Am 20.02.2018 um 20:14 schrieb Eric Rullens:
> Long time MCS51 and more recently STM8 user here.
>
> For STM8 I've noticed that "random" code is generated for the following:
>
> --------------------------------
> int sum(int a, int b, unsigned long d)
> {
> return a + b / d;
> }
>
> int main(void)
> {
> return sum(1, 2, 4);
> }
> --------------------------------
>
> This is using the 3.7.0 #10228 snapshot on Windows 10.0.16299.125.
>
> Compiling ten times as follows, and generating a checksum on the resulting
> images:
>
> --------------------------------
> sdcc -mstm8 test.c
> md5sum test.ihx
> --------------------------------
>
> 034855cad4e8eb12209ad31c9ccd7f9b *test.ihx 034855cad4e8eb12209ad31c9ccd7f9b
> *test.ihx
> 069a62e6676bd940cb01a36ab3a7f787 *test.ihx
> 069a62e6676bd940cb01a36ab3a7f787 *test.ihx 034855cad4e8eb12209ad31c9ccd7f9b
> *test.ihx 034855cad4e8eb12209ad31c9ccd7f9b *test.ihx
> 069a62e6676bd940cb01a36ab3a7f787 *test.ihx 034855cad4e8eb12209ad31c9ccd7f9b
> *test.ihx 034855cad4e8eb12209ad31c9ccd7f9b *test.ihx
> 069a62e6676bd940cb01a36ab3a7f787 *test.ihx
>
> The differences occur just after the call to divulong, as can be seen in the
> assembly code from runs 2 and 3.
>
> The assembly code for "sum" from run 2:
>
> --------------------------------
> ; test.c: 1: int sum(int a, int b, unsigned long d)
> ; -----------------------------------------
> ; function sum
> ; -----------------------------------------
> _sum:
> sub sp, #6
> ; test.c: 3: return a + b / d;
> ldw y, (0x0b, sp)
> clrw x
> tnzw y
> jrpl 00103$
> decw x
> 00103$:
> ld a, (0x10, sp)
> push a
> ld a, (0x10, sp)
> push a
> ld a, (0x10, sp)
> push a
> ld a, (0x10, sp)
> push a
> pushw y
> pushw x
> call __divulong
> addw sp, #8
> ldw (0x03, sp), y
> ldw y, (0x09, sp)
> ldw (0x01, sp), y
> addw x, (0x01, sp)
> ; test.c: 4: }
> addw sp, #6
> ret
> --------------------------------
>
> The assembly code for "sum" from run 3:
>
> --------------------------------
> ; test.c: 1: int sum(int a, int b, unsigned long d)
> ; -----------------------------------------
> ; function sum
> ; -----------------------------------------
> _sum:
> sub sp, #6
> ; test.c: 3: return a + b / d;
> ldw y, (0x0b, sp)
> clrw x
> tnzw y
> jrpl 00103$
> decw x
> 00103$:
> ld a, (0x10, sp)
> push a
> ld a, (0x10, sp)
> push a
> ld a, (0x10, sp)
> push a
> ld a, (0x10, sp)
> push a
> pushw y
> pushw x
> call __divulong
> addw sp, #8
> ldw (0x01, sp), y
> ldw y, (0x09, sp)
> ldw (0x05, sp), y
> addw x, (0x05, sp)
> ; test.c: 4: }
> addw sp, #6
> ret
> --------------------------------
>
> It looks like this may have been reported before for MCS51 as well:
>
> https://sourceforge.net/p/sdcc/mailman/message/35171634/
>
> But for the example above I don't see the issue for MCS51.
>
> Any thoughts?
>
> Eric Rullens
>
I suggest to file a bug report. Having sich a relatively small
reproducer could help track down the issue.
Philipp
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