forked from OSchip/llvm-project
[Attributor] Deduce dereferenceable based on accessed bytes map
Summary:
This patch introduces the deduction based on load/store instructions whose pointer operand is a non-inbounds GEP instruction.
For example if we have,
```
void f(int *u){
u[0] = 0;
u[1] = 1;
u[2] = 2;
}
```
then u must be dereferenceable(12).
This patch is inspired by D64258
Reviewers: jdoerfert, spatel, hfinkel, RKSimon, sstefan1, xbolva00, dtemirbulatov
Reviewed By: jdoerfert
Subscribers: jfb, lebedev.ri, xbolva00, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70714
This commit is contained in:
Hideto Ueno
parent
dfedae5001
commit
6c742fdbf4
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@ -1820,6 +1820,42 @@ struct DerefState : AbstractState {
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/// State representing for dereferenceable bytes.
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IncIntegerState<> DerefBytesState;
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/// Map representing for accessed memory offsets and sizes.
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/// A key is Offset and a value is size.
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/// If there is a load/store instruction something like,
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/// p[offset] = v;
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/// (offset, sizeof(v)) will be inserted to this map.
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/// std::map is used because we want to iterate keys in ascending order.
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std::map<int64_t, uint64_t> AccessedBytesMap;
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/// Helper function to calculate dereferenceable bytes from current known
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/// bytes and accessed bytes.
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///
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/// int f(int *A){
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/// *A = 0;
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/// *(A+2) = 2;
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/// *(A+1) = 1;
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/// *(A+10) = 10;
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/// }
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/// ```
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/// In that case, AccessedBytesMap is `{0:4, 4:4, 8:4, 40:4}`.
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/// AccessedBytesMap is std::map so it is iterated in accending order on
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/// key(Offset). So KnownBytes will be updated like this: |Access | KnownBytes
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/// |(0, 4)| 0 -> 4
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/// |(4, 4)| 4 -> 8
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/// |(8, 4)| 8 -> 12
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/// |(40, 4) | 12 (break)
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void computeKnownDerefBytesFromAccessedMap() {
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int64_t KnownBytes = DerefBytesState.getKnown();
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for (auto &Access : AccessedBytesMap) {
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if (KnownBytes < Access.first)
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break;
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KnownBytes = std::max(KnownBytes, Access.first + (int64_t)Access.second);
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}
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DerefBytesState.takeKnownMaximum(KnownBytes);
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}
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/// State representing that whether the value is globaly dereferenceable.
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BooleanState GlobalState;
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@ -1849,6 +1885,9 @@ struct DerefState : AbstractState {
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/// Update known dereferenceable bytes.
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void takeKnownDerefBytesMaximum(uint64_t Bytes) {
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DerefBytesState.takeKnownMaximum(Bytes);
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// Known bytes might increase.
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computeKnownDerefBytesFromAccessedMap();
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}
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/// Update assumed dereferenceable bytes.
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@ -1856,6 +1895,14 @@ struct DerefState : AbstractState {
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DerefBytesState.takeAssumedMinimum(Bytes);
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}
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/// Add accessed bytes to the map.
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void addAccessedBytes(int64_t Offset, uint64_t Size) {
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AccessedBytesMap[Offset] = std::max(AccessedBytesMap[Offset], Size);
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// Known bytes might increase.
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computeKnownDerefBytesFromAccessedMap();
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}
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/// Equality for DerefState.
