GCC Rust frontend adds `assert_zero_valid` intrinsic stub
GCC's Rust frontend adds a stub for the `assert_zero_valid` intrinsic, which will be fully implemented with layout engine support.
GCC’s Rust frontend has introduced a stub for the assert_zero_valid intrinsic. This intrinsic is intended to check if a type can be safely zero-initialized, typically by using layout engine support to detect problematic types like references or NonNull types. Currently, the stub always returns the unit type (), with full implementation deferred until layout engine capabilities are integrated.
In Details
The assert_zero_valid intrinsic is added to gcc/rust/backend/rust-compile-intrinsic.cc and handled by a new function in rust-intrinsic-handlers.cc. Its primary role is to panic if a type cannot be zero-initialized. Since gccrs lacks the necessary layout engine support to detect such types (e.g., references, NonNull), it's implemented as a stub returning (), with a new signature rule in rust-hir-type-check-intrinsic.cc.
- intrinsic
- A special function or operation provided by the compiler that often maps directly to a specific machine instruction or a highly optimized piece of code.
- zero-initialization
- The process of initializing variables with zero values. Certain types, like references or
NonNulltypes in Rust, cannot be safely zero-initialized. - layout engine
- A component within a compiler that determines the memory layout and size of data types.
- NonNull type
- A Rust type that is guaranteed to be non-null, often used for optimization purposes.