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[CodeGen] TwoAddressInstructionPass - Control NumVisited limit via command line option #84845

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[CodeGen] TwoAddressInstructionPass - Control NumVisited limit via command line option #84845

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13 changes: 10 additions & 3 deletions llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,13 @@ EnableRescheduling("twoaddr-reschedule",
cl::desc("Coalesce copies by rescheduling (default=true)"),
cl::init(true), cl::Hidden);

// Limit the number of rescheduling visits to dependent instructions.
// FIXME: Arbitrary limit to reduce compile time cost.
static cl::opt<unsigned> MaxVisits(
"twoaddr-visit-limit", cl::Hidden, cl::init(10),
cl::desc(
"Maximum number of rescheduling visits to dependent instructions"));

// Limit the number of dataflow edges to traverse when evaluating the benefit
// of commuting operands.
static cl::opt<unsigned> MaxDataFlowEdge(
Expand Down Expand Up @@ -921,7 +928,7 @@ bool TwoAddressInstructionPass::rescheduleMIBelowKill(
// Debug or pseudo instructions cannot be counted against the limit.
if (OtherMI.isDebugOrPseudoInstr())
continue;
if (NumVisited > 10) // FIXME: Arbitrary limit to reduce compile time cost.
if (NumVisited > MaxVisits)
return false;
++NumVisited;
if (OtherMI.hasUnmodeledSideEffects() || OtherMI.isCall() ||
Expand Down Expand Up @@ -1087,14 +1094,14 @@ bool TwoAddressInstructionPass::rescheduleKillAboveMI(
}
}

// Check if the reschedule will not break depedencies.
// Check if the reschedule will not break dependencies.
unsigned NumVisited = 0;
for (MachineInstr &OtherMI :
make_range(mi, MachineBasicBlock::iterator(KillMI))) {
// Debug or pseudo instructions cannot be counted against the limit.
if (OtherMI.isDebugOrPseudoInstr())
continue;
if (NumVisited > 10) // FIXME: Arbitrary limit to reduce compile time cost.
if (NumVisited > MaxVisits)
return false;
++NumVisited;
if (OtherMI.hasUnmodeledSideEffects() || OtherMI.isCall() ||
Expand Down