Debug info not preserved by llvm-as (LLParser)?

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1

Hi there,

If I run:

clang -S -emit-llvm -o - -g test.c

for a trivial test.c I see debug info in the IR as expected. However, if I run:

clang -S -emit-llvm -o - -g test.c | llvm-as | llvm-dis

the debug info is stripped. Is this intentional? If so, is there a way to force the debug metadata to make its way through the pipeline? This is on either LLVM 3.5 or LLVM 3.4.

This has come up for me because I was hoping to provide IR in place of source code in a certain part of our application and while it works any unit tests that rely on debug info are broken. Tracking down the issue let me to this.

Peter Zion

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(oops, dropped the ML by accident)

3

Hi David,

Indeed, I built stock 3.5.1 LLVM+Clang and the problem went away. Diffing the resulting IR I found that the clang I was using (stock Xcode ‘Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)’) was not including !llvm.module.flags with references to the DWARF and debug info versions. When I manually added this to the output from the Xcode Clang the problem went away; so I think it’s safe to assume that our compiler has the same problem as we are also not including the llvm.module.flags. Thanks for pointing me in the right direction!

Peter Zion