Improve support for non-32-bit types. (#643)

The main change here is to fill out the `BaseType` enumeration so that it covers the full range of 8/16/32/64-bit signed and unsigned integers, as well as 16/32/64-bit floating-point numbers, and then propagate that completion through various places in the code.

More details:

* The current `half`, `float`, `double`, `int`, and `uint` types are still the default names for their types, so things like `float16_t` and `int32_t` were added as `typedef`s.

* We still need to generate the full gamut of vector/matrix `typedef`s for the new types, so that things like `float16_t4x3` will work (yes, I know that is ugly as sin, but that's the HLSL syntax...).

* A few pieces of dead code from earlier in the compiler's life got removed, since I did a find-in-files for `BaseType::` and tried to either update or delete every site.

* A few call sites that were enumerating integer base types in an ad-hoc fashion were changed to use a single `isIntegerBaseType()` function that I added in `check.cpp`

* When compiling with dxc for shader model 6.2 and up, we enable the compiler's support for native 16-bit types via a flag.

* The public API enumeration for reflection of scalar types added cases for 8- and 16-bit integers (it already exposed the other cases we need)

* The lexer was updated to be extremely liberal in what kinds of suffixes it allows on literals. I also removed the logic that was treating, e.g., `0f` as a floating-point literal (it doesn't seem to be the right behavior). That would now be an integer literal with an invalid suffix.

* The logic in the parser that applies types to literals was updated to handle a few more cases: `LL` and `ULL` for 64-bit integers, and `H` for 16-bit floats.

* The mangling logic needed to be updated to handle the new cases, and I consolidated the handling of those types in their front-end and IR forms.

* Removed the explicit `BasicExpressionType::ToString` logic, since all basic types are `DeclRefType`s in the front end, and we can just print them out as such.

* As a bit of a gross hack, fudged the conversion costs so that `int` to `int64_t` conversion is a bit more costly. The problem there is that given an operation like `int(0) + uint(0)`, the best applicable candidates ended up being `+(uint,uint)` and `+(int64_t,int64_t)` because the cost of a single `int`-to-`uint` conversion was the same as the sum of the cost of an `int`-to-`int64_t` and a `uint`-to-`int64_t`. A better long-term fix here is to completely change our overload resolution strategy, but that is obviously way too big to squeeze into this change.

* Type layout computation was updated to handle all the new types and give them their natural size/alignment. Note that this does *not* work for down-level HLSL where `half` is treated as a synonym for `float`. It also doesn't deal with the fact that many of these types aren't actually allowed in constant buffers for certain shader models. A future change should work to add error messages for unsupported stuff during type layout (or just make the types themselves require support for certain capabilities)

1 files changed, 22 insertions, 46 deletions

diff --git a/source/slang/type-layout.cpp b/source/slang/type-layout.cpp
index d7a4e68bc..3fbb9b31b 100644
--- a/source/slang/type-layout.cpp
+++ b/source/slang/type-layout.cpp
@@ -34,43 +34,35 @@ struct DefaultLayoutRulesImpl : SimpleLayoutRulesImpl
     {
         switch (baseType)
         {
-        case BaseType::Int:
-        case BaseType::UInt:
-        case BaseType::Float:
-        case BaseType::Bool:
-            return SimpleLayoutInfo( LayoutResourceKind::Uniform, 4, 4 );
+        case BaseType::Void:    return SimpleLayoutInfo();
 
-        case BaseType::Double:
-            return SimpleLayoutInfo( LayoutResourceKind::Uniform, 8, 8 );
+        // Note: By convention, a `bool` in a constant buffer is stored as an `int.
+        // This default may eventually change, at which point this logic will need
+        // to be updated.
+        //
+        // TODO: We should probably warn in this case, since storing a `bool` in
+        // a constant buffer seems like a Bad Idea anyway.
+        //
+        case BaseType::Bool:    return SimpleLayoutInfo( LayoutResourceKind::Uniform, 4, 4 );
 
-        default:
-            SLANG_UNEXPECTED("uhandled scalar type");
-            UNREACHABLE_RETURN(SimpleLayoutInfo( LayoutResourceKind::Uniform, 0, 1 ));
-        }
-    }
 
