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MachineBasicBlock: Cleanup computeRegisterLiveness()
- Clean documentation comment - Change the API to accept an iterator so you can actually pass MachineBasicBlock::end() now. - Add more "const". git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238288 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -633,17 +633,18 @@ public:
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///< neighborhood.
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};
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/// computeRegisterLiveness - Return whether (physical) register \c Reg
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/// has been <def>ined and not <kill>ed as of just before \c MI.
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/// Return whether (physical) register \p Reg has been <def>ined and not
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/// <kill>ed as of just before \p Before.
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///
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/// Search is localised to a neighborhood of
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/// \c Neighborhood instructions before (searching for defs or kills) and
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/// Neighborhood instructions after (searching just for defs) MI.
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/// Search is localised to a neighborhood of \p Neighborhood instructions
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/// before (searching for defs or kills) and \p Neighborhood instructions
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/// after (searching just for defs) \p Before.
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///
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/// \c Reg must be a physical register.
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/// \p Reg must be a physical register.
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LivenessQueryResult computeRegisterLiveness(const TargetRegisterInfo *TRI,
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unsigned Reg, MachineInstr *MI,
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unsigned Neighborhood=10);
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unsigned Reg,
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const_iterator Before,
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unsigned Neighborhood=10) const;
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// Debugging methods.
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void dump() const;
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@ -1129,21 +1129,19 @@ getWeightIterator(MachineBasicBlock::const_succ_iterator I) const {
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/// instructions after (searching just for defs) MI.
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MachineBasicBlock::LivenessQueryResult
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MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI,
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unsigned Reg, MachineInstr *MI,
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unsigned Neighborhood) {
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unsigned Reg, const_iterator Before,
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unsigned Neighborhood) const {
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unsigned N = Neighborhood;
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MachineBasicBlock *MBB = MI->getParent();
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// Start by searching backwards from MI, looking for kills, reads or defs.
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MachineBasicBlock::iterator I(MI);
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// Start by searching backwards from Before, looking for kills, reads or defs.
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const_iterator I(Before);
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// If this is the first insn in the block, don't search backwards.
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if (I != MBB->begin()) {
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if (I != begin()) {
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do {
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--I;
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MachineOperandIteratorBase::PhysRegInfo Analysis =
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MIOperands(I).analyzePhysReg(Reg, TRI);
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ConstMIOperands(I).analyzePhysReg(Reg, TRI);
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if (Analysis.Defines)
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// Outputs happen after inputs so they take precedence if both are
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@ -1158,15 +1156,15 @@ MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI,
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// Defined or read without a previous kill - live.
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return Analysis.Reads ? LQR_Live : LQR_OverlappingLive;
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} while (I != MBB->begin() && --N > 0);
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} while (I != begin() && --N > 0);
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}
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// Did we get to the start of the block?
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if (I == MBB->begin()) {
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if (I == begin()) {
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// If so, the register's state is definitely defined by the live-in state.
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for (MCRegAliasIterator RAI(Reg, TRI, /*IncludeSelf=*/true);
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RAI.isValid(); ++RAI) {
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if (MBB->isLiveIn(*RAI))
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if (isLiveIn(*RAI))
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return (*RAI == Reg) ? LQR_Live : LQR_OverlappingLive;
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}
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@ -1175,13 +1173,13 @@ MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI,
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N = Neighborhood;
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// Try searching forwards from MI, looking for reads or defs.
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I = MachineBasicBlock::iterator(MI);
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// Try searching forwards from Before, looking for reads or defs.
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I = const_iterator(Before);
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// If this is the last insn in the block, don't search forwards.
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if (I != MBB->end()) {
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for (++I; I != MBB->end() && N > 0; ++I, --N) {
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if (I != end()) {
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for (++I; I != end() && N > 0; ++I, --N) {
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MachineOperandIteratorBase::PhysRegInfo Analysis =
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MIOperands(I).analyzePhysReg(Reg, TRI);
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ConstMIOperands(I).analyzePhysReg(Reg, TRI);
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if (Analysis.ReadsOverlap)
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// Used, therefore must have been live.
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