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bool operator==(const DerefState &R) {
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return this->DerefBytesState == R.DerefBytesState &&
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@ -2961,12 +2961,34 @@ struct AADereferenceableImpl : AADereferenceable {
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const StateType &getState() const override { return *this; }
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/// }
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/// Helper function for collecting accessed bytes in must-be-executed-context
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void addAccessedBytesForUse(Attributor &A, const Use *U,
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const Instruction *I) {
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const Value *UseV = U->get();
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if (!UseV->getType()->isPointerTy())
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return;
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Type *PtrTy = UseV->getType();
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const DataLayout &DL = A.getDataLayout();
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int64_t Offset;
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if (const Value *Base = getBasePointerOfAccessPointerOperand(
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I, Offset, DL, /*AllowNonInbounds*/ true)) {
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if (Base == &getAssociatedValue() && getPointerOperand(I) == UseV) {
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uint64_t Size = DL.getTypeStoreSize(PtrTy->getPointerElementType());
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addAccessedBytes(Offset, Size);
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}
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}
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return;
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}
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/// See AAFromMustBeExecutedContext
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bool followUse(Attributor &A, const Use *U, const Instruction *I) {
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bool IsNonNull = false;
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bool TrackUse = false;
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int64_t DerefBytes = getKnownNonNullAndDerefBytesForUse(
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A, *this, getAssociatedValue(), U, I, IsNonNull, TrackUse);
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addAccessedBytesForUse(A, U, I);
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takeKnownDerefBytesMaximum(DerefBytes);
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return TrackUse;
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}
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@ -48,8 +48,7 @@ define double @PR21780_only_access3_without_inbounds(double* %ptr) {
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define double @PR21780_without_inbounds(double* %ptr) {
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; CHECK-LABEL: @PR21780_without_inbounds(double* %ptr)
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; FIXME: this should be @PR21780_without_inbounds(double* nonnull dereferenceable(32) %ptr)
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; ATTRIBUTOR-LABEL: @PR21780_without_inbounds(double* nocapture nofree nonnull readonly align 8 dereferenceable(8) %ptr)
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; ATTRIBUTOR-LABEL: @PR21780_without_inbounds(double* nocapture nofree nonnull readonly align 8 dereferenceable(32) %ptr)
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%arrayidx1 = getelementptr double, double* %ptr, i64 1
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%arrayidx2 = getelementptr double, double* %ptr, i64 2
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@ -67,6 +66,7 @@ define double @PR21780_without_inbounds(double* %ptr) {
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define void @gep0(i8* %unused, i8* %other, i8* %ptr) {
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; CHECK-LABEL: @gep0(i8* %unused, i8* %other, i8* %ptr)
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; ATTRIBUTOR-LABEL: @gep0(i8* nocapture nofree readnone %unused, i8* nocapture nofree nonnull writeonly dereferenceable(1) %other, i8* nocapture nofree nonnull readonly dereferenceable(3) %ptr)
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%arrayidx0 = getelementptr i8, i8* %ptr, i64 0
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%arrayidx1 = getelementptr i8, i8* %ptr, i64 1
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%arrayidx2 = getelementptr i8, i8* %ptr, i64 2
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@ -82,6 +82,7 @@ define void @gep0(i8* %unused, i8* %other, i8* %ptr) {
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define void @ordering(i8* %ptr1, i32* %ptr2) {
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; CHECK-LABEL: @ordering(i8* %ptr1, i32* %ptr2)
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; ATTRIBUTOR-LABEL: @ordering(i8* nocapture nofree nonnull readonly dereferenceable(3) %ptr1, i32* nocapture nofree nonnull readonly dereferenceable(8) %ptr2)
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%a20 = getelementptr i32, i32* %ptr2, i64 0
