[llvm-commits] [llvm] r70633 - in /llvm/trunk: include/llvm/Analysis/ScalarEvolution.h lib/Analysis/ScalarEvolution.cpp

[Dan Gohman]

Author: djg
Date: Sat May  2 12:43:35 2009
New Revision: 70633

URL: http://llvm.org/viewvc/llvm-project?rev=70633&view=rev
Log:
When ScalarEvolution is told to forget the trip count for a loop, have
it also forget any SCEVs associated with loop-header PHIs in the loop,
as they may be dependent on trip count information.

Modified:
    llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolution.h?rev=70633&r1=70632&r2=70633&view=diff

==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolution.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolution.h Sat May  2 12:43:35 2009
@@ -333,6 +333,11 @@
     /// expression cannot be evaluated, return UnknownValue itself.
     SCEVHandle getSCEVAtScope(SCEV *S, const Loop *L);
 
+    /// forgetLoopPHIs - Delete the memoized SCEVs associated with the
+    /// PHI nodes in the given loop. This is used when the trip count of
+    /// the loop may have changed.
+    void forgetLoopPHIs(const Loop *L);
+
   public:
     static char ID; // Pass identification, replacement for typeid
     ScalarEvolution();

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=70633&r1=70632&r2=70633&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Sat May  2 12:43:35 2009
@@ -2111,9 +2111,7 @@
     // conservative estimates made without the benefit
     // of trip count information.
     if (ItCount.hasAnyInfo())
-      for (BasicBlock::iterator I = L->getHeader()->begin();
-           PHINode *PN = dyn_cast<PHINode>(I); ++I)
-        deleteValueFromRecords(PN);
+      forgetLoopPHIs(L);
   }
   return Pair.first->second;
 }
@@ -2124,6 +2122,16 @@
 /// is deleted.
 void ScalarEvolution::forgetLoopBackedgeTakenCount(const Loop *L) {
   BackedgeTakenCounts.erase(L);
+  forgetLoopPHIs(L);
+}
+
+/// forgetLoopPHIs - Delete the memoized SCEVs associated with the
+/// PHI nodes in the given loop. This is used when the trip count of
+/// the loop may have changed.
+void ScalarEvolution::forgetLoopPHIs(const Loop *L) {
+  for (BasicBlock::iterator I = L->getHeader()->begin();
+       PHINode *PN = dyn_cast<PHINode>(I); ++I)
+    deleteValueFromRecords(PN);
 }
 
 /// ComputeBackedgeTakenCount - Compute the number of times the backedge