[llvm-commits] [llvm] r96002 - /llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp

[Dan Gohman]

Author: djg
Date: Fri Feb 12 13:20:37 2010
New Revision: 96002

URL: http://llvm.org/viewvc/llvm-project?rev=96002&view=rev
Log:
Fix this code to avoid dereferencing an end() iterator in
offset distributions it doesn't expect.

Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=96002&r1=96001&r2=96002&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Fri Feb 12 13:20:37 2010
@@ -2271,6 +2271,10 @@
     const SCEV *Reg = *I;
     const ImmMapTy &Imms = Map.find(Reg)->second;
 
+    // It's not worthwhile looking for reuse if there's only one offset.
+    if (Imms.size() == 1)
+      continue;
+
     DEBUG(dbgs() << "Generating cross-use offsets for " << *Reg << ':';
           for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end();
                J != JE; ++J)
@@ -2299,7 +2303,7 @@
       };
       for (size_t i = 0, e = array_lengthof(OtherImms); i != e; ++i) {
         ImmMapTy::const_iterator M = OtherImms[i];
-        if (M == J) continue;
+        if (M == J || M == JE) continue;
 
         // Compute the difference between the two.
         int64_t Imm = (uint64_t)JImm - M->first;