https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101188
Senthil Kumar Selvaraj <saaadhu at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
CC| |saaadhu at gcc dot gnu.org
Ever confirmed|0 |1
Last reconfirmed| |2021-06-25
--- Comment #1 from Senthil Kumar Selvaraj <saaadhu at gcc dot gnu.org> ---
Confirmed with 12.0.0 20210625
Here's a reduced testcase that hangs indefinitely with avrtest - the log shows
call to address 0.
$ cat fail.c
#include <stdint.h>
#include <stdlib.h>
typedef uint8_t (*fn1)(void *a);
typedef void (*fn2)(void *a, const uint32_t *arg);
struct S {
uint8_t buffer[64];
uint16_t n;
fn2 f2;
void *a;
fn1 f1;
};
volatile uint16_t x;
void __attribute__((noinline))
foo(uint16_t n)
{
x = n;
}
void __attribute__((noinline)) testfn(struct S *self)
{
uint32_t arg;
foo(self->n);
self->n++;
self->f2(self->a, &arg);
self->buffer[0] = self->f1(self->a);
}
static unsigned char myfn2_called = 0;
static void
myfn2(void *a, const uint32_t * arg)
{
myfn2_called = 1;
}
static uint8_t
myfn1(void *a)
{ }
int main() {
struct S s;
s.n = 0; s.f2 = myfn2; s.f1 = myfn1;
testfn(&s);
if (myfn2_called != 1)
abort();
return 0;
}
$ avr-gcc -mmcu=atmega128 fail.c -O2 ~/code/avrtest/exit-atmega128.o --version
avr-gcc (GCC) 12.0.0 20210625 (experimental)
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ ~/code/avrtest/avrtest -mmcu=avr51 a.out
^C
The below code is at fault - there's an ldi to r31, followed by a load to Z
using R31:R30, and then an icall. The clobbering of r31 at 0x138 causes junk
values (0) to be read into Z, and icall calls address 0.
138: f4 e4 ldi r31, 0x44 ; 68
13a: ef 0e add r14, r31
13c: f1 1c adc r15, r1
13e: 32 96 adiw r30, 0x02 ; 2
140: 01 90 ld r0, Z+
142: f0 81 ld r31, Z
144: e0 2d mov r30, r0
146: be 01 movw r22, r28
148: 6f 5f subi r22, 0xFF ; 255
14a: 7f 4f sbci r23, 0xFF ; 255
14c: d7 01 movw r26, r14
14e: 8d 91 ld r24, X+
150: 9c 91 ld r25, X
152: 09 95 icall
