Interesting. Almost any change to the parameters - add one or remove one
- and the compilation behaves properly.
Regards,
Steve
Rick Jenkins wrote:
Compiling:-
****************************************************************
// ARRAY_BUG.C demonstrates a compiler bug
unsigned char transducer_type;
long output_scale;
void show_array_bug( int limit, int gain, int p_off, int q_off )
{
static const long std_gain[4] = { 0L, 1L, 2L, 3L };
output_scale = ((long)limit * std_gain[transducer_type]);
}
****************************************************************
With:-
$ msp430-gcc -mmcu=msp430x149 -O2 -S array_bug.c
Produces:-
****************************************************************
.file "array_bug.c"
.arch msp430x149
/* Hardware multiplier registers: */
__MPY=0x130
__MPYS=0x132
__MAC=0x134
__MACS=0x136
__OP2=0x138
__RESLO=0x13a
__RESHI=0x13c
__SUMEXT=0x13e
.text
.p2align 1,0
.type std_gain.0,@object
.size std_gain.0,16
std_gain.0:
.long 0
.long 1
.long 2
.long 3
.p2align 1,0
.global show_array_bug
.type show_array_bug,@function
/***********************
* Function `show_array_bug'
***********************/
show_array_bug:
/* prologue: frame size = 0 */
.L__FrameSize_show_array_bug=0x0
.L__FrameOffset_show_array_bug=0x0
/* prologue end (size=0) */
mov r15, r14
mov r14, r15
rla r15
subc r15, r15
inv r15
rla r14
rlc r15
rla r14
rlc r15
rla r14
rlc r15
rla r14
rlc r15
rla r14
rlc r15
mov r14, &output_scale
mov r15, &output_scale+2
ret
/* epilogue: not required */
/* function show_array_bug size 20 (19) */
.Lfe1:
.size show_array_bug,.Lfe1-show_array_bug
/********* End of function ******/
.comm transducer_type,1
.comm output_scale,4,2
/*********************************************************************
* File array_bug.c: code size: 20 words (0x14)
* incl. words in prologues: 0, epilogues: 1
*********************************************************************/
****************************************************************
Those unused parameters have a big effect on the code produced. In the
real function from which this is excerpted, they are all used, of
course.
