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Fix isEliminableCastPair to work correctly in the presence of pointers

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with different sizes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167018 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2012-10-30 16:03:32 +00:00
parent 92b469971e
commit 446cf94cdb
5 changed files with 61 additions and 13 deletions
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4
include/llvm/InstrTypes.h
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@ -594,7 +594,9 @@ public:
Type *SrcTy, ///< SrcTy of 1st cast
Type *MidTy, ///< DstTy of 1st cast & SrcTy of 2nd cast
Type *DstTy, ///< DstTy of 2nd cast
Type *IntPtrTy ///< Integer type corresponding to Ptr types, or null
Type *SrcIntPtrTy, ///< Integer type corresponding to Ptr SrcTy, or null
Type *MidIntPtrTy, ///< Integer type corresponding to Ptr MidTy, or null
Type *DstIntPtrTy ///< Integer type corresponding to Ptr DstTy, or null
);
/// @brief Return the opcode of this CastInst

16
lib/Transforms/InstCombine/InstCombineCasts.cpp
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@ -238,16 +238,20 @@ isEliminableCastPair(
// Get the opcodes of the two Cast instructions
Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
Instruction::CastOps secondOp = Instruction::CastOps(opcode);
Type *SrcIntPtrTy = TD && SrcTy->isPtrOrPtrVectorTy() ?
TD->getIntPtrType(SrcTy) : 0;
Type *MidIntPtrTy = TD && MidTy->isPtrOrPtrVectorTy() ?
TD->getIntPtrType(MidTy) : 0;
Type *DstIntPtrTy = TD && DstTy->isPtrOrPtrVectorTy() ?
TD->getIntPtrType(DstTy) : 0;
unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
DstTy,
TD ? TD->getIntPtrType(DstTy) : 0);
DstTy, SrcIntPtrTy, MidIntPtrTy,
DstIntPtrTy);
// We don't want to form an inttoptr or ptrtoint that converts to an integer
// type that differs from the pointer size.
if ((Res == Instruction::IntToPtr &&
(!TD || SrcTy != TD->getIntPtrType(DstTy))) ||
(Res == Instruction::PtrToInt &&
(!TD || DstTy != TD->getIntPtrType(SrcTy))))
if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) ||
(Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy))
Res = 0;
return Instruction::CastOps(Res);

6
lib/VMCore/ConstantFold.cpp
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@ -87,9 +87,13 @@ foldConstantCastPair(
Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
Instruction::CastOps secondOp = Instruction::CastOps(opc);
// Assume that pointers are never more than 64 bits wide.
IntegerType *FakeIntPtrTy = Type::getInt64Ty(DstTy->getContext());
// Let CastInst::isEliminableCastPair do the heavy lifting.
return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
Type::getInt64Ty(DstTy->getContext()));
FakeIntPtrTy, FakeIntPtrTy,
FakeIntPtrTy);
}
static Constant *FoldBitCast(Constant *V, Type *DestTy) {

11
lib/VMCore/Instructions.cpp
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@ -2141,7 +2141,8 @@ bool CastInst::isNoopCast(const DataLayout &DL) const {
/// If no such cast is permited, the function returns 0.
unsigned CastInst::isEliminableCastPair(
Instruction::CastOps firstOp, Instruction::CastOps secondOp,
Type *SrcTy, Type *MidTy, Type *DstTy, Type *IntPtrTy) {
Type *SrcTy, Type *MidTy, Type *DstTy, Type *SrcIntPtrTy, Type *MidIntPtrTy,
Type *DstIntPtrTy) {
// Define the 144 possibilities for these two cast instructions. The values
// in this matrix determine what to do in a given situation and select the
// case in the switch below. The rows correspond to firstOp, the columns
@ -2244,9 +2245,9 @@ unsigned CastInst::isEliminableCastPair(
return 0;
case 7: {
// ptrtoint, inttoptr -> bitcast (ptr -> ptr) if int size is >= ptr size
if (!IntPtrTy)
if (!SrcIntPtrTy || DstIntPtrTy != SrcIntPtrTy)
return 0;
unsigned PtrSize = IntPtrTy->getScalarSizeInBits();
unsigned PtrSize = SrcIntPtrTy->getScalarSizeInBits();
unsigned MidSize = MidTy->getScalarSizeInBits();
if (MidSize >= PtrSize)
return Instruction::BitCast;
@ -2285,9 +2286,9 @@ unsigned CastInst::isEliminableCastPair(
return 0;
case 13: {
// inttoptr, ptrtoint -> bitcast if SrcSize<=PtrSize and SrcSize==DstSize
if (!IntPtrTy)
if (!MidIntPtrTy)
return 0;
unsigned PtrSize = IntPtrTy->getScalarSizeInBits();
unsigned PtrSize = MidIntPtrTy->getScalarSizeInBits();
unsigned SrcSize = SrcTy->getScalarSizeInBits();
unsigned DstSize = DstTy->getScalarSizeInBits();
if (SrcSize <= PtrSize && SrcSize == DstSize)

37
unittests/VMCore/InstructionsTest.cpp
View File

@ -243,5 +243,42 @@ TEST(InstructionsTest, FPMathOperator) {
delete I;
}
TEST(InstructionsTest, isEliminableCastPair) {
LLVMContext &C(getGlobalContext());
Type* Int32Ty = Type::getInt32Ty(C);
Type* Int64Ty = Type::getInt64Ty(C);
Type* Int64PtrTy = Type::getInt64PtrTy(C);
// Source and destination pointers have same size -> bitcast.
EXPECT_EQ(CastInst::isEliminableCastPair(CastInst::PtrToInt,
CastInst::IntToPtr,
Int64PtrTy, Int64Ty, Int64PtrTy,
Int32Ty, 0, Int32Ty),
CastInst::BitCast);
// Source and destination pointers have different sizes -> fail.
EXPECT_EQ(CastInst::isEliminableCastPair(CastInst::PtrToInt,
CastInst::IntToPtr,
Int64PtrTy, Int64Ty, Int64PtrTy,
Int32Ty, 0, Int64Ty),
0U);
// Middle pointer big enough -> bitcast.
EXPECT_EQ(CastInst::isEliminableCastPair(CastInst::IntToPtr,
CastInst::PtrToInt,
Int64Ty, Int64PtrTy, Int64Ty,
0, Int64Ty, 0),
CastInst::BitCast);
// Middle pointer too small -> fail.
EXPECT_EQ(CastInst::isEliminableCastPair(CastInst::IntToPtr,
CastInst::PtrToInt,
Int64Ty, Int64PtrTy, Int64Ty,
0, Int32Ty, 0),
0U);
}
} // end anonymous namespace
} // end namespace llvm