[PATCH 0/2] target/s390x: Fix the floating-point multiply-and-add NaN rules

[PATCH 0/2] target/s390x: Fix the floating-point multiply-and-add NaN rules

[Ilya Leoshkevich]

Hi,

Peter reported on IRC that FMA NaN handling was likely broken on s390x.
Patch 1 of this series fixes the issue, patch 2 adds a test. For the
sake of readability, the test sacrifices the 90-character line length
rule.

Best regards,
Ilya

Ilya Leoshkevich (2):
  target/s390x: Fix the floating-point multiply-and-add NaN rules
  tests/tcg/s390x: Add the floating-point multiply-and-add test

 fpu/softfloat-specialize.c.inc    |  19 +++
 target/s390x/tcg/fpu_helper.c     |   8 +-
 target/s390x/tcg/vec_fpu_helper.c |  12 +-
 tests/tcg/s390x/Makefile.target   |   5 +-
 tests/tcg/s390x/float.h           | 104 +++++++++++++
 tests/tcg/s390x/fma.c             | 233 ++++++++++++++++++++++++++++++
 tests/tcg/s390x/vfminmax.c        | 223 ++++++++++------------------
 7 files changed, 449 insertions(+), 155 deletions(-)
 create mode 100644 tests/tcg/s390x/float.h
 create mode 100644 tests/tcg/s390x/fma.c

-- 
2.47.0

[PATCH 1/2] target/s390x: Fix the floating-point multiply-and-add NaN rules

[Ilya Leoshkevich]

Order the helper arguments to match the Principles of Operation.
Implement the "Results: MULTIPLY AND ADD" table in pickNaNMulAdd().

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 fpu/softfloat-specialize.c.inc    | 19 +++++++++++++++++++
 target/s390x/tcg/fpu_helper.c     |  8 ++++----
 target/s390x/tcg/vec_fpu_helper.c | 12 ++++++------
 3 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/fpu/softfloat-specialize.c.inc b/fpu/softfloat-specialize.c.inc
index 4e279b9bc40..62197373c93 100644
--- a/fpu/softfloat-specialize.c.inc
+++ b/fpu/softfloat-specialize.c.inc
@@ -635,6 +635,25 @@ static int pickNaNMulAdd(FloatClass a_cls, FloatClass b_cls, FloatClass c_cls,
         float_raise(float_flag_invalid | float_flag_invalid_imz, status);
     }
     return 3; /* default NaN */
+#elif defined(TARGET_S390X)
+    if (infzero) {
+        float_raise(float_flag_invalid | float_flag_invalid_imz, status);
+        return 3;
+    }
+
+    if (is_snan(a_cls)) {
+        return 0;
+    } else if (is_snan(b_cls)) {
+        return 1;
+    } else if (is_snan(c_cls)) {
+        return 2;
+    } else if (is_qnan(a_cls)) {
+        return 0;
+    } else if (is_qnan(b_cls)) {
+        return 1;
+    } else {
+        return 2;
+    }
 #elif defined(TARGET_SPARC)
     /* For (inf,0,nan) return c. */
     if (infzero) {
diff --git a/target/s390x/tcg/fpu_helper.c b/target/s390x/tcg/fpu_helper.c
index d8bd5748faf..5041c139627 100644
--- a/target/s390x/tcg/fpu_helper.c
+++ b/target/s390x/tcg/fpu_helper.c
@@ -780,7 +780,7 @@ uint32_t HELPER(kxb)(CPUS390XState *env, Int128 a, Int128 b)
 uint64_t HELPER(maeb)(CPUS390XState *env, uint64_t f1,
                       uint64_t f2, uint64_t f3)
 {
-    float32 ret = float32_muladd(f2, f3, f1, 0, &env->fpu_status);
+    float32 ret = float32_muladd(f3, f2, f1, 0, &env->fpu_status);
     handle_exceptions(env, false, GETPC());
     return ret;
 }
@@ -789,7 +789,7 @@ uint64_t HELPER(maeb)(CPUS390XState *env, uint64_t f1,
 uint64_t HELPER(madb)(CPUS390XState *env, uint64_t f1,
                       uint64_t f2, uint64_t f3)
 {
-    float64 ret = float64_muladd(f2, f3, f1, 0, &env->fpu_status);
+    float64 ret = float64_muladd(f3, f2, f1, 0, &env->fpu_status);
     handle_exceptions(env, false, GETPC());
     return ret;
 }
@@ -798,7 +798,7 @@ uint64_t HELPER(madb)(CPUS390XState *env, uint64_t f1,
 uint64_t HELPER(mseb)(CPUS390XState *env, uint64_t f1,
                       uint64_t f2, uint64_t f3)
 {
-    float32 ret = float32_muladd(f2, f3, f1, float_muladd_negate_c,
+    float32 ret = float32_muladd(f3, f2, f1, float_muladd_negate_c,
                                  &env->fpu_status);
     handle_exceptions(env, false, GETPC());
     return ret;
@@ -808,7 +808,7 @@ uint64_t HELPER(mseb)(CPUS390XState *env, uint64_t f1,
 uint64_t HELPER(msdb)(CPUS390XState *env, uint64_t f1,
                       uint64_t f2, uint64_t f3)
 {
-    float64 ret = float64_muladd(f2, f3, f1, float_muladd_negate_c,
+    float64 ret = float64_muladd(f3, f2, f1, float_muladd_negate_c,
                                  &env->fpu_status);
     handle_exceptions(env, false, GETPC());
     return ret;
diff --git a/target/s390x/tcg/vec_fpu_helper.c b/target/s390x/tcg/vec_fpu_helper.c
index 75cf605b9f4..1bbaa82fe8a 100644
--- a/target/s390x/tcg/vec_fpu_helper.c
+++ b/target/s390x/tcg/vec_fpu_helper.c
@@ -621,8 +621,8 @@ static void vfma32(S390Vector *v1, const S390Vector *v2, const S390Vector *v3,
     int i;
 
