... or a compiler optimizing aggressively?

By: Peter E. Fry (pfry.delete@this.tailbone.net), August 4, 2018 8:53 am
Room: Moderated Discussions
Heikki Kultala (heikki.kultala.delete@this.tut.fi) on August 4, 2018 8:13 am wrote:
[...]
> Are you sure it was the processor, not your compiler optimizaing those MUL's away?
>
> Compilers can be _very smart_ nowadays tracking where values come from and replacing big pieces
> of calculation code with compile-time calculated versions on naiively written benchmark programs.

Heh. I should have mentioned: I use the compiler for structure, but I write lots of bits in assembler. I think the AMD MUL deal was the first time I used GCC's inline assembler: compile to assembler, then assemble... uh... to assembler (listing) to get the precise instruction output. Oh, and the data was not known at compile time. Modern compilers are impressive, but...
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TopicPosted ByDate
TIL: simple vs complex addressing is resolved at rename time (probably)Travis2018/08/03 01:34 PM
  TIL: simple vs complex addressing is resolved at rename time (probably)foobar2018/08/04 01:40 AM
    TIL: simple vs complex addressing is resolved at rename time (probably)anon2018/08/04 05:05 AM
      TIL: simple vs complex addressing is resolved at rename time (probably)foobar2018/08/04 07:00 AM
        TIL: simple vs complex addressing is resolved at rename time (probably)anon2018/08/04 08:32 AM
          TIL: simple vs complex addressing is resolved at rename time (probably)foobar2018/08/04 09:48 AM
            TIL: simple vs complex addressing is resolved at rename time (probably)anon2018/08/04 10:19 AM
  Data-dependent instruction latencyPeter E. Fry2018/08/04 07:14 AM
    ... or a compiler optimizing aggressively?Heikki Kultala2018/08/04 08:13 AM
      ... or a compiler optimizing aggressively?Peter E. Fry2018/08/04 08:53 AM
    Data-dependent instruction latencyTravis2018/08/04 03:33 PM
      Data-dependent instruction latencyPeter E. Fry2018/08/05 09:13 AM
        Data-dependent instruction latencyTravis2018/08/05 04:55 PM
          Data-dependent instruction latencyPeter E. Fry2018/08/06 07:34 AM
            Data-dependent instruction latencyTravis2018/08/06 05:10 PM
              Data-dependent instruction latencyPeter E. Fry2018/08/07 07:09 AM
                Data-dependent instruction latencyPeter E. Fry2018/08/07 07:11 AM
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