[llvm-dev] mutateType on AllocaInst problem

[Pierre Gagelin via llvm-dev]

Hi,

I'm trying to replace pointer typed alloca instructions to allocate a
vector of pointers. The idea is to change from [1] to [2]:

[1]: %0 = alloca i<N>*
[2]: %0 = alloca <3 x i8*>

I did it this way:
  - first, create and insert [2] (for debug purpose, not necessary to
insert)
  - mutate type so that replaceAllUsesWith can be called in a correctly
typed way
  - replace all uses of the old allocation to the new one (not necessary
too)

Here's the associated code running on each alloca instructions from each
function given to the function pass:

void __replace_alloca_vector_IRBuilder(AllocaInst *AI) {
  if(AI->getAllocatedType()->isPointerTy()){
    LLVMContext *Context = &(AI->getContext());
    IRBuilder<> IRB(*Context);

    VectorType *FDP_fatvector = VectorType::get(
      PointerType::getInt8PtrTy(*Context),
      3
    );

    // two different ways depending on wether to create and insert or just
create
    // AllocaInst *FDP_AI = new AllocaInst(cast<Type>(FDP_fatvector));
    IRB.SetInsertPoint(AI);
    AllocaInst *FDP_AI = IRB.CreateAlloca(cast<Type>(FDP_fatvector));

    cast<Value>(AI)->mutateType(cast<Value>(FDP_AI)->getType());
    cast<Value>(AI)->replaceAllUsesWith(cast<Value>(FDP_AI));
  }
}

I am getting an error at optimization time. After my pass ran, during the
Bitcode Writer pass time:

opt: /home/pierre/Desktop/llvm/lib/Bitcode/Writer/ValueEnumerator.h:162:
unsigned int llvm::ValueEnumerator::getTypeID(llvm::Type*) const: Assertion
`I != TypeMap.end() && "Type not in ValueEnumerator!"' failed.
#0 0x0000000002a95b5c llvm::sys::PrintStackTrace(llvm::raw_ostream&)
/home/pierre/Desktop/llvm/lib/Support/Unix/Signals.inc:400:0
#1 0x0000000002a95edf PrintStackTraceSignalHandler(void*)
/home/pierre/Desktop/llvm/lib/Support/Unix/Signals.inc:468:0
#2 0x0000000002a94145 llvm::sys::RunSignalHandlers()
/home/pierre/Desktop/llvm/lib/Support/Signals.cpp:44:0
#3 0x0000000002a953a8 SignalHandler(int)
/home/pierre/Desktop/llvm/lib/Support/Unix/Signals.inc:254:0
#4 0x00007f04b0294d10 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x10d10)
#5 0x00007f04af6c2267 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x35267)
#6 0x00007f04af6c3eca abort (/lib/x86_64-linux-gnu/libc.so.6+0x36eca)
#7 0x00007f04af6bb03d (/lib/x86_64-linux-gnu/libc.so.6+0x2e03d)
#8 0x00007f04af6bb0f2 (/lib/x86_64-linux-gnu/libc.so.6+0x2e0f2)
#9 0x000000000204de7e llvm::ValueEnumerator::getTypeID(llvm::Type*) const
/home/pierre/Desktop/llvm/lib/Bitcode/Writer/ValueEnumerator.h:162:0
#10 0x00000000020454cc (anonymous
namespace)::ModuleBitcodeWriter::writeInstruction(llvm::Instruction const&,
unsigned int, llvm::SmallVectorImpl<unsigned int>&)
/home/pierre/Desktop/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:2509:0
#11 0x00000000020474eb (anonymous
namespace)::ModuleBitcodeWriter::writeFunction(llvm::Function const&,
llvm::DenseMap<llvm::Function const*, unsigned long,
llvm::DenseMapInfo<llvm::Function const*>,
llvm::detail::DenseMapPair<llvm::Function const*, unsigned long> >&)
/home/pierre/Desktop/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:2866:0
#12 0x000000000204be9d (anonymous
namespace)::ModuleBitcodeWriter::writeModule()
/home/pierre/Desktop/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:3588:0
#13 0x000000000204bc70 (anonymous
namespace)::ModuleBitcodeWriter::writeBlocks()
/home/pierre/Desktop/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:3537:0
#14 0x000000000204bc49 (anonymous namespace)::BitcodeWriter::write()
/home/pierre/Desktop/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:3532:0
#15 0x000000000204c419 llvm::WriteBitcodeToFile(llvm::Module const*,
llvm::raw_ostream&, bool, llvm::ModuleSummaryIndex const*, bool)
/home/pierre/Desktop/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp:3703:0
#16 0x0000000002037ed6 (anonymous
namespace)::WriteBitcodePass::runOnModule(llvm::Module&)
/home/pierre/Desktop/llvm/lib/Bitcode/Writer/BitcodeWriterPass.cpp:61:0
#17 0x00000000024da603 (anonymous
namespace)::MPPassManager::runOnModule(llvm::Module&)
/home/pierre/Desktop/llvm/lib/IR/LegacyPassManager.cpp:1603:0
#18 0x00000000024dad6d llvm::legacy::PassManagerImpl::run(llvm::Module&)
/home/pierre/Desktop/llvm/lib/IR/LegacyPassManager.cpp:1706:0
#19 0x00000000024dafad llvm::legacy::PassManager::run(llvm::Module&)
/home/pierre/Desktop/llvm/lib/IR/LegacyPassManager.cpp:1738:0
#20 0x00000000011b6d68 main
/home/pierre/Desktop/llvm/tools/opt/opt.cpp:673:0
#21 0x00007f04af6ada40 __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x20a40)
#22 0x000000000119b2b9 _start (/home/pierre/Desktop/build/bin/opt+0x119b2b9)
Stack dump:
0.    Program arguments: opt -load ../../../build/lib/LLVMFDP.so -fdp-func
type_out.bc -o type_out_func.bc
1.    Running pass 'Bitcode Writer' on module 'type_out.bc'.
Aborted (core dumped)

What is wrong with the vector type? Note that the exact same problem occurs
when I just try to mutate the type (removing replaceAllUsesWith) with the
new alloca instruction created but not inserted with IRBuilder.

Thanks a lot,
Pierre
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