[PATCH] D94882: [MC] Upgrade DWARF version to 5 upon .file 0

[David Blaikie via Phabricator via llvm-commits]

dblaikie added a comment.

In D94882#2504207 <https://reviews.llvm.org/D94882#2504207>, @jhenderson wrote:

> Maybe a silly suggestion (and one that would need more discussion on the mailing lists), but why not just change the default version to 5 more widely? How often do people deliberately deviate from the default DWARF version in practice? To me, the proposed change feels like a bit of a hack for what is likely fairly unusual usage, and is only temporary, since likely most toolchains will want to change to DWARF v5 at some point going forward.

ie: you're suggesting users needing to use DWARFv4 line tables would access that functionality with a flag passed to the assembler (as they do today if they want to opt in to DWARFv5)?

I think part of the problem is that people aren't used to (ie: build systems and other infrastructure isn't designed for) having to pass a dwarf version to their assembler - the line table format hasn't changed since DWARFv2. So if you have run `-gN -S`, you can pass the resulting file to the compiler/assembler without any flags. So even if we switch the default - then people who aren't ready to switch to DWARFv4 are going to be in a possibly difficult situation of trying to teach their build system how to pass the appropriate flags to the assembler, etc.

I think maybe the way to think about it is that there wouldn't be a default DWARF version - it could always be determined by the presence/absence of a file 0.


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