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%a12 = getelementptr i8, i8* %ptr1, i64 2
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%t12 = load i8, i8* %a12
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@ -99,6 +100,7 @@ define void @ordering(i8* %ptr1, i32* %ptr2) {
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define void @not_entry_but_guaranteed_to_execute(i8* %ptr) {
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; CHECK-LABEL: @not_entry_but_guaranteed_to_execute(i8* %ptr)
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; ATTRIBUTOR-LABEL: @not_entry_but_guaranteed_to_execute(i8* nocapture nofree nonnull readonly dereferenceable(3) %ptr)
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entry:
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br label %exit
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exit:
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@ -115,6 +117,7 @@ exit:
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define void @not_entry_not_guaranteed_to_execute(i8* %ptr, i1 %cond) {
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; CHECK-LABEL: @not_entry_not_guaranteed_to_execute(i8* %ptr, i1 %cond)
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; ATTRIBUTOR-LABEL: @not_entry_not_guaranteed_to_execute(i8* nocapture nofree readonly %ptr, i1 %cond)
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entry:
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br i1 %cond, label %loads, label %exit
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loads:
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@ -133,6 +136,7 @@ exit:
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define void @partial_in_entry(i16* %ptr, i1 %cond) {
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; CHECK-LABEL: @partial_in_entry(i16* %ptr, i1 %cond)
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; ATTRIBUTOR-LABEL: @partial_in_entry(i16* nocapture nofree nonnull readonly dereferenceable(4) %ptr, i1 %cond)
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entry:
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%arrayidx0 = getelementptr i16, i16* %ptr, i64 0
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%arrayidx1 = getelementptr i16, i16* %ptr, i64 1
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@ -152,6 +156,7 @@ exit:
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define void @volatile_is_not_dereferenceable(i16* %ptr) {
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; CHECK-LABEL: @volatile_is_not_dereferenceable(i16* %ptr)
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; ATTRIBUTOR-LABEL: @volatile_is_not_dereferenceable(i16* nofree %ptr)
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%arrayidx0 = getelementptr i16, i16* %ptr, i64 0
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%arrayidx1 = getelementptr i16, i16* %ptr, i64 1
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%arrayidx2 = getelementptr i16, i16* %ptr, i64 2
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@ -165,6 +170,7 @@ define void @volatile_is_not_dereferenceable(i16* %ptr) {
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define void @atomic_is_alright(i16* %ptr) {
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; CHECK-LABEL: @atomic_is_alright(i16* %ptr)
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; ATTRIBUTOR-LABEL: @atomic_is_alright(i16* nocapture nofree nonnull readonly align 2 dereferenceable(6) %ptr)
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%arrayidx0 = getelementptr i16, i16* %ptr, i64 0
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%arrayidx1 = getelementptr i16, i16* %ptr, i64 1
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%arrayidx2 = getelementptr i16, i16* %ptr, i64 2
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@ -178,6 +184,7 @@ declare void @may_not_return()
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define void @not_guaranteed_to_transfer_execution(i16* %ptr) {
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; CHECK-LABEL: @not_guaranteed_to_transfer_execution(i16* %ptr)
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; ATTRIBUTOR-LABEL: @not_guaranteed_to_transfer_execution(i16* nocapture nonnull readonly dereferenceable(2) %ptr)
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%arrayidx0 = getelementptr i16, i16* %ptr, i64 0
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%arrayidx1 = getelementptr i16, i16* %ptr, i64 1
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%arrayidx2 = getelementptr i16, i16* %ptr, i64 2
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@ -192,6 +199,7 @@ define void @not_guaranteed_to_transfer_execution(i16* %ptr) {
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define void @variable_gep_index(i8* %unused, i8* %ptr, i64 %variable_index) {
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; CHECK-LABEL: @variable_gep_index(i8* %unused, i8* %ptr, i64 %variable_index)
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; ATTRIBUTOR-LABEL: @variable_gep_index(i8* nocapture nofree readnone %unused, i8* nocapture nofree nonnull readonly dereferenceable(1) %ptr, i64 %variable_index)
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%arrayidx1 = getelementptr i8, i8* %ptr, i64 %variable_index
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%arrayidx2 = getelementptr i8, i8* %ptr, i64 2
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%t0 = load i8, i8* %ptr
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@ -204,6 +212,8 @@ define void @variable_gep_index(i8* %unused, i8* %ptr, i64 %variable_index) {