     for (i = 0; i < 4; i++) {
-        const float32 a = s390_vec_read_float32(v2, i);
-        const float32 b = s390_vec_read_float32(v3, i);
+        const float32 a = s390_vec_read_float32(v3, i);
+        const float32 b = s390_vec_read_float32(v2, i);
         const float32 c = s390_vec_read_float32(v4, i);
         float32 ret = float32_muladd(a, b, c, flags, &env->fpu_status);
 
@@ -645,8 +645,8 @@ static void vfma64(S390Vector *v1, const S390Vector *v2, const S390Vector *v3,
     int i;
 
     for (i = 0; i < 2; i++) {
-        const float64 a = s390_vec_read_float64(v2, i);
-        const float64 b = s390_vec_read_float64(v3, i);
+        const float64 a = s390_vec_read_float64(v3, i);
+        const float64 b = s390_vec_read_float64(v2, i);
         const float64 c = s390_vec_read_float64(v4, i);
         const float64 ret = float64_muladd(a, b, c, flags, &env->fpu_status);
 
@@ -664,8 +664,8 @@ static void vfma128(S390Vector *v1, const S390Vector *v2, const S390Vector *v3,
                     const S390Vector *v4, CPUS390XState *env, bool s, int flags,
                     uintptr_t retaddr)
 {
-    const float128 a = s390_vec_read_float128(v2);
-    const float128 b = s390_vec_read_float128(v3);
+    const float128 a = s390_vec_read_float128(v3);
+    const float128 b = s390_vec_read_float128(v2);
     const float128 c = s390_vec_read_float128(v4);
     uint8_t vxc, vec_exc = 0;
     float128 ret;
-- 
2.47.0

Re: [PATCH 1/2] target/s390x: Fix the floating-point multiply-and-add NaN rules

[Peter Maydell]

On Wed, 23 Oct 2024 at 01:02, Ilya Leoshkevich <iii@linux.ibm.com> wrote:
>
> Order the helper arguments to match the Principles of Operation.
> Implement the "Results: MULTIPLY AND ADD" table in pickNaNMulAdd().
>
> Reported-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM

[PATCH 2/2] tests/tcg/s390x: Add the floating-point multiply-and-add test

[Ilya Leoshkevich]

Add a test to prevent regressions.
Share some useful pieces with the vfminmax test.
Remove the duplicates from the floating point class values.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 tests/tcg/s390x/Makefile.target |   5 +-
 tests/tcg/s390x/float.h         | 104 ++++++++++++++
 tests/tcg/s390x/fma.c           | 233 ++++++++++++++++++++++++++++++++
 tests/tcg/s390x/vfminmax.c      | 223 +++++++++++-------------------
 4 files changed, 420 insertions(+), 145 deletions(-)
 create mode 100644 tests/tcg/s390x/float.h
 create mode 100644 tests/tcg/s390x/fma.c

diff --git a/tests/tcg/s390x/Makefile.target b/tests/tcg/s390x/Makefile.target
index 2dab4f45822..da5fe71a407 100644
--- a/tests/tcg/s390x/Makefile.target
+++ b/tests/tcg/s390x/Makefile.target
@@ -74,8 +74,11 @@ $(Z13_TESTS): CFLAGS+=-march=z13 -O2
 TESTS+=$(Z13_TESTS)
 
 ifneq ($(CROSS_CC_HAS_Z14),)
-Z14_TESTS=vfminmax
+Z14_TESTS=fma vfminmax
+fma: float.h
+fma: LDFLAGS+=-lm
 vfminmax: LDFLAGS+=-lm
+vfminmax: float.h
 $(Z14_TESTS): CFLAGS+=-march=z14 -O2
 TESTS+=$(Z14_TESTS)
 endif
diff --git a/tests/tcg/s390x/float.h b/tests/tcg/s390x/float.h
new file mode 100644
index 00000000000..9d1682b8fc5
--- /dev/null
+++ b/tests/tcg/s390x/float.h
@@ -0,0 +1,104 @@
+/*
+ * Helpers for floating-point tests.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#ifndef FLOAT_H
+#define FLOAT_H
+
+/*
+ * Floating-point value classes.
+ */
+#define N_FORMATS 3
+#define CLASS_MINUS_INF 0
+#define CLASS_MINUS_FN 1
+#define CLASS_MINUS_ZERO 2
+#define CLASS_PLUS_ZERO 3
+#define CLASS_PLUS_FN 4
+#define CLASS_PLUS_INF 5
+#define CLASS_QNAN 6
+#define CLASS_SNAN 7
+#define N_SIGNED_CLASSES 8
+static const size_t float_sizes[N_FORMATS] = {
+    /* M4 == 2: short    */ 4,
+    /* M4 == 3: long     */ 8,
+    /* M4 == 4: extended */ 16,
+};
+static const size_t e_bits[N_FORMATS] = {
+    /* M4 == 2: short    */ 8,
+    /* M4 == 3: long     */ 11,
+    /* M4 == 4: extended */ 15,
+};
+struct float_class {
+    size_t n;
+    unsigned char v[2][16];
+};
+static const struct float_class signed_floats[N_FORMATS][N_SIGNED_CLASSES] = {
+    /* M4 == 2: short */
+    {
+        /* -inf */ {1, {{0xff, 0x80, 0x00, 0x00}}},
+        /* -Fn */  {2, {{0xc2, 0x28, 0x00, 0x00},
+                        {0xc2, 0x29, 0x00, 0x00}}},
+        /* -0 */   {1, {{0x80, 0x00, 0x00, 0x00}}},
+        /* +0 */   {1, {{0x00, 0x00, 0x00, 0x00}}},
+        /* +Fn */  {2, {{0x42, 0x28, 0x00, 0x00},
+                        {0x42, 0x2a, 0x00, 0x00}}},
+        /* +inf */ {1, {{0x7f, 0x80, 0x00, 0x00}}},
+        /* QNaN */ {2, {{0x7f, 0xff, 0xff, 0xff},
+                        {0x7f, 0xff, 0xff, 0xfe}}},
+        /* SNaN */ {2, {{0x7f, 0xbf, 0xff, 0xff},
+                        {0x7f, 0xbf, 0xff, 0xfd}}},
+    },
+
+    /* M4 == 3: long */
+    {
+        /* -inf */ {1, {{0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* -Fn */  {2, {{0xc0, 0x45, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+                        {0xc0, 0x46, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* -0 */   {1, {{0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* +0 */   {1, {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* +Fn */  {2, {{0x40, 0x45, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+                        {0x40, 0x47, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* +inf */ {1, {{0x7f, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* QNaN */ {2, {{0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+                        {0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe}}},
+        /* SNaN */ {2, {{0x7f, 0xf7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+                        {0x7f, 0xf7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfd}}},
+    },
+
+    /* M4 == 4: extended */
+    {
+        /* -inf */ {1, {{0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* -Fn */  {2, {{0xc0, 0x04, 0x50, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+                        {0xc0, 0x04, 0x51, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* -0 */   {1, {{0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* +0 */   {1, {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* +Fn */  {2, {{0x40, 0x04, 0x50, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+                        {0x40, 0x04, 0x52, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* +inf */ {1, {{0x7f, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}}},
+        /* QNaN */ {2, {{0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+                        {0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe}}},
+        /* SNaN */ {2, {{0x7f, 0xff, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+                        {0x7f, 0xff, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfd}}},
+    },
+};
+static const unsigned char default_nans[N_FORMATS][16] = {
+    /* M4 == 2: short    */ {0x7f, 0xc0, 0x00, 0x00},
+    /* M4 == 3: long     */ {0x7f, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+    /* M4 == 4: extended */ {0x7f, 0xff, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+};
+
+static void dump_v(FILE *f, const void *v, size_t n)
+{
+    for (int i = 0; i < n; i++) {
+        fprintf(f, "%02x", ((const unsigned char *)v)[i]);
+    }
+}
+
+static void snan_to_qnan(char *v, int fmt)
+{
+    size_t bit = 1 + e_bits[fmt];
+    v[bit / 8] |= 1 << (7 - (bit % 8));
+}
+
+#endif
diff --git a/tests/tcg/s390x/fma.c b/tests/tcg/s390x/fma.c
new file mode 100644
index 00000000000..6872f59a7a6
--- /dev/null
+++ b/tests/tcg/s390x/fma.c
@@ -0,0 +1,233 @@
+/*
+ * Test floating-point multiply-and-add instructions.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include <fenv.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "float.h"
+
+union val {
+    float e;
+    double d;
+    long double x;
+    char buf[16];
+};
+
+/*
+ * PoP tables as close to the original as possible.
+ */
+static const char *table1[N_SIGNED_CLASSES][N_SIGNED_CLASSES] = {
+     /*         -inf           -Fn          -0             +0             +Fn          +inf           QNaN         SNaN     */
+    {/* -inf */ "P(+inf)",     "P(+inf)",   "Xi: T(dNaN)", "Xi: T(dNaN)", "P(-inf)",   "P(-inf)",     "P(b)",      "Xi: T(b*)"},
+    {/* -Fn  */ "P(+inf)",     "P(a*b)",    "P(+0)",       "P(-0)",       "P(a*b)",    "P(-inf)",     "P(b)",      "Xi: T(b*)"},
+    {/* -0   */ "Xi: T(dNaN)", "P(+0)",     "P(+0)",       "P(-0)",       "P(-0)",     "Xi: T(dNaN)", "P(b)",      "Xi: T(b*)"},
+    {/* +0   */ "Xi: T(dNaN)", "P(-0)",     "P(-0)",       "P(+0)",       "P(+0)",     "Xi: T(dNaN)", "P(b)",      "Xi: T(b*)"},
+    {/* +Fn  */ "P(-inf)",     "P(a*b)",    "P(-0)",       "P(+0)",       "P(a*b)",    "P(+inf)",     "P(b)",      "Xi: T(b*)"},
+    {/* +inf */ "P(-inf)",     "P(-inf)",   "Xi: T(dNaN)", "Xi: T(dNaN)", "P(+inf)",   "P(+inf)",     "P(b)",      "Xi: T(b*)"},
+    {/* QNaN */ "P(a)",        "P(a)",      "P(a)",        "P(a)",        "P(a)",      "P(a)",        "P(a)",      "Xi: T(b*)"},
+    {/* SNaN */ "Xi: T(a*)",   "Xi: T(a*)", "Xi: T(a*)",   "Xi: T(a*)",   "Xi: T(a*)", "Xi: T(a*)",   "Xi: T(a*)", "Xi: T(a*)"},
+};
+
+static const char *table2[N_SIGNED_CLASSES][N_SIGNED_CLASSES] = {
+     /*         -inf           -Fn        -0         +0         +Fn        +inf           QNaN    SNaN     */
+    {/* -inf */ "T(-inf)",     "T(-inf)", "T(-inf)", "T(-inf)", "T(-inf)", "Xi: T(dNaN)", "T(c)", "Xi: T(c*)"},
+    {/* -Fn  */ "T(-inf)",     "R(p+c)",  "R(p)",    "R(p)",    "R(p+c)",  "T(+inf)",     "T(c)", "Xi: T(c*)"},
+    {/* -0   */ "T(-inf)",     "R(c)",    "T(-0)",   "Rezd",    "R(c)",    "T(+inf)",     "T(c)", "Xi: T(c*)"},
+    {/* +0   */ "T(-inf)",     "R(c)",    "Rezd",    "T(+0)",   "R(c)",    "T(+inf)",     "T(c)", "Xi: T(c*)"},
+    {/* +Fn  */ "T(-inf)",     "R(p+c)",  "R(p)",    "R(p)",    "R(p+c)",  "T(+inf)",     "T(c)", "Xi: T(c*)"},
+    {/* +inf */ "Xi: T(dNaN)", "T(+inf)", "T(+inf)", "T(+inf)", "T(+inf)", "T(+inf)",     "T(c)", "Xi: T(c*)"},
+    {/* QNaN */ "T(p)",        "T(p)",    "T(p)",    "T(p)",    "T(p)",    "T(p)",        "T(p)", "Xi: T(c*)"},
+     /* SNaN: can't happen */
+};
+
+static void interpret_tables(union val *r, bool *xi, int fmt,
+                             int cls_a, const union val *a,
+                             int cls_b, const union val *b,
+                             int cls_c, const union val *c)
+{
+    const char *spec1 = table1[cls_a][cls_b];
+    const char *spec2;
+    union val p;
+    int cls_p;
+
+    *xi = false;
+
+    if (strcmp(spec1, "P(-inf)") == 0) {
+        cls_p = CLASS_MINUS_INF;
+    } else if (strcmp(spec1, "P(+inf)") == 0) {
+        cls_p = CLASS_PLUS_INF;
+    } else if (strcmp(spec1, "P(-0)") == 0) {
+        cls_p = CLASS_MINUS_ZERO;
+    } else if (strcmp(spec1, "P(+0)") == 0) {
+        cls_p = CLASS_PLUS_ZERO;
+    } else if (strcmp(spec1, "P(a)") == 0) {
+        cls_p = cls_a;
+        memcpy(&p, a, sizeof(p));
+    } else if (strcmp(spec1, "P(b)") == 0) {
+        cls_p = cls_b;
+        memcpy(&p, b, sizeof(p));
+    } else if (strcmp(spec1, "P(a*b)") == 0) {
+        /*
+         * In the general case splitting fma into multiplication and addition
+         * doesn't work, but this is the case with our test inputs.
+         */
+        cls_p = cls_a == cls_b ? CLASS_PLUS_FN : CLASS_MINUS_FN;
+        switch (fmt) {
+        case 0:
+            p.e = a->e * b->e;
+            break;
+        case 1:
+            p.d = a->d * b->d;
+            break;
+        case 2:
+            p.x = a->x * b->x;
+            break;
+        default:
+            fprintf(stderr, "Unsupported fmt: %d\n", fmt);
+            exit(1);
+        }
+    } else if (strcmp(spec1, "Xi: T(dNaN)") == 0) {
+        memcpy(r, default_nans[fmt], sizeof(*r));
+        *xi = true;
+        return;
+    } else if (strcmp(spec1, "Xi: T(a*)") == 0) {
+        memcpy(r, a, sizeof(*r));
+        snan_to_qnan(r->buf, fmt);
+        *xi = true;
+        return;
+    } else if (strcmp(spec1, "Xi: T(b*)") == 0) {
+        memcpy(r, b, sizeof(*r));
+        snan_to_qnan(r->buf, fmt);
+        *xi = true;
+        return;
+    } else {
+        fprintf(stderr, "Unsupported spec1: %s\n", spec1);
+        exit(1);
+    }
+
+    spec2 = table2[cls_p][cls_c];
+    if (strcmp(spec2, "T(-inf)") == 0) {
+        memcpy(r, signed_floats[fmt][CLASS_MINUS_INF].v[0], sizeof(*r));
+    } else if (strcmp(spec2, "T(+inf)") == 0) {
+        memcpy(r, signed_floats[fmt][CLASS_PLUS_INF].v[0], sizeof(*r));
+    } else if (strcmp(spec2, "T(-0)") == 0) {
+        memcpy(r, signed_floats[fmt][CLASS_MINUS_ZERO].v[0], sizeof(*r));
+    } else if (strcmp(spec2, "T(+0)") == 0 || strcmp(spec2, "Rezd") == 0) {
+        memcpy(r, signed_floats[fmt][CLASS_PLUS_ZERO].v[0], sizeof(*r));
+    } else if (strcmp(spec2, "R(c)") == 0 || strcmp(spec2, "T(c)") == 0) {
+        memcpy(r, c, sizeof(*r));
+    } else if (strcmp(spec2, "R(p)") == 0 || strcmp(spec2, "T(p)") == 0) {
+        memcpy(r, &p, sizeof(*r));
+    } else if (strcmp(spec2, "R(p+c)") == 0 || strcmp(spec2, "T(p+c)") == 0) {
+        switch (fmt) {
+        case 0:
+            r->e = p.e + c->e;
+            break;
+        case 1:
+            r->d = p.d + c->d;
+            break;
+        case 2:
+            r->x = p.x + c->x;
+            break;
+        default:
+            fprintf(stderr, "Unsupported fmt: %d\n", fmt);
+            exit(1);
+        }
+    } else if (strcmp(spec2, "Xi: T(dNaN)") == 0) {
+        memcpy(r, default_nans[fmt], sizeof(*r));
+        *xi = true;
+    } else if (strcmp(spec2, "Xi: T(c*)") == 0) {
+        memcpy(r, c, sizeof(*r));
+        snan_to_qnan(r->buf, fmt);
+        *xi = true;
+    } else {
+        fprintf(stderr, "Unsupported spec2: %s\n", spec2);
+        exit(1);
+    }
+}
+
+struct iter {
+    int fmt;
+    int cls[3];
+    int val[3];
+};
+
+static bool iter_next(struct iter *it)
+{
+    int i;
+
+    for (i = 2; i >= 0; i--) {
+        if (++it->val[i] != signed_floats[it->fmt][it->cls[i]].n) {
+            return true;
+        }
+        it->val[i] = 0;
+
+        if (++it->cls[i] != N_SIGNED_CLASSES) {
+            return true;
+        }
+        it->cls[i] = 0;
+    }
+
+    return ++it->fmt != N_FORMATS;
+}
+
+int main(void)
+{
+    int ret = EXIT_SUCCESS;
+    struct iter it = {};
+
+    do {
+        size_t n = float_sizes[it.fmt];
+        union val a, b, c, exp, res;
+        bool xi_exp, xi;
+
+        memcpy(&a, signed_floats[it.fmt][it.cls[0]].v[it.val[0]], sizeof(a));
+        memcpy(&b, signed_floats[it.fmt][it.cls[1]].v[it.val[1]], sizeof(b));
+        memcpy(&c, signed_floats[it.fmt][it.cls[2]].v[it.val[2]], sizeof(c));
+
+        interpret_tables(&exp, &xi_exp, it.fmt,
+                         it.cls[1], &b, it.cls[2], &c, it.cls[0], &a);
+
+        memcpy(&res, &a, sizeof(res));
+        feclearexcept(FE_ALL_EXCEPT);
+        switch (it.fmt) {
+        case 0:
+            asm("maebr %[a],%[b],%[c]"
+                : [a] "+f" (res.e) : [b] "f" (b.e), [c] "f" (c.e));
+            break;
+        case 1:
+            asm("madbr %[a],%[b],%[c]"
+                : [a] "+f" (res.d) : [b] "f" (b.d), [c] "f" (c.d));
+            break;
+        case 2:
+            asm("wfmaxb %[a],%[c],%[b],%[a]"
+                : [a] "+v" (res.x) : [b] "v" (b.x), [c] "v" (c.x));
+            break;
+        default:
+            fprintf(stderr, "Unsupported fmt: %d\n", it.fmt);
+            exit(1);
+        }
+        xi = fetestexcept(FE_ALL_EXCEPT) == FE_INVALID;
+
+        if (memcmp(&res, &exp, n) != 0 || xi != xi_exp) {
+            fprintf(stderr, "[  FAILED  ] ");
+            dump_v(stderr, &b, n);
+            fprintf(stderr, " * ");
+            dump_v(stderr, &c, n);
+            fprintf(stderr, " + ");
+            dump_v(stderr, &a, n);
+            fprintf(stderr, ": actual=");
+            dump_v(stderr, &res, n);
+            fprintf(stderr, "/%d, expected=", (int)xi);
+            dump_v(stderr, &exp, n);
+            fprintf(stderr, "/%d\n", (int)xi_exp);
+            ret = EXIT_FAILURE;
+        }
+    } while (iter_next(&it));
+
+    return ret;
+}
diff --git a/tests/tcg/s390x/vfminmax.c b/tests/tcg/s390x/vfminmax.c
index 22629df160e..e66285f7625 100644
--- a/tests/tcg/s390x/vfminmax.c
+++ b/tests/tcg/s390x/vfminmax.c
@@ -4,6 +4,8 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "float.h"
+
 /*
  * vfmin/vfmax instruction execution.
  */
@@ -21,98 +23,21 @@ static void vfminmax(unsigned int op,
                      unsigned int m4, unsigned int m5, unsigned int m6,
                      void *v1, const void *v2, const void *v3)
 {
-   insn[3] = (m6 << 4) | m5;
-   insn[4] = (m4 << 4) | 0x0e;
-   insn[5] = op;
+    insn[3] = (m6 << 4) | m5;
+    insn[4] = (m4 << 4) | 0x0e;
+    insn[5] = op;
 
