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Re: [PATCH] rl78 anddi3 improvement
- From: DJ Delorie <dj at redhat dot com>
- To: Sebastian Perta <Sebastian dot Perta at renesas dot com>
- Cc: law at redhat dot com, gcc-patches at gcc dot gnu dot org
- Date: Tue, 19 Dec 2017 14:59:26 -0500
- Subject: Re: [PATCH] rl78 anddi3 improvement
- Authentication-results: sourceware.org; auth=none
Right, when doing 64-bit operations on an 8-bit mcu with limited
registers, a hand-written assembler routine that you call as needed will
beat anything gcc spits out - for size-per-call. And I had a lot of
trouble getting gcc to deal with the rl78's limited register set and
addressing modes - compiling libgcc/libstdc++ is a torture test for
alloc/reload on small mcus. That forced me to be conservative, and add
the virtual ISA that gcc can work with.
So I'm OK with your approach, and if you come up with something even
better, I'm OK with that too :-)
(pending reviews, of course, that's next ;)