| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | pgbf(at)twiska(dot)com, pgsql-hackers(at)lists(dot)postgresql(dot)org |
| Subject: | Re: snapper vs. HEAD |
| Date: | 2020-03-30 04:26:52 |
| Message-ID: | 25532.1585542412@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
I wrote:
> I'm forced to the conclusion that the important difference between
> snapper and skate is that the latter uses --enable-cassert and the
> former doesn't, because that's the only remaining difference between
> how I built a working version before and the not-working version
> I have right now.
Confirmed: building gistget with --enable-cassert, and all of snapper's
compile/link options, produces something that passes regression.
The generated asm differs in a whole lot of details, but it looks like
the compiler remembers to annul the branch delay slot in all the
relevant places:
.loc 1 163 0
addcc %l7, -1, %l7
.L186:
be,pn %icc, .L80
add %l6, 48, %l6
...
.loc 1 189 0
be,a,pt %icc, .L186
addcc %l7, -1, %l7
...
.loc 1 183 0
lduh [%g4+12], %g4
andcc %g4, 1, %g0
be,a,pt %icc, .L186
addcc %l7, -1, %l7
andcc %o7, 0xff, %g0
bne,a,pt %icc, .L186
addcc %l7, -1, %l7
regards, tom lane
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