implement getelementptr.ll:test10

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21541 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index ad60a75f326ce546d1adfa5f8349bee5d8138ade..83d390d4aea999fac1162f3ab1315918921ee494 100644 (file)
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -2277,8 +2277,26 @@ Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
                              Constant::getNullValue(Offset->getType()));
     }
   } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
-    if (PtrBase != GEPRHS->getOperand(0))
+    // If the base pointers are different, but the indices are the same, just
+    // compare the base pointer.
+    if (PtrBase != GEPRHS->getOperand(0)) {
+      bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
+      if (IndicesTheSame)
+        for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
+          if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
+            IndicesTheSame = false;
+            break;
+          }
+
+      // If all indices are the same, just compare the base pointers.
+      if (IndicesTheSame)
+        return new SetCondInst(Cond, GEPLHS->getOperand(0),
+                               GEPRHS->getOperand(0));
+
+      // Otherwise, the base pointers are different and the indices are
+      // different, bail out.
       return 0;
+    }
 
     // If one of the GEPs has all zero indices, recurse.
     bool AllZeros = true;