[Bug tree-optimization/65773] [5 Regression] GCC 5.1 miscompiles LLVM function AArch64InstrInfo::loadRegFromStackSlot()

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65773

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |INVALID

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, the source in question is:
  const MachineInstrBuilder &MI = BuildMI(MBB, MBBI, DL, get(Opc))
                                      .addReg(DestReg, getDefRegState(true))
                                      .addFrameIndex(FI);
  if (Offset)  
    MI.addImm(0);
  MI.addMemOperand(MMO);
which in *.gimple dump looks like:
          try
            {
              D.382398 = &this->D.207751.D.207513.D.205713;
              D.382399 = llvm::MCInstrInfo::get (D.382398, Opc);
              D.325474 = llvm::BuildMI (MBB, MBBI, &D.325473, D.382399);
[return slot optimization]
              try
                {
                  D.382400 = llvm::getDefRegState (1);
                  D.382401 = llvm::MachineInstrBuilder::addReg (&D.325474,
DestReg, D.382400, 0);
                  MI = llvm::MachineInstrBuilder::addFrameIndex (D.382401, FI);
                }
              finally
                {
                  D.325474 = {CLOBBER};
                }
            }
          finally
            {
              llvm::DebugLoc::~DebugLoc (&D.325473);
              D.325473 = {CLOBBER};
            }
          if (Offset != 0) goto <D.382402>; else goto <D.382403>;
          <D.382402>:
          llvm::MachineInstrBuilder::addImm (MI, 0);
          goto <D.382404>;
          <D.382403>:
          <D.382404>:
          llvm::MachineInstrBuilder::addMemOperand (MI, MMO);
which suggests that the temporary that BuildMI returns goes out of scope at the
end of the
  const MachineInstrBuilder &MI = BuildMI(MBB, MBBI, DL, get(Opc))
                                      .addReg(DestReg, getDefRegState(true))
                                      .addFrameIndex(FI);
and sets the reference to the out of scope temporary.
  const
  MachineInstrBuilder &addReg(unsigned RegNo, unsigned flags = 0,
                              unsigned SubReg = 0) const {
ends with
    return *this;
and
  const MachineInstrBuilder &addFrameIndex(int Idx) const {
    MI->addOperand(*MF, MachineOperand::CreateFI(Idx));
    return *this;
  }
too.