From ed44ee33c2ffbdf13e5c8d211c162784b86661e6 Mon Sep 17 00:00:00 2001
From: Gareth Rees <gdr@ravenbrook.com>
Date: Mon, 18 Jun 2018 15:23:58 +0100
Subject: [PATCH] Awl asserts on fixes to unaligned exact references.

New MMQA test case conerr/61.c checks this.

Copied from Perforce
 Change: 193904
---
 mps/code/poolawl.c   | 11 ++++++--
 mps/code/poollo.c    |  1 +
 mps/test/conerr/61.c | 65 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 75 insertions(+), 2 deletions(-)
 create mode 100644 mps/test/conerr/61.c

diff --git a/mps/code/poolawl.c b/mps/code/poolawl.c
index 8c0a4673d5e..71b9075cc6e 100644
--- a/mps/code/poolawl.c
+++ b/mps/code/poolawl.c
@@ -995,12 +995,19 @@ static Res AWLFix(Pool pool, ScanState ss, Seg seg, Ref *refIO)
   if (base < SegBase(seg)) {
     return ResOK;
   }
+
+  /* Not a real reference if unaligned. */
+  if (!AddrIsAligned(base, PoolAlignment(pool))) {
+    AVER_CRITICAL(ss->rank == RankAMBIG);
+    return ResOK;
+  }
+
   i = awlIndexOfAddr(SegBase(seg), awl, base);
 
   switch(ss->rank) {
   case RankAMBIG:
-    /* not a real pointer if not aligned or not allocated */
-    if (!AddrIsAligned(base, sizeof(void *)) || !BTGet(awlseg->alloc, i))
+    /* not a real reference if not allocated */
+    if (!BTGet(awlseg->alloc, i))
       return ResOK;
     /* falls through */
   case RankEXACT:
diff --git a/mps/code/poollo.c b/mps/code/poollo.c
index d388bbacdc4..4a1ebea034a 100644
--- a/mps/code/poollo.c
+++ b/mps/code/poollo.c
@@ -717,6 +717,7 @@ static Res LOFix(Pool pool, ScanState ss, Seg seg, Ref *refIO)
     return ResOK;
   }
 
+  /* Not a real reference if unaligned. */
   if (!AddrIsAligned(base, PoolAlignment(pool))) {
     AVER_CRITICAL(ss->rank == RankAMBIG);
     return ResOK;
diff --git a/mps/test/conerr/61.c b/mps/test/conerr/61.c
new file mode 100644
index 00000000000..557375a8637
--- /dev/null
+++ b/mps/test/conerr/61.c
@@ -0,0 +1,65 @@
+/* 
+TEST_HEADER
+ id = $Id$
+ summary = AWL pool asserts on unaligned exact reference
+ language = c
+ link = myfmt.o testlib.o
+OUTPUT_SPEC
+ assert = true
+ assertfile P= poolawl.c
+ assertcond = ss->rank == RankAMBIG
+END_HEADER
+*/
+
+#include "testlib.h"
+#include "mpscawl.h"
+#include "myfmt.h"
+
+static void test(void)
+{
+ void *marker = &marker;
+ mps_arena_t arena;
+ mps_pool_t pool;
+ mps_thr_t thread;
+ mps_root_t root;
+ mps_fmt_t format;
+ mps_ap_t ap;
+ mps_addr_t p, q, unaligned;
+
+ cdie(mps_arena_create_k(&arena, mps_arena_class_vm(), mps_args_none), "create arena");
+ mps_arena_park(arena);
+ cdie(mps_thread_reg(&thread, arena), "register thread");
+ cdie(mps_root_create_thread(&root, arena, thread, marker), "create root");
+ cdie(mps_fmt_create_A(&format, arena, &fmtA), "create format");
+ MPS_ARGS_BEGIN(args) {
+   MPS_ARGS_ADD(args, MPS_KEY_FORMAT, format);
+   cdie(mps_pool_create_k(&pool, arena, mps_class_awl(), args), "pool");
+ } MPS_ARGS_END(args);
+ cdie(mps_ap_create(&ap, pool, mps_rank_exact()), "ap");
+
+ /* p is in the AWL pool */
+ p = allocone(ap, 0, NULL, NULL, sizeof(mycell));
+ unaligned = (void *)((char*)p + 1);
+
+ /* q is in the AWL pool with unaligned exact reference to p */
+ q = allocone(ap, 1, p, unaligned, sizeof(mycell));
+
+ mps_arena_start_collect(arena);
+ mps_arena_park(arena);
+
+ /* Keep q (and thus p) alive during the collection. */
+ report("q", "%p", q);
+
+ mps_ap_destroy(ap);
+ mps_pool_destroy(pool);
+ mps_fmt_destroy(format);
+ mps_root_destroy(root);
+ mps_thread_dereg(thread);
+ mps_arena_destroy(arena);
+}
+
+int main(void)
+{
+ easy_tramp(test);
+ return 0;
+}