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[ValueTracking] Return poison for zero-sized types #122647

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Merged
merged 2 commits into from
Jan 16, 2025
Merged

[ValueTracking] Return poison for zero-sized types #122647

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18069a2
[ValueTracking] Return `poison` for zero-sized types
pedroclobo Jan 12, 2025
ed8c894
[ValueTracking] Don't convert `poison` to `undef`
pedroclobo Jan 12, 2025
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18 changes: 9 additions & 9 deletions llvm/lib/Analysis/ValueTracking.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6187,14 +6187,14 @@ Value *llvm::isBytewiseValue(Value *V, const DataLayout &DL) {

LLVMContext &Ctx = V->getContext();

// Undef don't care.
auto *UndefInt8 = UndefValue::get(Type::getInt8Ty(Ctx));
// Poison don't care.
auto *PoisonInt8 = PoisonValue::get(Type::getInt8Ty(Ctx));
if (isa<UndefValue>(V))
return UndefInt8;
return PoisonInt8;

// Return Undef for zero-sized type.
// Return poison for zero-sized type.
if (DL.getTypeStoreSize(V->getType()).isZero())
return UndefInt8;
return PoisonInt8;

Constant *C = dyn_cast<Constant>(V);
if (!C) {
Expand Down Expand Up @@ -6252,23 +6252,23 @@ Value *llvm::isBytewiseValue(Value *V, const DataLayout &DL) {
return LHS;
if (!LHS || !RHS)
return nullptr;
if (LHS == UndefInt8)
if (LHS == PoisonInt8)
return RHS;
if (RHS == UndefInt8)
if (RHS == PoisonInt8)
return LHS;
return nullptr;
};

if (ConstantDataSequential *CA = dyn_cast<ConstantDataSequential>(C)) {
Value *Val = UndefInt8;
Value *Val = PoisonInt8;
for (unsigned I = 0, E = CA->getNumElements(); I != E; ++I)
if (!(Val = Merge(Val, isBytewiseValue(CA->getElementAsConstant(I), DL))))
return nullptr;
return Val;
}

if (isa<ConstantAggregate>(C)) {
Value *Val = UndefInt8;
Value *Val = PoisonInt8;
for (Value *Op : C->operands())
if (!(Val = Merge(Val, isBytewiseValue(Op, DL))))
return nullptr;
Expand Down
6 changes: 3 additions & 3 deletions llvm/test/Transforms/MemCpyOpt/fca2memcpy.ll
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Expand Up @@ -81,7 +81,7 @@ define void @addrproducer(ptr %src, ptr %dst) {
; CHECK-LABEL: @addrproducer(
; CHECK-NEXT: [[DST2:%.*]] = getelementptr [[S:%.*]], ptr [[DST]], i64 1
; CHECK-NEXT: call void @llvm.memmove.p0.p0.i64(ptr align 8 [[DST2]], ptr align 8 [[SRC:%.*]], i64 16, i1 false)
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 8 [[DST:%.*]], i8 undef, i64 16, i1 false)
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 8 [[DST:%.*]], i8 poison, i64 16, i1 false)
; CHECK-NEXT: ret void
;
%1 = load %S, ptr %src
Expand All @@ -94,7 +94,7 @@ define void @addrproducer(ptr %src, ptr %dst) {
define void @aliasaddrproducer(ptr %src, ptr %dst, ptr %dstidptr) {
; CHECK-LABEL: @aliasaddrproducer(
; CHECK-NEXT: [[TMP1:%.*]] = load [[S:%.*]], ptr [[SRC:%.*]], align 8
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 8 [[DST:%.*]], i8 undef, i64 16, i1 false)
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 8 [[DST:%.*]], i8 poison, i64 16, i1 false)
; CHECK-NEXT: [[DSTINDEX:%.*]] = load i32, ptr [[DSTIDPTR:%.*]], align 4
; CHECK-NEXT: [[DST2:%.*]] = getelementptr [[S]], ptr [[DST]], i32 [[DSTINDEX]]
; CHECK-NEXT: store [[S]] [[TMP1]], ptr [[DST2]], align 8
Expand All @@ -114,7 +114,7 @@ define void @noaliasaddrproducer(ptr %src, ptr noalias %dst, ptr noalias %dstidp
; CHECK-NEXT: [[DSTINDEX:%.*]] = or i32 [[TMP2]], 1
; CHECK-NEXT: [[DST2:%.*]] = getelementptr [[S:%.*]], ptr [[DST:%.*]], i32 [[DSTINDEX]]
; CHECK-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 8 [[DST2]], ptr align 8 [[SRC]], i64 16, i1 false)
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 8 [[SRC:%.*]], i8 undef, i64 16, i1 false)
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 8 [[SRC:%.*]], i8 poison, i64 16, i1 false)
; CHECK-NEXT: ret void
;
%1 = load %S, ptr %src
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/Transforms/MemCpyOpt/memcpy-to-memset.ll
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Expand Up @@ -7,7 +7,7 @@ declare void @llvm.memcpy.p0.p0.i64(ptr nocapture, ptr nocapture, i64, i1) nounw
define void @test_undef() nounwind {
; CHECK-LABEL: @test_undef(
; CHECK-NEXT: [[A:%.*]] = alloca i32, align 4
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 4 [[A]], i8 undef, i64 4, i1 false)
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 4 [[A]], i8 poison, i64 4, i1 false)
; CHECK-NEXT: ret void
;
%a = alloca i32, align 4
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/Transforms/MemCpyOpt/store-to-memset-is-nonzero-type.ll
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Expand Up @@ -5,7 +5,7 @@

