https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120347
Bug ID: 120347
Summary: invalid arm32/thumb assembly output
Product: gcc
Version: 15.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: arnd at linaro dot org
Target Milestone: ---
During build testing on the Linux kernel, I came across a new failure with
gcc-15.1 producing a single invalid instruction, in exactly one file/function:
/tmp/ccGz2dNz.s: Assembler messages:
/tmp/ccGz2dNz.s:681: Error: registers may not be the same -- `str r1,[r1],#4'
make[8]: *** [scripts/Makefile.build:195: drivers/gpu/drm/radeon/radeon_test.o]
Error 1
I managed to produce a reduced test case with the same output:
void *end;
void **start;
void main(void)
{
for (; end; start++) {
if (*start)
return;
*start = start;
}
}
$ arm-linux-gcc-15.1 -O2 -march=armv7-a -mthumb test.c -c
/tmp/ccjHgo9c.s:43: Error: registers may not be the same -- `str r3,[r3],#4'
See https://godbolt.org/z/4v41cnsbY for reference. The test case also
reproduces on current 'trunk' but not on gcc-14.2 or earlier.
