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[CodeGen][NewPM] Split MachineDominatorTree into a concrete analysis result #94571

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Merged
merged 3 commits into from
Jun 11, 2024
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[CodeGen][NewPM] Split MachineDominatorTree into a concrete analysis result #94571

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f7ef515
[CodeGen][NewPM] Split `MachineDominatorTree` into a concrete analysi…
paperchalice Jun 6, 2024
0f06f80
Add a flag to check whether dt exists
paperchalice Jun 6, 2024
8634aa6
Use std::optional
paperchalice Jun 7, 2024
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1 change: 1 addition & 0 deletions llvm/include/llvm/CodeGen/MachineDominators.h
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Expand Up @@ -266,6 +266,7 @@ class MachineDominatorTree : public DomTreeBase<MachineBasicBlock> {
/// \brief Analysis pass which computes a \c MachineDominatorTree.
class MachineDominatorTreeWrapperPass : public MachineFunctionPass {
MachineDominatorTree DT;
bool IsDomTreeEmpty = true;
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Why is this necessary?

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If a pass preserves machine dominator tree analysis and machine dominator tree analysis result doesn't exists, verifyAnalysis will verify an empty dominator tree, which will trigger assertion. In old implementation it is a unique_ptr and can be nullptr.

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Either make it std::optional or fix the verifier to not assert on the empty case


public:
static char ID;
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4 changes: 3 additions & 1 deletion llvm/lib/CodeGen/MachineDominators.cpp
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Expand Up @@ -70,6 +70,7 @@ MachineDominatorTreeWrapperPass::MachineDominatorTreeWrapperPass()
char &llvm::MachineDominatorsID = MachineDominatorTreeWrapperPass::ID;

bool MachineDominatorTreeWrapperPass::runOnMachineFunction(MachineFunction &F) {
IsDomTreeEmpty = false;
DT.calculate(F);
return false;
}
Expand All @@ -83,10 +84,11 @@ void MachineDominatorTree::calculate(MachineFunction &F) {
void MachineDominatorTreeWrapperPass::releaseMemory() {
DT.CriticalEdgesToSplit.clear();
DT.reset();
IsDomTreeEmpty = true;
}

void MachineDominatorTreeWrapperPass::verifyAnalysis() const {
if (VerifyMachineDomInfo)
if (VerifyMachineDomInfo && !IsDomTreeEmpty)
if (!DT.verify(MachineDominatorTree::VerificationLevel::Basic))
report_fatal_error("MachineDominatorTree verification failed!");
}
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