am c26cd1ae: Merge "Fix sizing of the modunion table on small heaps"

* commit 'c26cd1ae75aa947b452ebe208b1ceaa06f292378':
  Fix sizing of the modunion table on small heaps

3 files changed, 19 insertions, 17 deletions

diff --git a/vm/Misc.c b/vm/Misc.c
index f5fd34a5b..2c3926c16 100644
--- a/vm/Misc.c
+++ b/vm/Misc.c
@@ -571,16 +571,16 @@ size_t strlcpy(char *dst, const char *src, size_t size) {
  *  zero.  Actual allocation rounded up to page multiple.  Returns
  *  NULL on failure.
  */
-void *dvmAllocRegion(size_t size, int prot, const char *name) {
+void *dvmAllocRegion(size_t byteCount, int prot, const char *name) {
     void *base;
     int fd, ret;
 
-    size = ALIGN_UP_TO_PAGE_SIZE(size);
-    fd = ashmem_create_region(name, size);
+    byteCount = ALIGN_UP_TO_PAGE_SIZE(byteCount);
+    fd = ashmem_create_region(name, byteCount);
     if (fd == -1) {
         return NULL;
     }
-    base = mmap(NULL, size, prot, MAP_PRIVATE, fd, 0);
+    base = mmap(NULL, byteCount, prot, MAP_PRIVATE, fd, 0);
     ret = close(fd);
     if (base == MAP_FAILED) {
         return NULL;
diff --git a/vm/alloc/CardTable.c b/vm/alloc/CardTable.c
index 2de586e90..533d5bc8a 100644
--- a/vm/alloc/CardTable.c
+++ b/vm/alloc/CardTable.c
@@ -80,18 +80,19 @@ static bool allocCardTable(size_t heapMaximumSize)
     return true;
 }
 
-static bool allocModUnionTable(size_t heapMaximumSize)
+static bool allocModUnionTable(size_t heapSize)
 {
-    size_t length = heapMaximumSize / GC_CARD_SIZE / HB_BITS_PER_WORD;
-    assert(length * GC_CARD_SIZE * HB_BITS_PER_WORD == heapMaximumSize);
+    size_t cardsPerHeap = heapSize / GC_CARD_SIZE;
+    size_t byteLength = cardsPerHeap / CHAR_BIT;
+    assert(byteLength * GC_CARD_SIZE * CHAR_BIT == heapSize);
     int prot = PROT_READ | PROT_WRITE;
-    void *allocBase = dvmAllocRegion(length, prot, "dalvik-modunion-table");
+    void *allocBase = dvmAllocRegion(byteLength, prot, "dalvik-modunion-table");
     if (allocBase == NULL) {
         return false;
     }
     GcHeap *gcHeap = gDvm.gcHeap;
     gcHeap->modUnionTableBase = (u1*)allocBase;
-    gcHeap->modUnionTableLength = length;
+    gcHeap->modUnionTableLength = byteLength;
     return true;
 }
 
diff --git a/vm/alloc/MarkSweep.c b/vm/alloc/MarkSweep.c
index e26394c85..85a4a8e91 100644
--- a/vm/alloc/MarkSweep.c
+++ b/vm/alloc/MarkSweep.c
@@ -192,11 +192,12 @@ static void visitModUnionTable(Visitor *visitor, u1 *base, u1 *limit, void *arg)
     assert(base >= heapBase);
     u4 *bits = (u4*)gDvm.gcHeap->modUnionTableBase;
     /* compute the end address in the bit table */
-    size_t length = (limit - base) / GC_CARD_SIZE;
-    assert(length % sizeof(*bits) == 0);
-    length /= 4;
+    size_t byteLength = (limit - base) / GC_CARD_SIZE;
+    assert(byteLength <= gDvm.gcHeap->modUnionTableLength);
+    assert(byteLength % sizeof(*bits) == 0);
+    size_t wordLength = byteLength / sizeof(*bits);
     size_t i;
-    for (i = 0; i < length; ++i) {
+    for (i = 0; i < wordLength; ++i) {
         if (bits[i] == 0) {
             continue;
         }
@@ -693,12 +694,12 @@ static void scanGrayObjects(GcMarkContext *ctx)
  */
 void dvmHeapScanImmuneObjects(const GcMarkContext *ctx)
 {
-    ScanImmuneObjectContext ctx2;
-    memset(&ctx2, 0, sizeof(ctx2));
-    ctx2.threatenBoundary = (Object*)ctx->immuneLimit;
+    ScanImmuneObjectContext scanCtx;
+    memset(&scanCtx, 0, sizeof(scanCtx));
+    scanCtx.threatenBoundary = (Object*)ctx->immuneLimit;
     visitModUnionTable(scanImmuneObject,
                        (u1*)ctx->bitmap->base, (u1*)ctx->immuneLimit,
-                       (void *)&ctx2);
+                       (void *)&scanCtx);
     if (gDvm.verifyCardTable) {
         verifyImmuneObjects();
     }