Merge branch 'master' into Basilisk-release

21 files changed, 280 insertions, 195 deletions

diff --git a/js/src/ds/LifoAlloc.h b/js/src/ds/LifoAlloc.h
index f349cd476..b4e9c3418 100644
--- a/js/src/ds/LifoAlloc.h
+++ b/js/src/ds/LifoAlloc.h
@@ -15,6 +15,8 @@
 #include "mozilla/TemplateLib.h"
 #include "mozilla/TypeTraits.h"
 
+#include <new>
+
 // This data structure supports stacky LIFO allocation (mark/release and
 // LifoAllocScope). It does not maintain one contiguous segment; instead, it
 // maintains a bunch of linked memory segments. In order to prevent malloc/free
@@ -285,6 +287,20 @@ class LifoAlloc
         return allocImpl(n);
     }
 
+    template<typename T, typename... Args>
+    MOZ_ALWAYS_INLINE T*
+    allocInSize(size_t n, Args&&... args)
+    {
+        MOZ_ASSERT(n >= sizeof(T), "must request enough space to store a T");
+        static_assert(alignof(T) <= detail::LIFO_ALLOC_ALIGN,
+                      "LifoAlloc must provide enough alignment to store T");
+        void* ptr = alloc(n);
+        if (!ptr)
+            return nullptr;
+
+        return new (ptr) T(mozilla::Forward<Args>(args)...);
+    }
+
     MOZ_ALWAYS_INLINE
     void* allocInfallible(size_t n) {
         AutoEnterOOMUnsafeRegion oomUnsafe;
diff --git a/js/src/frontend/BytecodeEmitter.cpp b/js/src/frontend/BytecodeEmitter.cpp
index c7c615ccf..4eb7bf880 100644
--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -319,7 +319,7 @@ ScopeKindIsInBody(ScopeKind kind)
 static inline void
 MarkAllBindingsClosedOver(LexicalScope::Data& data)
 {
-    BindingName* names = data.names;
+    TrailingNamesArray& names = data.trailingNames;
     for (uint32_t i = 0; i < data.length; i++)
         names[i] = BindingName(names[i].name(), true);
 }
@@ -8978,7 +8978,8 @@ BytecodeEmitter::isRestParameter(ParseNode* pn, bool* result)
         if (bindings->nonPositionalFormalStart > 0) {
             // |paramName| can be nullptr when the rest destructuring syntax is
             // used: `function f(...[]) {}`.
-            JSAtom* paramName = bindings->names[bindings->nonPositionalFormalStart - 1].name();
+            JSAtom* paramName =
+                bindings->trailingNames[bindings->nonPositionalFormalStart - 1].name();
             *result = paramName && name == paramName;
             return true;
         }
diff --git a/js/src/frontend/ParseNode.cpp b/js/src/frontend/ParseNode.cpp
index ece3a45df..91f17625c 100644
--- a/js/src/frontend/ParseNode.cpp
+++ b/js/src/frontend/ParseNode.cpp
@@ -838,7 +838,7 @@ LexicalScopeNode::dump(int indent)
     if (!isEmptyScope()) {
         LexicalScope::Data* bindings = scopeBindings();
         for (uint32_t i = 0; i < bindings->length; i++) {
-            JSAtom* name = bindings->names[i].name();
+            JSAtom* name = bindings->trailingNames[i].name();
             JS::AutoCheckCannotGC nogc;
             if (name->hasLatin1Chars())
                 DumpName(name->latin1Chars(nogc), name->length());
diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
index 623379f61..7bfab87a3 100644
--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -19,6 +19,8 @@
 
 #include "frontend/Parser.h"
 
