Add facility that allows LoopPass to re-insert a loop into

Loop Pass Manager's queue.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34509 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 0 deletions

diff --git a/lib/Analysis/LoopPass.cpp b/lib/Analysis/LoopPass.cpp
index 22d542b05b..dc5c5683fb 100644
--- a/lib/Analysis/LoopPass.cpp
+++ b/lib/Analysis/LoopPass.cpp
@@ -50,6 +50,8 @@ private:
 /// LPPassManager manages FPPassManagers and CalLGraphSCCPasses.
 
 LPPassManager::LPPassManager(int Depth) : PMDataManager(Depth) { 
+  skipThisLoop = false;
+  redoThisLoop = false;
   LQ = new LoopQueue(); 
 }
 
@@ -64,6 +66,13 @@ void LPPassManager::deleteLoopFromQueue(Loop *L) {
   skipThisLoop = true;
 }
 
+// Reoptimize this loop. LPPassManager will re-insert this loop into the
+// queue. This allows LoopPass to change loop nest for the loop. This
+// utility may send LPPassManager into infinite loops so use caution.
+void LPPassManager::redoLoop(Loop *L) {
+  redoThisLoop = true;
+}
+
 // Recurse through all subloops and all loops  into LQ.
 static void addLoopIntoQueue(Loop *L, LoopQueue *LQ) {
   for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
@@ -89,6 +98,7 @@ bool LPPassManager::runOnFunction(Function &F) {
       
     Loop *L  = LQ->top();
     skipThisLoop = false;
+    redoThisLoop = false;
 
     // Run all passes on current SCC
     for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {  
@@ -124,6 +134,9 @@ bool LPPassManager::runOnFunction(Function &F) {
     
     // Pop the loop from queue after running all passes.
     LQ->pop();
+    
+    if (redoThisLoop)
+      LQ->push(L);
   }
 
   return Changed;