Re: Optimizing in assembly language

Randall Hyde <rhyde@transdimension.com> wrote:
[...]
: Clearly, given the necessary resources (time, skill, etc.), an expert
: assembly program *can* beat a compiler for a given *instance* of the
: program.


It's not clear to me. For a finite machine, given sufficient
resources, a programmer and a compiler could each find an optimum
(i.e., unbeatable) "instance" of the program.


: So here's my question: why can't we write an "optimizing assembler"
: that lets the programmer specify machine sequences and the assembler
: does the same kinds of "book keeping" that a HLL compiler would do.
: Sure, optimization is a bit more difficult at this level and you'd
: have to allow the programmer to disable the optimizations on a
: statement by statement basis (since sometimes the programmer really
: does know better).


AFIK, all low-level language translators (attempt to) decompile
decompile programs in their source language into some sort of
intermediate code that can be optimized and code-generated into the
target language. AFIK, such systems don't handle self-modifying code
and tend to have problems with indirect jumps.


Tom Payne

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