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Target attribute hooks questions
- From: Kyrill Tkachov <kyrylo dot tkachov at arm dot com>
- To: "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Tue, 05 May 2015 14:38:11 +0100
- Subject: Target attribute hooks questions
- Authentication-results: sourceware.org; auth=none
I'm looking at implementing target attributes for aarch64 and I have some questions about the hooks involved.
I haven't looked at this part of the compiler before, so forgive me if some of them seem obvious. I couldn't
figure it out from the documentation (https://gcc.gnu.org/onlinedocs/gccint/Target-Attributes.html#Target-Attributes)
* Seems to me that TARGET_OPTION_VALID_ATTRIBUTE_P is the most important one that parses
the string inside the __attribute__ ((target ("..."))) and sets the target-specific
flags appropriately. Is that correct?
* What is TARGET_ATTRIBUTE_TABLE used for? It's supposed to map attributes to handlers?
Isn't that what TARGET_OPTION_VALID_ATTRIBUTE_P is for?
* What is the use of TARGET_OPTION_SAVE and TARGET_OPTION_RESTORE? Is that used during
something like LTO when different object files and functions are compiled with different
flags? Are these functions just supposed to 'backup' various tuning and ISA decisions?
* Is TARGET_COMP_TYPE_ATTRIBUTES the one that's supposed to handle incompatible attributes
being specified? (for example incompatible endianness or architecture levels)?
Thanks for any insight,