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authorPeter Maydell <peter.maydell@linaro.org>2011-05-05 19:35:35 +0100
committerAurelien Jarno <aurelien@aurel32.net>2011-05-15 00:22:57 +0200
commit605a6aed56963360b744355d0c25da9e26a9bb0a (patch)
tree01eb1e9b1ef71d525971a77b57fe6069629b9154
parentde1db2a172074a9ed7756d21823a70181b9a1dfb (diff)
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target-arm: Fix VMLA, VMLS, VNMLS, VNMLA handling of NaNs
Correct handling of NaNs for VFP VMLA, VMLS, VNMLS and VNMLA requires that we implement the set of negations and additions specified by the ARM ARM; plausible looking simplifications like turning (-A + B) into (B - A) or computing (A + B) rather than (B + A) result in selecting the wrong NaN or returning a NaN with the wrong sign bit. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
-rw-r--r--target-arm/translate.c53
1 files changed, 40 insertions, 13 deletions
diff --git a/target-arm/translate.c b/target-arm/translate.c
index 59190f6..a8a3b2c 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -909,6 +909,26 @@ VFP_OP2(div)
#undef VFP_OP2
+static inline void gen_vfp_F1_mul(int dp)
+{
+ /* Like gen_vfp_mul() but put result in F1 */
+ if (dp) {
+ gen_helper_vfp_muld(cpu_F1d, cpu_F0d, cpu_F1d, cpu_env);
+ } else {
+ gen_helper_vfp_muls(cpu_F1s, cpu_F0s, cpu_F1s, cpu_env);
+ }
+}
+
+static inline void gen_vfp_F1_neg(int dp)
+{
+ /* Like gen_vfp_neg() but put result in F1 */
+ if (dp) {
+ gen_helper_vfp_negd(cpu_F1d, cpu_F0d);
+ } else {
+ gen_helper_vfp_negs(cpu_F1s, cpu_F0s);
+ }
+}
+
static inline void gen_vfp_abs(int dp)
{
if (dp)
@@ -3021,27 +3041,34 @@ static int disas_vfp_insn(CPUState * env, DisasContext *s, uint32_t insn)
for (;;) {
/* Perform the calculation. */
switch (op) {
- case 0: /* mac: fd + (fn * fm) */
- gen_vfp_mul(dp);
- gen_mov_F1_vreg(dp, rd);
+ case 0: /* VMLA: fd + (fn * fm) */
+ /* Note that order of inputs to the add matters for NaNs */
+ gen_vfp_F1_mul(dp);
+ gen_mov_F0_vreg(dp, rd);
gen_vfp_add(dp);
break;
- case 1: /* nmac: fd - (fn * fm) */
+ case 1: /* VMLS: fd + -(fn * fm) */
gen_vfp_mul(dp);
- gen_vfp_neg(dp);
- gen_mov_F1_vreg(dp, rd);
+ gen_vfp_F1_neg(dp);
+ gen_mov_F0_vreg(dp, rd);
gen_vfp_add(dp);
break;
- case 2: /* msc: -fd + (fn * fm) */
- gen_vfp_mul(dp);
- gen_mov_F1_vreg(dp, rd);
- gen_vfp_sub(dp);
+ case 2: /* VNMLS: -fd + (fn * fm) */
+ /* Note that it isn't valid to replace (-A + B) with (B - A)
+ * or similar plausible looking simplifications
+ * because this will give wrong results for NaNs.
+ */
+ gen_vfp_F1_mul(dp);
+ gen_mov_F0_vreg(dp, rd);
+ gen_vfp_neg(dp);
+ gen_vfp_add(dp);
break;
- case 3: /* nmsc: -fd - (fn * fm) */
+ case 3: /* VNMLA: -fd + -(fn * fm) */
gen_vfp_mul(dp);
+ gen_vfp_F1_neg(dp);
+ gen_mov_F0_vreg(dp, rd);
gen_vfp_neg(dp);
- gen_mov_F1_vreg(dp, rd);
- gen_vfp_sub(dp);
+ gen_vfp_add(dp);
break;
case 4: /* mul: fn * fm */
gen_vfp_mul(dp);