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[CodeGen][ShrinkWrap] Clarify StackAddressUsedBlockInfo meaning (#80679)

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Elizaveta Noskova 2024-04-03 11:22:43 +03:00 committed by GitHub
parent cd7517859e
commit 4dd103e9c6
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1 changed files with 8 additions and 3 deletions
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11
llvm/lib/CodeGen/ShrinkWrap.cpp
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@ -161,9 +161,11 @@ class ShrinkWrap : public MachineFunctionPass {
/// Current MachineFunction.
MachineFunction *MachineFunc = nullptr;
/// Is `true` for block numbers where we can guarantee no stack access
/// or computation of stack-relative addresses on any CFG path including
/// the block itself.
/// Is `true` for the block numbers where we assume possible stack accesses
/// or computation of stack-relative addresses on any CFG path including the
/// block itself. Is `false` for basic blocks where we can guarantee the
/// opposite. False positives won't lead to incorrect analysis results,
/// therefore this approach is fair.
BitVector StackAddressUsedBlockInfo;
/// Check if \p MI uses or defines a callee-saved register or
@ -948,6 +950,9 @@ bool ShrinkWrap::runOnMachineFunction(MachineFunction &MF) {
bool Changed = false;
// Initially, conservatively assume that stack addresses can be used in each
// basic block and change the state only for those basic blocks for which we
// were able to prove the opposite.
StackAddressUsedBlockInfo.resize(MF.getNumBlockIDs(), true);
bool HasCandidate = performShrinkWrapping(RPOT, RS.get());
StackAddressUsedBlockInfo.clear();