commit b0321032658d875bee7584d8e3a8cbdd275c99d5
author Alan Modra <amodra@gmail.com> Thu Sep 02 09:05:05 2021 +0930
committer Alan Modra <amodra@gmail.com> Wed Sep 22 17:14:17 2021 +0930
tree 09434b749884e6286edfef2caddc5a6155367831
parent a9b3c451be58f0fe660154323ace7ba72a4211ec

obstack.h __PTR_ALIGN vs. ubsan

Current ubsan complains on every use of __PTR_ALIGN (when ptrdiff_t is
as large as a pointer), due to making calculations relative to a NULL
pointer.  This patch avoids the problem by extracting out and
simplifying __BPTR_ALIGN for the usual case.  I've continued to use
ptrdiff_t here, where it might be better to throw away __BPTR_ALIGN
entirely and just assume uintptr_t exists.

	* obstack.h (__PTR_ALIGN): Expand and simplify __BPTR_ALIGN
	rather than calculating relative to a NULL pointer.