From: "andrzej zaborowski" <balrogg@gmail.com>
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Re: [4875] Remove unintended dereference, kills a warning (Jan Kiszka).
Date: Sat, 19 Jul 2008 08:24:44 +0200 [thread overview]
Message-ID: <fb249edb0807182324m3bbd4bb1gfe0d264133d2e891@mail.gmail.com> (raw)
In-Reply-To: <487DEB2D.5040302@web.de>
2008/7/16 Jan Kiszka <jan.kiszka@web.de>:
> Laurent Desnogues wrote:
>> On Wed, Jul 16, 2008 at 2:04 PM, Andreas Schwab <schwab@suse.de> wrote:
>>> Andrzej Zaborowski <balrogg@gmail.com> writes:
>>>
>>>> void OPPROTO op_tasb_rN(void)
>>>> {
>>>> - cond_t(*(int8_t *) env->gregs[PARAM1] == 0);
>>>> - *(int8_t *) env->gregs[PARAM1] |= 0x80;
>>>> + cond_t((env->gregs[PARAM1] && 0xff) == 0);
>>>> + *(int8_t *) &env->gregs[PARAM1] |= 0x80;
>>> That does not make any sense at all. The TAS insn operates on memory,
>>> not on a register (atomic operations only make sense on memory anyway).
>>
>> SH4 documentation says this:
>>
>> TAS.B @Rn
>> If (Rn) = 0, 1 → T, else 0 → T
>> 1 → MSB of (Rn)
>>
>> So indeed it looks like Jan and Andrzej patch is wrong.
>
> At least the audience is finally listening. ;)
>
> Is this one better?
I suspect one of these may be more correct, but I haven't seen the
docs. The below, like the original version, assumes that if the store
generates some kind of trap, the flag is still affected. Otherwise
cond_t needs to be the last.
diff --git a/target-sh4/op.c b/target-sh4/op.c
--- a/target-sh4/op.c
+++ b/target-sh4/op.c
@@ -592,13 +592,6 @@ void OPPROTO op_shlr16_Rn(void)
RETURN();
}
-void OPPROTO op_tasb_rN(void)
-{
- cond_t((env->gregs[PARAM1] & 0xff) == 0);
- *(int8_t *) &env->gregs[PARAM1] |= 0x80;
- RETURN();
-}
-
void OPPROTO op_movl_T0_rN(void)
{
env->gregs[PARAM1] = T0;
diff --git a/target-sh4/translate.c b/target-sh4/translate.c
--- a/target-sh4/translate.c
+++ b/target-sh4/translate.c
@@ -1077,7 +1077,12 @@ void _decode_opc(DisasContext * ctx)
gen_op_shlr16_Rn(REG(B11_8));
return;
case 0x401b: /* tas.b @Rn */
- gen_op_tasb_rN(REG(B11_8));
+ gen_op_movl_rN_T0(REG(B11_8));
+ gen_op_movl_T0_T1();
+ gen_op_ldub_T0_T0(ctx);
+ gen_op_cmp_eq_imm_T0(0);
+ gen_op_or_imm_T0(0x80);
+ gen_op_stb_T0_T1(ctx);
return;
case 0xf00d: /* fsts FPUL,FRn - FPSCR: Nothing */
gen_op_movl_fpul_FT0();
or
diff --git a/target-sh4/op.c b/target-sh4/op.c
--- a/target-sh4/op.c
+++ b/target-sh4/op.c
@@ -592,13 +592,6 @@ void OPPROTO op_shlr16_Rn(void)
RETURN();
}
-void OPPROTO op_tasb_rN(void)
-{
- cond_t((env->gregs[PARAM1] & 0xff) == 0);
- *(int8_t *) &env->gregs[PARAM1] |= 0x80;
- RETURN();
-}
-
void OPPROTO op_movl_T0_rN(void)
{
env->gregs[PARAM1] = T0;
diff --git a/target-sh4/op_mem.c b/target-sh4/op_mem.c
--- a/target-sh4/op_mem.c
+++ b/target-sh4/op_mem.c
@@ -76,3 +76,10 @@ void glue(op_stfq_DT0_T1, MEMSUFFIX) (void) {
glue(stfq, MEMSUFFIX) (T1, DT0);
RETURN();
}
+
+void glue(op_tasb_Rn, MEMSUFFIX) (void) {
+ uint8_t val = glue(ldub, MEMSUFFIX) (env->gregs[PARAM1]);
+ cond_t(val == 0);
+ glue(stb, MEMSUFFIX) (env->gregs[PARAM1], val | 0x80);
+ RETURN();
+}
diff --git a/target-sh4/translate.c b/target-sh4/translate.c
--- a/target-sh4/translate.c
+++ b/target-sh4/translate.c
@@ -80,6 +80,10 @@ static void sh4_translate_init()
gen_op_st##width##_##reg##_T1_raw(); \
}
+void gen_op_tasb_Rn(DisasContext *ctx, int reg) {
+ gen_op_tasb_Rn_raw(reg);
+}
+
#else
#define GEN_OP_LD(width, reg) \
@@ -93,6 +97,13 @@ static void sh4_translate_init()
else gen_op_st##width##_##reg##_T1_user();\
}
+void gen_op_tasb_Rn(DisasContext *ctx, int reg) {
+ if (ctx->memidx)
+ gen_op_tasb_Rn_kernel(reg);
+ else
+ gen_op_tasb_Rn_user(reg);
+}
+
#endif
GEN_OP_LD(ub, T0)
@@ -1077,7 +1088,7 @@ void _decode_opc(DisasContext * ctx)
gen_op_shlr16_Rn(REG(B11_8));
return;
case 0x401b: /* tas.b @Rn */
- gen_op_tasb_rN(REG(B11_8));
+ gen_op_tasb_Rn(ctx, REG(B11_8));
return;
case 0xf00d: /* fsts FPUL,FRn - FPSCR: Nothing */
gen_op_movl_fpul_FT0();
next prev parent reply other threads:[~2008-07-19 6:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-16 11:31 [Qemu-devel] [4875] Remove unintended dereference, kills a warning (Jan Kiszka) Andrzej Zaborowski
2008-07-16 11:36 ` Laurent Desnogues
2008-07-16 12:10 ` [Qemu-devel] " Jan Kiszka
2008-07-16 12:04 ` [Qemu-devel] " Andreas Schwab
2008-07-16 12:30 ` Laurent Desnogues
2008-07-16 12:35 ` [Qemu-devel] " Jan Kiszka
2008-07-19 6:24 ` andrzej zaborowski [this message]
2008-08-18 7:13 ` Jan Kiszka
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