To be clear, I just ran into the problem of the update of the carry flag but
I'm not at all a specialist of SPARC assembly.
From what I've understood, Paul is certainly right when suggesting to add a
fix for the SPARC64 case (for the addxcc and subxcc, not addx and subx) and I
send a new version of the patch (qemu-sparc-carry-xcc-2.patch)
I've also tried to take into account Blue Swirl's suggestion of storing the
intermediate results of the addition T0 + FLAG_SET(PSR_CARRY), but the result
wasn't correct in all cases (specifically if T0=0xFFFFFFFF). I think we
really need a '<' and '<=' comparison.
However, I've tried to refactor a bit the code to save some comparisons in
another version of the patch (qemu-sparc-carry-xcc-3.patch), really close to
the arm code, and hopefully equivalent to qemu-sparc-carry-xcc-2.patch (but
less sexy).
As far as the V flag is concerned, mmm, I'm not really sure whether we should
change something in the sparc code. If we compare to the arm code, we don't
take into account the fact that the carry flag is set before.
We'd probably need some extensive tests and their associated expected results.
Even
Le Lundi 10 Avril 2006 20:46, Laurent Desnogues a écrit :
> Blue Swirl a écrit :
> >> Doesn't this condition in addx and the corresponding line in subx need
> >> similar
> >> treatment?
> >
> > They don't change the flags.
>
> ADDX (now named ADDC in v9) doesn't change the flags, while ADDXcc
> (ADDCcc) does. The cc versions also compute overflow.
>
> cf. SPARC v9 on www.sparg.org
>
>
> Laurent
>
>
>
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
? qemu-sparc-carry-xcc-ops-2.patch
? qemu-sparc-carry-xcc-ops-3.patch
? qemu-sparc-carry-xcc-ops.patch
Index: op.c
===================================================================
RCS file: /sources/qemu/qemu/target-sparc/op.c,v
retrieving revision 1.18
diff -u -p -r1.18 op.c
--- op.c 30 Oct 2005 17:28:50 -0000 1.18
+++ op.c 10 Apr 2006 20:03:37 -0000
@@ -415,28 +415,50 @@ void OPPROTO op_addx_T1_T0(void)
void OPPROTO op_addx_T1_T0_cc(void)
{
target_ulong src1;
-
src1 = T0;
- T0 += T1 + FLAG_SET(PSR_CARRY);
- env->psr = 0;
+ if (FLAG_SET(PSR_CARRY))
+ {
+ T0 += T1 + 1;
+ env->psr = 0;
+#ifdef TARGET_SPARC64
+ if ((T0 & 0xffffffff) <= (src1 & 0xffffffff))
+ env->psr |= PSR_CARRY;
+ env->xcc = 0;
+ if (T0 <= src1)
+ env->xcc |= PSR_CARRY;
+#else
+ if (T0 <= src1)
+ env->psr |= PSR_CARRY;
+#endif
+ }
+ else
+ {
+ T0 += T1;
+ env->psr = 0;
+#ifdef TARGET_SPARC64
+ if ((T0 & 0xffffffff) < (src1 & 0xffffffff))
+ env->psr |= PSR_CARRY;
