Support Elbrus 2000 (Linux/e2k)

(a port of altlinux libgc-e2k.patch (8ed786c))

Issue #411 (bdwgc).

* include/gc/gc.h [__GNUC__ && !__INTEL_COMPILER && __e2k__]
(GC_reachable_here): Specify "r" contraint for ptr.
* include/gc/gc.h [__e2k__] (GC_stack_base): Declare reg_base field.
* include/private/gc_priv.h [E2K] (GC_push_all_register_sections,
GC_save_regs_in_stack, GC_get_procedure_stack): Declare.
* include/private/gc_priv.h [E2K && __ptr64__] (LOAD_TAGGED_VALUE):
Define macro.
* include/private/gc_priv.h (LOAD_WORD_OR_CONTINUE): Likewise.
* include/private/gcconfig.h [LINUX && __e2k__] (E2K, mach_type_known):
Likewise.
* include/private/gcconfig.h [E2K] (MACH_TYPE, CPP_WORDSZ, ALIGNMENT,
HBLKSIZE): Likewise.
* include/private/gcconfig.h [E2K && LINUX] (DATASTART): Likewise.
* mach_dep.c [E2K] (VA_SIZE, E2K_PSHTP_SIZE, get_stack_index):
Likewise.
* include/private/gcconfig.h [GC_GNUC_PREREQ(2,8)]
(HAVE_BUILTIN_UNWIND_INIT): Do not define if E2K.
* include/private/gcconfig.h [E2K && LINUX] (__dso_handle): Declare
extern variable.
* include/private/pthread_support.h [E2K] (GC_Thread_Rep): Declare
backing_store_end and backing_store_ptr fields.
* mach_dep.c [E2K]: Include errno.h, sys/syscall.h, asm/e2k_syswork.h.
* mach_dep.c [E2K] (e2k_rwap_lo_fields, e2k_rwap_hi_fields): Declare
struct.
* mach_dep.c [E2K] (e2k_rwap_lo_u, e2k_rwap_hi_u): Declare union.
* mach_dep.c [E2K] (GC_get_procedure_stack, GC_save_regs_in_stack):
Implement.
* mach_dep.c [E2K] (GC_with_callee_saves_pushed): Call
GC_save_regs_in_stack() (not saving the result).
* mark.c (GC_mark_from, GC_push_all_eager): Use LOAD_WORD_OR_CONTINUE()
instead of direct dereference of current_p.
* mark.c [!SMALL_CONFIG] (GC_mark_from): Do not prefetch if E2K.
* mark_rts.c [E2K] (GC_push_all_register_sections): Implement but
ignore traced_stack_sect (add TODO item).
* mark_rts.c [!THREADS && E2K] (GC_push_current_stack): Call
GC_get_procedure_stack() and GC_push_all_register_sections().
* misc.c [E2K] (GC_call_with_stack_base): Initialize reg_base to 0.
* misc.c [!THREADS && E2K] (GC_do_blocking_inner,
GC_get_my_stackbottom): Likewise.
* os_dep.c [((HAVE_PTHREAD_ATTR_GET_NP || HAVE_PTHREAD_GETATTR_NP)
&& THREADS || !HAVE_GET_STACK_BASE) && E2K] (GC_get_stack_base):
Likewise.
* pthread_support.c [E2K] (GC_get_my_stackbottom): Likewise.
* pthread_stop_world.c [E2K] (GC_suspend_handler): Call
GC_with_callee_saves_pushed().
* pthread_stop_world.c [E2K] (GC_store_stack_ptr): Call
GC_save_regs_in_stack() and GC_get_procedure_stack().
* pthread_stop_world.c [E2K] (GC_suspend_handler_inner): Call
free(me->backing_store_end) before return.
* pthread_stop_world.c [E2K] (GC_push_all_stacks): Declare bs_lo,
bs_hi, stack_size local variables; call GC_save_regs_in_stack() and
GC_get_procedure_stack() (and free() at the end) for self thread;
call GC_push_all_register_sections().
* pthread_support.c [E2K] (GC_do_blocking_inner): Call
GC_save_regs_in_stack(); add FIXME.

