The smaller size might be making the compiler decide to inline the function at
some call sites where it didn't before. You could experiment with
"-fno-inline-small-functions" (compiler option) and/or
"__attribute__((noinline))" on your function declaration:
void pulse_en (void) __attribute__((noinline));
void pulse_en (void)
{
...
}
Cheers,
--Dave
On Mar 17, 2012, at 9:17 PM, Parthasaradhi Nayani wrote:
>
> Hi all,
> I am working on an ATMEGA8. Since my code was getting close to 8K, I thought
> I would tweak the code. I have a function listed below
>
> void pulse_en (void)
> {
> set_EN; // Set EN
> _delay_loop_1 (255);
> clr_EN; // clear EN
> _delay_loop_1 (255);
> }
> Since the delay after the "clr" instruction had no meaning, I commented the
> line and compiled the code hoping I would save a couple of bytes. But to my
> surprise the code size increased to 7172 bytes compared to 7148 bytes with
> the function call in place. I looked at the list file and found that the
> function gets shifted to a different location with and without the function
> call. Here are the list file snippets
>
> With the call in place:
>
> 351
>
>
> pulse_en:
> 352 .LFB23:
> 353 .LM47:
> 354 /* prologue: function */
> 355 /* frame size = 0 */
> 356 .LM48:
> 357 0128 C29A sbi 56-32,2
> 358 .LBB80:
> 359 .LBB81:
> 360 .LM49:
> 361 012a 8FEF ldi r24,lo8(-1)
> 362 012c 982F mov r25,r24
> 363 .LVL17:
> 364 /* #APP */
> 365 ; 83
> "c:/winavr-20100110/lib/gcc/../../avr/include/util/delay_basic.h" 1
> 366 012e 9A95 1: dec r25
> 367 0130 01F4 brne 1b
> 368 ; 0 "" 2
> 369 /* #NOAPP */
> 370 .LBE81:
> 371 .LBE80:
> 372 .LM50:
> 373 0132 C298 cbi 56-32,2
> 374 .LBB82:
> 375 .LBB83:
> 376 .LM51:
> 377 /* #APP */
> 378 ; 83
> "c:/winavr-20100110/lib/gcc/../../avr/include/util/delay_basic.h" 1
> 379 0134 8A95 1: dec r24
> 380 0136 01F4 brne 1b
> 381 ; 0 "" 2
> 382 .LVL18:
> 383 /* epilogue start */
> 384 /* #NOAPP */
> 385 .LBE83:
> 386 .LBE82:
> 387 .LM52:
> 388 0138 0895 ret
>
> Without the call:
> 621 .LFE21:
> 623 .global pulse_en
> 625 pulse_en:
> 626 .LFB23:
> 627 .LM87:
> 628 /* prologue: function */
> 629 /* frame size = 0 */
> 630 .LM88:
> 631 01c2 C29A sbi 56-32,2
> 632 .LBB146:
> 633 .LBB147:
> 634 .LM89:
> 635 01c4 8FEF ldi r24,lo8(-1)
> 636 .LVL36:
> 637 /* #APP */
> 638 ; 83
> "c:/winavr-20100110/lib/gcc/../../avr/include/util/delay_basic.h" 1
> 639 01c6 8A95 1: dec r24
> 640 01c8 01F4 brne 1b
> 641 ; 0 "" 2
> 642 /* #NOAPP */
> 643 .LBE147:
> 644
>
>
> .LBE146:
> 645 .LM90:
> 646 01ca C298 cbi 56-32,2
> 647 /* epilogue start */
> 648 .LM91:
> 649 01cc 0895 ret
>
>
> Will some one please let me know why this is happening? If such is the case,
> perhaps extra code is being generated for other function too.
> I am using: avr-gcc (WinAVR 20100110) 4.3.3
>
> Thank you for your time.
>
> Regards,
> Nayani
>
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> AVR-GCC-list mailing list
> AVR-GCC-list@nongnu.org
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