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IR: Properly return nullptr when getAggregateElement is out-of-bounds

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We didn't properly handle the out-of-bounds case for
ConstantAggregateZero and UndefValue.  This would manifest as a crash
when the constant folder was asked to fold a load of a constant global
whose struct type has no operands.

This fixes PR22595.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229352 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2015-02-16 04:02:09 +00:00
parent 36fcfaf54e
commit 6de0a12927
3 changed files with 44 additions and 4 deletions
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6
include/llvm/IR/Constants.h
View File

@ -325,6 +325,9 @@ public:
/// index.
Constant *getElementValue(unsigned Idx) const;
/// \brief Return the number of elements in the array, vector, or struct.
unsigned getNumElements() const;
/// Methods for support type inquiry through isa, cast, and dyn_cast:
///
static bool classof(const Value *V) {
@ -1196,6 +1199,9 @@ public:
/// index.
UndefValue *getElementValue(unsigned Idx) const;
/// \brief Return the number of elements in the array, vector, or struct.
unsigned getNumElements() const;
void destroyConstant() override;
/// Methods for support type inquiry through isa, cast, and dyn_cast:

23
lib/IR/Constants.cpp
View File

@ -257,11 +257,11 @@ Constant *Constant::getAggregateElement(unsigned Elt) const {
if (const ConstantVector *CV = dyn_cast<ConstantVector>(this))
return Elt < CV->getNumOperands() ? CV->getOperand(Elt) : nullptr;
if (const ConstantAggregateZero *CAZ =dyn_cast<ConstantAggregateZero>(this))
return CAZ->getElementValue(Elt);
if (const ConstantAggregateZero *CAZ = dyn_cast<ConstantAggregateZero>(this))
return Elt < CAZ->getNumElements() ? CAZ->getElementValue(Elt) : nullptr;
if (const UndefValue *UV = dyn_cast<UndefValue>(this))
return UV->getElementValue(Elt);
return Elt < UV->getNumElements() ? UV->getElementValue(Elt) : nullptr;
if (const ConstantDataSequential *CDS =dyn_cast<ConstantDataSequential>(this))
return Elt < CDS->getNumElements() ? CDS->getElementAsConstant(Elt)
@ -764,6 +764,14 @@ Constant *ConstantAggregateZero::getElementValue(unsigned Idx) const {
return getStructElement(Idx);
}
unsigned ConstantAggregateZero::getNumElements() const {
const Type *Ty = getType();
if (const auto *AT = dyn_cast<ArrayType>(Ty))
return AT->getNumElements();
if (const auto *VT = dyn_cast<VectorType>(Ty))
return VT->getNumElements();
return Ty->getStructNumElements();
}
//===----------------------------------------------------------------------===//
// UndefValue Implementation
@ -797,7 +805,14 @@ UndefValue *UndefValue::getElementValue(unsigned Idx) const {
return getStructElement(Idx);
}
unsigned UndefValue::getNumElements() const {
const Type *Ty = getType();
if (const auto *AT = dyn_cast<ArrayType>(Ty))
return AT->getNumElements();
if (const auto *VT = dyn_cast<VectorType>(Ty))
return VT->getNumElements();
return Ty->getStructNumElements();
}
//===----------------------------------------------------------------------===//
// ConstantXXX Classes

19
test/Transforms/InstSimplify/load.ll Normal file
View File

@ -0,0 +1,19 @@
; RUN: opt < %s -instsimplify -S | FileCheck %s
@zeroinit = constant {} zeroinitializer
@undef = constant {} undef
define i32 @crash_on_zeroinit() {
; CHECK-LABEL: @crash_on_zeroinit
; CHECK: ret i32 0
%load = load i32* bitcast ({}* @zeroinit to i32*)
ret i32 %load
}
define i32 @crash_on_undef() {
; CHECK-LABEL: @crash_on_undef
; CHECK: ret i32 undef
%load = load i32* bitcast ({}* @undef to i32*)
ret i32 %load
}