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Re: Handling of -fpic in ASM_OUTPUT_MI_THUNK in sparc
- To: Jason Merrill <jason at cygnus dot com>
- Subject: Re: Handling of -fpic in ASM_OUTPUT_MI_THUNK in sparc
- From: John Carr <jfc at tiac dot net>
- Date: Thu, 20 Nov 1997 19:55:29 -0500
- cc: Teemu Torma <tot at trema dot com>, egcs at cygnus dot com
> Well, I suppose we could use call in all cases. That would simplify the
> code. Does anyone with more SPARC experience have an opinion?
On SPARC processors other than UltraSPARC call is at least as fast as
jmpl. On UltraSPARC using a call without a matching return confuses
the return prediction stack. It takes an extra 2-4 cycles to fetch
the correct set of instructions. (For this reason, I think the recent
change to use call instead of rd %pc for V9 PIC was wrong even though
rd takes longer to execute.)
This is another thing we shouldn't be touching at so late in the
release cycle. I have some changes I was planning to send after the
release.