https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90886
Bug ID: 90886
Summary: loop/while/for problem
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: joe at freakyacres dot com
Target Milestone: ---
I apologize because this all got a little bit above my head. But the following
code only runs the "for" loop once.
volatile unsigned char x;
int main() {
while (1) {
for (unsigned char i = 0 ; i < 128 ; i++) {
x = i;
}
}
}
Apparently compiles to...
$ avr-g++ -Os -mmcu=atmega328p main.cpp -o main.elf
$ avr-objdump --demangle -d main.elf
(other code omitted)
00000090 <main>:
90: 10 92 00 01 sts 0x0100, r1 ; 0x800100 <_edata>
00000094 <_exit>:
94: f8 94 cli
00000096 <__stop_program>:
96: ff cf rjmp .-2 ; 0x96 <__stop_program>
$ avr-g++ --version
Replacing the for loop 128 with any other value fixes the problem.
Much work was done at the github link below where minds much more advanced than
my own researched and confirmed what was happening.
https://github.com/arduino/Arduino/issues/8973
https://forum.arduino.cc/index.php?topic=621017.0
