Standardize on VIRT_ADDR_VARIES behavior.

Otherwise, valgrind does not work on some platforms.
Problem reported by Andreas Schwab in
<http://lists.gnu.org/archive/html/emacs-devel/2011-11/msg00081.html>.
* puresize.h (pure, PURE_P): Always behave as if VIRT_ADDR_VARIES
is set, removing the need for VIRT_ADDRESS_VARIES.
(PURE_P): Use a more-efficient implementation that needs just one
comparison, not two: on x86-64 with GCC 4.6.2, this cut down the
number of instructions from 6 (xorl, cmpq, jge, xorl, cmpq, setge)
to 4 (xorl, subq, cmpq, setbe).
* alloc.c (pure): Always extern now, since that's the
VIRT_ADDR_VARIES behavior.
(PURE_POINTER_P): Use a single comparison, not two, for
consistency with the new puresize.h.
* lisp.h (PNTR_COMPARISON_TYPE): Remove; no longer needed.
* m/ibms390.h, m/intel386.h, m/template.h, s/cygwin.h, s/hpux10-20.h:
Remove VIRT_ADDR_VARIES no longer needed.

Fixes: debbugs:10042

1 files changed, 1 insertions, 7 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 5d04bd77872..96d63f53cf9 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -203,9 +203,6 @@ static int malloc_hysteresis;
    remapping on more recent systems because this is less important
    nowadays than in the days of small memories and timesharing.  */
 
-#ifndef VIRT_ADDR_VARIES
-static
-#endif
 EMACS_INT pure[(PURESIZE + sizeof (EMACS_INT) - 1) / sizeof (EMACS_INT)] = {1,};
 #define PUREBEG (char *) pure
 
@@ -222,10 +219,7 @@ static ptrdiff_t pure_bytes_used_before_overflow;
 /* Value is non-zero if P points into pure space.  */
 
 #define PURE_POINTER_P(P)                                       \
-     (((PNTR_COMPARISON_TYPE) (P)                               \
-       < (PNTR_COMPARISON_TYPE) ((char *) purebeg + pure_size)) \
-      && ((PNTR_COMPARISON_TYPE) (P)                            \
-          >= (PNTR_COMPARISON_TYPE) purebeg))
+  ((uintptr_t) (P) - (uintptr_t) purebeg <= pure_size)
 
 /* Index in pure at which next pure Lisp object will be allocated.. */