From 735d099d31ecbe0496bbf2efa5fd80bb3c87595b Mon Sep 17 00:00:00 2001
From: Richard Brooksby <rb@ravenbrook.com>
Date: Sun, 13 Mar 2016 15:57:08 +0000
Subject: [PATCH] Removing white field from tracts.

Copied from Perforce
 Change: 190075
 ServerID: perforce.ravenbrook.com
---
 mps/code/seg.c   | 40 ----------------------------------------
 mps/code/trace.c |  9 +++++++--
 mps/code/tract.c |  4 ----
 mps/code/tract.h |  3 ---
 4 files changed, 7 insertions(+), 49 deletions(-)

diff --git a/mps/code/seg.c b/mps/code/seg.c
index 157aebb4a63..3efb85c1807 100644
--- a/mps/code/seg.c
+++ b/mps/code/seg.c
@@ -170,7 +170,6 @@ static Res SegInit(Seg seg, Pool pool, Addr base, Size size,
     AVER(TractP(tract) == NULL);
     AVER(!TractHasSeg(tract));
     AVER(TractPool(tract) == pool);
-    AVER(TractWhite(tract) == TraceSetEMPTY);
     TRACT_SET_SEG(tract, seg);
   }
   AVER(addr == SegLimit(seg));
@@ -227,7 +226,6 @@ static void SegFinish(Seg seg)
   limit = SegLimit(seg);
   TRACT_FOR(tract, addr, arena, base, limit) {
     AVERT(Tract, tract);
-    TractSetWhite(tract, TraceSetEMPTY);
     TRACT_UNSET_SEG(tract);
   }
   AVER(addr == SegLimit(seg));
@@ -686,27 +684,6 @@ Bool SegCheck(Seg seg)
   CHECKL(AddrIsArenaGrain(SegBase(seg), arena));
   CHECKL(AddrIsArenaGrain(SegLimit(seg), arena));
 
-  /* Each tract of the segment must agree about white traces. Note
-   * that even if the CHECKs are compiled away there is still a
-   * significant cost in looping over the tracts, hence the guard. See
-   * job003778. */
-#if defined(AVER_AND_CHECK_ALL)
-  {
-    Tract tract;
-    Addr addr;
-    TRACT_FOR(tract, addr, arena, SegBase(seg), SegLimit(seg)) {
-      Seg trseg = NULL; /* suppress compiler warning */
-
-      CHECKD_NOSIG(Tract, tract);
-      CHECKL(TRACT_SEG(&trseg, tract));
-      CHECKL(trseg == seg);
-      CHECKL(TractWhite(tract) == seg->white);
-      CHECKL(TractPool(tract) == pool);
-    }
-    CHECKL(addr == SegLimit(seg));
-  }
-#endif  /* AVER_AND_CHECK_ALL */
-
   /* The segment must belong to some pool, so it should be on a */
   /* pool's segment ring.  (Actually, this isn't true just after */
   /* the segment is initialized.) */
@@ -1248,9 +1225,6 @@ static void gcSegSetGrey(Seg seg, TraceSet grey)
 static void gcSegSetWhite(Seg seg, TraceSet white)
 {
   GCSeg gcseg;
-  Tract tract;
-  Arena arena;
-  Addr addr, base, limit;
 
   AVERT_CRITICAL(Seg, seg);            /* .seg.method.check */
   AVERT_CRITICAL(TraceSet, white);     /* .seg.method.check */
@@ -1258,20 +1232,6 @@ static void gcSegSetWhite(Seg seg, TraceSet white)
   AVERT_CRITICAL(GCSeg, gcseg);
   AVER_CRITICAL(&gcseg->segStruct == seg);
 
-  arena = PoolArena(SegPool(seg));
-  AVERT_CRITICAL(Arena, arena);
-  base = SegBase(seg);
-  limit = SegLimit(seg);
-  /* Each tract of the segment records white traces */
-  TRACT_FOR(tract, addr, arena, base, limit) {
-    Seg trseg = NULL; /* suppress compiler warning */
-    AVERT_CRITICAL(Tract, tract);
-    AVER_CRITICAL(TRACT_SEG(&trseg, tract));
-    AVER_CRITICAL(trseg == seg);
-    TractSetWhite(tract, BS_BITFIELD(Trace, white));
-  }
-  AVER(addr == limit);
-
   seg->white = BS_BITFIELD(Trace, white);
 }
 
diff --git a/mps/code/trace.c b/mps/code/trace.c
index 6d9cb0f0f98..bafe119c607 100644
--- a/mps/code/trace.c
+++ b/mps/code/trace.c
@@ -1336,8 +1336,13 @@ mps_res_t _mps_fix2(mps_ss_t mps_ss, mps_addr_t *mps_ref_io)
   }
 
   tract = PageTract(&chunk->pageTable[i]);
-  if (TraceSetInter(TractWhite(tract), ss->traces) == TraceSetEMPTY) {
-    /* Reference points to a tract that is not white for any of the
+  if (!TRACT_SEG(&seg, tract)) {
+    /* Reference points to a tract but not a segment, so it can't be white. */
+    goto done;
+  }
+
+  if (TraceSetInter(SegWhite(seg), ss->traces) == TraceSetEMPTY) {
+    /* Reference points to a segment that is not white for any of the
      * active traces. See <design/trace/#fix.tractofaddr> */
     STATISTIC_STAT
       ({
diff --git a/mps/code/tract.c b/mps/code/tract.c
index 9aa815f47ba..6bade6a340f 100644
--- a/mps/code/tract.c
+++ b/mps/code/tract.c
@@ -47,10 +47,7 @@ Bool TractCheck(Tract tract)
     CHECKL(AddrIsArenaGrain(TractBase(tract), TractArena(tract)));
   }
   if (TractHasSeg(tract)) {
-    CHECKL(TraceSetCheck(TractWhite(tract)));
     CHECKU(Seg, (Seg)TractP(tract));
-  } else {
-    CHECKL(TractWhite(tract) == TraceSetEMPTY);
   }
   return TRUE;
 }
@@ -66,7 +63,6 @@ void TractInit(Tract tract, Pool pool, Addr base)
   tract->pool.pool = pool;
   tract->base = base;
   tract->p = NULL;
-  tract->white = TraceSetEMPTY;
   tract->hasSeg = FALSE;
 
   AVERT(Tract, tract);
diff --git a/mps/code/tract.h b/mps/code/tract.h
index ce7c602a176..64eb319c51d 100644
--- a/mps/code/tract.h
+++ b/mps/code/tract.h
@@ -44,7 +44,6 @@ typedef struct TractStruct { /* Tract structure */
   PagePoolUnion pool; /* MUST BE FIRST (<design/arena/#tract.field> pool) */
   void *p;                     /* pointer for use of owning pool */
   Addr base;                   /* Base address of the tract */
-  TraceSet white : TraceLIMIT; /* traces for which tract is white */
   BOOLFIELD(hasSeg);           /* does tract have a seg in p? */
 } TractStruct;
 
@@ -60,8 +59,6 @@ extern Addr TractLimit(Tract tract, Arena arena);
 #define TractSetP(tract, pp)     ((void)((tract)->p = (pp)))
 #define TractHasSeg(tract)       ((Bool)(tract)->hasSeg)
 #define TractSetHasSeg(tract, b) ((void)((tract)->hasSeg = (b)))
-#define TractWhite(tract)        ((tract)->white)
-#define TractSetWhite(tract, w)  ((void)((tract)->white = (w)))
 
 extern Bool TractCheck(Tract tract);
 extern void TractInit(Tract tract, Pool pool, Addr base);