From 8e4e0f066ea4afb86247594c481fb0d795fb418a Mon Sep 17 00:00:00 2001
From: Richard Brooksby <rb@ravenbrook.com>
Date: Wed, 29 Jan 2014 15:13:22 +0000
Subject: [PATCH] Eliminating dodgy use of *segprefdefault() which could lead
 to implicit calls to memcpy.

Copied from Perforce
 Change: 184217
 ServerID: perforce.ravenbrook.com
---
 mps/code/arenacv.c  | 4 +++-
 mps/code/locus.c    | 9 ++++++++-
 mps/code/mpm.h      | 1 +
 mps/code/poolams.c  | 2 +-
 mps/code/poolmv2.c  | 2 +-
 mps/code/poolmvff.c | 2 +-
 mps/code/poolsnc.c  | 2 +-
 7 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/mps/code/arenacv.c b/mps/code/arenacv.c
index 01be2dd83fe..10ef9c45314 100644
--- a/mps/code/arenacv.c
+++ b/mps/code/arenacv.c
@@ -261,11 +261,13 @@ static void testAllocAndIterate(Arena arena, Pool pool,
                                 AllocatorClass allocator)
 {
   AllocInfoStruct offsetRegion, gapRegion, newRegion, topRegion;
-  SegPrefStruct pref = *SegPrefDefault();
+  SegPrefStruct pref;
   Count offset, gap, new;
   ZoneSet zone = (ZoneSet)2;
   int i;
 
+  SegPrefInit(&pref);
+  
   /* Testing the behaviour with various sizes of gaps in the page table. */
 
   /* Assume the allocation strategy is first-fit.  The idea of the tests is */
diff --git a/mps/code/locus.c b/mps/code/locus.c
index ff8d173d2bb..e3cbef3a8a2 100644
--- a/mps/code/locus.c
+++ b/mps/code/locus.c
@@ -39,6 +39,13 @@ SegPref SegPrefDefault(void)
   return &segPrefDefault;
 }
 
+/* SegPrefInit -- initialise a segment preference to the defaults */
+
+void SegPrefInit(SegPref pref)
+{
+  mps_lib_memcpy(pref, &segPrefDefault, sizeof(SegPrefStruct));
+}
+
 
 /* SegPrefExpress -- express a segment preference */
 
@@ -253,7 +260,7 @@ Res ChainAlloc(Seg *segReturn, Chain chain, Serial genNr, SegClass class,
   else
     zones = arena->topGen.zones;
 
-  pref = *SegPrefDefault(); /* FIXME: Ugh.  Should have SegPrefInit. */
+  SegPrefInit(&pref);
   SegPrefExpress(&pref, SegPrefCollected, NULL);
   SegPrefExpress(&pref, SegPrefZoneSet, &zones);
   res = SegAlloc(&seg, class, &pref, size, pool, withReservoirPermit, args);
diff --git a/mps/code/mpm.h b/mps/code/mpm.h
index 5998761e8e7..65f61c3b60c 100644
--- a/mps/code/mpm.h
+++ b/mps/code/mpm.h
@@ -626,6 +626,7 @@ extern Res ArenaNoExtend(Arena arena, Addr base, Size size);
 
 extern Bool SegPrefCheck(SegPref pref);
 extern SegPref SegPrefDefault(void);
+extern void SegPrefInit(SegPref pref);
 extern void SegPrefExpress(SegPref pref, SegPrefKind kind, void *p);
 
 extern void LocusInit(Arena arena);
diff --git a/mps/code/poolams.c b/mps/code/poolams.c
index 7f93dde0c49..a854d443b98 100644
--- a/mps/code/poolams.c
+++ b/mps/code/poolams.c
@@ -954,7 +954,7 @@ static Res AMSBufferFill(Addr *baseReturn, Addr *limitReturn,
   }
 
   /* No suitable segment found; make a new one. */
-  segPrefStruct = *SegPrefDefault();
+  SegPrefInit(&segPrefStruct);
   SegPrefExpress(&segPrefStruct, SegPrefCollected, NULL);
   res = AMSSegCreate(&seg, pool, size, &segPrefStruct, rankSet,
                      withReservoirPermit);
diff --git a/mps/code/poolmv2.c b/mps/code/poolmv2.c
index 53237d5861f..e72f3189ed2 100644
--- a/mps/code/poolmv2.c
+++ b/mps/code/poolmv2.c
@@ -290,7 +290,7 @@ static Res MVTInit(Pool pool, ArgList args)
   {
     ZoneSet zones;
     /* --- Loci needed here, what should the pref be? */
-    *MVTSegPref(mvt) = *SegPrefDefault();
+    SegPrefInit(MVTSegPref(mvt));
     zones = ZoneSetComp(ArenaDefaultZONESET);
     SegPrefExpress(MVTSegPref(mvt), SegPrefZoneSet, (void *)&zones);
   }
diff --git a/mps/code/poolmvff.c b/mps/code/poolmvff.c
index d5a5f363ad3..d2c2997e725 100644
--- a/mps/code/poolmvff.c
+++ b/mps/code/poolmvff.c
@@ -593,7 +593,7 @@ static Res MVFFInit(Pool pool, ArgList args)
     return res;
 
   mvff->segPref = (SegPref)p;
-  *mvff->segPref = *SegPrefDefault();
+  SegPrefInit(mvff->segPref);
   SegPrefExpress(mvff->segPref, arenaHigh ? SegPrefHigh : SegPrefLow, NULL);
   /* If using zoneset placement, just put it apart from the others. */
   zones = ZoneSetComp(ArenaDefaultZONESET);
diff --git a/mps/code/poolsnc.c b/mps/code/poolsnc.c
index 49cdceeb25d..87133f55718 100644
--- a/mps/code/poolsnc.c
+++ b/mps/code/poolsnc.c
@@ -391,7 +391,7 @@ static Res SNCInit(Pool pool, ArgList args)
   snc->freeSegs = NULL;
   /* Use the default segpref for the pool. At least this should avoid */
   /* clashes with collected pools */
-  snc->segPrefStruct = *SegPrefDefault();
+  SegPrefInit(&snc->segPrefStruct);
   snc->sig = SNCSig;
 
   AVERT(SNC, snc);