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[SCCP] Propagate non-null pointers #106090

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Merged
merged 1 commit into from
Aug 27, 2024
Merged

[SCCP] Propagate non-null pointers #106090

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34 changes: 33 additions & 1 deletion llvm/lib/Transforms/Utils/SCCPSolver.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -446,6 +446,12 @@ class SCCPInstVisitor : public InstVisitor<SCCPInstVisitor> {
return markConstant(ValueState[V], V, C);
}

bool markNotConstant(ValueLatticeElement &IV, Value *V, Constant *C);

bool markNotNull(ValueLatticeElement &IV, Value *V) {
return markNotConstant(IV, V, Constant::getNullValue(V->getType()));
}

/// markConstantRange - Mark the object as constant range with \p CR. If the
/// object is not a constant range with the range \p CR, add it to the
/// instruction work list so that the users of the instruction are updated
Expand Down Expand Up @@ -820,7 +826,11 @@ class SCCPInstVisitor : public InstVisitor<SCCPInstVisitor> {
return;
}
}
// Assume nothing about the incoming arguments without range.
if (A->hasNonNullAttr()) {
markNotNull(ValueState[A], A);
return;
}
// Assume nothing about the incoming arguments without attributes.
markOverdefined(A);
}

Expand Down Expand Up @@ -905,6 +915,15 @@ bool SCCPInstVisitor::markConstant(ValueLatticeElement &IV, Value *V,
return true;
}

bool SCCPInstVisitor::markNotConstant(ValueLatticeElement &IV, Value *V,
Constant *C) {
if (!IV.markNotConstant(C))
return false;
LLVM_DEBUG(dbgs() << "markNotConstant: " << *C << ": " << *V << '\n');
pushToWorkList(IV, V);
return true;
}

bool SCCPInstVisitor::markConstantRange(ValueLatticeElement &IV, Value *V,
const ConstantRange &CR) {
if (!IV.markConstantRange(CR))
Expand Down Expand Up @@ -1574,6 +1593,19 @@ void SCCPInstVisitor::visitGetElementPtrInst(GetElementPtrInst &I) {
if (ValueState[&I].isOverdefined())
return (void)markOverdefined(&I);

const ValueLatticeElement &PtrState = getValueState(I.getPointerOperand());
if (PtrState.isUnknownOrUndef())
return;

// gep inbounds/nuw of non-null is non-null.
if (PtrState.isNotConstant() && PtrState.getNotConstant()->isNullValue()) {
if (I.hasNoUnsignedWrap() ||
(I.isInBounds() &&
!NullPointerIsDefined(I.getFunction(), I.getAddressSpace())))
return (void)markNotNull(ValueState[&I], &I);
return (void)markOverdefined(&I);
}

SmallVector<Constant *, 8> Operands;
Operands.reserve(I.getNumOperands());

Expand Down
21 changes: 7 additions & 14 deletions llvm/test/Transforms/SCCP/pointer-nonnull.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,7 @@ define i1 @test_no_attr(ptr %p) {
define i1 @test_nonnull(ptr nonnull %p) {
; CHECK-LABEL: define i1 @test_nonnull(
; CHECK-SAME: ptr nonnull [[P:%.*]]) {
; CHECK-NEXT: [[CMP:%.*]] = icmp ne ptr [[P]], null
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK-NEXT: ret i1 true
;
%cmp = icmp ne ptr %p, null
ret i1 %cmp
Expand All @@ -24,8 +23,7 @@ define i1 @test_nonnull(ptr nonnull %p) {
define i1 @test_nonnull_eq(ptr nonnull %p) {
; CHECK-LABEL: define i1 @test_nonnull_eq(
; CHECK-SAME: ptr nonnull [[P:%.*]]) {
; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[P]], null
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK-NEXT: ret i1 false
;
%cmp = icmp eq ptr %p, null
ret i1 %cmp
Expand All @@ -34,8 +32,7 @@ define i1 @test_nonnull_eq(ptr nonnull %p) {
define i1 @test_dereferenceable(ptr dereferenceable(4) %p) {
; CHECK-LABEL: define i1 @test_dereferenceable(
; CHECK-SAME: ptr dereferenceable(4) [[P:%.*]]) {
; CHECK-NEXT: [[CMP:%.*]] = icmp ne ptr [[P]], null
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK-NEXT: ret i1 true
;
%cmp = icmp ne ptr %p, null
ret i1 %cmp
Expand All @@ -57,8 +54,7 @@ define i1 @test_gep_nuw(ptr nonnull %p, i64 %x) {
; CHECK-LABEL: define i1 @test_gep_nuw(
; CHECK-SAME: ptr nonnull [[P:%.*]], i64 [[X:%.*]]) {
; CHECK-NEXT: [[GEP:%.*]] = getelementptr nuw i8, ptr [[P]], i64 [[X]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne ptr [[GEP]], null
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK-NEXT: ret i1 true
;
%gep = getelementptr nuw i8, ptr %p, i64 %x
%cmp = icmp ne ptr %gep, null
Expand All @@ -69,8 +65,7 @@ define i1 @test_gep_inbounds(ptr nonnull %p, i64 %x) {
; CHECK-LABEL: define i1 @test_gep_inbounds(
; CHECK-SAME: ptr nonnull [[P:%.*]], i64 [[X:%.*]]) {
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 [[X]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne ptr [[GEP]], null
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK-NEXT: ret i1 true
;
%gep = getelementptr inbounds i8, ptr %p, i64 %x
%cmp = icmp ne ptr %gep, null
Expand All @@ -94,8 +89,7 @@ define i1 @test_select(i1 %c, ptr nonnull %p, i64 %x) {
; CHECK-SAME: i1 [[C:%.*]], ptr nonnull [[P:%.*]], i64 [[X:%.*]]) {
; CHECK-NEXT: [[GEP:%.*]] = getelementptr nuw i8, ptr [[P]], i64 [[X]]
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[C]], ptr [[P]], ptr [[GEP]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne ptr [[SEL]], null
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK-NEXT: ret i1 true
;
%gep = getelementptr nuw i8, ptr %p, i64 %x
%sel = select i1 %c, ptr %p, ptr %gep
Expand Down Expand Up @@ -127,8 +121,7 @@ define i1 @test_phi(i1 %c, ptr nonnull %p, i64 %x) {
; CHECK-NEXT: br label %[[JOIN]]
; CHECK: [[JOIN]]:
; CHECK-NEXT: [[PHI:%.*]] = phi ptr [ [[P]], %[[ENTRY]] ], [ [[GEP]], %[[IF]] ]
; CHECK-NEXT: [[CMP:%.*]] = icmp ne ptr [[PHI]], null
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK-NEXT: ret i1 true
;
entry:
br i1 %c, label %if, label %join
Expand Down
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