1 files changed, 12 insertions, 14 deletions

diff --git a/mark.c b/mark.c
index 996efa54..a743ba16 100644
--- a/mark.c
+++ b/mark.c
@@ -712,11 +712,11 @@ GC_INNER mse * GC_mark_from(mse *mark_stack_top, mse *mark_stack,
 #         endif /* ENABLE_TRACE */
           descr &= ~GC_DS_TAGS;
           credit -= WORDS_TO_BYTES(WORDSZ/2); /* guess */
-          while (descr != 0) {
-            if ((descr & SIGNB) != 0) {
-              current = *(word *)current_p;
-              FIXUP_POINTER(current);
-              if (current >= (word)least_ha && current < (word)greatest_ha) {
+          for (; descr != 0; descr <<= 1, current_p += sizeof(word)) {
+            if ((descr & SIGNB) == 0) continue;
+            LOAD_WORD_OR_CONTINUE(current, current_p);
+            FIXUP_POINTER(current);
+            if (current >= (word)least_ha && current < (word)greatest_ha) {
                 PREFETCH((ptr_t)current);
 #               ifdef ENABLE_TRACE
                   if (GC_trace_addr == current_p) {
@@ -727,10 +727,7 @@ GC_INNER mse * GC_mark_from(mse *mark_stack_top, mse *mark_stack,
 #               endif /* ENABLE_TRACE */
                 PUSH_CONTENTS((ptr_t)current, mark_stack_top,
                               mark_stack_limit, current_p);
-              }
             }
-            descr <<= 1;
-            current_p += sizeof(word);
           }
           continue;
         case GC_DS_PROC:
@@ -803,7 +800,8 @@ GC_INNER mse * GC_mark_from(mse *mark_stack_top, mse *mark_stack,
     {
 #     define PREF_DIST 4
 
-#     ifndef SMALL_CONFIG
+#     if !defined(SMALL_CONFIG) && !defined(E2K)
+        /* TODO: enable prefetching for E2K? */
         word deferred;
 
         /* Try to prefetch the next pointer to be examined ASAP.        */
@@ -836,11 +834,11 @@ GC_INNER mse * GC_mark_from(mse *mark_stack_top, mse *mark_stack,
         }
 #     endif
 
-      while ((word)current_p <= (word)limit) {
+      for (; (word)current_p <= (word)limit; current_p += ALIGNMENT) {
         /* Empirically, unrolling this loop doesn't help a lot. */
         /* Since PUSH_CONTENTS expands to a lot of code,        */
         /* we don't.                                            */
-        current = *(word *)current_p;
+        LOAD_WORD_OR_CONTINUE(current, current_p);
         FIXUP_POINTER(current);
         PREFETCH(current_p + PREF_DIST*CACHE_LINE_SIZE);
         if (current >= (word)least_ha && current < (word)greatest_ha) {
@@ -857,10 +855,9 @@ GC_INNER mse * GC_mark_from(mse *mark_stack_top, mse *mark_stack,
           PUSH_CONTENTS((ptr_t)current, mark_stack_top,
                         mark_stack_limit, current_p);
         }
-        current_p += ALIGNMENT;
       }
 
-#     ifndef SMALL_CONFIG
+#     if !defined(SMALL_CONFIG) && !defined(E2K)
         /* We still need to mark the entry we previously prefetched.    */
         /* We already know that it passes the preliminary pointer       */
         /* validity test.                                               */
@@ -1582,8 +1579,9 @@ GC_API void GC_CALL GC_push_all_eager(void *bottom, void *top)
     lim = (word *)(((word)top) & ~(ALIGNMENT-1)) - 1;
     for (current_p = (ptr_t)(((word)bottom + ALIGNMENT-1) & ~(ALIGNMENT-1));
          (word)current_p <= (word)lim; current_p += ALIGNMENT) {
-      REGISTER word q = *(word *)current_p;
+      REGISTER word q;
 
+      LOAD_WORD_OR_CONTINUE(q, current_p);
       GC_PUSH_ONE_STACK(q, current_p);
     }
 #   undef GC_greatest_plausible_heap_addr