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[v3,1/2] target/s390x: Fix R[NOX]SBG with T=1

Message ID 20230316172205.281369-2-iii@linux.ibm.com
State New
Headers show
Series target/s390x: Fix R[NOX]SBG with T=1 | expand

Commit Message

Ilya Leoshkevich March 16, 2023, 5:22 p.m. UTC 
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.

Exposed by commit e2e641fa3d5 ("tcg: Change default temp lifetime to
TEMP_TB").

Fixes: d6c6372e186e ("target-s390: Implement R[NOX]SBG")
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 target/s390x/tcg/translate.c | 4 ++++
 1 file changed, 4 insertions(+)
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Patch

diff --git a/target/s390x/tcg/translate.c b/target/s390x/tcg/translate.c
index 14c3896d529..0fb36e04be8 100644
--- a/target/s390x/tcg/translate.c
+++ b/target/s390x/tcg/translate.c
@@ -3695,11 +3695,15 @@  static DisasJumpType op_rosbg(DisasContext *s, DisasOps *o)
     int i3 = get_field(s, i3);
     int i4 = get_field(s, i4);
     int i5 = get_field(s, i5);
+    TCGv_i64 orig_out;
     uint64_t mask;
 
     /* If this is a test-only form, arrange to discard the result.  */
     if (i3 & 0x80) {
+        tcg_debug_assert(o->out != NULL);
+        orig_out = o->out;
         o->out = tcg_temp_new_i64();
+        tcg_gen_mov_i64(o->out, orig_out);
     }
 
     i3 &= 63;