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More handling of DBG_VALUE.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96294 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -490,10 +490,12 @@ MachineInstr *RALocal::reloadVirtReg(MachineBasicBlock &MBB, MachineInstr *MI,
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// If the virtual register is already available, just update the instruction
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// and return.
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if (unsigned PR = getVirt2PhysRegMapSlot(VirtReg)) {
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MarkPhysRegRecentlyUsed(PR); // Already have this value available!
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MI->getOperand(OpNum).setReg(PR); // Assign the input register
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if (!MI->isDebugValue())
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if (!MI->isDebugValue()) {
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// Do not do these for DBG_VALUE as they can affect codegen.
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MarkPhysRegRecentlyUsed(PR); // Already have this value available!
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getVirtRegLastUse(VirtReg) = std::make_pair(MI, OpNum);
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}
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return MI;
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}
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@ -694,7 +696,13 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
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bool usedOutsideBlock = isPhysReg ? false :
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UsedInMultipleBlocks.test(MO.getReg() -
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TargetRegisterInfo::FirstVirtualRegister);
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if (!isPhysReg && !usedOutsideBlock)
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if (!isPhysReg && !usedOutsideBlock) {
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// DBG_VALUE complicates this: if the only refs of a register outside
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// this block are DBG_VALUE, we can't keep the reg live just for that,
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// as it will cause the reg to be spilled at the end of this block when
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// it wouldn't have been otherwise. Nullify the DBG_VALUEs when that
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// happens.
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bool UsedByDebugValueOnly = false;
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for (MachineRegisterInfo::reg_iterator UI = MRI.reg_begin(MO.getReg()),
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UE = MRI.reg_end(); UI != UE; ++UI)
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// Two cases:
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@ -702,12 +710,26 @@ void RALocal::ComputeLocalLiveness(MachineBasicBlock& MBB) {
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// - used in the same block before it is defined (loop)
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if (UI->getParent() != &MBB ||
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(MO.isDef() && UI.getOperand().isUse() && precedes(&*UI, MI))) {
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if (UI->isDebugValue()) {
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UsedByDebugValueOnly = true;
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continue;
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}
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// A non-DBG_VALUE use means we can leave DBG_VALUE uses alone.
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UsedInMultipleBlocks.set(MO.getReg() -
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TargetRegisterInfo::FirstVirtualRegister);
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usedOutsideBlock = true;
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UsedByDebugValueOnly = false;
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break;
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}
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if (UsedByDebugValueOnly)
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for (MachineRegisterInfo::reg_iterator UI = MRI.reg_begin(MO.getReg()),
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UE = MRI.reg_end(); UI != UE; ++UI)
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if (UI->isDebugValue() &&
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(UI->getParent() != &MBB ||
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(MO.isDef() && precedes(&*UI, MI))))
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UI.getOperand().setReg(0U);
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}
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// Physical registers and those that are not live-out of the block
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// are killed/dead at their last use/def within this block.
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if (isPhysReg || !usedOutsideBlock) {
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