     asm("vl %%v25,%[v2]\n"
         "vl %%v26,%[v3]\n"
         "ex 0,%[insn]\n"
         "vst %%v24,%[v1]\n"
         : [v1] "=m" (*(char (*)[16])v1)
-        : [v2] "m" (*(char (*)[16])v2)
-        , [v3] "m" (*(char (*)[16])v3)
-        , [insn] "m"(insn)
+        : [v2] "m" (*(const char (*)[16])v2)
+        , [v3] "m" (*(const char (*)[16])v3)
+        , [insn] "m" (insn)
         : "v24", "v25", "v26");
 }
 
-/*
- * Floating-point value classes.
- */
-#define N_FORMATS 3
-#define N_SIGNED_CLASSES 8
-static const size_t float_sizes[N_FORMATS] = {
-    /* M4 == 2: short    */ 4,
-    /* M4 == 3: long     */ 8,
-    /* M4 == 4: extended */ 16,
-};
-static const size_t e_bits[N_FORMATS] = {
-    /* M4 == 2: short    */ 8,
-    /* M4 == 3: long     */ 11,
-    /* M4 == 4: extended */ 15,
-};
-static const unsigned char signed_floats[N_FORMATS][N_SIGNED_CLASSES][2][16] = {
-    /* M4 == 2: short */
-    {
-        /* -inf */ {{0xff, 0x80, 0x00, 0x00},
-                    {0xff, 0x80, 0x00, 0x00}},
-        /* -Fn */  {{0xc2, 0x28, 0x00, 0x00},
-                    {0xc2, 0x29, 0x00, 0x00}},
-        /* -0 */   {{0x80, 0x00, 0x00, 0x00},
-                    {0x80, 0x00, 0x00, 0x00}},
-        /* +0 */   {{0x00, 0x00, 0x00, 0x00},
-                    {0x00, 0x00, 0x00, 0x00}},
-        /* +Fn */  {{0x42, 0x28, 0x00, 0x00},
-                    {0x42, 0x2a, 0x00, 0x00}},
-        /* +inf */ {{0x7f, 0x80, 0x00, 0x00},
-                    {0x7f, 0x80, 0x00, 0x00}},
-        /* QNaN */ {{0x7f, 0xff, 0xff, 0xff},
-                    {0x7f, 0xff, 0xff, 0xfe}},
-        /* SNaN */ {{0x7f, 0xbf, 0xff, 0xff},
-                    {0x7f, 0xbf, 0xff, 0xfd}},
-    },
-
-    /* M4 == 3: long */
-    {
-        /* -inf */ {{0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* -Fn */  {{0xc0, 0x45, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0xc0, 0x46, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* -0 */   {{0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* +0 */   {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* +Fn */  {{0x40, 0x45, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0x40, 0x47, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* +inf */ {{0x7f, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0x7f, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* QNaN */ {{0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
-                    {0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe}},
-        /* SNaN */ {{0x7f, 0xf7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
-                    {0x7f, 0xf7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfd}},
-    },
-
-    /* M4 == 4: extended */
-    {
-        /* -inf */ {{0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* -Fn */  {{0xc0, 0x04, 0x50, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0xc0, 0x04, 0x51, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* -0 */   {{0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* +0 */   {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* +Fn */  {{0x40, 0x04, 0x50, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0x40, 0x04, 0x52, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* +inf */ {{0x7f, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
-                    {0x7f, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
-        /* QNaN */ {{0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
-                    {0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe}},
-        /* SNaN */ {{0x7f, 0xff, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
-                    {0x7f, 0xff, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfd}},
-    },
-};
-
 /*
  * PoP tables as close to the original as possible.
  */
@@ -285,13 +210,6 @@ struct signed_test {
     },
 };
 
