Re: New flag: TREE_THIS_NOTRAP

[Andrew Haley <aph at redhat dot com>]

Frank Ch. Eigler writes:
 > 
 > aph wrote:
 > 
 > > [...]
 > > + /* Nonzero means this node will not trap.  In an INDIRECT_REF, means
 > > +    accessing the memory pointed to won't generate a trap.  However,
 > > +    this only applies to an object when used appropriately: it doesn't
 > > +    mean that writing a READONLY mem won't trap.  */
 > > [...]
 > 
 > This flag could be useful for mudflap's purposes also, in that the
 > passes could treat incoming INDIRECT_REFs marked with this flag as
 > "not to be instrumented".  However, I am a little confused about the
 > exact meaning of "used appropriately" above - it sounds a little less
 > restricted than mudflap's notions of pointer checking.

It just means that this flag doesn't override other meanings, such as
writing to a read-only mem or reading from a write-only or
execute-only mem.

Andrew.