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LiveRegUnits::removeRegsInMask safety.
Clobbering is exclusive not inclusive on register units. For liveness, we need to consider all the preserved registers. e.g. A regmask that clobbers YMM0 may preserve XMM0. Units are only clobbered when all super-registers are clobbered. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192623 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -17,21 +17,30 @@
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#include "llvm/CodeGen/MachineInstrBundle.h"
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using namespace llvm;
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/// Return true if the given MachineOperand clobbers the given register unit.
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/// A register unit is only clobbered if all its super-registers are clobbered.
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static bool operClobbersUnit(const MachineOperand *MO, unsigned Unit,
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const MCRegisterInfo *MCRI) {
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for (MCRegUnitRootIterator RI(Unit, MCRI); RI.isValid(); ++RI) {
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for (MCSuperRegIterator SI(*RI, MCRI, true); SI.isValid(); ++SI) {
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if (!MO->clobbersPhysReg(*SI))
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return false;
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}
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}
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return true;
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}
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/// We assume the high bits of a physical super register are not preserved
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/// unless the instruction has an implicit-use operand reading the
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/// super-register or a register unit for the upper bits is available.
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void LiveRegUnits::removeRegsInMask(const MachineOperand &Op,
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const MCRegisterInfo &MCRI) {
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const uint32_t *Mask = Op.getRegMask();
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unsigned Bit = 0;
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for (unsigned R = 0; R < MCRI.getNumRegs(); ++R) {
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if ((*Mask & (1u << Bit)) == 0)
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removeReg(R, MCRI);
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++Bit;
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if (Bit >= 32) {
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Bit = 0;
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++Mask;
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}
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SparseSet<unsigned>::iterator LUI = LiveUnits.begin();
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while (LUI != LiveUnits.end()) {
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if (operClobbersUnit(&Op, *LUI, &MCRI))
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LUI = LiveUnits.erase(LUI);
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else
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++LUI;
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}
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}
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