[llvm-dev] Why is printing an Instruction so slow?

don hinton via llvm-dev llvm-dev at lists.llvm.org
Mon Oct 5 09:05:15 PDT 2015

Hi Steve:

llvm::errs() is unbuffered, so that might explain it.  Could you try
llvm::outs() instead and see if that helps.


On Mon, Oct 5, 2015 at 11:17 AM, Stephen Thomas via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi all,
> When writing my custom passes, I often emit log messages to llvm::errs()
> like so:
> llvm::errs() << "Could not handle instruction: " << *Inst << std::endl;
> where Inst is a pointer to an Instruction.
> I've profiled my code and found that this way of printing an Instruction
> takes a very long time: indeed, it is the bottleneck of my pass.
> Of course, I could always switch these log messages off for production
> runs, but during development and debugging, I'd like to have them on to
> make debugging much easier.
> Is there a faster way to print an Instruction?
> Thanks,
> Steve
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20151005/aecb8c5b/attachment.html>

More information about the llvm-dev mailing list