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[InstSimplify] Support constant folding to vector of pointers

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ConstantFolding crashes when trying to InstSimplify the following load:

@a = private unnamed_addr constant %mst {
     i8* inttoptr (i64 -1 to i8*),
     i8* inttoptr (i64 -1 to i8*)
}, align 8

%x = load <2 x i8*>* bitcast (%mst* @a to <2 x i8*>*), align 8

This patch fix this by adding support to this type of folding:

%x = load <2 x i8*>* bitcast (%mst* @a to <2 x i8*>*), align 8
==> gets folded to:
  %x = <2 x i8*> <i8* inttoptr (i64 -1 to i8*), i8* inttoptr (i64 -1 to i8*)>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220380 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bruno Cardoso Lopes
2014-10-22 12:18:48 +00:00
parent 8546076401
commit 5165ff9878
2 changed files with 47 additions and 2 deletions
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14
lib/Analysis/ConstantFolding.cpp
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@@ -55,7 +55,8 @@ static Constant *FoldBitCast(Constant *C, Type *DestTy,
// Catch the obvious splat cases.
if (C->isNullValue() && !DestTy->isX86_MMXTy())
return Constant::getNullValue(DestTy);
if (C->isAllOnesValue() && !DestTy->isX86_MMXTy())
if (C->isAllOnesValue() && !DestTy->isX86_MMXTy() &&
!DestTy->isPtrOrPtrVectorTy()) // Don't get ones for ptr types!
return Constant::getAllOnesValue(DestTy);
// Handle a vector->integer cast.
@@ -197,7 +198,7 @@ static Constant *FoldBitCast(Constant *C, Type *DestTy,
// Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
unsigned Ratio = NumDstElt/NumSrcElt;
unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits();
unsigned DstBitSize = TD.getTypeSizeInBits(DstEltTy);
// Loop over each source value, expanding into multiple results.
for (unsigned i = 0; i != NumSrcElt; ++i) {
@@ -213,6 +214,15 @@ static Constant *FoldBitCast(Constant *C, Type *DestTy,
ConstantInt::get(Src->getType(), ShiftAmt));
ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
// Truncate the element to an integer with the same pointer size and
// convert the element back to a pointer using a inttoptr.
if (DstEltTy->isPointerTy()) {
IntegerType *DstIntTy = Type::getIntNTy(C->getContext(), DstBitSize);
Constant *CE = ConstantExpr::getTrunc(Elt, DstIntTy);
Result.push_back(ConstantExpr::getIntToPtr(CE, DstEltTy));
continue;
}
// Truncate and remember this piece.
Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
}