SimplifyCFG: GEPs with just one non-constant index are also cheap.

llvm-svn: 126452
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index c670885..3968d6e 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -247,11 +247,13 @@
     if (PBB->getFirstNonPHIOrDbg() != I)
       return false;
     break;
-  case Instruction::GetElementPtr:
-    // GEPs are cheap if all indices are constant.
-    if (!cast<GetElementPtrInst>(I)->hasAllConstantIndices())
+  case Instruction::GetElementPtr: {
+    // GEPs are cheap if all indices are constant or if there's only one index.
+    GetElementPtrInst *GEP = cast<GetElementPtrInst>(I);
+    if (!GEP->hasAllConstantIndices() && GEP->getNumIndices() > 1)
       return false;
     break;
+  }
   case Instruction::Add:
   case Instruction::Sub:
   case Instruction::And: