Re: [PATCH 1/2] target/s390x: Fix R[NOX]SBG with T=1

[David Hildenbrand]

On 15.03.23 00:34, Ilya Leoshkevich wrote:
> RXSBG usage in the "filetests" test from the wasmtime testsuite makes
> tcg_reg_alloc_op() attempt to temp_load() a TEMP_VAL_DEAD temporary,
> causing an assertion failure:
>
>      0x01000a70:  ec14 b040 3057  rxsbg    %r1, %r4, 0xb0, 0x40, 0x30
>
>      OP after optimization and liveness analysis:
>       ---- 0000000001000a70 0000000000000004 0000000000000006
>       rotl_i64 tmp2,r4,$0x30                   dead: 1 2  pref=0xffff
>       and_i64 tmp2,tmp2,$0x800000000000ffff    dead: 1  pref=0xffff
>      [xor_i64 tmp3,tmp3,tmp2                   dead: 1 2  pref=0xffff]
>       and_i64 cc_dst,tmp3,$0x800000000000ffff  sync: 0  dead: 0 1 2  pref=0xffff
>       mov_i64 psw_addr,$0x1000a76              sync: 0  dead: 0 1  pref=0xffff
>       mov_i32 cc_op,$0x6                       sync: 0  dead: 0 1  pref=0xffff
>       call lookup_tb_ptr,$0x6,$1,tmp8,env      dead: 1  pref=none
>       goto_ptr tmp8                            dead: 0
>       set_label $L0
>       exit_tb $0x7fffe809d183
>
>      ../tcg/tcg.c:3865: tcg fatal error
>
> The reason is that tmp3 does not have an initial value, which confuses
> the register allocator. This also affects the correctness of the
> results.
>
> Fix by assigning R1 to it.
>
> Fixes: d6c6372e186e ("target-s390: Implement R[NOX]SBG")
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---

Reviewed-by: David Hildenbrand <david@redhat.com>

--
Thanks,

David / dhildenb