[clang] [clang][HLSL] Add sign intrinsic part 3 (PR #101989)

[Farzon Lotfi via cfe-commits]

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@@ -1725,5 +1725,76 @@ _HLSL_AVAILABILITY(shadermodel, 6.0)
 _HLSL_BUILTIN_ALIAS(__builtin_hlsl_wave_get_lane_index)
 __attribute__((convergent)) uint WaveGetLaneIndex();
 
+//===----------------------------------------------------------------------===//
+// sign builtins
+//===----------------------------------------------------------------------===//
+
+/// \fn T sign(T Val)
+/// \brief Returns -1 if \a Val is less than zero; 0 if \a Val equals zero; and
+/// 1 if \a Val is greater than zero. \param Val The input value.
+
+#ifdef __HLSL_ENABLE_16_BIT
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_sign)
+int16_t sign(int16_t);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_sign)
+int16_t2 sign(int16_t2);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_sign)
+int16_t3 sign(int16_t3);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_sign)
+int16_t4 sign(int16_t4);
+#endif
+
+_HLSL_16BIT_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_elementwise_sign)
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farzonl wrote:

The docs for sign indicate that the return type is an integer
https://learn.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-sign .

You have the templare type correct, so what that means is this case needs to be `int16_t`  to `int16_t4`.

Also be aware that half  will be upgraded to float if `__HLSL_ENABLE_16_BIT` is not set so there probably should be some tests to make sure it can also be `int` to `int4` 

https://github.com/llvm/llvm-project/pull/101989