delorie.com/archives/browse.cgi   search  
Mail Archives: djgpp/2000/04/10/17:21:55

From: Gero Timann <geti AT online DOT de>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: inefficiency of GCC output code & -O problem
Date: Mon, 10 Apr 2000 21:36:55 +0200
Organization: 1&1 Telekommunikation GmbH
Lines: 44
Message-ID: <38F22D57.4A5D799B@online.de>
References: <38F20E7A DOT 3330E9A4 AT mtu-net DOT ru>
NNTP-Posting-Host: p3e9bdd93.dip0.t-ipconnect.de
Mime-Version: 1.0
X-Trace: news.online.de 955396150 22017 62.155.221.147 (10 Apr 2000 19:49:10 GMT)
X-Complaints-To: abuse AT online DOT de
NNTP-Posting-Date: 10 Apr 2000 19:49:10 GMT
X-Mailer: Mozilla 4.7 [en] (Win95; I)
X-Accept-Language: en,de,fr
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

Hi,Hi!

Do you have already look at the output of the new pgcc/ecgs-gcc 
compiler ? (Andris Pavenis has ported this to the DJGPP-environment,
downloadable from
   http://ieva05.lanet.lv/~pavenis/
)
Many of the awfull code-generations and C++-problems, you described, 
are replaced/solved now.

Gero

"Alexei A. Frounze" wrote:

> Hi!
>
> 1st question...
>
> Why GCC output too much redundant code?
> I mean, it always put values to the CPU registers, although it's possible to
> make the same operation w/o taking registers?
>
> Also why GCC does type cast of byte/word <-> dword values so awful? It allocates
> some extra bytes on the stack, put values there and get them back...
>
> Is it a normal thing, if one instruction that adds something to ESP(or EBP) is
> followed by sutracting instruction that works with the same register?
>
> ... I'll find some extra info later ...
>
> 2nd question...
>
> Why the "-O2" switch works normally for pure C source code and makes compiler
> failing on the source with inline assembly (in the .S file made out of such .C
> an error encounters:
> "Error: Error: Missing ')' assumed"
> "Error: Error: Ignoring junk `(%ebp))' after expression")?
> W/o the -O2 switch it's compiled fine. Isn't it a little bit strange?
>
> Thanks in advance.
> Alexei A. Frounze
> -----------------------------------------
> Homepage: http://alexfru.chat.ru
> Mirror:   http://members.xoom.com/alexfru

- Raw text -


  webmaster     delorie software   privacy  
  Copyright 2019   by DJ Delorie     Updated Jul 2019