[PATCH v2] target/s390x: Fix CC set by CONVERT TO FIXED/LOGICAL

[PATCH v2] target/s390x: Fix CC set by CONVERT TO FIXED/LOGICAL

[Ulrich Weigand]

The FP-to-integer conversion instructions need to set CC 3 whenever
a "special case" occurs; this is the case whenever the instruction
also signals the IEEE invalid exception.  (See e.g. figure 19-18
in the Principles of Operation.)

However, qemu currently will set CC 3 only in the case where the
input was a NaN.  This is indeed one of the special cases, but
there are others, most notably the case where the input is out
of range of the target data type.

This patch fixes the problem by switching these instructions to
the "static" CC method and computing the correct result directly
in the helper.  (It cannot be re-computed later as the information
about the invalid exception is no longer available.)

This fixes a bug observed when running the wasmtime test suite
under the s390x-linux-user target.

Signed-off-by: Ulrich Weigand <ulrich.weigand@de.ibm.com>
---
 target/s390x/fpu_helper.c | 51 +++++++++++++++++++++++++++++++++++++++++++----
 target/s390x/helper.h     | 24 +++++++++++-----------
 target/s390x/translate.c  | 39 +++++++++++-------------------------
 3 files changed, 71 insertions(+), 43 deletions(-)

diff --git a/target/s390x/fpu_helper.c b/target/s390x/fpu_helper.c
index 13af158..50250cf 100644
--- a/target/s390x/fpu_helper.c
+++ b/target/s390x/fpu_helper.c
@@ -168,6 +168,34 @@ uint32_t set_cc_nz_f128(float128 v)
     }
 }
 
+/* condition codes for FP to integer conversion ops */
+static uint32_t set_cc_conv_f32(float32 v, float_status *stat)
+{
+    if (stat->float_exception_flags & float_flag_invalid) {
+        return 3;
+    } else {
+        return set_cc_nz_f32(v);
+    }
+}
+
+static uint32_t set_cc_conv_f64(float64 v, float_status *stat)
+{
+    if (stat->float_exception_flags & float_flag_invalid) {
+        return 3;
+    } else {
+        return set_cc_nz_f64(v);
+    }
+}
+
+static uint32_t set_cc_conv_f128(float128 v, float_status *stat)
+{
+    if (stat->float_exception_flags & float_flag_invalid) {
+        return 3;
+    } else {
+        return set_cc_nz_f128(v);
+    }
+}
+
 static inline uint8_t round_from_m34(uint32_t m34)
 {
     return extract32(m34, 0, 4);
@@ -506,6 +534,7 @@ uint64_t HELPER(cgeb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
 {
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
     int64_t ret = float32_to_int64(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f32(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
@@ -520,6 +549,7 @@ uint64_t HELPER(cgdb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
 {
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
     int64_t ret = float64_to_int64(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f64(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
@@ -535,6 +565,7 @@ uint64_t HELPER(cgxb)(CPUS390XState *env, uint64_t h, uint64_t l, uint32_t m34)
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
     float128 v2 = make_float128(h, l);
     int64_t ret = float128_to_int64(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f128(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
@@ -549,6 +580,7 @@ uint64_t HELPER(cfeb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
 {
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
     int32_t ret = float32_to_int32(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f32(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
@@ -563,6 +595,7 @@ uint64_t HELPER(cfdb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
 {
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
     int32_t ret = float64_to_int32(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f64(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
@@ -578,6 +611,7 @@ uint64_t HELPER(cfxb)(CPUS390XState *env, uint64_t h, uint64_t l, uint32_t m34)
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
     float128 v2 = make_float128(h, l);
     int32_t ret = float128_to_int32(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f128(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
@@ -592,6 +626,8 @@ uint64_t HELPER(clgeb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
 {
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
     uint64_t ret = float32_to_uint64(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f32(v2, &env->fpu_status);
+
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
     if (float32_is_any_nan(v2)) {
@@ -605,6 +641,7 @@ uint64_t HELPER(clgdb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
 {
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
     uint64_t ret = float64_to_uint64(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f64(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
@@ -618,11 +655,13 @@ uint64_t HELPER(clgdb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
 uint64_t HELPER(clgxb)(CPUS390XState *env, uint64_t h, uint64_t l, uint32_t m34)
 {
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
-    uint64_t ret = float128_to_uint64(make_float128(h, l), &env->fpu_status);
+    float128 v2 = make_float128(h, l);
+    uint64_t ret = float128_to_uint64(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f128(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
-    if (float128_is_any_nan(make_float128(h, l))) {
+    if (float128_is_any_nan(v2)) {
         return 0;
     }
     return ret;
@@ -633,6 +672,7 @@ uint64_t HELPER(clfeb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
 {
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
     uint32_t ret = float32_to_uint32(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f32(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
@@ -647,6 +687,7 @@ uint64_t HELPER(clfdb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
 {
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
     uint32_t ret = float64_to_uint32(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f64(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
@@ -660,11 +701,13 @@ uint64_t HELPER(clfdb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
 uint64_t HELPER(clfxb)(CPUS390XState *env, uint64_t h, uint64_t l, uint32_t m34)
 {
     int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
-    uint32_t ret = float128_to_uint32(make_float128(h, l), &env->fpu_status);
+    float128 v2 = make_float128(h, l);
+    uint32_t ret = float128_to_uint32(v2, &env->fpu_status);
+    env->cc_op = set_cc_conv_f128(v2, &env->fpu_status);
 
     s390_restore_bfp_rounding_mode(env, old_mode);
     handle_exceptions(env, xxc_from_m34(m34), GETPC());
-    if (float128_is_any_nan(make_float128(h, l))) {
+    if (float128_is_any_nan(v2)) {
         return 0;
     }
     return ret;
diff --git a/target/s390x/helper.h b/target/s390x/helper.h
index ba045f5..6215ca0 100644
--- a/target/s390x/helper.h
+++ b/target/s390x/helper.h
@@ -64,18 +64,18 @@ DEF_HELPER_FLAGS_5(cxb, TCG_CALL_NO_WG_SE, i32, env, i64, i64, i64, i64)
 DEF_HELPER_FLAGS_3(keb, TCG_CALL_NO_WG, i32, env, i64, i64)
 DEF_HELPER_FLAGS_3(kdb, TCG_CALL_NO_WG, i32, env, i64, i64)
 DEF_HELPER_FLAGS_5(kxb, TCG_CALL_NO_WG, i32, env, i64, i64, i64, i64)
-DEF_HELPER_FLAGS_3(cgeb, TCG_CALL_NO_WG, i64, env, i64, i32)
-DEF_HELPER_FLAGS_3(cgdb, TCG_CALL_NO_WG, i64, env, i64, i32)
-DEF_HELPER_FLAGS_4(cgxb, TCG_CALL_NO_WG, i64, env, i64, i64, i32)
-DEF_HELPER_FLAGS_3(cfeb, TCG_CALL_NO_WG, i64, env, i64, i32)
-DEF_HELPER_FLAGS_3(cfdb, TCG_CALL_NO_WG, i64, env, i64, i32)
-DEF_HELPER_FLAGS_4(cfxb, TCG_CALL_NO_WG, i64, env, i64, i64, i32)
-DEF_HELPER_FLAGS_3(clgeb, TCG_CALL_NO_WG, i64, env, i64, i32)
-DEF_HELPER_FLAGS_3(clgdb, TCG_CALL_NO_WG, i64, env, i64, i32)
-DEF_HELPER_FLAGS_4(clgxb, TCG_CALL_NO_WG, i64, env, i64, i64, i32)
-DEF_HELPER_FLAGS_3(clfeb, TCG_CALL_NO_WG, i64, env, i64, i32)
-DEF_HELPER_FLAGS_3(clfdb, TCG_CALL_NO_WG, i64, env, i64, i32)
-DEF_HELPER_FLAGS_4(clfxb, TCG_CALL_NO_WG, i64, env, i64, i64, i32)
+DEF_HELPER_3(cgeb, i64, env, i64, i32)
+DEF_HELPER_3(cgdb, i64, env, i64, i32)
+DEF_HELPER_4(cgxb, i64, env, i64, i64, i32)
+DEF_HELPER_3(cfeb, i64, env, i64, i32)
+DEF_HELPER_3(cfdb, i64, env, i64, i32)
+DEF_HELPER_4(cfxb, i64, env, i64, i64, i32)
+DEF_HELPER_3(clgeb, i64, env, i64, i32)
+DEF_HELPER_3(clgdb, i64, env, i64, i32)
+DEF_HELPER_4(clgxb, i64, env, i64, i64, i32)
+DEF_HELPER_3(clfeb, i64, env, i64, i32)
+DEF_HELPER_3(clfdb, i64, env, i64, i32)
+DEF_HELPER_4(clfxb, i64, env, i64, i64, i32)
 DEF_HELPER_FLAGS_3(fieb, TCG_CALL_NO_WG, i64, env, i64, i32)
 DEF_HELPER_FLAGS_3(fidb, TCG_CALL_NO_WG, i64, env, i64, i32)
 DEF_HELPER_FLAGS_4(fixb, TCG_CALL_NO_WG, i64, env, i64, i64, i32)
diff --git a/target/s390x/translate.c b/target/s390x/translate.c
index e243624..53129fb 100644
--- a/target/s390x/translate.c
+++ b/target/s390x/translate.c
@@ -563,21 +563,6 @@ static void set_cc_nz_u64(DisasContext *s, TCGv_i64 val)
     gen_op_update1_cc_i64(s, CC_OP_NZ, val);
 }
 
