Use reverse iterators when updating the vector, since scanning from
the end will reduce erase() runtimes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15093 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocIterativeScan.cpp b/lib/CodeGen/RegAllocIterativeScan.cpp
index 7f7b281..9f0c5e8 100644
--- a/lib/CodeGen/RegAllocIterativeScan.cpp
+++ b/lib/CodeGen/RegAllocIterativeScan.cpp
@@ -230,20 +230,21 @@
}
// expire any remaining active intervals
- for (IntervalPtrs::iterator i = active_.begin(); i != active_.end(); ) {
+ for (IntervalPtrs::reverse_iterator
+ i = active_.rbegin(); i != active_.rend(); ) {
unsigned reg = (*i)->reg;
DEBUG(std::cerr << "\tinterval " << **i << " expired\n");
if (MRegisterInfo::isVirtualRegister(reg))
reg = vrm_->getPhys(reg);
prt_->delRegUse(reg);
- i = active_.erase(i);
+ i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
}
// expire any remaining inactive intervals
- for (IntervalPtrs::iterator
- i = inactive_.begin(); i != inactive_.end(); ) {
+ for (IntervalPtrs::reverse_iterator
+ i = inactive_.rbegin(); i != inactive_.rend(); ) {
DEBUG(std::cerr << "\tinterval " << **i << " expired\n");
- i = inactive_.erase(i);
+ i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
}
// return true if we spilled anything
@@ -267,7 +268,8 @@
void RA::processActiveIntervals(IntervalPtrs::value_type cur)
{
DEBUG(std::cerr << "\tprocessing active intervals:\n");
- for (IntervalPtrs::iterator i = active_.begin(); i != active_.end();) {
+ for (IntervalPtrs::reverse_iterator
+ i = active_.rbegin(); i != active_.rend();) {
unsigned reg = (*i)->reg;
// remove expired intervals
if ((*i)->expiredAt(cur->start())) {
@@ -276,7 +278,7 @@
reg = vrm_->getPhys(reg);
prt_->delRegUse(reg);
// remove from active
- i = active_.erase(i);
+ i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
}
// move inactive intervals to inactive list
else if (!(*i)->liveAt(cur->start())) {
@@ -287,7 +289,7 @@
// add to inactive
inactive_.push_back(*i);
// remove from active
- i = active_.erase(i);
+ i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
}
else {
++i;
@@ -298,14 +300,15 @@
void RA::processInactiveIntervals(IntervalPtrs::value_type cur)
{
DEBUG(std::cerr << "\tprocessing inactive intervals:\n");
- for (IntervalPtrs::iterator i = inactive_.begin(); i != inactive_.end();) {
+ for (IntervalPtrs::reverse_iterator
+ i = inactive_.rbegin(); i != inactive_.rend();) {
unsigned reg = (*i)->reg;
// remove expired intervals
if ((*i)->expiredAt(cur->start())) {
DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
// remove from inactive
- i = inactive_.erase(i);
+ i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
}
// move re-activated intervals in active list
else if ((*i)->liveAt(cur->start())) {
@@ -316,7 +319,7 @@
// add to active
active_.push_back(*i);
// remove from inactive
- i = inactive_.erase(i);
+ i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
}
else {
++i;