Merge remote-tracking branch 'savannah/master' into HEAD

1 files changed, 18 insertions, 29 deletions

diff --git a/src/alloc.c b/src/alloc.c
index a31b4a045e2..12f53bdd6d8 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -1947,6 +1947,9 @@ resize_string_data (Lisp_Object string, ptrdiff_t cidx_byte,
       /* No need to reallocate, as the size change falls within the
          alignment slop.  */
       XSTRING (string)->u.s.size_byte = new_nbytes;
+#ifdef GC_CHECK_STRING_BYTES
+      SDATA_NBYTES (old_sdata) = new_nbytes;
+#endif
       new_charaddr = data + cidx_byte;
       memmove (new_charaddr + new_clen, new_charaddr + clen,
                nbytes - (cidx_byte + (clen - 1)));
@@ -4658,7 +4661,16 @@ mark_maybe_object (Lisp_Object obj)
       break;
     }
 
-  void *po = (char *) XLP (obj) + (offset - LISP_WORD_TAG (type_tag));
+  bool overflow
+    = INT_SUBTRACT_WRAPV (offset, LISP_WORD_TAG (type_tag), &offset);
+#if !defined WIDE_EMACS_INT || USE_LSB_TAG
+  /* If we don't use wide integers, then `intptr_t' should always be
+     large enough to not overflow.  Furthermore, when using the least
+     significant bits as tag bits, the tag is small enough to not
+     overflow either.  */
+  eassert (!overflow);
+#endif
+  void *po = (char *) ((intptr_t) (char *) XLP (obj) + offset);
 
   /* If the pointer is in the dump image and the dump has a record
      of the object starting at the place where the pointer points, we
@@ -4869,7 +4881,7 @@ mark_memory (void const *start, void const *end)
          On a host with 32-bit pointers and 64-bit Lisp_Objects,
          a Lisp_Object might be split into registers saved into
          non-adjacent words and P might be the low-order word's value.  */
-      p += (intptr_t) lispsym;
+      p = (char *) ((uintptr_t) p + (uintptr_t) lispsym);
       mark_maybe_pointer (p);
 
       verify (alignof (Lisp_Object) % GC_POINTER_ALIGNMENT == 0);
@@ -4986,27 +4998,6 @@ typedef union
 #endif
 } stacktop_sentry;
 
-/* Force callee-saved registers and register windows onto the stack.
-   Use the platform-defined __builtin_unwind_init if available,
-   obviating the need for machine dependent methods.  */
-#ifndef HAVE___BUILTIN_UNWIND_INIT
-# ifdef __sparc__
-   /* This trick flushes the register windows so that all the state of
-      the process is contained in the stack.
-      FreeBSD does not have a ta 3 handler, so handle it specially.
-      FIXME: Code in the Boehm GC suggests flushing (with 'flushrs') is
-      needed on ia64 too.  See mach_dep.c, where it also says inline
-      assembler doesn't work with relevant proprietary compilers.  */
-#  if defined __sparc64__ && defined __FreeBSD__
-#   define __builtin_unwind_init() asm ("flushw")
-#  else
-#   define __builtin_unwind_init() asm ("ta 3")
-#  endif
-# else
-#  define __builtin_unwind_init() ((void) 0)
-# endif
-#endif
-
 /* Yield an address close enough to the top of the stack that the
    garbage collector need not scan above it.  Callers should be
    declared NO_INLINE.  */
@@ -5042,16 +5033,14 @@ typedef union
    We have to mark Lisp objects in CPU registers that can hold local
    variables or are used to pass parameters.
 
-   This code assumes that calling setjmp saves registers we need
+   If __builtin_unwind_init is available, it should suffice to save
+   registers.
+
+   Otherwise, assume that calling setjmp saves registers we need
    to see in a jmp_buf which itself lies on the stack.  This doesn't
    have to be true!  It must be verified for each system, possibly
    by taking a look at the source code of setjmp.
 
-   If __builtin_unwind_init is available (defined by GCC >= 2.8) we
-   can use it as a machine independent method to store all registers
-   to the stack.  In this case the macros described in the previous
-   two paragraphs are not used.
-
    Stack Layout
 
    Architectures differ in the way their processor stack is organized.