-static void gen_set_cc_nz_f32(DisasContext *s, TCGv_i64 val)
-{
-    gen_op_update1_cc_i64(s, CC_OP_NZ_F32, val);
-}
-
-static void gen_set_cc_nz_f64(DisasContext *s, TCGv_i64 val)
-{
-    gen_op_update1_cc_i64(s, CC_OP_NZ_F64, val);
-}
-
-static void gen_set_cc_nz_f128(DisasContext *s, TCGv_i64 vh, TCGv_i64 vl)
-{
-    gen_op_update2_cc_i64(s, CC_OP_NZ_F128, vh, vl);
-}
-
 /* CC value is in env->cc_op */
 static void set_cc_static(DisasContext *s)
 {
@@ -1836,7 +1821,7 @@ static DisasJumpType op_cfeb(DisasContext *s, DisasOps *o)
     }
     gen_helper_cfeb(o->out, cpu_env, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f32(s, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1849,7 +1834,7 @@ static DisasJumpType op_cfdb(DisasContext *s, DisasOps *o)
     }
     gen_helper_cfdb(o->out, cpu_env, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f64(s, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1862,7 +1847,7 @@ static DisasJumpType op_cfxb(DisasContext *s, DisasOps *o)
     }
     gen_helper_cfxb(o->out, cpu_env, o->in1, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f128(s, o->in1, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1875,7 +1860,7 @@ static DisasJumpType op_cgeb(DisasContext *s, DisasOps *o)
     }
     gen_helper_cgeb(o->out, cpu_env, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f32(s, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1888,7 +1873,7 @@ static DisasJumpType op_cgdb(DisasContext *s, DisasOps *o)
     }
     gen_helper_cgdb(o->out, cpu_env, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f64(s, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1901,7 +1886,7 @@ static DisasJumpType op_cgxb(DisasContext *s, DisasOps *o)
     }
     gen_helper_cgxb(o->out, cpu_env, o->in1, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f128(s, o->in1, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1914,7 +1899,7 @@ static DisasJumpType op_clfeb(DisasContext *s, DisasOps *o)
     }
     gen_helper_clfeb(o->out, cpu_env, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f32(s, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1927,7 +1912,7 @@ static DisasJumpType op_clfdb(DisasContext *s, DisasOps *o)
     }
     gen_helper_clfdb(o->out, cpu_env, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f64(s, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1940,7 +1925,7 @@ static DisasJumpType op_clfxb(DisasContext *s, DisasOps *o)
     }
     gen_helper_clfxb(o->out, cpu_env, o->in1, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f128(s, o->in1, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1953,7 +1938,7 @@ static DisasJumpType op_clgeb(DisasContext *s, DisasOps *o)
     }
     gen_helper_clgeb(o->out, cpu_env, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f32(s, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1966,7 +1951,7 @@ static DisasJumpType op_clgdb(DisasContext *s, DisasOps *o)
     }
     gen_helper_clgdb(o->out, cpu_env, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f64(s, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
@@ -1979,7 +1964,7 @@ static DisasJumpType op_clgxb(DisasContext *s, DisasOps *o)
     }
     gen_helper_clgxb(o->out, cpu_env, o->in1, o->in2, m34);
     tcg_temp_free_i32(m34);
-    gen_set_cc_nz_f128(s, o->in1, o->in2);
+    set_cc_static(s);
     return DISAS_NEXT;
 }
 
-- 
1.8.3.1


-- 
  Dr. Ulrich Weigand
  GNU/Linux compilers and toolchain
  Ulrich.Weigand@de.ibm.com

Re: [PATCH v2] target/s390x: Fix CC set by CONVERT TO FIXED/LOGICAL

[Richard Henderson]

On 6/28/21 9:35 AM, Ulrich Weigand wrote:
> @@ -506,6 +534,7 @@ uint64_t HELPER(cgeb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
>   {
>       int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
>       int64_t ret = float32_to_int64(v2, &env->fpu_status);
> +    env->cc_op = set_cc_conv_f32(v2, &env->fpu_status);
>   
>       s390_restore_bfp_rounding_mode(env, old_mode);
>       handle_exceptions(env, xxc_from_m34(m34), GETPC());

Don't you need to wait until after handle_exceptions, and the handling of suppressing 
exceptions, to write back to cc_op?

I'm thinking that should be able to remove TCGv_i32 cc_op in the translator and manually 
write back to the slot instead.  We already do a good job of caching the value within 
DisasContext -- I imagine that the final code wouldn't even change too much.

Which would allow us to drop

> -DEF_HELPER_FLAGS_3(cgeb, TCG_CALL_NO_WG, i64, env, i64, i32)
> -DEF_HELPER_FLAGS_3(cgdb, TCG_CALL_NO_WG, i64, env, i64, i32)
> -DEF_HELPER_FLAGS_4(cgxb, TCG_CALL_NO_WG, i64, env, i64, i64, i32)
> -DEF_HELPER_FLAGS_3(cfeb, TCG_CALL_NO_WG, i64, env, i64, i32)
> -DEF_HELPER_FLAGS_3(cfdb, TCG_CALL_NO_WG, i64, env, i64, i32)
> -DEF_HELPER_FLAGS_4(cfxb, TCG_CALL_NO_WG, i64, env, i64, i64, i32)
> -DEF_HELPER_FLAGS_3(clgeb, TCG_CALL_NO_WG, i64, env, i64, i32)
> -DEF_HELPER_FLAGS_3(clgdb, TCG_CALL_NO_WG, i64, env, i64, i32)
> -DEF_HELPER_FLAGS_4(clgxb, TCG_CALL_NO_WG, i64, env, i64, i64, i32)
> -DEF_HELPER_FLAGS_3(clfeb, TCG_CALL_NO_WG, i64, env, i64, i32)
> -DEF_HELPER_FLAGS_3(clfdb, TCG_CALL_NO_WG, i64, env, i64, i32)
> -DEF_HELPER_FLAGS_4(clfxb, TCG_CALL_NO_WG, i64, env, i64, i64, i32)
> +DEF_HELPER_3(cgeb, i64, env, i64, i32)
> +DEF_HELPER_3(cgdb, i64, env, i64, i32)
> +DEF_HELPER_4(cgxb, i64, env, i64, i64, i32)
> +DEF_HELPER_3(cfeb, i64, env, i64, i32)
> +DEF_HELPER_3(cfdb, i64, env, i64, i32)
> +DEF_HELPER_4(cfxb, i64, env, i64, i64, i32)
> +DEF_HELPER_3(clgeb, i64, env, i64, i32)
> +DEF_HELPER_3(clgdb, i64, env, i64, i32)
> +DEF_HELPER_4(clgxb, i64, env, i64, i64, i32)
> +DEF_HELPER_3(clfeb, i64, env, i64, i32)
> +DEF_HELPER_3(clfdb, i64, env, i64, i32)
> +DEF_HELPER_4(clfxb, i64, env, i64, i64, i32)

this bit.

I'll experiment this afternoon.


r~

Re: [PATCH v2] target/s390x: Fix CC set by CONVERT TO FIXED/LOGICAL

[Ulrich Weigand]

On Mon, Jun 28, 2021 at 11:45:27AM -0700, Richard Henderson wrote:
> On 6/28/21 9:35 AM, Ulrich Weigand wrote:
> >@@ -506,6 +534,7 @@ uint64_t HELPER(cgeb)(CPUS390XState *env, uint64_t v2, uint32_t m34)
> >  {
> >      int old_mode = s390_swap_bfp_rounding_mode(env, round_from_m34(m34));
> >      int64_t ret = float32_to_int64(v2, &env->fpu_status);
> >+    env->cc_op = set_cc_conv_f32(v2, &env->fpu_status);
> >      s390_restore_bfp_rounding_mode(env, old_mode);
> >      handle_exceptions(env, xxc_from_m34(m34), GETPC());
> 
> Don't you need to wait until after handle_exceptions, and the
> handling of suppressing exceptions, to write back to cc_op?

Good point.  I'll post an updated v3 with this change.

> I'm thinking that should be able to remove TCGv_i32 cc_op in the
> translator and manually write back to the slot instead.  We already
> do a good job of caching the value within DisasContext -- I imagine
> that the final code wouldn't even change too much.

I see.  If this works out, I'll update my patch accordingly
-- please let me know.

Thanks,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU/Linux compilers and toolchain
  Ulrich.Weigand@de.ibm.com

Re: [PATCH v2] target/s390x: Fix CC set by CONVERT TO FIXED/LOGICAL

[Richard Henderson]

On 6/30/21 3:49 AM, Ulrich Weigand wrote:
>> I'm thinking that should be able to remove TCGv_i32 cc_op in the
>> translator and manually write back to the slot instead.  We already
>> do a good job of caching the value within DisasContext -- I imagine
>> that the final code wouldn't even change too much.
> 
> I see.  If this works out, I'll update my patch accordingly
> -- please let me know.

I posted that on Monday:

https://patchew.org/QEMU/20210629002930.3013776-1-richard.henderson@linaro.org/

There are actually slightly fewer stores to the cc_op slot in the generated code, because 
some of them migrate to the helpers.  But for normal integer code the generated *is* 
identical.


r~