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[SCEV] Handle and/or in applyLoopGuards()

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applyLoopGuards() already combines conditions from multiple nested
guards. However, it cannot use multiple conditions on the same guard,
combined using and/or. Add support for this by recursing into either
`and` or `or`, depending on the direction of the branch.

Differential Revision: https://reviews.llvm.org/D101692
This commit is contained in:
Nikita Popov 2021-05-01 16:59:06 +02:00
parent b739e40444
commit b57784b03b
2 changed files with 39 additions and 25 deletions
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26
lib/Analysis/ScalarEvolution.cpp
View File

@ -13485,16 +13485,30 @@ const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) {
if (!LoopEntryPredicate || LoopEntryPredicate->isUnconditional())
continue;
// TODO: use information from more complex conditions, e.g. AND expressions.
auto *Cmp = dyn_cast<ICmpInst>(LoopEntryPredicate->getCondition());
if (!Cmp)
bool EnterIfTrue = LoopEntryPredicate->getSuccessor(0) == Pair.second;
SmallVector<Value *, 8> Worklist;
SmallPtrSet<Value *, 8> Visited;
Worklist.push_back(LoopEntryPredicate->getCondition());
while (!Worklist.empty()) {
Value *Cond = Worklist.pop_back_val();
if (!Visited.insert(Cond).second)
continue;
auto Predicate = Cmp->getPredicate();
if (LoopEntryPredicate->getSuccessor(1) == Pair.second)
Predicate = CmpInst::getInversePredicate(Predicate);
if (auto *Cmp = dyn_cast<ICmpInst>(Cond)) {
auto Predicate =
EnterIfTrue ? Cmp->getPredicate() : Cmp->getInversePredicate();
CollectCondition(Predicate, getSCEV(Cmp->getOperand(0)),
getSCEV(Cmp->getOperand(1)), RewriteMap);
continue;
}
Value *L, *R;
if (EnterIfTrue ? match(Cond, m_LogicalAnd(m_Value(L), m_Value(R)))
: match(Cond, m_LogicalOr(m_Value(L), m_Value(R)))) {
Worklist.push_back(L);
Worklist.push_back(R);
}
}
}
// Also collect information from assumptions dominating the loop.

