MInstruction*
Loop::popFromWorklist()
{
MInstruction* toReturn = worklist_.popCopy();
toReturn->setNotInWorklist();
return toReturn;
}
// Iterate backward on all instruction and attempt to truncate operations for
// each instruction which respect the following list of predicates: Has been
// analyzed by range analysis, the range has no rounding errors, all uses cases
// are truncating the result.
//
// If the truncation of the operation is successful, then the instruction is
// queue for later updating the graph to restore the type correctness by
// converting the operands that need to be truncated.
//
// We iterate backward because it is likely that a truncated operation truncates
// some of its operands.
bool
RangeAnalysis::truncate()
{
IonSpew(IonSpew_Range, "Do range-base truncation (backward loop)");
Vector<MInstruction *, 16, SystemAllocPolicy> worklist;
for (PostorderIterator block(graph_.poBegin()); block != graph_.poEnd(); block++) {
for (MInstructionReverseIterator iter(block->rbegin()); iter != block->rend(); iter++) {
// Set truncated flag if range analysis ensure that it has no
// rounding errors and no freactional part.
const Range *r = iter->range();
if (!r || r->hasRoundingErrors())
continue;
// Ensure all observable uses are truncated.
if (!AllUsesTruncate(*iter))
continue;
// Truncate this instruction if possible.
if (!iter->truncate())
continue;
// Delay updates of inputs/outputs to avoid creating node which
// would be removed by the truncation of the next operations.
iter->setInWorklist();
if (!worklist.append(*iter))
return false;
}
}
// Update inputs/outputs of truncated instructions.
IonSpew(IonSpew_Range, "Do graph type fixup (dequeue)");
while (!worklist.empty()) {
MInstruction *ins = worklist.popCopy();
ins->setNotInWorklist();
RemoveTruncatesOnOutput(ins);
AdjustTruncatedInputs(ins);
}
return true;
}
