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[ConstantFold] Return the correct type when folding a GEP with vector indices.

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As Eli pointed out (and I got wrong in the first place), langref says: "The
getelementptr returns a vector of pointers, instead of a single address, when one
or more of its arguments is a vector. In such cases, all vector arguments should
have the same number of elements, and every scalar argument will be effectively
broadcast into a vector during address calculation."

Costantfold for gep doesn't really take in account this paragraph, returning a
pointer instead of a vector of pointer which triggers an assertion in RAUW,
as we're trying to replace values with mistmatching types.

Differential Revision:  https://reviews.llvm.org/D37928

llvm-svn: 313394
This commit is contained in:
Davide Italiano 2017-09-15 20:53:05 +00:00
parent 980730befa
commit d75c714e9b
2 changed files with 23 additions and 1 deletions
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13
lib/IR/ConstantFold.cpp
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@ -2062,9 +2062,20 @@ Constant *llvm::ConstantFoldGetElementPtr(Type *PointeeTy, Constant *C,
Type *Ty = GetElementPtrInst::getIndexedType(PointeeTy, Idxs);
assert(Ty && "Invalid indices for GEP!");
Type *OrigGEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
Type *GEPTy = PointerType::get(Ty, PtrTy->getAddressSpace());
if (VectorType *VT = dyn_cast<VectorType>(C->getType()))
GEPTy = VectorType::get(GEPTy, VT->getNumElements());
GEPTy = VectorType::get(OrigGEPTy, VT->getNumElements());
// The GEP returns a vector of pointers when one of more of
// its arguments is a vector.
for (unsigned i = 0, e = Idxs.size(); i != e; ++i) {
if (auto *VT = dyn_cast<VectorType>(Idxs[i]->getType())) {
GEPTy = VectorType::get(OrigGEPTy, VT->getNumElements());
break;
}
}
return Constant::getNullValue(GEPTy);
}
}

11
test/Transforms/InstCombine/pr34627.ll Normal file
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@ -0,0 +1,11 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -instcombine %s |FileCheck %s
define <2 x i16> @patatino() {
; CHECK-LABEL: @patatino(
; CHECK-NEXT: ret <2 x i16> zeroinitializer
;
%tmp2 = getelementptr inbounds [1 x i16], [1 x i16]* null, i16 0, <2 x i16> undef
%tmp3 = ptrtoint <2 x i16*> %tmp2 to <2 x i16>
ret <2 x i16> %tmp3
}