Re: Recent TCG commit breaks PPC

[Richard Henderson]

On 1/16/21 4:38 AM, BALATON Zoltan wrote:
> Hello,
> 
> 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;

Ok, riscv32 seems to have the same problem.  I'm on it.
I'll note that check-acceptance passes, so this points out a hole in our 
testing...


r~

> (gdb) bt
> #0  0x0000555555afd4ee in ts_are_copies (ts2=0x7fff8c008f90,
> ts1=0x7fff8c001510) at tcg/optimize.c:68
> #1  0x0000555555afd4ee in tcg_opt_gen_mov
>     (s=s@entry=0x7fff8c000b60, op=op@entry=0x7fff8c6b2348, 
> dst=140735542203664,
> src=140735542235024) at tcg/optimize.c:191
> #2  0x0000555555afe05a in tcg_opt_gen_movi
>     (s=s@entry=0x7fff8c000b60, temps_used=temps_used@entry=0x7ffff51e63c0,
> op=op@entry=0x7fff8c6b2348, dst=<optimized out>,
>     val=<optimized out>) at include/tcg/tcg.h:731
> #3  0x0000555555aff79f in tcg_optimize (s=s@entry=0x7fff8c000b60) at
> tcg/optimize.c:1189
> #4  0x0000555555b13c39 in tcg_gen_code (s=0x7fff8c000b60,
> tb=tb@entry=0x7fffb3181380 <code_gen_buffer+4088659>) at tcg/tcg.c:4490
> #5  0x0000555555b1b485 in tb_gen_code
>     (cpu=cpu@entry=0x55555651c870, pc=pc@entry=4287582720,
> cs_base=cs_base@entry=0, flags=flags@entry=24576, cflags=-16777216,
>     cflags@entry=0) at accel/tcg/translate-all.c:1952
> #6  0x0000555555b7c303 in tb_find (cf_mask=0, tb_exit=0, last_tb=0x0, cpu=0x0)
> at accel/tcg/cpu-exec.c:454
> #7  0x0000555555b7c303 in cpu_exec (cpu=cpu@entry=0x55555651c870) at
> accel/tcg/cpu-exec.c:810
> #8  0x0000555555ab5ea2 in tcg_cpus_exec (cpu=cpu@entry=0x55555651c870) at
> accel/tcg/tcg-cpus.c:57
> #9  0x0000555555ab7a03 in rr_cpu_thread_fn (arg=arg@entry=0x55555651c870) at
> accel/tcg/tcg-cpus-rr.c:217
> #10 0x0000555555cc355a in qemu_thread_start (args=<optimized out>) at
> util/qemu-thread-posix.c:521
> #11 0x00007ffff6cc004c in start_thread () at /lib64/libpthread.so.0
> #12 0x00007ffff6bf13af in clone () at /lib64/libc.so.6
> 
> This can be reproduced for example with booting AROS as described here:
> 
> http://zero.eik.bme.hu/~balaton/qemu/amiga/#aros
> 
> The segfault happens during boot.
> 
> Regards,
> BALATON Zoltan