define void @array_zero(ptr %p) {
; CHECK-LABEL: @array_zero(
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 1 [[P:%.*]], i8 undef, i64 0, i1 false)
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 1 [[P:%.*]], i8 poison, i64 0, i1 false)
; CHECK-NEXT: ret void
;
store [0 x i8] zeroinitializer, ptr %p
Expand All @@ -25,7 +25,7 @@ define void @array_nonzero(ptr %p) {

define void @struct_zero(ptr %p) {
; CHECK-LABEL: @struct_zero(
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 1 [[P:%.*]], i8 undef, i64 0, i1 false)
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 1 [[P:%.*]], i8 poison, i64 0, i1 false)
; CHECK-NEXT: ret void
;
store { } zeroinitializer, ptr %p
Expand Down
52 changes: 26 additions & 26 deletions llvm/unittests/Analysis/ValueTrackingTest.cpp
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Expand Up @@ -2769,8 +2769,8 @@ const std::pair<const char *, const char *> IsBytewiseValueTests[] = {
"ptr null",
},
{
"i8 undef",
"ptr undef",
"i8 poison",
"ptr poison",
},
{
"i8 0",
Expand All @@ -2789,8 +2789,8 @@ const std::pair<const char *, const char *> IsBytewiseValueTests[] = {
"i8 -1",
},
{
"i8 undef",
"i16 undef",
"i8 poison",
"i16 poison",
},
{
"i8 0",
Expand Down Expand Up @@ -2869,28 +2869,28 @@ const std::pair<const char *, const char *> IsBytewiseValueTests[] = {
"ptr inttoptr (i96 -1 to ptr)",
},
{
"i8 undef",
"i8 poison",
"[0 x i8] zeroinitializer",
},
{
"i8 undef",
"[0 x i8] undef",
"i8 poison",
"[0 x i8] poison",
},
{
"i8 undef",
"i8 poison",
"[5 x [0 x i8]] zeroinitializer",
},
{
"i8 undef",
"[5 x [0 x i8]] undef",
"i8 poison",
"[5 x [0 x i8]] poison",
},
{
"i8 0",
"[6 x i8] zeroinitializer",
},
{
"i8 undef",
"[6 x i8] undef",
"i8 poison",
"[6 x i8] poison",
},
{
"i8 1",
Expand All @@ -2910,15 +2910,15 @@ const std::pair<const char *, const char *> IsBytewiseValueTests[] = {
},
{
"i8 1",
"[4 x i8] [i8 1, i8 undef, i8 1, i8 1]",
"[4 x i8] [i8 1, i8 poison, i8 1, i8 1]",
},
{
"i8 0",
"<6 x i8> zeroinitializer",
},
{
"i8 undef",
"<6 x i8> undef",
"i8 poison",
"<6 x i8> poison",
},
{
"i8 1",
Expand All @@ -2938,15 +2938,15 @@ const std::pair<const char *, const char *> IsBytewiseValueTests[] = {
},
{
"i8 5",
"<2 x i8> < i8 5, i8 undef >",
"<2 x i8> < i8 5, i8 poison >",
},
{
"i8 0",
"[2 x [2 x i16]] zeroinitializer",
},
{
"i8 undef",
"[2 x [2 x i16]] undef",
"i8 poison",
"[2 x [2 x i16]] poison",
},
{
"i8 -86",
Expand All @@ -2959,28 +2959,28 @@ const std::pair<const char *, const char *> IsBytewiseValueTests[] = {
"[2 x i16] [i16 -21836, i16 -21846]]",
},
{
"i8 undef",
"i8 poison",
"{ } zeroinitializer",
},
{
"i8 undef",
"{ } undef",
"i8 poison",
"{ } poison",
},
{
"i8 undef",
"i8 poison",
"{ {}, {} } zeroinitializer",
},
{
"i8 undef",
"{ {}, {} } undef",
"i8 poison",
"{ {}, {} } poison",
},
{
"i8 0",
"{i8, i64, ptr} zeroinitializer",
},
{
"i8 undef",
"{i8, i64, ptr} undef",
"i8 poison",
"{i8, i64, ptr} poison",
},
{
"i8 -86",
Expand Down
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