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, 3 deletions

diff --git a/source/slang/parser.cpp b/source/slang/parser.cpp
index e3982aee4..37cc24459 100644
--- a/source/slang/parser.cpp
+++ b/source/slang/parser.cpp
@@ -4035,8 +4035,17 @@ namespace Slang
                     {
                         suffixType = parser->getSession()->getIntType();
                     }
-                    // TODO: probably need `ll` and `ull`
-                    // TODO: are there other suffixes we need to handle?
+                    // `ull` suffix -> `uint64_t`
+                    else if(uCount == 1 && lCount == 2)
+                    {
+                        suffixType = parser->getSession()->getUInt64Type();
+                    }
+                    // `ll` suffix -> `int64_t`
+                    else if(uCount == 0 && lCount == 2)
+                    {
+                        suffixType = parser->getSession()->getInt64Type();
+                    }
+                    // TODO: do we need suffixes for smaller integer types?
                     else
                     {
                         parser->sink->diagnose(token, Diagnostics::invalidIntegerLiteralSuffix, suffix);
@@ -4070,6 +4079,7 @@ namespace Slang
                 {
                     int fCount = 0;
                     int lCount = 0;
+                    int hCount = 0;
                     int unknownCount = 0;
                     while(*suffixCursor)
                     {
@@ -4083,6 +4093,10 @@ namespace Slang
                             lCount++;
                             break;
 
+                        case 'h': case 'H':
+                            hCount++;
+                            break;
+
                         default:
                             unknownCount++;
                             break;
@@ -4099,11 +4113,16 @@ namespace Slang
                     {
                         suffixType = parser->getSession()->getFloatType();
                     }
-                    // `l` or `lf` suffix on float -> `double`
+                    // `l` or `lf` suffix on floating-point literal -> `double`
                     else if(lCount == 1 && (fCount <= 1))
                     {
                         suffixType = parser->getSession()->getDoubleType();
                     }
+                    // `h` or `hf` suffix on floating-point literal -> `half`
+                    else if(lCount == 1 && (fCount <= 1))
+                    {
+                        suffixType = parser->getSession()->getHalfType();
+                    }
                     // TODO: are there other suffixes we need to handle?
                     else
                     {