[LLVMdev] Folding instructions

[Fernando Magno Quintao Pereira]

Dear LLVMers,

    I am trying to fold memory operands in the way that is done in
RegAllocLocal.cpp, or in LiveIntervalAnalysis.cpp, but I am getting errors
that
I don't know how to fix. Could someone tell me which steps should I take
in order
to correctly fold memory operands? The code that I am using is:

const TargetMachine & target_machine =
this->machine_function->getTarget();
const MRegisterInfo *ri = target_machine.getRegisterInfo();
MachineInstr * fmi = ri->foldMemoryOperand(mi, u, slot);
if(fmi) {
   numFolded++;
   MachineBasicBlock * mbb = mi->getParent();
   this->vrm->virtFolded(v_reg, mi, u, fmi);
   //std::cerr << "Folding " << NeatPrint::mi2string(*mi,
*this->machine_function) << "\n";
   // TODO: see if it is not necessary to iterate
   // again on the instruction.
   return mbb->insert(mbb->erase(mi), fmi);
}

With this code, my register allocator passes many tests, but crashes in
some.
Curiously, if I uncomment the printing line, it passes some more tests.
gdb gives me
the error trace below. Could someone point me directions? I am not
deleting fmi
before the spiller runs, so, maybe I am not calling some methods from LLVM
to
indicate the folding.

Thanks a lot,

Fernando

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x80000004
0x94abb19c in std::_Rb_tree_rebalance_for_erase ()
(gdb) where
#0  0x94abb19c in std::_Rb_tree_rebalance_for_erase ()
#1  0x0073dd40 in std::_Rb_tree<llvm::MachineInstr*,
std::pair<llvm::MachineInstr* const, std::pair<unsigned int,
llvm::VirtRegMap::ModRef> >, std::_Select1st<std::pair<llvm::MachineInstr*
const, std::pair<unsigned int, llvm::VirtRegMap::ModRef> > >,
std::less<llvm::MachineInstr*>,
std::allocator<std::pair<llvm::MachineInstr* const, std::pair<unsigned
int, llvm::VirtRegMap::ModRef> > > >::erase (this=0x8d1afcc,
__position={_M_node = 0x8d1c520}) at
/usr/include/c++/4.0.0/bits/stl_iterator_base_funcs.h:994
#2  0x0073df9c in std::_Rb_tree<llvm::MachineInstr*,
std::pair<llvm::MachineInstr* const, std::pair<unsigned int,
llvm::VirtRegMap::ModRef> >, std::_Select1st<std::pair<llvm::MachineInstr*
const, std::pair<unsigned int, llvm::VirtRegMap::ModRef> > >,
std::less<llvm::MachineInstr*>,
std::allocator<std::pair<llvm::MachineInstr* const, std::pair<unsigned
int, llvm::VirtRegMap::ModRef> > > >::erase (this=0x8d1afcc,
__first={_M_node = 0x8d1d6e0}, __last={_M_node = 0x8d1d6e0}) at
/usr/include/c++/4.0.0/bits/stl_tree.h:1073
#3  0x0073e04c in std::_Rb_tree<llvm::MachineInstr*,
std::pair<llvm::MachineInstr* const, std::pair<unsigned int,
llvm::VirtRegMap::ModRef> >, std::_Select1st<std::pair<llvm::MachineInstr*
const, std::pair<unsigned int, llvm::VirtRegMap::ModRef> > >,
std::less<llvm::MachineInstr*>,
std::allocator<std::pair<llvm::MachineInstr* const, std::pair<unsigned
int, llvm::VirtRegMap::ModRef> > > >::erase (this=0x8d1afcc,
__x=@0xbfffe57c) at /usr/include/c++/4.0.0/bits/stl_tree.h:1007
#4  0x0073e094 in std::multimap<llvm::MachineInstr*, std::pair<unsigned
int, llvm::VirtRegMap::ModRef>, std::less<llvm::MachineInstr*>,
std::allocator<std::pair<llvm::MachineInstr* const, std::pair<unsigned
int, llvm::VirtRegMap::ModRef> > > >::erase (this=0x8d1afcc,
__x=@0xbfffe57c) at /usr/include/c++/4.0.0/bits/stl_multimap.h:414
#5  0x0073e0e4 in llvm::VirtRegMap::RemoveFromFoldedVirtMap
(this=0x8d1afa0, MI=0x8b417f0) at VirtRegMap.h:145
#6  0x0019f398 in (anonymous namespace)::LocalSpiller::RewriteMBB
(this=0x8b29460, MBB=@0x8b31230, VRM=@0x8d1afa0) at VirtRegMap.cpp:715
#7  0x007435b8 in (anonymous
namespace)::LocalSpiller::runOnMachineFunction (this=0x8b29460,
MF=@0x8b2b9d0, VRM=@0x8d1afa0) at VirtRegMap.cpp:219
#8  0x00155708 in (anonymous
namespace)::RegAllocChordal_Fer::runOnMachineFunction (this=0x8b0d280,
mf=@0x8b2b9d0) at ChordalAlloc_Fernando.cpp:757
#9  0x003e5ce4 in llvm::MachineFunctionPass::runOnFunction
(this=0x8b0d280, F=@0x8b02940) at
/private/var/automount/u/gs3/fernando/Programs/ppc_llvm/include/llvm/CodeGen/MachineFunctionPass.h:38
#10 0x0086ad88 in llvm::FunctionPassManagerT::runPass (this=0x8b02360,
P=0x8b0d280, F=0x8b02940) at PassManagerT.h:795
#11 0x008892ec in llvm::PassManagerT<llvm::FTraits>::runPasses
(this=0x8b02378, M=0x8b02940, LastUserOf=@0xbfffeab8) at
PassManagerT.h:596
#12 0x0088c9b4 in llvm::PassManagerT<llvm::FTraits>::runOnUnit
(this=0x8b02378, M=0x8b02940) at PassManagerT.h:282
#13 0x0086af54 in llvm::FunctionPassManagerT::runOnFunction
(this=0x8b02360, F=@0x8b02940) at PassManagerT.h:884
#14 0x002463d4 in llvm::FunctionPass::runOnModule (this=0x8b02360,
M=@0x8b00850) at Pass.cpp:249
#15 0x0086ae8c in llvm::ModulePassManager::runPass (this=0x8b005c0,
P=0x8b02360, M=0x8b00850) at PassManagerT.h:837
#16 0x00888be4 in llvm::PassManagerT<llvm::MTraits>::runPasses
(this=0x8b005d8, M=0x8b00850, LastUserOf=@0xbfffecd8) at
PassManagerT.h:596
#17 0x0088add8 in llvm::PassManagerT<llvm::MTraits>::runOnUnit
(this=0x8b005d8, M=0x8b00850) at PassManagerT.h:282
#18 0x002450c4 in llvm::ModulePassManager::runOnModule (this=0x8b005c0,
M=@0x8b00850) at PassManagerT.h:905
#19 0x0024539c in llvm::PassManager::run (this=0xbffff388, M=@0x8b00850)
at Pass.cpp:85
#20 0x00004dd0 in main (argc=5, argv=0xbffff4dc) at llc.cpp:234