-static void dump_v(FILE *f, const void *v, size_t n)
-{
-    for (int i = 0; i < n; i++) {
-        fprintf(f, "%02x", ((const unsigned char *)v)[i]);
-    }
-}
-
 static int signed_test(struct signed_test *test, int m4, int m5,
                        const void *v1_exp, bool xi_exp,
                        const void *v2, const void *v3)
@@ -320,10 +238,28 @@ static int signed_test(struct signed_test *test, int m4, int m5,
     return 0;
 }
 
-static void snan_to_qnan(char *v, int m4)
+struct iter {
+    int cls[2];
+    int val[2];
+};
+
+static bool iter_next(struct iter *it, int fmt)
 {
-    size_t bit = 1 + e_bits[m4 - 2];
-    v[bit / 8] |= 1 << (7 - (bit % 8));
+    int i;
+
+    for (i = 1; i >= 0; i--) {
+        if (++it->val[i] != signed_floats[fmt][it->cls[i]].n) {
+            return true;
+        }
+        it->val[i] = 0;
+
+        if (++it->cls[i] != N_SIGNED_CLASSES) {
+            return true;
+        }
+        it->cls[i] = 0;
+    }
+
+    return false;
 }
 
 int main(void)
@@ -333,72 +269,71 @@ int main(void)
 
     for (i = 0; i < sizeof(signed_tests) / sizeof(signed_tests[0]); i++) {
         struct signed_test *test = &signed_tests[i];
-        int m4;
+        int fmt;
 
-        for (m4 = 2; m4 <= 4; m4++) {
-            const unsigned char (*floats)[2][16] = signed_floats[m4 - 2];
-            size_t float_size = float_sizes[m4 - 2];
+        for (fmt = 0; fmt < N_FORMATS; fmt++) {
+            size_t float_size = float_sizes[fmt];
+            int m4 = fmt + 2;
             int m5;
 
             for (m5 = 0; m5 <= 8; m5 += 8) {
                 char v1_exp[16], v2[16], v3[16];
                 bool xi_exp = false;
+                struct iter it = {};
                 int pos = 0;
-                int i2;
 
-                for (i2 = 0; i2 < N_SIGNED_CLASSES * 2; i2++) {
-                    int i3;
+                do {
+                    const char *spec = test->table[it.cls[0]][it.cls[1]];
 
-                    for (i3 = 0; i3 < N_SIGNED_CLASSES * 2; i3++) {
-                        const char *spec = test->table[i2 / 2][i3 / 2];
+                    memcpy(&v2[pos],
+                           signed_floats[fmt][it.cls[0]].v[it.val[0]],
+                           float_size);
+                    memcpy(&v3[pos],
+                           signed_floats[fmt][it.cls[1]].v[it.val[1]],
+                           float_size);
+                    if (strcmp(spec, "T(a)") == 0 ||
+                        strcmp(spec, "Xi: T(a)") == 0) {
+                        memcpy(&v1_exp[pos], &v2[pos], float_size);
+                    } else if (strcmp(spec, "T(b)") == 0 ||
+                               strcmp(spec, "Xi: T(b)") == 0) {
+                        memcpy(&v1_exp[pos], &v3[pos], float_size);
+                    } else if (strcmp(spec, "Xi: T(a*)") == 0) {
+                        memcpy(&v1_exp[pos], &v2[pos], float_size);
+                        snan_to_qnan(&v1_exp[pos], fmt);
+                    } else if (strcmp(spec, "Xi: T(b*)") == 0) {
+                        memcpy(&v1_exp[pos], &v3[pos], float_size);
+                        snan_to_qnan(&v1_exp[pos], fmt);
+                    } else if (strcmp(spec, "T(M(a,b))") == 0) {
+                        /*
+                         * Comparing floats is risky, since the compiler might
+                         * generate the same instruction that we are testing.
+                         * Compare ints instead. This works, because we get
+                         * here only for +-Fn, and the corresponding test
+                         * values have identical exponents.
+                         */
+                        int v2_int = *(int *)&v2[pos];
+                        int v3_int = *(int *)&v3[pos];
 
