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Debug Info: Simplify Frame Index handling in DBG_VALUE Machine Instructions

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Rather than using the full power of target-specific addressing modes in
DBG_VALUEs with Frame Indicies, simply use Frame Index + Offset. This
reduces the complexity of debug info handling down to two
representations of values (reg+offset and frame index+offset) rather
than three or four.

Ideally we could ensure that frame indicies had been eliminated by the
time we reached an assembly or dwarf generation, but I haven't spent the
time to figure out where the FIs are leaking through into that & whether
there's a good place to convert them. Some FI+offset=>reg+offset
conversion is done (see PrologEpilogInserter, for example) which is
necessary for some SelectionDAG assumptions about registers, I believe,
but it might be possible to make this a more thorough conversion &
ensure there are no remaining FIs no matter how instruction selection
is performed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184066 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Blaikie
2013-06-16 20:34:15 +00:00
parent b7770e0b85
commit 6d9dbd5526
14 changed files with 115 additions and 139 deletions
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47
lib/CodeGen/RegAllocFast.cpp
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@ -297,25 +297,21 @@ void RAFast::spillVirtReg(MachineBasicBlock::iterator MI,
LiveDbgValueMap[LRI->VirtReg];
for (unsigned li = 0, le = LRIDbgValues.size(); li != le; ++li) {
MachineInstr *DBG = LRIDbgValues[li];
const MDNode *MDPtr =
DBG->getOperand(DBG->getNumOperands()-1).getMetadata();
int64_t Offset = 0;
if (DBG->getOperand(1).isImm())
Offset = DBG->getOperand(1).getImm();
const MDNode *MDPtr = DBG->getOperand(2).getMetadata();
int64_t Offset = DBG->getOperand(1).getImm();
DebugLoc DL;
if (MI == MBB->end()) {
// If MI is at basic block end then use last instruction's location.
MachineBasicBlock::iterator EI = MI;
DL = (--EI)->getDebugLoc();
}
else
} else
DL = MI->getDebugLoc();
if (MachineInstr *NewDV =
TII->emitFrameIndexDebugValue(*MF, FI, Offset, MDPtr, DL)) {
MachineBasicBlock *MBB = DBG->getParent();
MBB->insert(MI, NewDV);
DEBUG(dbgs() << "Inserting debug info due to spill:" << "\n" << *NewDV);
}
MachineBasicBlock *MBB = DBG->getParent();
MachineInstr *NewDV =
BuildMI(*MBB, MI, DL, TII->get(TargetOpcode::DBG_VALUE))
.addFrameIndex(FI).addImm(Offset).addMetadata(MDPtr);
(void)NewDV;
DEBUG(dbgs() << "Inserting debug info due to spill:" << "\n" << *NewDV);
}
// Now this register is spilled there is should not be any DBG_VALUE
// pointing to this register because they are all pointing to spilled value
@ -863,21 +859,16 @@ void RAFast::AllocateBasicBlock() {
const MDNode *MDPtr =
MI->getOperand(MI->getNumOperands()-1).getMetadata();
DebugLoc DL = MI->getDebugLoc();
if (MachineInstr *NewDV =
TII->emitFrameIndexDebugValue(*MF, SS, Offset, MDPtr, DL)) {
DEBUG(dbgs() << "Modifying debug info due to spill:" <<
"\t" << *MI);
MachineBasicBlock *MBB = MI->getParent();
MBB->insert(MBB->erase(MI), NewDV);
// Scan NewDV operands from the beginning.
MI = NewDV;
ScanDbgValue = true;
break;
} else {
// We can't allocate a physreg for a DebugValue; sorry!
DEBUG(dbgs() << "Unable to allocate vreg used by DBG_VALUE");
MO.setReg(0);
}
MachineBasicBlock *MBB = MI->getParent();
MachineInstr *NewDV = BuildMI(*MBB, MBB->erase(MI), DL,
TII->get(TargetOpcode::DBG_VALUE))
.addFrameIndex(SS).addImm(Offset).addMetadata(MDPtr);
DEBUG(dbgs() << "Modifying debug info due to spill:"
<< "\t" << *NewDV);
// Scan NewDV operands from the beginning.
MI = NewDV;
ScanDbgValue = true;
break;
}
}
LiveDbgValueMap[Reg].push_back(MI);