SWDEV-398297 - HIP Documentation Updates for ROCm 5.6-needed for 23.10 (#3250)

Change-Id: I514a0a941fcc6ebd940f5c6c6700c3c305f04a56

docs/reference/kernel_language.md

@@ -126,15 +126,15 @@ The `__restrict__` keyword tells the compiler that the associated memory pointer
 
 ## Built-In Variables
 
-(coordinate_builtins)=
 ### Coordinate Built-Ins
 Built-ins determine the coordinate of the active work item in the execution grid. They are defined in amd_hip_runtime.h (rather than being implicitly defined by the compiler).
 In HIP, built-ins coordinate variable definitions are the same as in Cuda, for instance:
 threadIdx.x, blockIdx.y, gridDim.y, etc.
 The products gridDim.x * blockDim.x, gridDim.y * blockDim.y and gridDim.z * blockDim.z are always less than 2^32.
+Coordinates builtins are implemented as structures for better performance. When used with printf, they needs to be casted to integer types explicitly.
 
 ### warpSize
-The warpSize variable is of type int and contains the warp size (in threads) for the target device. Note that all current Nvidia devices return 32 for this variable, and all current AMD devices return 64. Device code should use the warpSize built-in to develop portable wave-aware code.
+The warpSize variable is of type int and contains the warp size (in threads) for the target device. Note that all current Nvidia devices return 32 for this variable, and current AMD devices return 64 for gfx9 and 32 for gfx10 and above. The warpSize variable should only be used in device functions. Device code should use the warpSize built-in to develop portable wave-aware code.
 
 
 ## Vector Types