Replace all uses of an instruction to delete with an Undef value at llvm?
I would like to replace all uses of an instruction, which is a function call that I want to delete, with an Undef value.
First, I declare my undef value like this
UndefValue *undefval;
and then I try to replace all the uses of my instruction
currentInst->replaceAllUsesWith(undefval);
currentInst is an
Instruction* currentInst;
value which refers to my current instruction. This causes LLVM to produce the following error ans assertion:
opt: /home/troulakis/Documents/LLVM_Project/llvm/llvm/lib/IR/Value.cpp:332: void llvm::Value::replaceAllUsesWith(llvm::Value *): Assertion `New->getType() == getType() && "replaceAllUses of value with new value of different type!"' failed.
0 0x160e678 llvm::sys::PrintStackTrace(_IO_FILE*) (/usr/local/bin/opt+0x160e678) 1 0x160fbdb (/usr/local/bin/opt+0x160fbdb) 2 0x7f7752596340 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x10340) 3 0x7f77515aacc9 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x36cc9) 4 0x7f77515ae0d8 abort (/lib/x86_64-linux-gnu/libc.so.6+0x3a0d8) 5 0x7f77515a3b86 (/lib/x86_64-linux-gnu/libc.so.6+0x2fb86) 6 0x7f77515a3c32 (/lib/x86_64-linux-gnu/libc.so.6+0x2fc32) 7 0x15be04f (/usr/local/bin/opt+0x15be04f) 8 0x7f775136fda7 (anonymous namespace)::MyPass::runOnFunction(llvm::Function&) (../../../Release+Asserts/lib/PassRAF.so+0x6da7) 9 0x15a1ab4 llvm::FPPassManager::runOnFunction(llvm::Function&) (/usr/local/bin/opt+0x15a1ab4) 10 0x15a1d3b llvm::FPPassManager::runOnModule(llvm::Module&) (/usr/local/bin/opt+0x15a1d3b) 11 0x15a22d7 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/usr/local/bin/opt+0x15a22d7) 12 0x5af6db main (/usr/local/bin/opt+0x5af6db) 13 0x7f7751595ec5 __libc_start_main (/lib/x86_64- linux-gnu/libc.so.6+0x21ec5) 14 0x59f559 _start (/usr/local/bin/opt+0x59f559)
Stack dump:
Program arguments: opt -load ../../../Release+Asserts/lib/PassRAF.so -time-passes -instnamer -PassRAF
Running pass 'Function Pass Manager' on module ''.
./PassRAF: line 15: 7227 Aborted (core dumped)
Any ideas what's wrong? I have wrong declare of undef value?
When you write this:
UndefValue *undefval;
You're just declaring a pointer of type UndefValue , and not storing anything in it. Instead, you need to get an instance of UndefValue for the type of the instruction you want to replace, using the UndefValue::get factory function. Something like this:
currentInst->replaceAllUsesWith(UndefValue::get(currentInst->getType())
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