I have found what I think may be a bug with switch() But cannot reproduce
with a simple example. (Not exactly a Bug, but 256 Bytes of wasted space are
inserted in the machine code after a switch() statement, independent of the
optimise parameter .
I am using the Latest WIN32 Build (mspgcc-setup-2002-08-14) but earlier
versions have the bug as well.
My compile command line is as follows
g:\projects\msp_source\p1>msp430-gcc -c -g -O2 -mmcu=msp430x149 -Wall -Wstri
ct-prototypes -Wa,-ahlms=test.lst -Wall test.c
Extract from the Listing showing the flaw
10:test.c **** switch(c)
74 .stabn 68,0,10,.LM3-diag
75 .LM3:
76 0004 3F50 CFFF add #llo(-49), r15
77 0008 3F90 4A00 cmp #llo(74), r15
78 000c 4E2C jhs .L2
79 000e 0F5F rla r15
80 0010 104F 0000 br .L12(r15) ; .L12
81 .p2align 1,0
82 .L12:
83 0014 0000 .word .L2
84 0016 0000 .word .L2
85 0018 0000 .word .L2
... (for 256 bytes of FlashRom space)
155 00a4 0000 .word .L2
156 00a6 0000 .word .L2
157 .L6:
11:test.c **** {
12:test.c ****
13:test.c **** case 't' : //
14:test.c **** break;
The following is the minimum I have been able to create, and still reproduce
the flaw.
If I alter each case to become sequential (IE: 1,2,..7) The bug disappears.
If the last case statement is removed, the flaw disappears. Seems very
sensitive to something in the code
//-
test.c ---------------------------------------------------------------------
-------------------------------------------------------
#include <signal.h>
void diag(void)
{
int c;
if (c)
{
switch(c)
{
case 't' : //
break;
case 'a' :
break;
case 'c' : //
_EINT();
break;
case 's' : // Set time
break;
case '1' : // test ints
break;
case 'z' : // configure various parameters for device
break;
case 'f' : //
break;
case 'e' : //
break;
}
}
}
//--------------------------------------------------------------------------
--------------------
Am I doing something wrong to make the compiler produce this curious output,
or is this really a bug?
Cheers
Harry R. Lemmens