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define void @multi_index_gep(<4 x i8>* %ptr) {
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; CHECK-LABEL: @multi_index_gep(<4 x i8>* %ptr)
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; FIXME: %ptr should be dereferenceable(4)
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; ATTRIBUTOR-LABEL: @multi_index_gep(<4 x i8>* nocapture nofree nonnull readonly dereferenceable(1) %ptr)
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%arrayidx00 = getelementptr <4 x i8>, <4 x i8>* %ptr, i64 0, i64 0
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%t0 = load i8, i8* %arrayidx00
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ret void
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@ -213,6 +223,7 @@ define void @multi_index_gep(<4 x i8>* %ptr) {
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define void @not_byte_multiple(i9* %ptr) {
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; CHECK-LABEL: @not_byte_multiple(i9* %ptr)
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; ATTRIBUTOR-LABEL: @not_byte_multiple(i9* nocapture nofree nonnull readonly dereferenceable(2) %ptr)
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%arrayidx0 = getelementptr i9, i9* %ptr, i64 0
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%t0 = load i9, i9* %arrayidx0
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ret void
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@ -222,6 +233,7 @@ define void @not_byte_multiple(i9* %ptr) {
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define void @no_pointer_deref(i16* %ptr) {
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; CHECK-LABEL: @no_pointer_deref(i16* %ptr)
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; ATTRIBUTOR-LABEL: @no_pointer_deref(i16* nocapture nofree readonly %ptr)
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%arrayidx1 = getelementptr i16, i16* %ptr, i64 1
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%arrayidx2 = getelementptr i16, i16* %ptr, i64 2
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%t1 = load i16, i16* %arrayidx1
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@ -233,6 +245,7 @@ define void @no_pointer_deref(i16* %ptr) {
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define void @non_consecutive(i32* %ptr) {
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; CHECK-LABEL: @non_consecutive(i32* %ptr)
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; ATTRIBUTOR-LABEL: @non_consecutive(i32* nocapture nofree nonnull readonly dereferenceable(8) %ptr)
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%arrayidx1 = getelementptr i32, i32* %ptr, i64 1
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%arrayidx0 = getelementptr i32, i32* %ptr, i64 0
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%arrayidx3 = getelementptr i32, i32* %ptr, i64 3
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@ -246,6 +259,7 @@ define void @non_consecutive(i32* %ptr) {
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define void @more_bytes(i32* dereferenceable(8) %ptr) {
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; CHECK-LABEL: @more_bytes(i32* dereferenceable(8) %ptr)
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; ATTRIBUTOR-LABEL: @more_bytes(i32* nocapture nofree nonnull readonly dereferenceable(16) %ptr)
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%arrayidx3 = getelementptr i32, i32* %ptr, i64 3
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%arrayidx1 = getelementptr i32, i32* %ptr, i64 1
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%arrayidx0 = getelementptr i32, i32* %ptr, i64 0
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@ -261,6 +275,7 @@ define void @more_bytes(i32* dereferenceable(8) %ptr) {
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define void @more_bytes_and_not_null(i32* dereferenceable_or_null(8) %ptr) {
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; CHECK-LABEL: @more_bytes_and_not_null(i32* dereferenceable_or_null(8) %ptr)
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; ATTRIBUTOR-LABEL: @more_bytes_and_not_null(i32* nocapture nofree nonnull readonly dereferenceable(16) %ptr)
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%arrayidx3 = getelementptr i32, i32* %ptr, i64 3
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%arrayidx1 = getelementptr i32, i32* %ptr, i64 1
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%arrayidx0 = getelementptr i32, i32* %ptr, i64 0
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@ -276,6 +291,7 @@ define void @more_bytes_and_not_null(i32* dereferenceable_or_null(8) %ptr) {
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define void @better_bytes(i32* dereferenceable(100) %ptr) {
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; CHECK-LABEL: @better_bytes(i32* dereferenceable(100) %ptr)
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; ATTRIBUTOR-LABEL: @better_bytes(i32* nocapture nofree nonnull readonly dereferenceable(100) %ptr)
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%arrayidx3 = getelementptr i32, i32* %ptr, i64 3
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%arrayidx1 = getelementptr i32, i32* %ptr, i64 1
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%arrayidx0 = getelementptr i32, i32* %ptr, i64 0
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@ -289,6 +305,7 @@ define void @better_bytes(i32* dereferenceable(100) %ptr) {
