using bugpoint

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1

I would like to use bugpoint to debug some of my passes. I have read the documentation, but I don't completely understand it.

I have a bitcode file X.bc that I transform using the following commands:

opt -mypass1 -f -o X.1.bc X.bc // transform with mypass1
llvm-link -f -o X.2.bc X.1.bc support.bc // link with support.bc
opt -mypass2 -f -o X.3.bc X.2.bc // transform with mypass2

After transforming X.bc into X.3.bc, if my passes work then I can run X.3.bc with llc using the following command:

llc X.3.bc arg1 arg2

That llc command is currently seg faulting because of a bug in one of my passes or in support.bc. Can I use bugpoint to find a smaller version of X.bc that produces the same problem? Specifically how would I call bugpoint to do that?

Thanks,
Ryan

2

Hi Ryan,

I have a bitcode file X.bc that I transform using the following commands:

opt -mypass1 -f -o X.1.bc X.bc // transform with mypass1
llvm-link -f -o X.2.bc X.1.bc support.bc // link with support.bc
opt -mypass2 -f -o X.3.bc X.2.bc // transform with mypass2

I suggest you do a debug build of LLVM and your pass (so assertions are
enabled), and add "-verify" to the opt command line after "-mypassX".
This may already be enough to narrow down where things are going wrong.

Ciao,

Duncan.

3

bugpoint X.3.bc -run-llc -tool-args arg1 arg2

/jakob

4

I made a mistake in my original description of the problem. I meant to say that after transforming X.bc into X.3.bc, if my passes work then I can run the program through the the lli interpreter, (not the llc compiler), using:

lli X.3.bc arg1 arg2

That lli command is currently seg faulting because of a bug in one of my
passes or in support.bc. Can I use bugpoint to find a smaller version of
X.bc that produces the same problem? Specifically how would I call
bugpoint to do that? Do I use bugpoint with the -run-lli? I was thinking I need to use -run-custom because the problem is in my transformations, not lli.

Jakob Stoklund Olesen wrote: