Re: [Qemu-devel] [PATCH] target-arm: Set the right overflow bit for neon 32 and 64 bit saturating add/sub.

[Christophe Lyon <christophe.lyon@st.com>]

On 21.01.2011 18:58, Peter Maydell wrote:
> I've reviewed this patch and tested it in the usual way
> and can confirm that it now sets the right saturation bit;
> mostly it is OK. However...
Thanks!

 
[...]
> the indentation in this hunk is wrong -- qemu standard is four-space.

Oops. What is the "official" emacs configuration to get the right qemu style?


> You can check for this sort of thing by running scripts/checkpatch.pl,
Thanks for the pointer.

Here is an updated patch with these minor fixes.

Christophe.


Signed-off-by: Christophe Lyon <christophe.lyon@st.com>
---
 target-arm/helpers.h     |   12 ++++--
 target-arm/neon_helper.c |   89 ++++++++++++++++++++++++++++++++++++++++++++++
 target-arm/op_helper.c   |   49 -------------------------
 target-arm/translate.c   |   18 ++++-----
 4 files changed, 105 insertions(+), 63 deletions(-)

diff --git a/target-arm/helpers.h b/target-arm/helpers.h
index b88ebae..8a2564e 100644
--- a/target-arm/helpers.h
+++ b/target-arm/helpers.h
@@ -137,10 +137,6 @@ DEF_HELPER_2(rsqrte_f32, f32, f32, env)
 DEF_HELPER_2(recpe_u32, i32, i32, env)
 DEF_HELPER_2(rsqrte_u32, i32, i32, env)
 DEF_HELPER_4(neon_tbl, i32, i32, i32, i32, i32)
-DEF_HELPER_2(neon_add_saturate_u64, i64, i64, i64)
-DEF_HELPER_2(neon_add_saturate_s64, i64, i64, i64)
-DEF_HELPER_2(neon_sub_saturate_u64, i64, i64, i64)
-DEF_HELPER_2(neon_sub_saturate_s64, i64, i64, i64)
 
 DEF_HELPER_2(add_cc, i32, i32, i32)
 DEF_HELPER_2(adc_cc, i32, i32, i32)
@@ -160,10 +156,18 @@ DEF_HELPER_3(neon_qadd_u8, i32, env, i32, i32)
 DEF_HELPER_3(neon_qadd_s8, i32, env, i32, i32)
 DEF_HELPER_3(neon_qadd_u16, i32, env, i32, i32)
 DEF_HELPER_3(neon_qadd_s16, i32, env, i32, i32)
+DEF_HELPER_3(neon_qadd_u32, i32, env, i32, i32)
+DEF_HELPER_3(neon_qadd_s32, i32, env, i32, i32)
 DEF_HELPER_3(neon_qsub_u8, i32, env, i32, i32)
 DEF_HELPER_3(neon_qsub_s8, i32, env, i32, i32)
 DEF_HELPER_3(neon_qsub_u16, i32, env, i32, i32)
 DEF_HELPER_3(neon_qsub_s16, i32, env, i32, i32)
+DEF_HELPER_3(neon_qsub_u32, i32, env, i32, i32)
+DEF_HELPER_3(neon_qsub_s32, i32, env, i32, i32)
+DEF_HELPER_3(neon_qadd_u64, i64, env, i64, i64)
+DEF_HELPER_3(neon_qadd_s64, i64, env, i64, i64)
+DEF_HELPER_3(neon_qsub_u64, i64, env, i64, i64)
+DEF_HELPER_3(neon_qsub_s64, i64, env, i64, i64)
 
 DEF_HELPER_2(neon_hadd_s8, i32, i32, i32)
 DEF_HELPER_2(neon_hadd_u8, i32, i32, i32)
diff --git a/target-arm/neon_helper.c b/target-arm/neon_helper.c
index 20f3c16..c1619c0 100644
--- a/target-arm/neon_helper.c
+++ b/target-arm/neon_helper.c
@@ -198,6 +198,28 @@ NEON_VOP_ENV(qadd_u16, neon_u16, 2)
 #undef NEON_FN
 #undef NEON_USAT
 
+uint32_t HELPER(neon_qadd_u32)(CPUState *env, uint32_t a, uint32_t b)
+{
+    uint32_t res = a + b;
+    if (res < a) {
+        SET_QC();
+        res = ~0;
+    }
+    return res;
+}
+
+uint64_t HELPER(neon_qadd_u64)(CPUState *env, uint64_t src1, uint64_t src2)
+{
+  uint64_t res;
+
+  res = src1 + src2;
+  if (res < src1) {
+    SET_QC();
+    res = ~(uint64_t)0;
+  }
+  return res;
+}
+
 #define NEON_SSAT(dest, src1, src2, type) do { \
     int32_t tmp = (uint32_t)src1 + (uint32_t)src2; \
     if (tmp != (type)tmp) { \
@@ -218,6 +240,28 @@ NEON_VOP_ENV(qadd_s16, neon_s16, 2)
 #undef NEON_FN
 #undef NEON_SSAT
 
+uint32_t HELPER(neon_qadd_s32)(CPUState *env, uint32_t a, uint32_t b)
+{
+    uint32_t res = a + b;
+    if (((res ^ a) & SIGNBIT) && !((a ^ b) & SIGNBIT)) {
+        SET_QC();
+        res = ~(((int32_t)a >> 31) ^ SIGNBIT);
+    }
+    return res;
+}
+
+uint64_t HELPER(neon_qadd_s64)(CPUState *env, uint64_t src1, uint64_t src2)
+{
+  uint64_t res;
+
+  res = src1 + src2;
+  if (((res ^ src1) & SIGNBIT64) && !((src1 ^ src2) & SIGNBIT64)) {
+    SET_QC();
+    res = ((int64_t)src1 >> 63) ^ ~SIGNBIT64;
+  }
+  return res;
+}
+
 #define NEON_USAT(dest, src1, src2, type) do { \
     uint32_t tmp = (uint32_t)src1 - (uint32_t)src2; \
     if (tmp != (type)tmp) { \
@@ -234,6 +278,29 @@ NEON_VOP_ENV(qsub_u16, neon_u16, 2)
 #undef NEON_FN
 #undef NEON_USAT
 
+uint32_t HELPER(neon_qsub_u32)(CPUState *env, uint32_t a, uint32_t b)
+{
+    uint32_t res = a - b;
+    if (res > a) {
+        SET_QC();
+        res = 0;
+    }
+    return res;
+}
+
+uint64_t HELPER(neon_qsub_u64)(CPUState *env, uint64_t src1, uint64_t src2)
+{
+  uint64_t res;
+
+  if (src1 < src2) {
+    SET_QC();
+    res = 0;
+  } else {
+    res = src1 - src2;
+  }
+  return res;
+}
+
 #define NEON_SSAT(dest, src1, src2, type) do { \
     int32_t tmp = (uint32_t)src1 - (uint32_t)src2; \
     if (tmp != (type)tmp) { \
@@ -254,6 +321,28 @@ NEON_VOP_ENV(qsub_s16, neon_s16, 2)
 #undef NEON_FN
 #undef NEON_SSAT
 
