Be a bit more efficient when processing the active and inactive

lists. Instead of scanning the vector backwards, scan it forward and
swap each element we want to erase. Then at the end erase all removed
intervals at once. This doesn't save much: 0.08s out of 4s when
compiling 176.gcc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16136 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/RegAllocIterativeScan.cpp b/lib/CodeGen/RegAllocIterativeScan.cpp
index 764c884fafe648d64155a0817ea3d7b6af393bd0..ffeb68d9ddac5f72c1ad213ea5cfcbc6ae1c47f2 100644 (file)
--- a/lib/CodeGen/RegAllocIterativeScan.cpp
+++ b/lib/CodeGen/RegAllocIterativeScan.cpp
@@ -264,63 +264,68 @@ void RA::initIntervalSets() {
 void RA::processActiveIntervals(IntervalPtrs::value_type cur)
 {
   DEBUG(std::cerr << "\tprocessing active intervals:\n");
-  for (IntervalPtrs::reverse_iterator
-         i = active_.rbegin(); i != active_.rend();) {
-    unsigned reg = (*i)->reg;
+  IntervalPtrs::iterator ii = active_.begin(), ie = active_.end();
+  while (ii != ie) {
+    LiveInterval* i = *ii;
+    unsigned reg = i->reg;
+
     // remove expired intervals
-    if ((*i)->expiredAt(cur->start())) {
-      DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
+    if (i->expiredAt(cur->start())) {
+      DEBUG(std::cerr << "\t\tinterval " << *i << " expired\n");
       if (MRegisterInfo::isVirtualRegister(reg))
         reg = vrm_->getPhys(reg);
       prt_->delRegUse(reg);
-      // remove from active
-      i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
+      // swap with last element and move end iterator back one position
+      std::iter_swap(ii, --ie);
     }
     // move inactive intervals to inactive list
-    else if (!(*i)->liveAt(cur->start())) {
-      DEBUG(std::cerr << "\t\tinterval " << **i << " inactive\n");
+    else if (!i->liveAt(cur->start())) {
+      DEBUG(std::cerr << "\t\tinterval " << *i << " inactive\n");
       if (MRegisterInfo::isVirtualRegister(reg))
         reg = vrm_->getPhys(reg);
       prt_->delRegUse(reg);
       // add to inactive
-      inactive_.push_back(*i);
-      // remove from active
-      i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
+      inactive_.push_back(i);
+      // swap with last element and move end iterator back one postion
+      std::iter_swap(ii, --ie);
     }
     else {
-      ++i;
+      ++ii;
     }
   }
+  active_.erase(ie, active_.end());
 }
 
 void RA::processInactiveIntervals(IntervalPtrs::value_type cur)
 {
   DEBUG(std::cerr << "\tprocessing inactive intervals:\n");
-  for (IntervalPtrs::reverse_iterator
-         i = inactive_.rbegin(); i != inactive_.rend();) {
-    unsigned reg = (*i)->reg;
+  IntervalPtrs::iterator ii = inactive_.begin(), ie = inactive_.end();
+  while (ii != ie) {
+    LiveInterval* i = *ii;
+    unsigned reg = i->reg;
 
     // remove expired intervals
-    if ((*i)->expiredAt(cur->start())) {
-      DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
-      // remove from inactive
-      i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
+    if (i->expiredAt(cur->start())) {
+      DEBUG(std::cerr << "\t\tinterval " << *i << " expired\n");
+      // swap with last element and move end iterator back one position
+      std::iter_swap(ii, --ie);
     }
     // move re-activated intervals in active list
-    else if ((*i)->liveAt(cur->start())) {
-      DEBUG(std::cerr << "\t\tinterval " << **i << " active\n");
+    else if (i->liveAt(cur->start())) {
+      DEBUG(std::cerr << "\t\tinterval " << *i << " active\n");
       if (MRegisterInfo::isVirtualRegister(reg))
         reg = vrm_->getPhys(reg);
       prt_->addRegUse(reg);
       // add to active
-      active_.push_back(*i);
-      // remove from inactive
-      i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
+      active_.push_back(i);
+      // swap with last element and move end iterator back one position
+      std::iter_swap(ii, --ie);
     }
     else {
-      ++i;
+      ++ii;
     }
   }
+  inactive_.erase(ie, inactive_.end());
 }
 