+ env->xcc = 0;
+ if (T0 < src1)
+ env->xcc |= PSR_CARRY;
+#else
+ if (T0 < src1)
+ env->psr |= PSR_CARRY;
+#endif
+ }
#ifdef TARGET_SPARC64
if (!(T0 & 0xffffffff))
env->psr |= PSR_ZERO;
if ((int32_t) T0 < 0)
env->psr |= PSR_NEG;
- if ((T0 & 0xffffffff) < (src1 & 0xffffffff))
- env->psr |= PSR_CARRY;
if ((((src1 & 0xffffffff) ^ (T1 & 0xffffffff) ^ -1) &
((src1 & 0xffffffff) ^ (T0 & 0xffffffff))) & (1 << 31))
env->psr |= PSR_OVF;
- env->xcc = 0;
if (!T0)
env->xcc |= PSR_ZERO;
if ((int64_t) T0 < 0)
env->xcc |= PSR_NEG;
- if (T0 < src1)
- env->xcc |= PSR_CARRY;
if (((src1 ^ T1 ^ -1) & (src1 ^ T0)) & (1ULL << 63))
env->xcc |= PSR_OVF;
#else
@@ -444,8 +466,6 @@ void OPPROTO op_addx_T1_T0_cc(void)
env->psr |= PSR_ZERO;
if ((int32_t) T0 < 0)
env->psr |= PSR_NEG;
- if (T0 < src1)
- env->psr |= PSR_CARRY;
if (((src1 ^ T1 ^ -1) & (src1 ^ T0)) & (1 << 31))
env->psr |= PSR_OVF;
#endif
@@ -505,28 +525,50 @@ void OPPROTO op_subx_T1_T0(void)
void OPPROTO op_subx_T1_T0_cc(void)
{
target_ulong src1;
-
src1 = T0;
- T0 -= T1 + FLAG_SET(PSR_CARRY);
- env->psr = 0;
+ if (FLAG_SET(PSR_CARRY))
+ {
+ T0 -= T1 + 1;
+ env->psr = 0;
+#ifdef TARGET_SPARC64
+ if ((src1 & 0xffffffff) <= (T1 & 0xffffffff))
+ env->psr |= PSR_CARRY;
+ env->xcc = 0;
+ if (src1 <= T1)
+ env->xcc |= PSR_CARRY;
+#else
+ if (src1 <= T1)
+ env->psr |= PSR_CARRY;
+#endif
+ }
+ else
+ {
+ T0 -= T1;
+ env->psr = 0;
+#ifdef TARGET_SPARC64
+ if ((src1 & 0xffffffff) < (T1 & 0xffffffff))
+ env->psr |= PSR_CARRY;
+ env->xcc = 0;
+ if (src1 < T1)
+ env->xcc |= PSR_CARRY;
+#else
+ if (src1 < T1)
+ env->psr |= PSR_CARRY;
+#endif
+ }
#ifdef TARGET_SPARC64
if (!(T0 & 0xffffffff))
env->psr |= PSR_ZERO;
if ((int32_t) T0 < 0)
env->psr |= PSR_NEG;
- if ((src1 & 0xffffffff) < (T1 & 0xffffffff))
- env->psr |= PSR_CARRY;
if ((((src1 & 0xffffffff) ^ (T1 & 0xffffffff)) &
((src1 & 0xffffffff) ^ (T0 & 0xffffffff))) & (1 << 31))
env->psr |= PSR_OVF;
- env->xcc = 0;
if (!T0)
env->xcc |= PSR_ZERO;
if ((int64_t) T0 < 0)
env->xcc |= PSR_NEG;
- if (src1 < T1)
- env->xcc |= PSR_CARRY;
if (((src1 ^ T1) & (src1 ^ T0)) & (1ULL << 63))
env->xcc |= PSR_OVF;
#else
@@ -534,8 +576,6 @@ void OPPROTO op_subx_T1_T0_cc(void)
env->psr |= PSR_ZERO;
if ((int32_t) T0 < 0)
env->psr |= PSR_NEG;
- if (src1 < T1)
- env->psr |= PSR_CARRY;
if (((src1 ^ T1) & (src1 ^ T0)) & (1 << 31))
env->psr |= PSR_OVF;
#endif
? qemu-sparc-carry-xcc-ops-2.patch
? qemu-sparc-carry-xcc-ops.patch
Index: op.c
===================================================================
RCS file: /sources/qemu/qemu/target-sparc/op.c,v
retrieving revision 1.18