-    virtual SimpleLayoutInfo GetScalarLayout(slang::TypeReflection::ScalarType scalarType)
-    {
-        switch( scalarType )
-        {
-        case slang::TypeReflection::ScalarType::Void:       return SimpleLayoutInfo();
-        case slang::TypeReflection::ScalarType::None:       return SimpleLayoutInfo();
+        case BaseType::Int8:    return SimpleLayoutInfo( LayoutResourceKind::Uniform, 1,1);
+        case BaseType::Int16:   return SimpleLayoutInfo( LayoutResourceKind::Uniform, 2,2);
+        case BaseType::Int:     return SimpleLayoutInfo( LayoutResourceKind::Uniform, 4,4);
+        case BaseType::Int64:   return SimpleLayoutInfo( LayoutResourceKind::Uniform, 8,8);
 
-        // TODO(tfoley): At some point we don't want to lay out `bool` as 4 bytes by default...
-        case slang::TypeReflection::ScalarType::Bool:       return SimpleLayoutInfo( LayoutResourceKind::Uniform, 4,4);
-        case slang::TypeReflection::ScalarType::Int32:      return SimpleLayoutInfo( LayoutResourceKind::Uniform, 4,4);
-        case slang::TypeReflection::ScalarType::UInt32:     return SimpleLayoutInfo( LayoutResourceKind::Uniform, 4,4);
-        case slang::TypeReflection::ScalarType::Int64:      return SimpleLayoutInfo( LayoutResourceKind::Uniform, 8,8);
-        case slang::TypeReflection::ScalarType::UInt64:     return SimpleLayoutInfo( LayoutResourceKind::Uniform, 8,8);
+        case BaseType::UInt8:   return SimpleLayoutInfo( LayoutResourceKind::Uniform, 1,1);
+        case BaseType::UInt16:  return SimpleLayoutInfo( LayoutResourceKind::Uniform, 2,2);
+        case BaseType::UInt:    return SimpleLayoutInfo( LayoutResourceKind::Uniform, 4,4);
+        case BaseType::UInt64:  return SimpleLayoutInfo( LayoutResourceKind::Uniform, 8,8);
 
-        // TODO(tfoley): What actually happens if you use `half` in a constant buffer?
-        case slang::TypeReflection::ScalarType::Float16:    return SimpleLayoutInfo( LayoutResourceKind::Uniform, 2,2);
-        case slang::TypeReflection::ScalarType::Float32:    return SimpleLayoutInfo( LayoutResourceKind::Uniform, 4,4);
-        case slang::TypeReflection::ScalarType::Float64:    return SimpleLayoutInfo( LayoutResourceKind::Uniform, 8,8);
+        case BaseType::Half:    return SimpleLayoutInfo( LayoutResourceKind::Uniform, 2,2);
+        case BaseType::Float:   return SimpleLayoutInfo( LayoutResourceKind::Uniform, 4,4);
+        case BaseType::Double:  return SimpleLayoutInfo( LayoutResourceKind::Uniform, 8,8);
 
         default:
-            SLANG_UNEXPECTED("unhandled scalar type");
-            UNREACHABLE_RETURN(SimpleLayoutInfo());
+            SLANG_UNEXPECTED("uhandled scalar type");
+            UNREACHABLE_RETURN(SimpleLayoutInfo( LayoutResourceKind::Uniform, 0, 1 ));
         }
     }
 
@@ -267,14 +259,6 @@ struct DefaultVaryingLayoutRulesImpl : DefaultLayoutRulesImpl
             1);
     }
 
-    virtual SimpleLayoutInfo GetScalarLayout(slang::TypeReflection::ScalarType)
-    {
-        // Assume that all scalars take up one "slot"
-        return SimpleLayoutInfo(
-            getKind(),
-            1);
-    }
-
     SimpleLayoutInfo GetVectorLayout(SimpleLayoutInfo, size_t) override
     {
         // Vectors take up one slot by default
@@ -318,14 +302,6 @@ struct GLSLSpecializationConstantLayoutRulesImpl : DefaultLayoutRulesImpl
             1);
     }
 
-    virtual SimpleLayoutInfo GetScalarLayout(slang::TypeReflection::ScalarType)
-    {
-        // Assume that all scalars take up one "slot"
-        return SimpleLayoutInfo(
-            getKind(),
-            1);
-    }
-
     SimpleLayoutInfo GetVectorLayout(SimpleLayoutInfo, size_t elementCount) override
     {
         // GLSL doesn't support vectors of specialization constants,