 void RA::updateSpillWeights(unsigned reg, SpillWeights::value_type weight)

diff --git a/lib/CodeGen/RegAllocLinearScan.cpp b/lib/CodeGen/RegAllocLinearScan.cpp
index b9af3970e0e641ab667a0b8d7ccc4ec361db016a..181f061986a966fffe338e805f06e725213db47c 100644 (file)
--- a/lib/CodeGen/RegAllocLinearScan.cpp
+++ b/lib/CodeGen/RegAllocLinearScan.cpp
@@ -231,63 +231,68 @@ void RA::initIntervalSets()
 void RA::processActiveIntervals(IntervalPtrs::value_type cur)
 {
   DEBUG(std::cerr << "\tprocessing active intervals:\n");
-  for (IntervalPtrs::reverse_iterator
-         i = active_.rbegin(); i != active_.rend();) {
-    unsigned reg = (*i)->reg;
+  IntervalPtrs::iterator ii = active_.begin(), ie = active_.end();
+  while (ii != ie) {
+    LiveInterval* i = *ii;
+    unsigned reg = i->reg;
+
     // remove expired intervals
-    if ((*i)->expiredAt(cur->start())) {
-      DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
+    if (i->expiredAt(cur->start())) {
+      DEBUG(std::cerr << "\t\tinterval " << *i << " expired\n");
       if (MRegisterInfo::isVirtualRegister(reg))
         reg = vrm_->getPhys(reg);
       prt_->delRegUse(reg);
-      // remove from active
-      i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
+      // swap with last element and move end iterator back one position
+      std::iter_swap(ii, --ie);
     }
     // move inactive intervals to inactive list
-    else if (!(*i)->liveAt(cur->start())) {
-      DEBUG(std::cerr << "\t\tinterval " << **i << " inactive\n");
+    else if (!i->liveAt(cur->start())) {
+      DEBUG(std::cerr << "\t\tinterval " << *i << " inactive\n");
       if (MRegisterInfo::isVirtualRegister(reg))
         reg = vrm_->getPhys(reg);
       prt_->delRegUse(reg);
       // add to inactive
-      inactive_.push_back(*i);
-      // remove from active
-      i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
+      inactive_.push_back(i);
+      // swap with last element and move end iterator back one postion
+      std::iter_swap(ii, --ie);
     }
     else {
-      ++i;
+      ++ii;
     }
   }
+  active_.erase(ie, active_.end());
 }
 
 void RA::processInactiveIntervals(IntervalPtrs::value_type cur)
 {
   DEBUG(std::cerr << "\tprocessing inactive intervals:\n");
-  for (IntervalPtrs::reverse_iterator
-         i = inactive_.rbegin(); i != inactive_.rend();) {
-    unsigned reg = (*i)->reg;
+  IntervalPtrs::iterator ii = inactive_.begin(), ie = inactive_.end();
+  while (ii != ie) {
+    LiveInterval* i = *ii;
+    unsigned reg = i->reg;
 
     // remove expired intervals
-    if ((*i)->expiredAt(cur->start())) {
-      DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
-      // remove from inactive
-      i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
+    if (i->expiredAt(cur->start())) {
+      DEBUG(std::cerr << "\t\tinterval " << *i << " expired\n");
+      // swap with last element and move end iterator back one position
+      std::iter_swap(ii, --ie);
     }
     // move re-activated intervals in active list
-    else if ((*i)->liveAt(cur->start())) {
-      DEBUG(std::cerr << "\t\tinterval " << **i << " active\n");
+    else if (i->liveAt(cur->start())) {
+      DEBUG(std::cerr << "\t\tinterval " << *i << " active\n");
       if (MRegisterInfo::isVirtualRegister(reg))
         reg = vrm_->getPhys(reg);
       prt_->addRegUse(reg);
       // add to active
-      active_.push_back(*i);
-      // remove from inactive
-      i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
+      active_.push_back(i);
+      // swap with last element and move end iterator back one position
+      std::iter_swap(ii, --ie);
     }
     else {
-      ++i;
+      ++ii;
     }
   }
+  inactive_.erase(ie, inactive_.end());
 }
 
 void RA::updateSpillWeights(unsigned reg, SpillWeights::value_type weight)