)
index->addFlag(FLAG_COFORALL_INDEX_VAR);
loop->mContinueLabel = continueLabel;
loop->mBreakLabel = breakLabel;
loop->insertAtTail(new DefExpr(continueLabel));
retval->insertAtTail(new DefExpr(index));
retval->insertAtTail(new DefExpr(iterator));
retval->insertAtTail(iterInit);
retval->insertAtTail(new BlockStmt(iterMove, BLOCK_TYPE));
retval->insertAtTail(loop);
retval->insertAtTail(new DefExpr(breakLabel));
retval->insertAtTail(new CallExpr("_freeIterator", iterator));
return retval;
}
