[PATCH] D53342: [SimplifyLibCalls] Mark known arguments with nonnull

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 marked an inline comment as done.
xbolva00 added inline comments.


================
Comment at: lib/Transforms/Utils/SimplifyLibCalls.cpp:255
 
+  setNonNullParam(CI, 0);
   // We don't do anything if length is not constant.
----------------
jdoerfert wrote:
> Why is non-null supposed to be "allowed" for the destination but not the source in case the length is 0?
s = NULL;
strncat(d, s, 0) -> valid

The strncat() function is similar, except that

       *  it will use at most n bytes from src; and

       *  src does not need to be null-terminated if it  contains  n  or  more
          bytes.

       As  with  strcat(),  the resulting string in dest is always null-termi‐
       nated.

so "d" (dest) is always null terminated (and must be nonnull).


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