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, 8 insertions, 4 deletions

diff --git a/source/slang/slang-stdlib.cpp b/source/slang/slang-stdlib.cpp
index bd2ce2561..5a4718af4 100644
--- a/source/slang/slang-stdlib.cpp
+++ b/source/slang/slang-stdlib.cpp
@@ -102,15 +102,19 @@ namespace Slang
 
         { "bool",	BaseType::Bool,     BOOL_MASK,  kBaseTypeConversionKind_Unsigned,   kBaseTypeConversionRank_Bool },
 
-        // TODO: should declare explicit types for 8-, 16-, 32- and 64-bit integers
-        { "int",	BaseType::Int,      SINT_MASK,  kBaseTypeConversionKind_Signed,     kBaseTypeConversionRank_Int32},
+        { "int8_t",	    BaseType::Int8,     SINT_MASK,  kBaseTypeConversionKind_Signed,     kBaseTypeConversionRank_Int8},
+        { "int16_t",	BaseType::Int16,    SINT_MASK,  kBaseTypeConversionKind_Signed,     kBaseTypeConversionRank_Int16},
+        { "int",	    BaseType::Int,      SINT_MASK,  kBaseTypeConversionKind_Signed,     kBaseTypeConversionRank_Int32},
+        { "int64_t",	BaseType::Int64,    SINT_MASK,  kBaseTypeConversionKind_Signed,     kBaseTypeConversionRank_Int64},
 
         { "half",	BaseType::Half,     FLOAT_MASK, kBaseTypeConversionKind_Float,      kBaseTypeConversionRank_Int16},
         { "float",	BaseType::Float,    FLOAT_MASK, kBaseTypeConversionKind_Float,      kBaseTypeConversionRank_Int32},
         { "double",	BaseType::Double,   FLOAT_MASK, kBaseTypeConversionKind_Float,      kBaseTypeConversionRank_Int64},
 
-        { "uint",	BaseType::UInt,     UINT_MASK,  kBaseTypeConversionKind_Unsigned,   kBaseTypeConversionRank_Int32},
-        { "uint64_t", BaseType::UInt64, UINT_MASK,  kBaseTypeConversionKind_Unsigned,   kBaseTypeConversionRank_Int64},
+        { "uint8_t",	BaseType::UInt8,    UINT_MASK,  kBaseTypeConversionKind_Unsigned,   kBaseTypeConversionRank_Int8},
+        { "uint16_t",	BaseType::UInt16,   UINT_MASK,  kBaseTypeConversionKind_Unsigned,   kBaseTypeConversionRank_Int16},
+        { "uint",	    BaseType::UInt,     UINT_MASK,  kBaseTypeConversionKind_Unsigned,   kBaseTypeConversionRank_Int32},
+        { "uint64_t",   BaseType::UInt64,   UINT_MASK,  kBaseTypeConversionKind_Unsigned,   kBaseTypeConversionRank_Int64},
     };
 
     // Given two base types, we need to be able to compute the cost of converting between them.