Rewrite the physreg part of findLastUseBefore().
To find the last use of a register unit, start from the bottom and scan
upwards until a user is found.
<rdar://problem/13353090>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176706 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 22b35d5..f1b8394 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -972,9 +972,9 @@
// Return the last use of reg between NewIdx and OldIdx.
SlotIndex findLastUseBefore(unsigned Reg) {
- SlotIndex LastUse = NewIdx;
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
+ SlotIndex LastUse = NewIdx;
for (MachineRegisterInfo::use_nodbg_iterator
UI = MRI.use_nodbg_begin(Reg),
UE = MRI.use_nodbg_end();
@@ -984,30 +984,42 @@
if (InstSlot > LastUse && InstSlot < OldIdx)
LastUse = InstSlot;
}
- } else {
- MachineInstr* MI = LIS.getSlotIndexes()->getInstructionFromIndex(NewIdx);
- MachineBasicBlock::iterator MII(MI);
- ++MII;
- MachineBasicBlock* MBB = MI->getParent();
- for (; MII != MBB->end(); ++MII){
- if (MII->isDebugValue())
- continue;
- if (LIS.getInstructionIndex(MII) < OldIdx)
- break;
- for (MachineInstr::mop_iterator MOI = MII->operands_begin(),
- MOE = MII->operands_end();
- MOI != MOE; ++MOI) {
- const MachineOperand& mop = *MOI;
- if (!mop.isReg() || mop.getReg() == 0 ||
- TargetRegisterInfo::isVirtualRegister(mop.getReg()))
- continue;
-
- if (TRI.hasRegUnit(mop.getReg(), Reg))
- LastUse = LIS.getInstructionIndex(MII);
- }
- }
+ return LastUse;
}
- return LastUse;
+
+ // This is a regunit interval, so scanning the use list could be very
+ // expensive. Scan upwards from OldIdx instead.
+ assert(NewIdx < OldIdx && "Expected upwards move");
+ SlotIndexes *Indexes = LIS.getSlotIndexes();
+ MachineBasicBlock *MBB = Indexes->getMBBFromIndex(NewIdx);
+
+ // OldIdx may not correspond to an instruction any longer, so set MII to
+ // point to the next instruction after OldIdx, or MBB->end().
+ MachineBasicBlock::iterator MII = MBB->end();
+ if (MachineInstr *MI = Indexes->getInstructionFromIndex(
+ Indexes->getNextNonNullIndex(OldIdx)))
+ if (MI->getParent() == MBB)
+ MII = MI;
+
+ MachineBasicBlock::iterator Begin = MBB->begin();
+ while (MII != Begin) {
+ if ((--MII)->isDebugValue())
+ continue;
+ SlotIndex Idx = Indexes->getInstructionIndex(MII);
+
+ // Stop searching when NewIdx is reached.
+ if (!SlotIndex::isEarlierInstr(NewIdx, Idx))
+ return NewIdx;
+
+ // Check if MII uses Reg.
+ for (MIBundleOperands MO(MII); MO.isValid(); ++MO)
+ if (MO->isReg() &&
+ TargetRegisterInfo::isPhysicalRegister(MO->getReg()) &&
+ TRI.hasRegUnit(MO->getReg(), Reg))
+ return Idx;
+ }
+ // Didn't reach NewIdx. It must be the first instruction in the block.
+ return NewIdx;
}
};