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[BFI] Simplify computeMassInLoops. NFC (#213200)

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Iterate backwards with a plain iterator instead of dancing with
prev(base()).
This commit is contained in:
Fangrui Song 2026-07-30 23:14:21 -07:00 committed by GitHub
parent 14192adddc
commit 6a38e4e097
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1 changed files with 9 additions and 8 deletions
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17
llvm/include/llvm/Analysis/BlockFrequencyInfoImpl.h
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@ -1173,16 +1173,17 @@ template <class BT> void BlockFrequencyInfoImpl<BT>::initializeLoops() {
}
template <class BT> void BlockFrequencyInfoImpl<BT>::computeMassInLoops() {
// Visit loops with the deepest first, and the top-level loops last.
for (auto L = Loops.rbegin(), E = Loops.rend(); L != E; ++L) {
// Visit loops with the deepest first, and the top-level loops last. The first
// computeMassInLoop returns false if *L contains an irreducible sub-SCC.
// computeIrreducibleMass then packages each such SCC into a new loop,
// inserted immediately after *L.
for (auto L = Loops.end(), B = Loops.begin(); L != B;) {
--L;
if (computeMassInLoop(*L))
continue;
auto Next = std::next(L);
computeIrreducibleMass(&*L, L.base());
L = std::prev(Next);
if (computeMassInLoop(*L))
continue;
llvm_unreachable("unhandled irreducible control flow");
computeIrreducibleMass(&*L, std::next(L));
if (!computeMassInLoop(*L))
llvm_unreachable("unhandled irreducible control flow");
}
}