[clang] [llvm] [MC,llvm-readobj,yaml2obj] Support CREL relocation format (PR #91280)

[James Henderson via cfe-commits]

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@@ -86,6 +86,8 @@ DYNAMIC_TAG(RELRSZ, 35)  // Size of Relr relocation table.
 DYNAMIC_TAG(RELR, 36)    // Address of relocation table (Relr entries).
 DYNAMIC_TAG(RELRENT, 37) // Size of a Relr relocation entry.
 
+DYNAMIC_TAG(CREL,  38)   // CREL relocation table
+
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jh7370 wrote:

> I understand the concern but this is just impossible given the essential state of the generic ABI...

I don't understand this comment. There's an active mailing list, where proposals are discussed and adopted, even if there's no fully published document, so a different proposal could easily come up whilst this is still under review. Perhaps it'll be implemented in GNU/Solaris/... initially with the same generic value. Whose meaning of the value should then win?

In the worst case, maybe the generic ABI list ends up rejecting this crel proposal. The values aren't reserved for LLVM usage, so the next proposal to come along will use those same values and we then have a clash between what LLVM wants to use the value for (and there might be objects out there using that value, if this feature is adopted in an LLVM release), which would cause us all sorts of headaches in the future.

https://github.com/llvm/llvm-project/pull/91280