+uint32_t HELPER(neon_qsub_s32)(CPUState *env, uint32_t a, uint32_t b)
+{
+    uint32_t res = a - b;
+    if (((res ^ a) & SIGNBIT) && ((a ^ b) & SIGNBIT)) {
+        SET_QC();
+        res = ~(((int32_t)a >> 31) ^ SIGNBIT);
+    }
+    return res;
+}
+
+uint64_t HELPER(neon_qsub_s64)(CPUState *env, uint64_t src1, uint64_t src2)
+{
+  uint64_t res;
+
+  res = src1 - src2;
+  if (((res ^ src1) & SIGNBIT64) && ((src1 ^ src2) & SIGNBIT64)) {
+    SET_QC();
+    res = ((int64_t)src1 >> 63) ^ ~SIGNBIT64;
+  }
+  return res;
+}
+
 #define NEON_FN(dest, src1, src2) dest = (src1 + src2) >> 1
 NEON_VOP(hadd_s8, neon_s8, 4)
 NEON_VOP(hadd_u8, neon_u8, 4)
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index 43baa63..3de2610 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -424,52 +424,3 @@ uint32_t HELPER(ror_cc)(uint32_t x, uint32_t i)
         return ((uint32_t)x >> shift) | (x << (32 - shift));
     }
 }
-
-uint64_t HELPER(neon_add_saturate_s64)(uint64_t src1, uint64_t src2)
-{
-    uint64_t res;
-
-    res = src1 + src2;
-    if (((res ^ src1) & SIGNBIT64) && !((src1 ^ src2) & SIGNBIT64)) {
-        env->QF = 1;
-        res = ((int64_t)src1 >> 63) ^ ~SIGNBIT64;
-    }
-    return res;
-}
-
-uint64_t HELPER(neon_add_saturate_u64)(uint64_t src1, uint64_t src2)
-{
-    uint64_t res;
-
-    res = src1 + src2;
-    if (res < src1) {
-        env->QF = 1;
-        res = ~(uint64_t)0;
-    }
-    return res;
-}
-
-uint64_t HELPER(neon_sub_saturate_s64)(uint64_t src1, uint64_t src2)
-{
-    uint64_t res;
-
-    res = src1 - src2;
-    if (((res ^ src1) & SIGNBIT64) && ((src1 ^ src2) & SIGNBIT64)) {
-        env->QF = 1;
-        res = ((int64_t)src1 >> 63) ^ ~SIGNBIT64;
-    }
-    return res;
-}
-
-uint64_t HELPER(neon_sub_saturate_u64)(uint64_t src1, uint64_t src2)
-{
-    uint64_t res;
-
-    if (src1 < src2) {
-        env->QF = 1;
-        res = 0;
-    } else {
-        res = src1 - src2;
-    }
-    return res;
-}
diff --git a/target-arm/translate.c b/target-arm/translate.c
index 41cbb96..ab4aa29 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -3539,12 +3539,6 @@ static inline void gen_neon_rsb(int size, TCGv t0, TCGv t1)
 #define gen_helper_neon_pmin_s32  gen_helper_neon_min_s32
 #define gen_helper_neon_pmin_u32  gen_helper_neon_min_u32
 
-/* FIXME: This is wrong.  They set the wrong overflow bit.  */
-#define gen_helper_neon_qadd_s32(a, e, b, c) gen_helper_add_saturate(a, b, c)
-#define gen_helper_neon_qadd_u32(a, e, b, c) gen_helper_add_usaturate(a, b, c)
-#define gen_helper_neon_qsub_s32(a, e, b, c) gen_helper_sub_saturate(a, b, c)
-#define gen_helper_neon_qsub_u32(a, e, b, c) gen_helper_sub_usaturate(a, b, c)
-
 #define GEN_NEON_INTEGER_OP_ENV(name) do { \
     switch ((size << 1) | u) { \
     case 0: \
@@ -4233,16 +4227,20 @@ static int disas_neon_data_insn(CPUState * env, DisasContext *s, uint32_t insn)
                 switch (op) {
                 case 1: /* VQADD */
                     if (u) {
-                        gen_helper_neon_add_saturate_u64(CPU_V001);
+                        gen_helper_neon_qadd_u64(cpu_V0, cpu_env,
+                                                 cpu_V0, cpu_V1);
                     } else {
-                        gen_helper_neon_add_saturate_s64(CPU_V001);
+                        gen_helper_neon_qadd_s64(cpu_V0, cpu_env,
+                                                 cpu_V0, cpu_V1);
                     }
                     break;
                 case 5: /* VQSUB */
                     if (u) {
-                        gen_helper_neon_sub_saturate_u64(CPU_V001);
+                        gen_helper_neon_qsub_u64(cpu_V0, cpu_env,
+                                                 cpu_V0, cpu_V1);
                     } else {
-                        gen_helper_neon_sub_saturate_s64(CPU_V001);
+                        gen_helper_neon_qsub_s64(cpu_V0, cpu_env,
+                                                 cpu_V0, cpu_V1);
                     }
                     break;
                 case 8: /* VSHL */
-- 
1.7.2.3