[llvm-commits] [llvm] r156383 - in /llvm/trunk: include/llvm/Bitcode/LLVMBitCodes.h lib/Bitcode/Reader/BitcodeReader.cpp

[Bill Wendling]

On May 22, 2012, at 3:55 AM, Kuperstein, Michael M wrote:

> Hello,
> 
> The commit below (156383) broke binary compatibility with LLVM 3.0. 
> The LLVM 3.1 branch generates bitcode files with the new TYPE_CODE_FUNCTION, and can read both. However, 3.0 still generated TYPE_CODE_FUNCTION_OLD (it is named TYPE_CODE_FUNCTION in 3.0, the change to OLD was made somewhere between 3.0 and the final 3.1 branch) records. This means 3.1 is still able to read 3.0 bitcode, but 3.2 will not be able to.
> 
> I'm attaching a small test-case. I will be happy to provide a proper patch that resurrects TYPE_CODE_FUNCTION_OLD, if that's helpful.
> 
I'm not really in favor of reverting this behavior. The old code was in there by accident. It's unfortunate that some bitcodes were generated with the outdated codes, but it's not something we should wish to perpetuate. There is a workaround: use the 3.0 or 3.1 `llvm-dis' tool to create a text version of the bitcode file and then run the new `llvm-as' on it.

-bw