Bug 1165904 - Don't call methods on null pointers to fix some -fsanitize=null errors. r=terrence

--HG--
extra : rebase_source : 40b83720b22aa77fec3c1071ca063ad2beb02d99

js/src/gc/Heap.h

@@ -1123,6 +1123,7 @@ inline uintptr_t
 ArenaHeader::address() const
 {
     uintptr_t addr = reinterpret_cast<uintptr_t>(this);
+    MOZ_ASSERT(addr);
     MOZ_ASSERT(!(addr & ArenaMask));
     MOZ_ASSERT(Chunk::withinArenasRange(addr));
     return addr;
@@ -1186,7 +1187,8 @@ ArenaHeader::setNextDelayedMarking(ArenaHeader* aheader)
     MOZ_ASSERT(!(uintptr_t(aheader) & ArenaMask));
     MOZ_ASSERT(!auxNextLink && !hasDelayedMarking);
     hasDelayedMarking = 1;
-    auxNextLink = aheader->arenaAddress() >> ArenaShift;
+    if (aheader)
+        auxNextLink = aheader->arenaAddress() >> ArenaShift;
 }
 
 inline void
@@ -1209,7 +1211,8 @@ ArenaHeader::setNextAllocDuringSweep(ArenaHeader* aheader)
 {
     MOZ_ASSERT(!auxNextLink && !allocatedDuringIncremental);
     allocatedDuringIncremental = 1;
-    auxNextLink = aheader->arenaAddress() >> ArenaShift;
+    if (aheader)
+        auxNextLink = aheader->arenaAddress() >> ArenaShift;
 }
 
 inline void

js/src/gc/Marking.cpp

@@ -1948,8 +1948,10 @@ js::TenuringTracer::traceObjectSlots(NativeObject* nobj, uint32_t start, uint32_
     HeapSlot* dynStart;
     HeapSlot* dynEnd;
     nobj->getSlotRange(start, length, &fixedStart, &fixedEnd, &dynStart, &dynEnd);
-    traceSlots(fixedStart->unsafeGet(), fixedEnd->unsafeGet());
+    if (fixedStart)
-    traceSlots(dynStart->unsafeGet(), dynEnd->unsafeGet());
+        traceSlots(fixedStart->unsafeGet(), fixedEnd->unsafeGet());
+    if (dynStart)
+        traceSlots(dynStart->unsafeGet(), dynEnd->unsafeGet());
 }
 
 void

js/src/jit/JitFrames.h

@@ -373,13 +373,10 @@ class JitFrameLayout : public CommonFrameLayout
         return offsetof(JitFrameLayout, numActualArgs_);
     }
     static size_t offsetOfThis() {
-        JitFrameLayout* base = nullptr;
+        return sizeof(JitFrameLayout);
-        return reinterpret_cast<size_t>(&base->argv()[0]);
     }
     static size_t offsetOfActualArgs() {
-        JitFrameLayout* base = nullptr;
+        return offsetOfThis() + sizeof(Value);
-        // +1 to skip |this|.
-        return reinterpret_cast<size_t>(&base->argv()[1]);
     }
     static size_t offsetOfActualArg(size_t arg) {
         return offsetOfActualArgs() + arg * sizeof(Value);