N. Coesel wrote:
----- Original Message -----
From: "Peter Jansen" <[email protected]>
To: "Ivan Shcherbakov" <[email protected]>; "GCC for MSP430 -
http://mspgcc.sf.net"; <[email protected]>;
<[email protected]>
Sent: Wednesday, September 09, 2009 8:52 AM
Subject: Re: [Mspgcc-users] Announcement: MSP430-GCC 4.3.4
Hi Ivan,
Excellent news..
I tested it on a large code base I have, and it makes bigger code that
3.2.3 even with -Os.
For example with the MSP430_169_forweb project from
http://www.olimex.com/dev/soft/msp430/MSP430-169LCD.zip
The size with 3.2.3 is
text data bss dec hex filename
6048 522 1026 7596 1dac main.elf
With 4.3.4,
text data bss dec hex filename
8398 4 1542 9944 26d8 main.elf
I have had similar results on the H8 platform. Perhaps its better to
concentrate on porting to the latest version of GCC 3.x. The biggest problem
in GCC 3.x in general is that the long long (64 bit) type support is broken
(can lead to unexpected results).
There are a great many advantages to gcc 4.3 over gcc 3.x, and this is a
huge positive step for msp430-gcc.
It is a known issue that gcc 4.x can produce larger code than gcc 3.x in
some circumstances, and the effect is particularly noticeable for small
devices. One reason is, as Ivan pointed out, inlining of functions that
are used only once in a file. The correct handling of this is to either
declare the function "static" if it is internal to the file (in which
case only the inline version is generated), or "extern" (in which case
only the non-inline version is generated).
More generally, gcc 4.x is more aggressive in inlining functions than
previous generations. This is because function call overhead is
typically a bigger issue than a little extra code size on most of gcc's
targets. There are parameters used to tune gcc into getting a balance
here, which may not be ideal for small micros. Certainly in the case of
avr-gcc, users have found that a few command-line options can make a big
difference to the code size. Here are some options that are commonly
used with avr-gcc, to try out with msp430-gcc:
--param inline-call-cost=3" (or 2),
"-fno-split-wide-types" and "-fno-inline-small-functions"
mvh.,
David
