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[ValueTracking] Teach isKnownNonNullFromDominatingCondition about AND

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`isKnownNonNullFromDominatingCondition` is able to prove non-null basing on `br` or `guard`
by `%p != null` condition, but is unable to do so basing on `(%p != null) && %other_cond`.
This patch allows it to do so.

Differential Revision: https://reviews.llvm.org/D50172
Reviewed By: reames

llvm-svn: 338990
This commit is contained in:
Max Kazantsev 2018-08-06 06:11:36 +00:00
parent ab15b0a38f
commit 4217d9c40c
2 changed files with 110 additions and 10 deletions
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38
lib/Analysis/ValueTracking.cpp
View File

@ -1861,18 +1861,36 @@ static bool isKnownNonNullFromDominatingCondition(const Value *V,
continue;
for (auto *CmpU : U->users()) {
if (const BranchInst *BI = dyn_cast<BranchInst>(CmpU)) {
assert(BI->isConditional() && "uses a comparison!");
SmallVector<const User *, 4> WorkList;
SmallPtrSet<const User *, 4> Visited;
Visited.insert(CmpU);
WorkList.push_back(CmpU);
BasicBlock *NonNullSuccessor =
BI->getSuccessor(Pred == ICmpInst::ICMP_EQ ? 1 : 0);
BasicBlockEdge Edge(BI->getParent(), NonNullSuccessor);
if (Edge.isSingleEdge() && DT->dominates(Edge, CtxI->getParent()))
while (!WorkList.empty()) {
auto *Curr = WorkList.pop_back_val();
// If a user is an AND, add all its users to the work list.
if (auto *BO = dyn_cast<BinaryOperator>(Curr))
if (BO->getOpcode() == Instruction::And) {
for (auto *BOU : BO->users())
if (Visited.insert(BOU).second)
WorkList.push_back(BOU);
continue;
}
if (const BranchInst *BI = dyn_cast<BranchInst>(Curr)) {
assert(BI->isConditional() && "uses a comparison!");
BasicBlock *NonNullSuccessor =
BI->getSuccessor(Pred == ICmpInst::ICMP_EQ ? 1 : 0);
BasicBlockEdge Edge(BI->getParent(), NonNullSuccessor);
if (Edge.isSingleEdge() && DT->dominates(Edge, CtxI->getParent()))
return true;
} else if (Pred == ICmpInst::ICMP_NE &&
match(Curr, m_Intrinsic<Intrinsic::experimental_guard>()) &&
DT->dominates(cast<Instruction>(Curr), CtxI)) {
return true;
} else if (Pred == ICmpInst::ICMP_NE &&
match(CmpU, m_Intrinsic<Intrinsic::experimental_guard>()) &&
DT->dominates(cast<Instruction>(CmpU), CtxI)) {
return true;
}
}
}
}

82
test/Transforms/LICM/hoist-deref-load.ll
View File

@ -556,5 +556,87 @@ for.end: ; preds = %for.inc, %entry, %e
ret void
}
; Check that branch by condition "null check AND something" allows to hoist the
; load.
define void @test14(i32* noalias %a, i32* %b, i32* dereferenceable_or_null(4) %c, i32 %n, i1 %dummy_cond) #0 {
; CHECK-LABEL: @test14
; CHECK: load i32, i32* %c, align 4
; CHECK: for.body:
entry:
%not_null = icmp ne i32* %c, null
%dummy_and = and i1 %not_null, %dummy_cond
br i1 %dummy_and, label %not.null, label %for.end
not.null:
%cmp11 = icmp sgt i32 %n, 0
br i1 %cmp11, label %for.body, label %for.end
for.body: ; preds = %not.null, %for.inc
%indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %not.null ]
%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
%0 = load i32, i32* %arrayidx, align 4
%cmp1 = icmp sgt i32 %0, 0
br i1 %cmp1, label %if.then, label %for.inc
if.then: ; preds = %for.body
%1 = load i32, i32* %c, align 4
%arrayidx3 = getelementptr inbounds i32, i32* %b, i64 %indvars.iv
%2 = load i32, i32* %arrayidx3, align 4
%mul = mul nsw i32 %2, %1
store i32 %mul, i32* %arrayidx, align 4
br label %for.inc
for.inc: ; preds = %for.body, %if.then
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.inc, %entry, %not.null
ret void
}
; Check that guard by condition "null check AND something" allows to hoist the
; load.
define void @test15(i32* noalias %a, i32* %b, i32* dereferenceable_or_null(4) %c, i32 %n, i1 %dummy_cond) #0 {
; CHECK-LABEL: @test15
; CHECK: load i32, i32* %c, align 4
; CHECK: for.body:
entry:
%not_null = icmp ne i32* %c, null
%dummy_and = and i1 %not_null, %dummy_cond
call void(i1, ...) @llvm.experimental.guard(i1 %dummy_and) [ "deopt"() ]
%cmp11 = icmp sgt i32 %n, 0
br i1 %cmp11, label %for.body, label %for.end
for.body: ; preds = %entry, %for.inc
%indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
%0 = load i32, i32* %arrayidx, align 4
%cmp1 = icmp sgt i32 %0, 0
br i1 %cmp1, label %if.then, label %for.inc
if.then: ; preds = %for.body
%1 = load i32, i32* %c, align 4
%arrayidx3 = getelementptr inbounds i32, i32* %b, i64 %indvars.iv
%2 = load i32, i32* %arrayidx3, align 4
%mul = mul nsw i32 %2, %1
store i32 %mul, i32* %arrayidx, align 4
br label %for.inc
for.inc: ; preds = %for.body, %if.then
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.inc, %entry
ret void
}
attributes #0 = { nounwind uwtable }
!0 = !{i64 4}