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define void @bitcast(i32* %arg) {
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; CHECK-LABEL: @bitcast(i32* %arg)
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; ATTRIBUTOR-LABEL: @bitcast(i32* nocapture nofree nonnull readonly dereferenceable(8) %arg)
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%ptr = bitcast i32* %arg to float*
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%arrayidx0 = getelementptr float, float* %ptr, i64 0
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%arrayidx1 = getelementptr float, float* %ptr, i64 1
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@ -299,6 +316,7 @@ define void @bitcast(i32* %arg) {
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define void @bitcast_different_sizes(double* %arg1, i8* %arg2) {
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; CHECK-LABEL: @bitcast_different_sizes(double* %arg1, i8* %arg2)
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; ATTRIBUTOR-LABEL: @bitcast_different_sizes(double* nocapture nofree nonnull readonly dereferenceable(12) %arg1, i8* nocapture nofree nonnull readonly dereferenceable(16) %arg2)
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%ptr1 = bitcast double* %arg1 to float*
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%a10 = getelementptr float, float* %ptr1, i64 0
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%a11 = getelementptr float, float* %ptr1, i64 1
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@ -317,6 +335,7 @@ define void @bitcast_different_sizes(double* %arg1, i8* %arg2) {
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define void @negative_offset(i32* %arg) {
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; CHECK-LABEL: @negative_offset(i32* %arg)
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; ATTRIBUTOR-LABEL: @negative_offset(i32* nocapture nofree nonnull readonly dereferenceable(4) %arg)
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%ptr = bitcast i32* %arg to float*
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%arrayidx0 = getelementptr float, float* %ptr, i64 0
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%arrayidx1 = getelementptr float, float* %ptr, i64 -1
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@ -327,6 +346,7 @@ define void @negative_offset(i32* %arg) {
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define void @stores(i32* %arg) {
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; CHECK-LABEL: @stores(i32* %arg)
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; ATTRIBUTOR-LABEL: @stores(i32* nocapture nofree nonnull writeonly dereferenceable(8) %arg)
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%ptr = bitcast i32* %arg to float*
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%arrayidx0 = getelementptr float, float* %ptr, i64 0
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%arrayidx1 = getelementptr float, float* %ptr, i64 1
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@ -337,6 +357,7 @@ define void @stores(i32* %arg) {
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define void @load_store(i32* %arg) {
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; CHECK-LABEL: @load_store(i32* %arg)
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; ATTRIBUTOR-LABEL: @load_store(i32* nocapture nofree nonnull dereferenceable(8) %arg)
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%ptr = bitcast i32* %arg to float*
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%arrayidx0 = getelementptr float, float* %ptr, i64 0
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%arrayidx1 = getelementptr float, float* %ptr, i64 1
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@ -344,3 +365,21 @@ define void @load_store(i32* %arg) {
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store float 2.0, float* %arrayidx1
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ret void
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}
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define void @different_size1(i32* %arg) {
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; CHECK-LABEL: @different_size1(i32* %arg)
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; ATTRIBUTOR-LABEL: @different_size1(i32* nocapture nofree nonnull writeonly dereferenceable(8) %arg)
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%arg-cast = bitcast i32* %arg to double*
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store double 0.000000e+00, double* %arg-cast
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store i32 0, i32* %arg
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ret void
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}
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define void @different_size2(i32* %arg) {
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; CHECK-LABEL: @different_size2(i32* %arg)
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; ATTRIBUTOR-LABEL: @different_size2(i32* nocapture nofree nonnull writeonly dereferenceable(8) %arg)
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store i32 0, i32* %arg
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%arg-cast = bitcast i32* %arg to double*
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store double 0.000000e+00, double* %arg-cast
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ret void
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}
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