[clang] [HLSL] Add NativeInt16Type langopt to control whether short type is supported. Enabled by default for all but HLSL. (PR #165584)

[Sarah Spall via cfe-commits]

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@@ -399,7 +399,7 @@ static void InitializeStandardPredefinedMacros(const TargetInfo &TI,
     Builder.defineMacro("__HLSL_202y",
                         Twine((unsigned)LangOptions::HLSLLangStd::HLSL_202y));
 
-    if (LangOpts.NativeHalfType)
+    if (LangOpts.NativeHalfType && LangOpts.NativeInt16Type)
       Builder.defineMacro("__HLSL_ENABLE_16_BIT", "1");
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spall wrote:

I think if either of these aren't enabled, the definitions defined when '__HLSL_ENABLE_16_BIT' will/could fail.  My main reason for thinking this is, which requires half actually be 16 bits. 
https://github.com/llvm/llvm-project/blob/784b74c6ef8a7f6ffaa7ab250eb35696dd833426/clang/lib/Headers/hlsl/hlsl_intrinsics.h#L72

https://github.com/llvm/llvm-project/pull/165584