vkd3d-shader/hlsl: Prefer overload candidates without component count narrowing.

Approved-by: Francisco Casas (@fcasas)
Approved-by: Henri Verbeet (@hverbeet)
Merge-Request: https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/1313

libs/vkd3d-shader/hlsl.y

@@ -2998,6 +2998,52 @@ static bool func_is_compatible_match(struct hlsl_ctx *ctx, const struct hlsl_ir_
     return true;
 }
 
+static int function_parameter_compare(const struct hlsl_ir_var *candidate,
+        const struct hlsl_ir_var *ref, const struct hlsl_ir_node *arg)
+{
+    struct
+    {
+        unsigned int count;
+    } c, r, a;
+    int ret;
+
+    /* TODO: Non-numeric types. */
+    if (!hlsl_is_numeric_type(arg->data_type))
+        return 0;
+
+    c.count = hlsl_type_component_count(candidate->data_type);
+    r.count = hlsl_type_component_count(ref->data_type);
+    a.count = hlsl_type_component_count(arg->data_type);
+
+    /* Prefer candidates without component count narrowing. E.g., given an
+     * float4 argument, half4 is a better match than float2. */
+    if ((ret = (a.count > r.count) - (a.count > c.count)))
+        return ret;
+
+    return 0;
+}
+
+static int function_compare(const struct hlsl_ir_function_decl *candidate,
+        const struct hlsl_ir_function_decl *ref, const struct parse_initializer *args)
+{
+    bool any_worse = false, any_better = false;
+    unsigned int i;
+    int ret;
+
+    for (i = 0; i < args->args_count; ++i)
+    {
+        ret = function_parameter_compare(candidate->parameters.vars[i], ref->parameters.vars[i], args->args[i]);
+        if (ret < 0)
+            any_worse = true;
+        else if (ret > 0)
+            any_better = true;
+    }
+
+    /* We consider a candidate better if at least one parameter is a better
+     * match, and none are a worse match. */
+    return any_better - any_worse;
+}
+
 static struct hlsl_ir_function_decl *find_function_call(struct hlsl_ctx *ctx,
         const char *name, const struct parse_initializer *args, bool is_compile,
         const struct vkd3d_shader_location *loc)
@@ -3006,6 +3052,7 @@ static struct hlsl_ir_function_decl *find_function_call(struct hlsl_ctx *ctx,
     struct vkd3d_string_buffer *s;
     struct hlsl_ir_function *func;
     struct rb_entry *entry;
+    int compare;
     size_t i;
     struct
     {
@@ -3022,6 +3069,23 @@ static struct hlsl_ir_function_decl *find_function_call(struct hlsl_ctx *ctx,
         if (!func_is_compatible_match(ctx, decl, is_compile, args))
             continue;
 
+        if (candidates.count)
+        {
+            compare = function_compare(decl, candidates.candidates[0], args);
+
+            /* The candidate is worse; skip it. */
+            if (compare < 0)
+                continue;
+
+            /* The candidate is better; replace the current candidates. */
+            if (compare > 0)
+            {
+                candidates.candidates[0] = decl;
+                candidates.count = 1;
+                continue;
+            }
+        }
+
         if (!(hlsl_array_reserve(ctx, (void **)&candidates.candidates,
                 &candidates.capacity, candidates.count + 1, sizeof(decl))))
         {

tests/hlsl/function-overload.shader_test

@@ -198,7 +198,7 @@ todo(sm<6) draw quad
 probe (0, 0) rgba(1.0, 1.0, 1.0, 1.0)
 
 % Component type narrowing is preferred over component count narrowing.
-[pixel shader todo]
+[pixel shader]
 float f(half4 x) { return 1.0; }
 float f(float2 x) { return 2.0; }
 
@@ -208,7 +208,7 @@ float4 main() : sv_target
 }
 
 [test]
-todo(sm<6) draw quad
+draw quad
 probe (0, 0) rgba(1.0, 1.0, 1.0, 1.0)
 
 % Let C be the common type that would be produced in an arithmetic expression
@@ -218,7 +218,7 @@ probe (0, 0) rgba(1.0, 1.0, 1.0, 1.0)
 % (same as the parameter) and "int2" for the second function (same base type as
 % the argument, but narrower), so the first function is preferred.
 
-[pixel shader todo]
+[pixel shader]
 
 float4 func(float4 x)
 {
@@ -236,8 +236,8 @@ float4 main() : sv_target
 }
 
 [test]
-todo(sm<6) draw quad
-todo(sm<6) probe (0, 0) rgba(0.0, 0.0, 0.0, 0.0)
+draw quad
+probe (0, 0) rgba(0.0, 0.0, 0.0, 0.0)
 
 % Let C be the common type that would be produced in an arithmetic expression
 % between the parameter and argument types. If C is the same as the argument,