Revise (T *)(ptr - ptr_cst) pattern
Canonicalizes pointer arithmetic patterns for better optimization.
This commit refines a GCC pattern for pointer arithmetic involving type casting. The pattern (T *)(ptr - ptr_cst) is now directly canonicalized to (T *)ptr p+ cst. This change simplifies the GENERIC representation, allowing subsequent optimizations to more effectively recognize and process pointer arithmetic. The pattern was originally introduced to avoid issues with build_fold_addr_expr_with_type, and this revision ensures more robust simplification.
In Details
The match.pd file is being updated to modify the canonicalization of the pattern (T *)(ptr - ptr_cst). Previously, this pattern might have been avoided or handled indirectly. The revision applies the GENERIC simplification directly to the pattern, transforming it into (T *)ptr p+ cst. This change aims to ensure consistent and predictable representation of pointer arithmetic involving constant offsets, facilitating further optimizations.
- Pointer Arithmetic
- Performing arithmetic operations (like addition or subtraction) on memory addresses stored in pointers. The result is a new memory address.
- Canonicalization
- The process of transforming an expression or data structure into a standard or canonical form, simplifying comparisons and further processing.
- GENERIC
- GCC's first intermediate representation (IR), which is language-independent and tree-based. It represents the structure of the code before lower-level optimizations.
- Tree Optimization
- A phase of the compiler that operates on GCC's intermediate representations (like GENERIC or GIMPLE) to improve code performance or reduce its size.
- build_fold_addr_expr_with_type
- An internal GCC function likely used to construct expressions representing memory addresses with associated types.