Re: snapper vs. HEAD - Mailing list pgsql-hackers

From Tom Lane
Subject Re: snapper vs. HEAD
Date
Msg-id 25532.1585542412@sss.pgh.pa.us
Whole thread Raw
In response to Re: snapper vs. HEAD  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: snapper vs. HEAD  ("Tom Turelinckx" <pgbf@twiska.com>)
List 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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