[llvm-commits] [llvm] r96448 - /llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp

[Dan Gohman]

Author: djg
Date: Tue Feb 16 20:39:31 2010
New Revision: 96448

URL: http://llvm.org/viewvc/llvm-project?rev=96448&view=rev
Log:
Fix SCEVExpander's existing PHI reuse checking to recognize the
case where there are loop-invariant instructions somehow left
inside the loop, and in a position where they won't dominate
the IV increment position.

Modified:
    llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp

Modified: llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp?rev=96448&r1=96447&r2=96448&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp Tue Feb 16 20:39:31 2010
@@ -658,6 +658,19 @@
             IncV = 0;
             break;
           }
+          // If any of the operands don't dominate the insert position, bail.
+          // Addrec operands are always loop-invariant, so this can only happen
+          // if there are instructions which haven't been hoisted.
+          for (User::op_iterator OI = IncV->op_begin()+1,
+               OE = IncV->op_end(); OI != OE; ++OI)
+            if (Instruction *OInst = dyn_cast<Instruction>(OI))
+              if (!SE.DT->dominates(OInst, IVIncInsertPos)) {
+                IncV = 0;
+                break;
+              }
+          if (!IncV)
+            break;
+          // Advance to the next instruction.
           IncV = dyn_cast<Instruction>(IncV->getOperand(0));
           if (!IncV)
             break;