Implicit bindings will cause very confusing crashes in the backend at
present, so this is intended at least partially as a stop gap until we
get them implemented (see #110722).
However, I do think that this is useful in the longer term as well as an
off-by-default warning, as it is quite easy to miss a binding or two
when using explicit bindings and the results of that can be surprisingly
hard to debug. I've filed #135907 to track turning this into an
off-by-default warning or removing it eventually as we see fit.
This is first part for support cbuffer/tbuffer.
The format for cbuffer/tbuffer is
BufferType [Name] [: register(b#)] { VariableDeclaration [: packoffset(c#.xyzw)]; ... };
More details at https://docs.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-constants
New keyword 'cbuffer' and 'tbuffer' are added.
New AST node HLSLBufferDecl is added.
Build AST for simple cbuffer/tbuffer without attribute support.
The special thing is variables declared inside cbuffer is exposed into global scope.
So isTransparentContext should return true for HLSLBuffer.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D129883
