Holding my nose and moving the accumulation routine to GEPOperator

instead of the instruction. I've left a forwarding wrapper for the
instruction so users with the instruction don't need to create
a GEPOperator themselves.

This lets us remove the copy of this code in instsimplify.

I've looked at most of the other copies of similar code, and this is the
only one I've found that is actually exactly the same. The one in
InlineCost is very close, but it requires re-mapping non-constant
indices through the cost analysis value simplification map. I could add
direct support for this to the generic routine, but it seems overly
specific.

llvm-svn: 169853

1 files changed, 1 insertions, 34 deletions

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 00689475a41..dd109bde3ac 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -657,39 +657,6 @@ Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
                            RecursionLimit);
 }
 
-/// \brief Accumulate the constant integer offset a GEP represents.
-///
-/// Given a getelementptr instruction/constantexpr, accumulate the constant
-/// offset from the base pointer into the provided APInt 'Offset'. Returns true
-/// if the GEP has all-constant indices. Returns false if any non-constant
-/// index is encountered leaving the 'Offset' in an undefined state. The
-/// 'Offset' APInt must be the bitwidth of the target's pointer size.
-static bool accumulateGEPOffset(const DataLayout &TD, GEPOperator *GEP,
-                                APInt &Offset) {
-  unsigned IntPtrWidth = TD.getPointerSizeInBits();
-  assert(IntPtrWidth == Offset.getBitWidth());
-
-  gep_type_iterator GTI = gep_type_begin(GEP);
-  for (User::op_iterator I = GEP->op_begin() + 1, E = GEP->op_end(); I != E;
-       ++I, ++GTI) {
-    ConstantInt *OpC = dyn_cast<ConstantInt>(*I);
-    if (!OpC) return false;
-    if (OpC->isZero()) continue;
-
-    // Handle a struct index, which adds its field offset to the pointer.
-    if (StructType *STy = dyn_cast<StructType>(*GTI)) {
-      unsigned ElementIdx = OpC->getZExtValue();
-      const StructLayout *SL = TD.getStructLayout(STy);
-      Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
-      continue;
-    }
-
-    APInt TypeSize(IntPtrWidth, TD.getTypeAllocSize(GTI.getIndexedType()));
-    Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
-  }
-  return true;
-}
-
 /// \brief Compute the base pointer and cumulative constant offsets for V.
 ///
 /// This strips all constant offsets off of V, leaving it the base pointer, and
@@ -710,7 +677,7 @@ static Constant *stripAndComputeConstantOffsets(const DataLayout &TD,
   Visited.insert(V);
   do {
     if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
-      if (!GEP->isInBounds() || !accumulateGEPOffset(TD, GEP, Offset))
+      if (!GEP->isInBounds() || !GEP->accumulateConstantOffset(TD, Offset))
         break;
       V = GEP->getPointerOperand();
     } else if (Operator::getOpcode(V) == Instruction::BitCast) {