llvm-project

2db83868 - [HLSL] Implement default constant buffer $Globals (2nd attempt) (#128589)

[HLSL] Implement default constant buffer $Globals (2nd attempt) (#128589) All variable declarations in the global scope that are not resources, static or empty are implicitly added to implicit constant buffer `$Globals`. They are created in `hlsl_constant` address space and collected in an implicit `HLSLBufferDecl` node that is added to the AST at the end of the translation unit. Codegen is the same as for explicit constant buffers. Fixes #123801 This is a second attempt to implement this feature. The first attempt had to be reverted because of memory leaks. The problem was adding a `SmallVector` member on `HLSLBufferDecl` node to represent a list of default buffer declarations. When this vector needed to grow, it allocated memory that was never released, because all memory used by AST nodes must be allocated by `ASTContext` allocator and is released all at once. Destructors on AST nodes are never called. It this change the list of default buffer declarations is collected in a `SmallVector` instance on `SemaHLSL`. The `HLSLBufDecl` representing `$Globals` is created at the end of the translation unit when the number of declarations is known, and the list is copied into an array allocated by the `ASTContext` allocator.