6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-02-04 07:32:13 +00:00
Code Issues Projects Releases Wiki Activity

When determining the new index for an insertelement, we may not assume that an

Browse Source 
index greater than the size of the vector is invalid. The shuffle may be
shrinking the size of the vector. Fixes a crash!

Also drop the maximum recursion depth of the safety check for this
optimization to five.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183080 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2013-06-01 20:51:31 +00:00
parent a0b34d6c4a
commit e4546cb71e
2 changed files with 20 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
lib/Transforms/InstCombine/InstCombineVectorOps.cpp
View File

@ -497,7 +497,7 @@ Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
/// Return true if we can evaluate the specified expression tree if the vector
/// elements were shuffled in a different order.
static bool CanEvaluateShuffled(Value *V, ArrayRef<int> Mask,
unsigned Depth = 100) {
unsigned Depth = 5) {
// We can always reorder the elements of a constant.
if (isa<Constant>(V))
return true;
@ -718,19 +718,21 @@ InstCombiner::EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask) {
}
case Instruction::InsertElement: {
int Element = cast<ConstantInt>(I->getOperand(2))->getLimitedValue();
if (Element < 0 || Element >= (int)Mask.size()) {
// Such instructions are valid and exhibit undefined behaviour.
return UndefValue::get(I->getType());
}
// The insertelement was inserting at Element. Figure out which element
// that becomes after shuffling. The answer is guaranteed to be unique
// by CanEvaluateShuffled.
bool Found = false;
int Index = 0;
for (int e = Mask.size(); Index != e; ++Index)
if (Mask[Index] == Element)
for (int e = Mask.size(); Index != e; ++Index) {
if (Mask[Index] == Element) {
Found = true;
break;
}
}
if (!Found)
return UndefValue::get(I->getType());
Value *V = EvaluateInDifferentElementOrder(I->getOperand(0), Mask);
return InsertElementInst::Create(V, I->getOperand(1),
Builder->getInt32(Index), "", I);

11
test/Transforms/InstCombine/vec_shuffle.ll
View File

@ -174,3 +174,14 @@ define <2 x i8> @test13b(i8 %x) {
%B = shufflevector <2 x i8> %A, <2 x i8> undef, <2 x i32> <i32 undef, i32 0>
ret <2 x i8> %B
}
define <2 x i8> @test13c(i8 %x1, i8 %x2) {
; CHECK: @test13c
; CHECK-NEXT: insertelement <2 x i8> {{.*}}, i32 0
; CHECK-NEXT: insertelement <2 x i8> {{.*}}, i32 1
; CHECK-NEXT: ret
%A = insertelement <4 x i8> undef, i8 %x1, i32 0
%B = insertelement <4 x i8> %A, i8 %x2, i32 2
%C = shufflevector <4 x i8> %B, <4 x i8> undef, <2 x i32> <i32 0, i32 2>
ret <2 x i8> %C
}