/*
* 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" bounded
* ranges. Simple means it's a range of the form "low..high" or "low..high by
* stride". 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.
*
* 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, 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" // doesn't handle # operator
* - "var r = 1..10"; for i in r" // not an anonymous range
* - "forall i in 1..10" // does not 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)
{
CallExpr* range = NULL;
Expr* stride = NULL;
if (CallExpr* call = toCallExpr(iteratorExpr))
{
// 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());
}
// assume the call is the range (checked below) and set default stride
else
{
range = call;
stride = new SymExpr(new_IntSymbol(1));
}
// see if we're looking at a builder for a bounded range. the builder is
// iteratable since range has these() iterators
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));
}
}
}
//
// Find the _waitEndCount and _endCountFree calls that comes after 'fromHere'.
// Since these two calls come together, it is prettier to insert
// our stuff after the latter.
//
static Expr* findTailInsertionPoint(Expr* fromHere, bool isCoforall) {
Expr* curr = fromHere;
if (isCoforall) curr = curr->parentExpr;
CallExpr* result = NULL;
while ((curr = curr->next)) {
if (CallExpr* call = toCallExpr(curr))
if (call->isNamed("_waitEndCount")) {
result = call;
break;
}
}
INT_ASSERT(result);
CallExpr* freeEC = toCallExpr(result->next);
// Currently these two calls come together.
INT_ASSERT(freeEC && freeEC->isNamed("_endCountFree"));
return freeEC;
}
/*
* 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* ParamForLoop::buildParamForLoop(VarSymbol* indexVar,
Expr* range,
BlockStmt* stmts)
{
VarSymbol* lowVar = newParamVar();
VarSymbol* highVar = newParamVar();
VarSymbol* strideVar = newParamVar();
LabelSymbol* breakLabel = new LabelSymbol("_breakLabel");
LabelSymbol* continueLabel = new LabelSymbol("_unused_continueLabel");
CallExpr* call = toCallExpr(range);
Expr* low = NULL;
Expr* high = NULL;
Expr* stride = NULL;
BlockStmt* outer = new BlockStmt();
if (call && call->isNamed("chpl_by"))
{
stride = call->get(2)->remove();
call = toCallExpr(call->get(1));
}
else
{
stride = new SymExpr(new_IntSymbol(1));
}
if (call && call->isNamed("chpl_build_bounded_range"))
{
low = call->get(1)->remove();
high = call->get(1)->remove();
}
else
{
USR_FATAL(range, "iterators for param-for-loops must be bounded literal ranges");
}
outer->insertAtTail(new DefExpr(indexVar, new_IntSymbol((int64_t) 0)));
outer->insertAtTail(new DefExpr(lowVar));
outer->insertAtTail(new CallExpr(PRIM_MOVE, lowVar, low));
outer->insertAtTail(new DefExpr(highVar));
outer->insertAtTail(new CallExpr(PRIM_MOVE, highVar, high));
outer->insertAtTail(new DefExpr(strideVar));
outer->insertAtTail(new CallExpr(PRIM_MOVE, strideVar, stride));
outer->insertAtTail(new ParamForLoop(indexVar,
lowVar,
highVar,
strideVar,
continueLabel,
breakLabel,
stmts));
// this continueLabel will be replaced by a per-iteration one.
outer->insertAtTail(new DefExpr(continueLabel));
outer->insertAtTail(new DefExpr(breakLabel));
return buildChapelStmt(outer);
}
