[llvm-commits] CVS: llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

LoopStrengthReduce.cpp updated: 1.18 -> 1.19
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Log message:

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Make LSR ignore GEP's that have loop variant base values, as we currently
cannot codegen them


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Diffs of the changes:  (+10 -0)

 LoopStrengthReduce.cpp |   10 ++++++++++
 1 files changed, 10 insertions(+)


Index: llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
diff -u llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:1.18 llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:1.19
--- llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:1.18	Mon Aug  1 19:41:11 2005
+++ llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp	Mon Aug  1 20:32:29 2005
@@ -251,6 +251,9 @@
                                                                 UIntPtrTy));
     } else {
       SCEVHandle Idx = SE->getSCEV(GEP->getOperand(i));
+
+      // If this operand is reducible, and it's not the one we are looking at
+      // currently, do not process the GEP at this time.
       if (CanReduceSCEV(Idx, L))
         return;
       Base = SCEVAddExpr::get(Base, GetAdjustedIndex(Idx,
@@ -287,6 +290,13 @@
 
   assert(CanReduceSCEV(GEPIndexExpr, L) && "Non reducible idx??");
 
+  // FIXME: If the base is not loop invariant, we currently cannot emit this.
+  if (!Base->isLoopInvariant(L)) {
+    DEBUG(std::cerr << "IGNORING GEP due to non-invaiant base: "
+                    << *Base << "\n");
+    return;
+  }
+  
   Base = SCEVAddExpr::get(Base, cast<SCEVAddRecExpr>(GEPIndexExpr)->getStart());
   SCEVHandle Stride = cast<SCEVAddRecExpr>(GEPIndexExpr)->getOperand(1);