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Re: [avr-gcc-list] Inconsisten behaviour of switch statement
From: |
Joerg Wunsch |
Subject: |
Re: [avr-gcc-list] Inconsisten behaviour of switch statement |
Date: |
Tue, 27 Mar 2007 07:10:06 +0200 (MET DST) |
Paulo Marques <address@hidden> wrote:
> This is not a "missed optimization".
I agree.
> I would need some time to build an actual test case to show this.
> Unfortunately, time is something that I don't have abundantly right
> now :(
I tried a quick test with some variations of:
volatile int i;
extern void dosomething(int);
void
decide(void)
{
switch (i) {
case 0: dosomething(42); break;
case 1: dosomething(99); break;
case 5: dosomething(95); break;
case 65200: dosomething(90); break;
case 30100: dosomething(85); break;
default: dosomething(0); break;
}
}
....and could not get it to reproduce the bug. While it is never using
a jump table for such a relatively small switch statement, it always
loaded i into a register pair first, and then decided on it. This is
with GCC 4.1.1.
Knut, can you provide us an example that reproduces the problem?
--
cheers, J"org .-.-. --... ...-- -.. . DL8DTL
http://www.sax.de/~joerg/ NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)
- [avr-gcc-list] Inconsisten behaviour of switch statement, Schwichtenberg, Knut, 2007/03/26
- Re: [avr-gcc-list] Inconsisten behaviour of switch statement, Preston Wilson, 2007/03/26
- RE: [avr-gcc-list] Inconsisten behaviour of switch statement, Eric Weddington, 2007/03/26
- RE: [avr-gcc-list] Inconsisten behaviour of switch statement, Schwichtenberg, Knut, 2007/03/26
- RE: [avr-gcc-list] Inconsisten behaviour of switch statement, Eric Weddington, 2007/03/26
- RE: [avr-gcc-list] Inconsisten behaviour of switch statement, Dave Hansen, 2007/03/26
- RE: [avr-gcc-list] Inconsisten behaviour of switch statement, Eric Weddington, 2007/03/26
- RE: [avr-gcc-list] Inconsisten behaviour of switch statement, Paulo Marques, 2007/03/26
- Re: [avr-gcc-list] Inconsisten behaviour of switch statement,
Joerg Wunsch <=
- RE: [avr-gcc-list] Inconsisten behaviour of switch statement, Schwichtenberg, Knut, 2007/03/27
- Re: [avr-gcc-list] Inconsisten behaviour of switch statement, Joerg Wunsch, 2007/03/27
- RE: [avr-gcc-list] Inconsisten behaviour of switch statement, Schwichtenberg, Knut, 2007/03/27
- RE: [avr-gcc-list] Inconsisten behaviour of switch statement, Eric Weddington, 2007/03/27