HashMap and Vec micro-opts #482
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Summary 4 files modified with Vec::with_capacity() optimizations: | File | Change | Capacity | |-------------------------------------|-------------------------------|--------------------------------------------| | awk/interpreter/mod.rs:64 | gather_values | count as usize | | awk/interpreter/mod.rs:76 | print_to_string | argc as usize | | text/cut.rs:129 | cut_bytes | line.len() | | cc/arch/x86_64/codegen.rs:1901 | stack_arg_indices | insn.src.len() | | cc/ir/linearize.rs:841-845 | struct_params, complex_params | func.params.len() | | cc/arch/x86_64/codegen.rs:3737-3753 | 7 inline asm arrays | operand_count, outputs.len(), inputs.len() |
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Pull request overview
This PR optimizes memory allocation for HashMap and Vec collections by pre-allocating capacity where the size can be reasonably estimated, reducing the number of reallocations during runtime.
Key changes:
- Pre-allocating HashMap capacity based on input sizes or reasonable defaults
- Pre-allocating Vec capacity when the final size is known upfront
- Adding named constants for default capacities to improve code maintainability
Reviewed changes
Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.
Show a summary per file
| File | Description |
|---|---|
| tree/mv.rs | Pre-allocate inode_map HashMap capacity based on sources length |
| text/sed.rs | Pre-allocate counts HashMap capacity based on vec length |
| text/cut.rs | Pre-allocate result Vec capacity based on input line length |
| sh/shell/mod.rs | Add constant and pre-allocate saved_command_locations HashMap with default capacity |
| sh/shell/environment.rs | Pre-allocate exported HashMap capacity based on global_scope size |
| cc/token/preprocess.rs | Add constant and pre-allocate macros HashMap with default capacity |
| cc/symbol.rs | Add constant and pre-allocate name_map HashMap with default capacity |
| cc/ir/linearize.rs | Add constants and pre-allocate multiple HashMaps and Vecs with appropriate capacities |
| cc/arch/x86_64/codegen.rs | Pre-allocate multiple Vec capacities based on computed operand counts |
| awk/interpreter/mod.rs | Pre-allocate Vec capacities based on known count parameters |
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