* [Qemu-devel] TCG sar UB
@ 2011-08-22 10:47 malc
0 siblings, 0 replies; only message in thread
From: malc @ 2011-08-22 10:47 UTC (permalink / raw)
To: qemu-devel; +Cc: Richard Henderson
While booting linux-test 0.2 following sequence of instructions is seen:
IN:
0xc03227aa: mov %esi,%edx
0xc03227ac: xor %ecx,%ecx
0xc03227ae: movzwl 0x12(%esp),%ebp
0xc03227b3: mov %edi,%eax
0xc03227b5: sar %cl,%eax
0xc03227b7: and $0x1,%eax
0xc03227ba: je 0xc0322802
OP after liveness analysis:
mov_i32 tmp0,esi
mov_i32 edx,tmp0
nopn $0x2,$0x2
movi_i32 ecx,$0x0
discard cc_src
movi_i32 cc_dst,$0x0
mov_i32 tmp2,esp
movi_i32 tmp13,$0x12
add_i32 tmp2,tmp2,tmp13
qemu_ld16u tmp0,tmp2,$0x0
mov_i32 ebp,tmp0
mov_i32 tmp0,edi
mov_i32 eax,tmp0
nopn $0x2,$0x2
mov_i32 tmp0,eax
nopn $0x2,$0x2
movi_i32 tmp1,$0x0
nopn $0x2,$0x2
movi_i32 tmp10,$0xffffffff
sar_i32 tmp3,tmp0,tmp10
Doesn't make much sense to me, guest clearly asked for 0 and not -1,
besides -1 violates TCG's sar constraints and PPC obliges by emiting
illegal instruction in this case.
--
mailto:av1474@comtv.ru
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2011-08-22 10:47 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-08-22 10:47 [Qemu-devel] TCG sar UB malc
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.