[PATCH] D50039: [LibCalls] Added nonnull atribute to libc function args

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 added a subscriber: rsmith.
xbolva00 added a comment.

In https://reviews.llvm.org/D50039#1183214, @efriedma wrote:

> I don't think we can reasonably do this for the functions which take a pointer+size pair; see http://lists.llvm.org/pipermail/cfe-dev/2017-January/052066.html etc.  Maybe we can mark specific calls where we know the size is nonzero.
>
> Not sure how this should interact with -fno-delete-null-pointer-checks; maybe we can make that work "correctly" by just doing all our nonnull marking on individual calls, even for the functions which take null-terminated strings.


so @rsmith 's list is what we want to follow for this type of transformation?

ISO C:

  memcpy, memmove, memset, memcmp, memchr, memrchr
  strncpy [param 1 only], strncat [param 1 only], strncmp

Extensions:

  strndup, memccpy, mempcpy, strnlen, bcopy, bzero, bcmp, memfrob,
  strncasecmp, strncasecmp_l [not parameter 4], stpncpy

Side note: GCC has no problem to optimize/remove condition (maybe we have already ubsan checker for 0/null for mem* functions, or maybe is under development, I saw it somewhere)
int foo(void *p, int n) {

  memset(p, 0, n);
  if (!p)
      abort();
  return 1;

}


Repository:
  rL LLVM

https://reviews.llvm.org/D50039