-                        memcpy(&v2[pos], floats[i2 / 2][i2 % 2], float_size);
-                        memcpy(&v3[pos], floats[i3 / 2][i3 % 2], float_size);
-                        if (strcmp(spec, "T(a)") == 0 ||
-                            strcmp(spec, "Xi: T(a)") == 0) {
+                        if ((v2_int < v3_int) ==
+                            ((test->op == VFMIN) != (v2_int < 0))) {
                             memcpy(&v1_exp[pos], &v2[pos], float_size);
-                        } else if (strcmp(spec, "T(b)") == 0 ||
-                                   strcmp(spec, "Xi: T(b)") == 0) {
-                            memcpy(&v1_exp[pos], &v3[pos], float_size);
-                        } else if (strcmp(spec, "Xi: T(a*)") == 0) {
-                            memcpy(&v1_exp[pos], &v2[pos], float_size);
-                            snan_to_qnan(&v1_exp[pos], m4);
-                        } else if (strcmp(spec, "Xi: T(b*)") == 0) {
-                            memcpy(&v1_exp[pos], &v3[pos], float_size);
-                            snan_to_qnan(&v1_exp[pos], m4);
-                        } else if (strcmp(spec, "T(M(a,b))") == 0) {
-                            /*
-                             * Comparing floats is risky, since the compiler
-                             * might generate the same instruction that we are
-                             * testing. Compare ints instead. This works,
-                             * because we get here only for +-Fn, and the
-                             * corresponding test values have identical
-                             * exponents.
-                             */
-                            int v2_int = *(int *)&v2[pos];
-                            int v3_int = *(int *)&v3[pos];
-
-                            if ((v2_int < v3_int) ==
-                                ((test->op == VFMIN) != (v2_int < 0))) {
-                                memcpy(&v1_exp[pos], &v2[pos], float_size);
-                            } else {
-                                memcpy(&v1_exp[pos], &v3[pos], float_size);
-                            }
                         } else {
-                            fprintf(stderr, "Unexpected spec: %s\n", spec);
-                            return 1;
+                            memcpy(&v1_exp[pos], &v3[pos], float_size);
                         }
-                        xi_exp |= spec[0] == 'X';
-                        pos += float_size;
+                    } else {
+                        fprintf(stderr, "Unexpected spec: %s\n", spec);
+                        return 1;
+                    }
+                    xi_exp |= spec[0] == 'X';
+                    pos += float_size;
 
-                        if ((m5 & 8) || pos == 16) {
-                            ret |= signed_test(test, m4, m5,
-                                               v1_exp, xi_exp, v2, v3);
-                            pos = 0;
-                            xi_exp = false;
-                        }
+                    if ((m5 & 8) || pos == 16) {
+                        ret |= signed_test(test, m4, m5,
+                                           v1_exp, xi_exp, v2, v3);
+                        pos = 0;
+                        xi_exp = false;
                     }
-                }
+                } while (iter_next(&it, fmt));
 
                 if (pos != 0) {
                     ret |= signed_test(test, m4, m5, v1_exp, xi_exp, v2, v3);
-- 
2.47.0

Re: [PATCH 2/2] tests/tcg/s390x: Add the floating-point multiply-and-add test

[Peter Maydell]

On Wed, 23 Oct 2024 at 01:02, Ilya Leoshkevich <iii@linux.ibm.com> wrote:
>
> Add a test to prevent regressions.
> Share some useful pieces with the vfminmax test.
> Remove the duplicates from the floating point class values.
>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>  tests/tcg/s390x/Makefile.target |   5 +-
>  tests/tcg/s390x/float.h         | 104 ++++++++++++++
>  tests/tcg/s390x/fma.c           | 233 ++++++++++++++++++++++++++++++++
>  tests/tcg/s390x/vfminmax.c      | 223 +++++++++++-------------------
>  4 files changed, 420 insertions(+), 145 deletions(-)
>  create mode 100644 tests/tcg/s390x/float.h
>  create mode 100644 tests/tcg/s390x/fma.c

I haven't looked at this very closely, but it's only test
code, so

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM