[llvm-commits] [PATCH][RFC] Disable data region directives

[Joe Abbey]

Jim,

Without going into too much detail, current llc produced ios-arm assembly cannot be assembled by Xcode <= 4.4.1.  This is because as of r157062 .data_region directives are being emitted in asm.  The latest and greatest Apple cctools have no issue, but alas... older Xcodes are left in the lurch despite still being in use.

The intention is to provide a switch to llc to omit the emission of .data_regions so that older assemblers can still proceed.  Since the directive seems primarily useful for introspection tools, it seems harmless to disable.  I've tested this internally and it seems to be the case that the directives are optional, but I'm sure you have a better perspective on the purpose of identifying data regions through Mach-O  load commands.

As an aside, I'd <3 someone to update https://developer.apple.com/library/mac/#documentation/developertools/conceptual/MachORuntime/Reference/reference.html

Joe
 
> 
> I don't understand why this is desirable. Can you elaborate? What's the use case?
> 
>> I propose the following patch to disable data region directive generation:
>> 
>>   -disable-data-region-directives         - Disable data region directives which older assemblers reject

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