MSL: Fix casting in constant expressions with different sizes.
Previous casting in constant expressions used as_type<> between
types of different overall sizes.
Add check for overall size (width * vecsize) to ensure as_type<> will work,
otherwise use regular cast. Also beef up test of integer values to also check
vecsize, and use regular casts for those.
diff --git a/spirv_msl.cpp b/spirv_msl.cpp
index 76c5565..9eef7c5 100644
--- a/spirv_msl.cpp
+++ b/spirv_msl.cpp
@@ -13880,18 +13880,21 @@
assert(out_type.basetype != SPIRType::Boolean);
assert(in_type.basetype != SPIRType::Boolean);
- bool integral_cast = type_is_integral(out_type) && type_is_integral(in_type);
- bool same_size_cast = out_type.width == in_type.width;
+ bool integral_cast = type_is_integral(out_type) && type_is_integral(in_type) && (out_type.vecsize == in_type.vecsize);
+ bool same_size_cast = (out_type.width * out_type.vecsize) == (in_type.width * in_type.vecsize);
- if (integral_cast && same_size_cast)
+ // Bitcasting can only be used between types of the same overall size.
+ // And always formally cast between integers, because it's trivial, and also
+ // because Metal can internally cast the results of some integer ops to a larger
+ // size (eg. short shift right becomes int), which means chaining integer ops
+ // together may introduce size variations that SPIR-V doesn't know about.
+ if (same_size_cast && !integral_cast)
{
- // Trivial bitcast case, casts between integers.
- return type_to_glsl(out_type);
+ return "as_type<" + type_to_glsl(out_type) + ">";
}
else
{
- // Fall back to the catch-all bitcast in MSL.
- return "as_type<" + type_to_glsl(out_type) + ">";
+ return type_to_glsl(out_type);
}
}