diff -u -p -r1.18 op.c
--- op.c 30 Oct 2005 17:28:50 -0000 1.18
+++ op.c 10 Apr 2006 18:57:46 -0000
@@ -415,16 +415,17 @@ void OPPROTO op_addx_T1_T0(void)
void OPPROTO op_addx_T1_T0_cc(void)
{
target_ulong src1;
-
+ target_ulong has_carry = FLAG_SET(PSR_CARRY);
src1 = T0;
- T0 += T1 + FLAG_SET(PSR_CARRY);
+ T0 += T1 + has_carry;
env->psr = 0;
#ifdef TARGET_SPARC64
if (!(T0 & 0xffffffff))
env->psr |= PSR_ZERO;
if ((int32_t) T0 < 0)
env->psr |= PSR_NEG;
- if ((T0 & 0xffffffff) < (src1 & 0xffffffff))
+ if (((T0 & 0xffffffff) < (src1 & 0xffffffff)) ||
+ (has_carry && ((T0 & 0xffffffff) <= (src1 & 0xffffffff))))
env->psr |= PSR_CARRY;
if ((((src1 & 0xffffffff) ^ (T1 & 0xffffffff) ^ -1) &
((src1 & 0xffffffff) ^ (T0 & 0xffffffff))) & (1 << 31))
@@ -435,7 +436,7 @@ void OPPROTO op_addx_T1_T0_cc(void)
env->xcc |= PSR_ZERO;
if ((int64_t) T0 < 0)
env->xcc |= PSR_NEG;
- if (T0 < src1)
+ if (T0 < src1 || (has_carry && T0 <= src1))
env->xcc |= PSR_CARRY;
if (((src1 ^ T1 ^ -1) & (src1 ^ T0)) & (1ULL << 63))
env->xcc |= PSR_OVF;
@@ -444,7 +445,7 @@ void OPPROTO op_addx_T1_T0_cc(void)
env->psr |= PSR_ZERO;
if ((int32_t) T0 < 0)
env->psr |= PSR_NEG;
- if (T0 < src1)
+ if (T0 < src1 || (has_carry && T0 <= src1))
env->psr |= PSR_CARRY;
if (((src1 ^ T1 ^ -1) & (src1 ^ T0)) & (1 << 31))
env->psr |= PSR_OVF;
@@ -505,16 +506,17 @@ void OPPROTO op_subx_T1_T0(void)
void OPPROTO op_subx_T1_T0_cc(void)
{
target_ulong src1;
-
+ target_ulong has_carry = FLAG_SET(PSR_CARRY);
src1 = T0;
- T0 -= T1 + FLAG_SET(PSR_CARRY);
+ T0 -= T1 + has_carry;
env->psr = 0;
#ifdef TARGET_SPARC64
if (!(T0 & 0xffffffff))
env->psr |= PSR_ZERO;
if ((int32_t) T0 < 0)
env->psr |= PSR_NEG;
- if ((src1 & 0xffffffff) < (T1 & 0xffffffff))
+ if (((src1 & 0xffffffff) < (T1 & 0xffffffff)) ||
+ (has_carry && ((src1 & 0xffffffff) <= (T1 & 0xffffffff))))
env->psr |= PSR_CARRY;
if ((((src1 & 0xffffffff) ^ (T1 & 0xffffffff)) &
((src1 & 0xffffffff) ^ (T0 & 0xffffffff))) & (1 << 31))
@@ -525,7 +527,7 @@ void OPPROTO op_subx_T1_T0_cc(void)
env->xcc |= PSR_ZERO;
if ((int64_t) T0 < 0)
env->xcc |= PSR_NEG;
- if (src1 < T1)
+ if (src1 < T1 || (has_carry && src1 <= T1))
env->xcc |= PSR_CARRY;
if (((src1 ^ T1) & (src1 ^ T0)) & (1ULL << 63))
env->xcc |= PSR_OVF;
@@ -534,7 +536,7 @@ void OPPROTO op_subx_T1_T0_cc(void)
env->psr |= PSR_ZERO;
if ((int32_t) T0 < 0)
env->psr |= PSR_NEG;
- if (src1 < T1)
+ if (src1 < T1 || (has_carry && src1 <= T1))
env->psr |= PSR_CARRY;
if (((src1 ^ T1) & (src1 ^ T0)) & (1 << 31))
env->psr |= PSR_OVF;
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