Re: Recent TCG commit breaks PPC

[BALATON Zoltan]

On Sat, 16 Jan 2021, Richard Henderson wrote:
> On 1/16/21 4:38 AM, BALATON Zoltan wrote:
> > Commit 8fe35e0444be (tcg/optimize: Use tcg_constant_internal with constant
> > folding) seems to break PPC emulation for me:
> >
> > Thread 3 "qemu-system-ppc" received signal SIGSEGV, Segmentation fault.
> > [Switching to Thread 0x7ffff51e7700 (LWP 22636)]
> > 0x0000555555afd4ee in ts_are_copies (ts2=0x7fff8c008f90, ts1=0x7fff8c001510) at
> > ../tcg/optimize.c:68
> > 68        return ts_info(ts)->next_copy != ts;
>
> I don't replicate this assertion.
>
> Interestingly, I replicate a different assertion:
>
> qemu-system-ppc: ../qemu/tcg/tcg.c:1210: tcg_temp_alloc: Assertion `n < 512'
> failed.
> Aborted (core dumped)
>
> What compiler version(s) are you guys using?

With --enable-debug (that I don't normally use because it makes PPC 
emulation too slow) I get the same assertion:

qemu-system-ppc: ../tcg/tcg.c:1210: tcg_temp_alloc: Assertion `n < 512' 
failed.

Thread 3 "qemu-system-ppc" received signal SIGABRT, Aborted.

(gdb) bt
#0  0x00007ffff6b29a7a in raise () at /lib64/libc.so.6
#1  0x00007ffff6b12524 in abort () at /lib64/libc.so.6
#2  0x00007ffff6b1240f in _nl_load_domain.cold.0 () at /lib64/libc.so.6
#3  0x00007ffff6b1e9a2 in  () at /lib64/libc.so.6
#4  0x0000555555c5e7a6 in tcg_temp_alloc (s=0x7fff50000b60) at tcg/tcg.c:1210
#5  0x0000555555c5efcb in tcg_constant_internal (type=TCG_TYPE_I32, 
val=-7401584) at tcg/tcg.c:1436
#6  0x0000555555c7f921 in tcg_opt_gen_movi
    (s=0x7fff50000b60, temps_used=0x7ffff51e94c0, op=0x7fff505d6308, 
dst=140734535570720, val=18446744073702150032)
    at tcg/optimize.c:247
#7  0x0000555555c81e4b in tcg_optimize (s=0x7fff50000b60) at tcg/optimize.c:1178
#8  0x0000555555c6580a in tcg_gen_code (s=0x7fff50000b60, tb=0x7fffb3181a00) at 
tcg/tcg.c:4490
#9  0x0000555555c34f9c in tb_gen_code (cpu=0x5555567851e0, pc=4287582720, 
cs_base=0, flags=24576, cflags=-16777216)
    at accel/tcg/translate-all.c:1952
#10 0x0000555555c79842 in tb_find (cpu=0x5555567851e0, last_tb=0x0, tb_exit=0, 
cf_mask=0) at accel/tcg/cpu-exec.c:454
#11 0x0000555555c7a109 in cpu_exec (cpu=0x5555567851e0) at 
accel/tcg/cpu-exec.c:810
#12 0x0000555555c6e906 in tcg_cpus_exec (cpu=0x5555567851e0) at 
accel/tcg/tcg-cpus.c:57
#13 0x0000555555cbf18e in rr_cpu_thread_fn (arg=0x5555567851e0) at 
accel/tcg/tcg-cpus-rr.c:217
#14 0x0000555555ea8531 in qemu_thread_start (args=0x5555567c63d0) at 
util/qemu-thread-posix.c:521
#15 0x00007ffff6cc004c in start_thread () at /lib64/libpthread.so.0
#16 0x00007ffff6bf13af in clone () at /lib64/libc.so.6

Previous one was when configuring without --enable-debug, so maybe it 
depends on compiler flags (-O2 vs. -O0).

Regards,
BALATON Zoltan