| From: | Greg Stark <stark(at)mit(dot)edu> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Xi Wang <xi(dot)wang(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [RFC] overflow checks optimized away |
| Date: | 2015-12-03 16:56:17 |
| Message-ID: | CAM-w4HNKwWShhVf6jKgQA=bc7UhmXveO-wQ43QAtThAb1=jv6A@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Dec 3, 2015 at 2:51 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I can't see us moving the compiler goalposts one inch for this.
> "I'm going to break building on your compiler in order to work around
> bugs in somebody else's compiler" isn't gonna fly.
Fwiw the builtins offer a carrot as well. They promise to use
architecture features like arithmetic status flags which can be faster
than explicit comparisons and also avoid extra branches that can mess
up cache and branch prediction.
I was proposing to implement wrappers around them that do the checks
manually if they're not present.
--
greg
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