llvm dev - Apr 2016 - [Sparc] Undefined temporary symbol

Hi,

I'm trying to work out what to do to eliminate an "Undefined temporary
symbol", which has appeared after I had thought I'd cleared up the last
problems trying to implement __builtin_setjmp.

I know that the symbol it's referring to is "sinkMBB" in the two
BuildMI instructions in the code fragment below, as the problem goes away if I
remove these lines temporarily (although the algorithm doesn't work then).

What must I do to eliminate the Undefined Temporary Symbol error, later in the
compilation process (raised at ElfObjectWriter.cpp:803)?

Chris Dewhurst, Lero, University of Limerick

+   const BasicBlock *BB = MBB->getBasicBlock();
+   MachineFunction::iterator It = ++MBB->getIterator();
+   MachineBasicBlock *thisMBB = MBB;
+   const BasicBlock* mainBB = BasicBlock::Create(BB->getContext(),
"setjmp.main");
+   MachineBasicBlock *mainMBB = MF->CreateMachineBasicBlock(mainBB);
+   mainMBB->setHasAddressTaken();
+   const BasicBlock* sinkBB = BasicBlock::Create(BB->getContext(),
"setjmp.sink");
+   MachineBasicBlock *sinkMBB = MF->CreateMachineBasicBlock(sinkBB);
+   sinkMBB->setHasAddressTaken();
+
+   MF->insert(It, mainMBB);
+   MF->insert(It, sinkMBB);
+
+   // Transfer the remainder of BB and its successor edges to sinkMBB.
+   sinkMBB->splice(sinkMBB->begin(), MBB,
+                   std::next(MachineBasicBlock::iterator(MI)),
+                   MBB->end());
+   sinkMBB->transferSuccessorsAndUpdatePHIs(MBB);
+
+   MachineInstrBuilder MIB;
+
+   unsigned LabelReg = MRI.createVirtualRegister(&SP::IntRegsRegClass);
+   unsigned BufReg = MI->getOperand(1).getReg();
+
+   MIB = BuildMI(*thisMBB, MI, DL, TII->get(SP::SETHIi))
+             .addReg(LabelReg, RegState::Define)
+             .addMBB(sinkMBB, SparcMCExpr::VK_Sparc_HI);
+   MIB.setMemRefs(MMOBegin, MMOEnd);
+
+   MIB = BuildMI(*thisMBB, MI, DL, TII->get(SP::ADDri))
+             .addReg(LabelReg)
+             .addReg(LabelReg)
+             .addMBB(sinkMBB, SparcMCExpr::VK_Sparc_LO);
+   MIB.setMemRefs(MMOBegin, MMOEnd);
+
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Sounds like you haven't updated the machine CFG to keep the basic block
containing the label alive. See how addSuccessor is used in the X86
lowering.

On Wed, Apr 27, 2016 at 3:49 PM, Chris.Dewhurst via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi,
>
> I'm trying to work out what to do to eliminate an "Undefined
temporary
> symbol", which has appeared after I had thought I'd cleared up the
last
> problems trying to implement __builtin_setjmp.
>
> I know that the symbol it's referring to is "sinkMBB" in the
two BuildMI
> instructions in the code fragment below, as the problem goes away if I
> remove these lines temporarily (although the algorithm doesn't work
then).
>
> What must I do to eliminate the Undefined Temporary Symbol error, later in
> the compilation process (raised at ElfObjectWriter.cpp:803)?
>
> Chris Dewhurst, Lero, University of Limerick
>
> +   const BasicBlock *BB = MBB->getBasicBlock();
> +   MachineFunction::iterator It = ++MBB->getIterator();
> +   MachineBasicBlock *thisMBB = MBB;
> +   const BasicBlock* mainBB = BasicBlock::Create(BB->getContext(),
> "setjmp.main");
> +   MachineBasicBlock *mainMBB = MF->CreateMachineBasicBlock(mainBB);
> +   mainMBB->setHasAddressTaken();
> +   const BasicBlock* sinkBB = BasicBlock::Create(BB->getContext(),
> "setjmp.sink");
> +   MachineBasicBlock *sinkMBB = MF->CreateMachineBasicBlock(sinkBB);
> +   sinkMBB->setHasAddressTaken();
> +
> +   MF->insert(It, mainMBB);
> +   MF->insert(It, sinkMBB);
> +
> +   // Transfer the remainder of BB and its successor edges to sinkMBB.
> +   sinkMBB->splice(sinkMBB->begin(), MBB,
> +                   std::next(MachineBasicBlock::iterator(MI)),
> +                   MBB->end());
> +   sinkMBB->transferSuccessorsAndUpdatePHIs(MBB);
> +
> +   MachineInstrBuilder MIB;
> +
> +   unsigned LabelReg =
MRI.createVirtualRegister(&SP::IntRegsRegClass);
> +   unsigned BufReg = MI->getOperand(1).getReg();
> +
> +   MIB = BuildMI(*thisMBB, MI, DL, TII->get(SP::SETHIi))
> +             .addReg(LabelReg, RegState::Define)
> +             .addMBB(sinkMBB, SparcMCExpr::VK_Sparc_HI);
> +   MIB.setMemRefs(MMOBegin, MMOEnd);
> +
> +   MIB = BuildMI(*thisMBB, MI, DL, TII->get(SP::ADDri))
> +             .addReg(LabelReg)
> +             .addReg(LabelReg)
> +             .addMBB(sinkMBB, SparcMCExpr::VK_Sparc_LO);
> +   MIB.setMemRefs(MMOBegin, MMOEnd);
> +
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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