LLVM: Instruction does not dominate all uses

I think that after splitting, instructions are located in different basic blocks. If I split the block into 10-15 instructions, all is OK. How can I predict/check and avoid this errors?

If your pass just splits basicblocks, and takes as input a correct IR file, then there is no reason to be errors of dominations in the resulting IR. There are some reason that could induce this kind of error : * you moved or created new instructions * you added transitions between basicblocks that did not exist before

It would help if you provided more details. A minimal LLVM IR snippet of the code before splitting, and then after splitting. In general what @JulienH. said makes sense.

I'm sorry, i have other passes and one of them add/modifies instructions via llvm::InlineAsm and llvm::ReplaceInstWithInst

Your post still misses details, it would help if I could see the full IR, or at least a larger subset of it. Anyway, each time you delete an instruction, you should check that this instruction has no later use (in your error message, you see there exist some use_empty() function in LLVM)

1 Answer 1

In your first version, you had instruction after a terminator instruction, which was incorrect since this instruction is never executed.

In your second version (not mentioned here, please use stackoverflow instead of private emails. ) are using %call (in the store inst) before defining it (%call = . ), so clearly your definition does not precede every use. But as I said, the store should not be after the invoke, because invoke is a terminatorinst.

The solution is to put your store in the next basic block (you can create a new one) :

%invoke.cont %call = invoke i8* @_ZNKSs5c_strEv(%"class.std::basic_string"* @loadedFile) to label %invoke.cont2_before unwind label %lpad1 invoke.cont2_before: ; preds = %invoke.cont store i8* %call, i8** %reduced_var br label %invoke.cont2 invoke.cont2: ; preds = %main_block, %invoke.cont2_before %call4 = invoke i32 @_ZStorSt13_Ios_OpenmodeS_(i32 8, i32 16) to label %invoke.cont3_before unwind label %lpad1