[PATCH] D52401: Remove redundant null pointer check in operator delete

[Fangrui Song via Phabricator]

MaskRay added a comment.

I just checked an extremely old version of glibc fetched from https://ftp.gnu.org/pub/gnu/glibc/

glibc-2.0.1.tar.gz	1997-02-04 03:00	3.7M

`malloc/malloc.c`

  #if __STD_C
  void fREe(Void_t* mem)
  #else
  void fREe(mem) Void_t* mem;
  #endif
  {
    arena *ar_ptr;
    mchunkptr p;                          /* chunk corresponding to mem */
  
  #if defined(_LIBC) || defined(MALLOC_HOOKS)
    if (__free_hook != NULL) {
      (*__free_hook)(mem);
      return;
    }
  #endif
  
    if (mem == 0)                              /* free(0) has no effect */
      return;

`__free_hook` (defaults to NULL) is a user-supplied hook (https://www.gnu.org/software/libc/manual/html_node/Hooks-for-Malloc.html). If this failed for `operator delete`, it would mean various other `free(NULL)` would also fail.


Repository:
  rL LLVM

https://reviews.llvm.org/D52401