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Allow Post-RA LICM to hoist reserved register reads.
When using register masks, registers like %rip are clobbered by the register mask. LICM should still be able to hoist instructions reading %rip from a loop containing calls. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150288 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -68,6 +68,7 @@ namespace {
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MachineRegisterInfo *MRI;
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const InstrItineraryData *InstrItins;
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bool PreRegAlloc;
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BitVector ReservedRegs;
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// Various analyses that we use...
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AliasAnalysis *AA; // Alias analysis info.
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@ -337,6 +338,8 @@ bool MachineLICM::runOnMachineFunction(MachineFunction &MF) {
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for (TargetRegisterInfo::regclass_iterator I = TRI->regclass_begin(),
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E = TRI->regclass_end(); I != E; ++I)
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RegLimit[(*I)->getID()] = TRI->getRegPressureLimit(*I, MF);
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} else {
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ReservedRegs = TRI->getReservedRegs(MF);
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}
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// Get our Loop information...
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@ -426,6 +429,9 @@ void MachineLICM::ProcessMI(MachineInstr *MI,
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"Not expecting virtual register!");
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if (!MO.isDef()) {
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// Allow reserved register reads to be hoisted.
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if (ReservedRegs.test(Reg))
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continue;
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if (Reg && (PhysRegDefs.test(Reg) || PhysRegClobbers.test(Reg)))
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// If it's using a non-loop-invariant register, then it's obviously not
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// safe to hoist.
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@ -531,6 +537,11 @@ void MachineLICM::HoistRegionPostRA() {
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const MachineOperand &MO = MI->getOperand(j);
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if (!MO.isReg() || MO.isDef() || !MO.getReg())
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continue;
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// Allow hoisting of reserved register reads that aren't call preserved.
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// For example %rip.
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// IsLoopInvariantInst() already checks MRI->isConstantPhysReg().
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if (ReservedRegs.test(MO.getReg()))
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continue;
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if (PhysRegDefs.test(MO.getReg()) ||
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PhysRegClobbers.test(MO.getReg())) {
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// If it's using a non-loop-invariant register, then it's obviously
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