32
test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info.ll
View File

@ -489,14 +489,14 @@ define void @test_guard_if_and_enter(i32* nocapture readonly %data, i64 %count)
; CHECK-NEXT: %cmp.and = and i1 %cmp.ult, %cmp.ne
; CHECK-NEXT: --> %cmp.and U: full-set S: full-set
; CHECK-NEXT: %iv = phi i64 [ %iv.next, %loop ], [ 0, %entry ]
; CHECK-NEXT: --> {0,+,1}<nuw><%loop> U: [0,-1) S: [0,-1) Exits: (-1 + %count) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {0,+,1}<nuw><%loop> U: [0,4) S: [0,4) Exits: (-1 + %count) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %idx = getelementptr inbounds i32, i32* %data, i64 %iv
; CHECK-NEXT: --> {%data,+,4}<%loop> U: full-set S: full-set Exits: (-4 + (4 * %count) + %data) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {%data,+,4}<nuw><%loop> U: full-set S: full-set Exits: (-4 + (4 * %count) + %data) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add nuw i64 %iv, 1
; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: %count LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,5) S: [1,5) Exits: %count LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @test_guard_if_and_enter
; CHECK-NEXT: Loop %loop: backedge-taken count is (-1 + %count)
; CHECK-NEXT: Loop %loop: max backedge-taken count is -2
; CHECK-NEXT: Loop %loop: max backedge-taken count is 3
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (-1 + %count)
; CHECK-NEXT: Predicates:
; CHECK: Loop %loop: Trip multiple is 1
@ -563,14 +563,14 @@ define void @test_guard_if_and_and(i32* nocapture readonly %data, i64 %count, i1
; CHECK-NEXT: %cmp.and = and i1 %cmp.ult, %cmp.and1
; CHECK-NEXT: --> %cmp.and U: full-set S: full-set
; CHECK-NEXT: %iv = phi i64 [ %iv.next, %loop ], [ 0, %entry ]
; CHECK-NEXT: --> {0,+,1}<nuw><%loop> U: [0,-1) S: [0,-1) Exits: (-1 + %count) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {0,+,1}<nuw><%loop> U: [0,4) S: [0,4) Exits: (-1 + %count) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %idx = getelementptr inbounds i32, i32* %data, i64 %iv
; CHECK-NEXT: --> {%data,+,4}<%loop> U: full-set S: full-set Exits: (-4 + (4 * %count) + %data) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {%data,+,4}<nuw><%loop> U: full-set S: full-set Exits: (-4 + (4 * %count) + %data) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add nuw i64 %iv, 1
; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: %count LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,5) S: [1,5) Exits: %count LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @test_guard_if_and_and
; CHECK-NEXT: Loop %loop: backedge-taken count is (-1 + %count)
; CHECK-NEXT: Loop %loop: max backedge-taken count is -2
; CHECK-NEXT: Loop %loop: max backedge-taken count is 3
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (-1 + %count)
; CHECK-NEXT: Predicates:
; CHECK: Loop %loop: Trip multiple is 1
@ -639,14 +639,14 @@ define void @test_guard_if_or_skip(i32* nocapture readonly %data, i64 %count) {
; CHECK-NEXT: %cmp.or = or i1 %cmp.uge, %cmp.eq
; CHECK-NEXT: --> %cmp.or U: full-set S: full-set
; CHECK-NEXT: %iv = phi i64 [ %iv.next, %loop ], [ 0, %entry ]
; CHECK-NEXT: --> {0,+,1}<nuw><%loop> U: [0,-1) S: [0,-1) Exits: (-1 + %count) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {0,+,1}<nuw><%loop> U: [0,4) S: [0,4) Exits: (-1 + %count) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %idx = getelementptr inbounds i32, i32* %data, i64 %iv
; CHECK-NEXT: --> {%data,+,4}<%loop> U: full-set S: full-set Exits: (-4 + (4 * %count) + %data) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {%data,+,4}<nuw><%loop> U: full-set S: full-set Exits: (-4 + (4 * %count) + %data) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add nuw i64 %iv, 1
; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: %count LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,5) S: [1,5) Exits: %count LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @test_guard_if_or_skip
; CHECK-NEXT: Loop %loop: backedge-taken count is (-1 + %count)
; CHECK-NEXT: Loop %loop: max backedge-taken count is -2
; CHECK-NEXT: Loop %loop: max backedge-taken count is 3
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (-1 + %count)
; CHECK-NEXT: Predicates:
; CHECK: Loop %loop: Trip multiple is 1
@ -713,14 +713,14 @@ define void @test_guard_if_or_or(i32* nocapture readonly %data, i64 %count, i1 %
; CHECK-NEXT: %cmp.or = or i1 %cmp.uge, %cmp.or1
; CHECK-NEXT: --> %cmp.or U: full-set S: full-set
; CHECK-NEXT: %iv = phi i64 [ %iv.next, %loop ], [ 0, %entry ]
; CHECK-NEXT: --> {0,+,1}<nuw><%loop> U: [0,-1) S: [0,-1) Exits: (-1 + %count) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {0,+,1}<nuw><%loop> U: [0,4) S: [0,4) Exits: (-1 + %count) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %idx = getelementptr inbounds i32, i32* %data, i64 %iv
; CHECK-NEXT: --> {%data,+,4}<%loop> U: full-set S: full-set Exits: (-4 + (4 * %count) + %data) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {%data,+,4}<nuw><%loop> U: full-set S: full-set Exits: (-4 + (4 * %count) + %data) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add nuw i64 %iv, 1
; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: %count LoopDispositions: { %loop: Computable }
; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,5) S: [1,5) Exits: %count LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @test_guard_if_or_or
; CHECK-NEXT: Loop %loop: backedge-taken count is (-1 + %count)
; CHECK-NEXT: Loop %loop: max backedge-taken count is -2
; CHECK-NEXT: Loop %loop: max backedge-taken count is 3
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (-1 + %count)
; CHECK-NEXT: Predicates:
; CHECK: Loop %loop: Trip multiple is 1