How do I print out an Instruction in LLVM?

问题

for (BasicBlock::iterator i = bb->begin(), e = bb->end(); i != e; ++i) {
    i.print(errs()); ???

I am writing an LLVM PASS and I want to get the list of instructions inside the basic block, but how do print them out on the console so I can see them? The code above shows the code i have tried, it iterates through every instruction in the basic block but I get the error below for the print function.

error: ‘llvm::BasicBlock::iterator’ has no member named ‘print’ i.print(errs());

Is there a better approach to printing out instructions?

回答1:

The problem is that you are trying to print the iterator and not an instruction. You can try one of the following approaches. You can print the instructions in a basic block by either printing the basic block or printing each instruction:

BasicBlock* bb = ...; // 
errs() << *bb;
for (BasicBlock::iterator i = bb->begin(), e = bb->end(); i != e; ++i) {
  Instruction* ii = &*i;
  errs() << *ii << "\n";

Both prints will output the same results.

来源：https://stackoverflow.com/questions/41959551/how-do-i-print-out-an-instruction-in-llvm