[clang] [compiler-rt] [CopyProf] Add interceptors and custom allocator. (PR #232851)

[Snehasish Kumar via cfe-commits]

https://github.com/snehasish commented:

This PR is pretty big. Could you break it up to make it easier for humans to review? Here is a suggestion which I put together with the help of AI..

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| PR | Contents | Implementation/build | Tests | Total added |
|---|---|---:|---:|---:|
| 1 | Libc write interceptors, initialization, zero-length handling, constructor/destructor temporary semantics | ~330 | ~90 | ~420 |
| 2 | Allocator implementation and API, metadata, thread caches, allocation-contract tests | ~350 | ~200 | ~550 |
| 3 | C heap interceptors, allocation shadow updates, checking owned memory during destruction | ~200 | ~190 | ~390 |
| 4 | C++ `new`/`delete` interceptors and driver wiring, per-object cost accounting and reporting | ~330 | ~100 | ~430 |




https://github.com/llvm/llvm-project/pull/232851