Commit da2fc4c9 authored by Hans Wennborg's avatar Hans Wennborg
Browse files

Merging r229352: 

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r229352 | majnemer | 2015-02-15 20:02:09 -0800 (Sun, 15 Feb 2015) | 8 lines

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

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.
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llvm-svn: 229588
parent a2c28378

llvm/include/llvm/IR/Constants.h

+6 −0
Original line number Diff line number Diff line
@@ -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:

llvm/lib/IR/Constants.cpp

+19 −4
Original line number Diff line number Diff line
@@ -258,10 +258,10 @@ Constant *Constant::getAggregateElement(unsigned Elt) const { 
    return Elt < CV->getNumOperands() ? CV->getOperand(Elt) : nullptr;



  if (const ConstantAggregateZero *CAZ = dyn_cast<ConstantAggregateZero>(this))

    return CAZ->getElementValue(Elt);

    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

llvm/test/Transforms/InstSimplify/load.ll

0 → 100644
+19 −0
Original line number Diff line number Diff line 
; 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

}