[GR-47755] Refactor dwarf constants.

[graalvmbot]

No description provided.

[koutheir]

@adinn, the constant DW_CFA_CIE_version is defined as 1. According to DWARF standards version 2 through 5, the value that should be specified is never 1. Is this a bug? If so, which CIE version are you generating in GraalVM?

DWARF version	CIE version number
2.0.0	2
3	3
4	4
5	4

[koutheir]

@adinn, given that GraalVM does not emit the fields address_size and segment_size of the CIE, this version must be 2 or 3.

Am I missing something?

[adinn]

@koutheir

I believe that the frame section generates DWARF that is compatible with DWARF version 2 (which, I think, is what you were suggesting).

Section 7.23 of the DWARF 2 standard states that the initial version is 1, that being the version appropriate to the current standard (i.e. DWARF 2).

Likewise, Appendix F of the DWARF 4 standard states that the correct version for for DWARF 2 content is 1.

So, I don't think we are generating invalid frame content.

However it is arguable that the enum should not actually specify DW_CFA_CIE_version as 1 since version values 3 and 4 are also legitimate.

In other cases where the generator has made a choice for a version or some other range value it has used a local definition rather than an enum (see for example DwarfDebugInfo.LANG_ENCODING).

It might be better to define enum tags providing the encoding appropriate to each DWARF level e.g.

DW_CFA_CIE_version_DWARF_2(byte)1)
DW_CFA_CIE_version_DWARF_3(byte)3)
DW_CFA_CIE_version_DWARF_4(byte)4)

If you raise an issue for that I will be happy to fix it.

[koutheir]

You're right, I confused the CIE version with another version in the standard text of version 2.0.0. I'm sorry.