skia2/resources/sksl/shared/StructsInFunctions.sksl
John Stiles 3934647d22 Reland "Implement operator== and != for Metal structs and arrays."
This is a reland of 830c69ca66

Original change's description:
> Implement operator== and != for Metal structs and arrays.
>
> GLSL/SkSL assumes that == and != on struct/array types should work.
> We need to emit equality and inequality operators whenever we find code
> that compares a struct or array.
>
> Structs and arrays can be arbitrarily nested, and either type can
> contain a matrix. All of these things need custom equality operators in
> Metal. Therefore, we need to recursively generate comparison operators
> when any of these types are encountered.
>
> For arrays we get lucky, and we can cover all possible array types and
> sizes with a single templated operator== method. Structs and matrices
> have no such luck, and are generated separately on a per-type basis.
>
> For each of these types, operator== is implemented as an equality check
> on each field, and operator!= is implemented in terms of operator==.
> Equality and inequality are always emitted together. (Previously, matrix
> equality and inequality were emitted and implemented independently, but
> this is no longer the case.)
>
> Change-Id: I69ee01c0a390d7db6bcb2253ed6336ab20cc4d1d
> Bug: skia:11908, skia:11924
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/402016
> Auto-Submit: John Stiles <johnstiles@google.com>
> Commit-Queue: Brian Osman <brianosman@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>

Bug: skia:11908, skia:11924, skia:11929
Change-Id: I6336b6125e9774c1ca73e3d497e3466f11f6f25f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/402559
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2021-04-29 22:55:58 +00:00

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/*#pragma settings NoInline*/
uniform half4 colorRed, colorGreen;
struct S { float x; int y; };
struct Nested { S a, b; };
S returns_a_struct() {
S s;
s.x = 1;
s.y = 2;
return s;
}
S constructs_a_struct() {
return S(2, 3);
}
float accepts_a_struct(S s) {
return s.x + float(s.y);
}
void modifies_a_struct(inout S s) {
s.x++;
s.y++;
}
half4 main(float2 coords) {
S s = returns_a_struct();
float x = accepts_a_struct(s);
modifies_a_struct(s);
S expected = constructs_a_struct();
Nested n1, n2, n3;
n1.a = returns_a_struct();
n1.b = n1.a;
n2 = n1;
n3 = n2;
modifies_a_struct(n3.b);
bool valid = (x == 3) && (s.x == 2) && (s.y == 3) &&
(s == expected) && (s == S(2, 3)) && (s != returns_a_struct()) &&
(n1 == n2) && (n1 != n3) && (n3 == Nested(S(1, 2), S(2, 3)));
return valid ? colorGreen : colorRed;
}