Don't duplicate the work done by a gep into a "bitcast" if the gep has

more than one use.

Fixes PR10322.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134883 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index 92c10f5546..278016c6ec 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -785,6 +785,14 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
   // getelementptr instructions into a single instruction.
   //
   if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) {
+
+    // If this GEP has only 0 indices, it is the same pointer as
+    // Src. If Src is not a trivial GEP too, don't combine
+    // the indices.
+    if (GEP.hasAllZeroIndices() && !Src->hasAllZeroIndices() &&
+        !Src->hasOneUse())
+      return 0;
+
     // Note that if our source is a gep chain itself that we wait for that
     // chain to be resolved before we perform this transformation.  This
     // avoids us creating a TON of code in some cases.