enhance bugpoint to reduce global initializers

[lattner]

Bugzilla Link	960
Resolution	FIXED
Resolved on	Feb 22, 2010 12:43
Version	trunk
OS	All
CC	@isanbard

Extended Description

It would be wonderful if someone would enhance bugpoint to prune down the list of global var initializers
when some are required to provoke a compiler crash. Domagoj Babic produced a patch that does exactly
this:
http://lists.cs.uiuc.edu/pipermail/llvmbugs/2006-October/002004.html

... but his patch does not use the list reducer. It would be great if someone could pick this up and finish
it.

-Chris

[isanbard]

I have a potential patch for this (it compiles! Ship it!). Is there a test case that I can use to verify this
against Domagoj's patch?

-bw

[lattner]

I'd suggest going into lib/CodeGen/AsmPrinter.cpp. In the
AsmPrinter::EmitGlobalConstant method, add:

assert(CV->isNullValue());

you just inserted a 'bug'. Recompile llc, then use:

bugpoint -run-llc myprogram.bc

Which should reduce it down to just one global that has a non-zero initializer.

-Chris

[isanbard]

Putting that line in didn't work. Bugpoint didn't even execute that method. :-(

-bw

[lattner]

Right, bugpoint doesn't run the code generator.  however, it should fork off llc, which should.

Make sure you have a complex-enough .bc file, and use bugpoint -run-llc.

[isanbard]

I did run it with -run-llc, but nothing. I thought that the file was complex enough. Anyway, Domagoj
checked and it did produce the same result as his patch. I submitted the patch. It can stand some
improvement (like not cloning the Module each time).

-bw

[isanbard]

Here's the patch:

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20061023/039047.html

[lattner]

Isn't this done, if so, shouldn't it be closed?

-Chris

[isanbard]

Good point. Fixed here:

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20061023/039047.html