| Message ID | 1464310815-13554-11-git-send-email-rth@twiddle.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 27/05/16 04:00, Richard Henderson wrote: > diff --git a/tci.c b/tci.c > index b488c0d..53b3f71 100644 > --- a/tci.c > +++ b/tci.c > @@ -1236,6 +1236,9 @@ uintptr_t tcg_qemu_tb_exec(CPUArchState *env, uint8_t *tb_ptr) > tcg_abort(); > } > break; > + case INDEX_op_fence: > + smp_mb(); > + break; > default: > TODO(); > break; A bit of bike-shedding. While there's no common ISA term for "memory barrier" (also known as a "membar", "memory fence", etc.), we already refer to it as a "memory barrier" (or "mb") in include/qemu/atomic.h and docs/atomics.txt. Why don't be consistent and avoid introducing yet another term for the same thing? Kind regards, Sergey
Hi Sergey, Sergey Fedorov writes: > On 27/05/16 04:00, Richard Henderson wrote: >> diff --git a/tci.c b/tci.c >> index b488c0d..53b3f71 100644 >> --- a/tci.c >> +++ b/tci.c >> @@ -1236,6 +1236,9 @@ uintptr_t tcg_qemu_tb_exec(CPUArchState *env, uint8_t *tb_ptr) >> tcg_abort(); >> } >> break; >> + case INDEX_op_fence: >> + smp_mb(); >> + break; >> default: >> TODO(); >> break; > > A bit of bike-shedding. While there's no common ISA term for "memory > barrier" (also known as a "membar", "memory fence", etc.), we already > refer to it as a "memory barrier" (or "mb") in include/qemu/atomic.h and > docs/atomics.txt. Why don't be consistent and avoid introducing yet > another term for the same thing? > Fair point. Do you think tcg_out_mb() is better then? Thanks,
On 27/05/16 17:17, Pranith Kumar wrote: > Hi Sergey, > > Sergey Fedorov writes: > >> On 27/05/16 04:00, Richard Henderson wrote: >>> diff --git a/tci.c b/tci.c >>> index b488c0d..53b3f71 100644 >>> --- a/tci.c >>> +++ b/tci.c >>> @@ -1236,6 +1236,9 @@ uintptr_t tcg_qemu_tb_exec(CPUArchState *env, uint8_t *tb_ptr) >>> tcg_abort(); >>> } >>> break; >>> + case INDEX_op_fence: >>> + smp_mb(); >>> + break; >>> default: >>> TODO(); >>> break; >> A bit of bike-shedding. While there's no common ISA term for "memory >> barrier" (also known as a "membar", "memory fence", etc.), we already >> refer to it as a "memory barrier" (or "mb") in include/qemu/atomic.h and >> docs/atomics.txt. Why don't be consistent and avoid introducing yet >> another term for the same thing? >> > Fair point. Do you think tcg_out_mb() is better then? Yes, if used together with 'INDEX_op_mb', of course. Kind regards, Sergey
On Fri, May 27, 2016 at 10:20 AM, Sergey Fedorov <serge.fdrv@gmail.com> wrote: >>>> + case INDEX_op_fence: >>>> + smp_mb(); >>>> + break; >>>> default: >>>> TODO(); >>>> break; >>> A bit of bike-shedding. While there's no common ISA term for "memory >>> barrier" (also known as a "membar", "memory fence", etc.), we already >>> refer to it as a "memory barrier" (or "mb") in include/qemu/atomic.h and >>> docs/atomics.txt. Why don't be consistent and avoid introducing yet >>> another term for the same thing? >>> >> Fair point. Do you think tcg_out_mb() is better then? > > Yes, if used together with 'INDEX_op_mb', of course. > OK. I'll make the change. Thanks for the feedback!
diff --git a/tcg/tci/tcg-target.inc.c b/tcg/tci/tcg-target.inc.c index fa74d52..bf65416 100644 --- a/tcg/tci/tcg-target.inc.c +++ b/tcg/tci/tcg-target.inc.c @@ -255,6 +255,7 @@ static const TCGTargetOpDef tcg_target_op_defs[] = { { INDEX_op_bswap32_i32, { R, R } }, #endif + { INDEX_op_fence, { } }, { -1 }, }; @@ -800,6 +801,8 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, const TCGArg *args, } tcg_out_i(s, *args++); break; + case INDEX_op_fence: + break; case INDEX_op_mov_i32: /* Always emitted via tcg_out_mov. */ case INDEX_op_mov_i64: case INDEX_op_movi_i32: /* Always emitted via tcg_out_movi. */ diff --git a/tci.c b/tci.c index b488c0d..53b3f71 100644 --- a/tci.c +++ b/tci.c @@ -1236,6 +1236,9 @@ uintptr_t tcg_qemu_tb_exec(CPUArchState *env, uint8_t *tb_ptr) tcg_abort(); } break; + case INDEX_op_fence: + smp_mb(); + break; default: TODO(); break;
Cc: Stefan Weil <sw@weilnetz.de> Signed-off-by: Richard Henderson <rth@twiddle.net> --- tcg/tci/tcg-target.inc.c | 3 +++ tci.c | 3 +++ 2 files changed, 6 insertions(+)