[PATCH v8 0/2] MR178: vkd3d-shader/hlsl: Add support for sign() intrinsic.

[Ethan Lee (＠flibitijibibo)]

This replicates what seems to be happening when using sign() with shader model 3, which is roughly...

```
int pos = (int) (x > 0);
int neg = -((int) (x < 0));
int result = pos + neg;
```

Fixes https://bugs.winehq.org/show_bug.cgi?id=54826

--
  v8: tests: Add tests for sign() intrinsic.
      vkd3d-shader/hlsl: Add support for sign() intrinsic.

https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/178

[PATCH v8 1/2] vkd3d-shader/hlsl: Add support for sign() intrinsic.

[Ethan Lee]

From: Ethan Lee

Signed-off-by: Ethan Lee 
---
 libs/vkd3d-shader/hlsl.y | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/libs/vkd3d-shader/hlsl.y b/libs/vkd3d-shader/hlsl.y
index 10deda75..4cc2ab56 100644
--- a/libs/vkd3d-shader/hlsl.y
+++ b/libs/vkd3d-shader/hlsl.y
@@ -3143,6 +3143,41 @@ static bool intrinsic_saturate(struct hlsl_ctx *ctx,
     return !!add_unary_arithmetic_expr(ctx, params->instrs, HLSL_OP1_SAT, arg, loc);
 }

+static bool intrinsic_sign(struct hlsl_ctx *ctx,
+        const struct parse_initializer *params, const struct vkd3d_shader_location *loc)
+{
+    struct hlsl_ir_node *zero, *lt, *neg, *op1, *op2, *arg = params->args[0];
+
+    struct hlsl_type *int_type = hlsl_get_numeric_type(ctx, arg->data_type->class, HLSL_TYPE_INT,
+            arg->data_type->dimx, arg->data_type->dimy);
+
+    if (!(zero = hlsl_new_float_constant(ctx, 0.0f, loc)))
+        return false;
+    list_add_tail(params->instrs, &zero->entry);
+
+    /* Check if 0 < arg, cast bool to int */
+
+    if (!(lt = add_binary_comparison_expr(ctx, params->instrs, HLSL_OP2_LESS, zero, arg, loc)))
+        return false;
+
+    if (!(op1 = add_implicit_conversion(ctx, params->instrs, lt, int_type, loc)))
+        return false;
+
+    /* Check if arg < 0, cast bool to int and invert (meaning true is -1) */
+
+    if (!(lt = add_binary_comparison_expr(ctx, params->instrs, HLSL_OP2_LESS, arg, zero, loc)))
+        return false;
+
+    if (!(op2 = add_implicit_conversion(ctx, params->instrs, lt, int_type, loc)))
+        return false;
+
+    if (!(neg = add_unary_arithmetic_expr(ctx, params->instrs, HLSL_OP1_NEG, op2, loc)))
+        return false;
+
+    /* Adding these two together will make 1 when > 0, -1 when < 0, and 0 when neither */
+    return !!add_binary_arithmetic_expr(ctx, params->instrs, HLSL_OP2_ADD, neg, op1, loc);
+}
+
 static bool intrinsic_sin(struct hlsl_ctx *ctx,
         const struct parse_initializer *params, const struct vkd3d_shader_location *loc)
 {
@@ -3402,6 +3437,7 @@ intrinsic_functions[] =
     {"round",                               1, true,  intrinsic_round},
     {"rsqrt",                               1, true,  intrinsic_rsqrt},
     {"saturate",                            1, true,  intrinsic_saturate},
+    {"sign",                                1, true,  intrinsic_sign},
     {"sin",                                 1, true,  intrinsic_sin},
     {"smoothstep",                          3, true,  intrinsic_smoothstep},
     {"sqrt",                                1, true,  intrinsic_sqrt},

[PATCH v8 2/2] tests: Add tests for sign() intrinsic.

[Ethan Lee]

From: Ethan Lee

Signed-off-by: Ethan Lee 
---
 Makefile.am            |  1 +
 tests/sign.shader_test | 45 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)
 create mode 100644 tests/sign.shader_test

diff --git a/Makefile.am b/Makefile.am
index 3f1ec171..93c5cf59 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -153,6 +153,7 @@ vkd3d_shader_tests = \
    tests/saturate.shader_test \
    tests/shader-interstage-interface.shader_test \
    tests/side-effects.shader_test \
+	tests/sign.shader_test \
    tests/sqrt.shader_test \
    tests/step.shader_test \
    tests/swizzle-constant-prop.shader_test \
diff --git a/tests/sign.shader_test b/tests/sign.shader_test
new file mode 100644
index 00000000..c63f3d35
--- /dev/null
+++ b/tests/sign.shader_test
@@ -0,0 +1,45 @@
+[pixel shader]
+uniform float f;
+
+float4 main() : sv_target
+{
+    return sign(f);
+}
+
+[test]
+uniform 0 float4 1.0 0.0 0.0 0.0
+draw quad
+probe all rgba (1.0, 1.0, 1.0, 1.0)
+uniform 0 float4 -1.0 0.0 0.0 0.0
+draw quad
+probe all rgba (-1.0, -1.0, -1.0, -1.0)
+uniform 0 float4 0.0 0.0 0.0 0.0
+draw quad
+probe all rgba (0.0, 0.0, 0.0, 0.0)
+
+[pixel shader]
+uniform float4 f;
+
+float4 main() : sv_target
+{
+    return sign(f);
+}
+
+[test]
+uniform 0 float4 1.0 2.0 3.0 4.0
+draw quad
+probe all rgba (1.0, 1.0, 1.0, 1.0)
+
+[pixel shader]
+uniform float2x2 f;
+
+float4 main() : sv_target
+{
+    return sign(f);
+}
+
+[test]
+uniform 0 float4 1.0 2.0 0.0 0.0
+uniform 4 float4 3.0 4.0 0.0 0.0
+draw quad
+probe all rgba (1.0, 1.0, 1.0, 1.0)

[PATCH v8 0/2] MR178: vkd3d-shader/hlsl: Add support for sign() intrinsic. - approved

[Zebediah Figura (＠zfigura)]

This merge request was approved by Zebediah Figura.

[Giovanni Mascellani (＠giomasce)]

Giovanni Mascellani (@giomasce) commented about libs/vkd3d-shader/hlsl.y:
> +static bool intrinsic_sign(struct hlsl_ctx *ctx,
> -
>    const struct parse_initializer *params, const struct vkd3d_shader_location *loc)
>
> +{
> - struct hlsl_ir_node *zero, *lt, *neg, *op1, *op2, *arg = params->args[0];
> -
> - struct hlsl_type *int_type = hlsl_get_numeric_type(ctx, arg->data_type->class, HLSL_TYPE_INT,
> -
>        arg->data_type->dimx, arg->data_type->dimy);
> -
> - if (!(zero = hlsl_new_float_constant(ctx, 0.0f, loc)))
> -
>    return false;
> - list_add_tail(params->instrs, &zero->entry);
> -
> - /* Check if 0 < arg, cast bool to int */
> -
> - if (!(lt = add_binary_comparison_expr(ctx, params->instrs, HLSL_OP2_LESS, zero, arg, loc)))

This means that expressions of type other than `float` are casted to `float`. In principle that should be correct in the end, because AFAIU the sign should always be mapped correctly, but it makes me a bit nervous. Could the type of zero be set to coincide with the type of the argument?