@@ -1432,16 +1432,64 @@ static Constant *foldGEPOfGEP(GEPOperator *GEP, Type *PointeeTy, bool InBounds,
14321432 if (GEP->getInRange ())
14331433 return nullptr ;
14341434
1435- // Only handle simple case with leading zero index. We cannot perform an
1436- // actual addition as we don't know the correct index type size to use.
14371435 Constant *Idx0 = cast<Constant>(Idxs[0 ]);
1438- if (!Idx0->isNullValue ())
1436+ if (Idx0->isNullValue ()) {
1437+ // Handle the simple case of a zero index.
1438+ SmallVector<Value*, 16 > NewIndices;
1439+ NewIndices.reserve (Idxs.size () + GEP->getNumIndices ());
1440+ NewIndices.append (GEP->idx_begin (), GEP->idx_end ());
1441+ NewIndices.append (Idxs.begin () + 1 , Idxs.end ());
1442+ return ConstantExpr::getGetElementPtr (
1443+ GEP->getSourceElementType (), cast<Constant>(GEP->getPointerOperand ()),
1444+ NewIndices, InBounds && GEP->isInBounds ());
1445+ }
1446+
1447+ gep_type_iterator LastI = gep_type_end (GEP);
1448+ for (gep_type_iterator I = gep_type_begin (GEP), E = gep_type_end (GEP);
1449+ I != E; ++I)
1450+ LastI = I;
1451+
1452+ // We can't combine GEPs if the last index is a struct type.
1453+ if (!LastI.isSequential ())
1454+ return nullptr ;
1455+ // We could perform the transform with non-constant index, but prefer leaving
1456+ // it as GEP of GEP rather than GEP of add for now.
1457+ ConstantInt *CI = dyn_cast<ConstantInt>(Idx0);
1458+ if (!CI)
1459+ return nullptr ;
1460+
1461+ // TODO: This code may be extended to handle vectors as well.
1462+ auto *LastIdx = cast<Constant>(GEP->getOperand (GEP->getNumOperands ()-1 ));
1463+ Type *LastIdxTy = LastIdx->getType ();
1464+ if (LastIdxTy->isVectorTy ())
14391465 return nullptr ;
14401466
14411467 SmallVector<Value*, 16 > NewIndices;
14421468 NewIndices.reserve (Idxs.size () + GEP->getNumIndices ());
1443- NewIndices.append (GEP->idx_begin (), GEP->idx_end ());
1469+ NewIndices.append (GEP->idx_begin (), GEP->idx_end () - 1 );
1470+
1471+ // Add the last index of the source with the first index of the new GEP.
1472+ // Make sure to handle the case when they are actually different types.
1473+ if (LastIdxTy != Idx0->getType ()) {
1474+ unsigned CommonExtendedWidth =
1475+ std::max (LastIdxTy->getIntegerBitWidth (),
1476+ Idx0->getType ()->getIntegerBitWidth ());
1477+ CommonExtendedWidth = std::max (CommonExtendedWidth, 64U );
1478+
1479+ Type *CommonTy =
1480+ Type::getIntNTy (LastIdxTy->getContext (), CommonExtendedWidth);
1481+ if (Idx0->getType () != CommonTy)
1482+ Idx0 = ConstantFoldCastInstruction (Instruction::SExt, Idx0, CommonTy);
1483+ if (LastIdx->getType () != CommonTy)
1484+ LastIdx =
1485+ ConstantFoldCastInstruction (Instruction::SExt, LastIdx, CommonTy);
1486+ if (!Idx0 || !LastIdx)
1487+ return nullptr ;
1488+ }
1489+
1490+ NewIndices.push_back (ConstantExpr::get (Instruction::Add, Idx0, LastIdx));
14441491 NewIndices.append (Idxs.begin () + 1 , Idxs.end ());
1492+
14451493 return ConstantExpr::getGetElementPtr (
14461494 GEP->getSourceElementType (), cast<Constant>(GEP->getPointerOperand ()),
14471495 NewIndices, InBounds && GEP->isInBounds ());
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