+#include <new>
+
 #include "jsapi.h"
 #include "jsatom.h"
 #include "jscntxt.h"
@@ -1451,16 +1453,26 @@ template <typename Scope>
 static typename Scope::Data*
 NewEmptyBindingData(ExclusiveContext* cx, LifoAlloc& alloc, uint32_t numBindings)
 {
+    using Data = typename Scope::Data;
     size_t allocSize = Scope::sizeOfData(numBindings);
-    typename Scope::Data* bindings = static_cast<typename Scope::Data*>(alloc.alloc(allocSize));
-    if (!bindings) {
+    auto* bindings = alloc.allocInSize<Data>(allocSize, numBindings);
+    if (!bindings)
         ReportOutOfMemory(cx);
-        return nullptr;
-    }
-    PodZero(bindings);
     return bindings;
 }
 
+/**
+ * Copy-construct |BindingName|s from |bindings| into |cursor|, then return
+ * the location one past the newly-constructed |BindingName|s.
+ */
+static MOZ_MUST_USE BindingName*
+FreshlyInitializeBindings(BindingName* cursor, const Vector<BindingName>& bindings)
+{
+    for (const BindingName& binding : bindings)
+        new (cursor++) BindingName(binding);
+    return cursor;
+}
+
 template <>
 Maybe<GlobalScope::Data*>
 Parser<FullParseHandler>::newGlobalScopeData(ParseContext::Scope& scope)
@@ -1505,22 +1517,20 @@ Parser<FullParseHandler>::newGlobalScopeData(ParseContext::Scope& scope)
             return Nothing();
 
         // The ordering here is important. See comments in GlobalScope.
-        BindingName* start = bindings->names;
+        BindingName* start = bindings->trailingNames.start();
         BindingName* cursor = start;
 
-        PodCopy(cursor, funs.begin(), funs.length());
-        cursor += funs.length();
+        cursor = FreshlyInitializeBindings(cursor, funs);
 
         bindings->varStart = cursor - start;
-        PodCopy(cursor, vars.begin(), vars.length());
-        cursor += vars.length();
+        cursor = FreshlyInitializeBindings(cursor, vars);
 
         bindings->letStart = cursor - start;
-        PodCopy(cursor, lets.begin(), lets.length());
-        cursor += lets.length();
+        cursor = FreshlyInitializeBindings(cursor, lets);
 
         bindings->constStart = cursor - start;
-        PodCopy(cursor, consts.begin(), consts.length());
+        cursor = FreshlyInitializeBindings(cursor, consts);
+
         bindings->length = numBindings;
     }
 
@@ -1572,22 +1582,20 @@ Parser<FullParseHandler>::newModuleScopeData(ParseContext::Scope& scope)
             return Nothing();
 
         // The ordering here is important. See comments in ModuleScope.
-        BindingName* start = bindings->names;
+        BindingName* start = bindings->trailingNames.start();
         BindingName* cursor = start;
 
-        PodCopy(cursor, imports.begin(), imports.length());
-        cursor += imports.length();
+        cursor = FreshlyInitializeBindings(cursor, imports);
 
         bindings->varStart = cursor - start;
-        PodCopy(cursor, vars.begin(), vars.length());
-        cursor += vars.length();
+        cursor = FreshlyInitializeBindings(cursor, vars);
 
         bindings->letStart = cursor - start;
-        PodCopy(cursor, lets.begin(), lets.length());
-        cursor += lets.length();
+        cursor = FreshlyInitializeBindings(cursor, lets);
 
         bindings->constStart = cursor - start;
-        PodCopy(cursor, consts.begin(), consts.length());
+        cursor = FreshlyInitializeBindings(cursor, consts);
+
         bindings->length = numBindings;
     }
 
@@ -1623,16 +1631,16 @@ Parser<FullParseHandler>::newEvalScopeData(ParseContext::Scope& scope)
         if (!bindings)
             return Nothing();
 
-        BindingName* start = bindings->names;
+        BindingName* start = bindings->trailingNames.start();
         BindingName* cursor = start;
 
         // Keep track of what vars are functions. This is only used in BCE to omit
         // superfluous DEFVARs.
-        PodCopy(cursor, funs.begin(), funs.length());
-        cursor += funs.length();
+        cursor = FreshlyInitializeBindings(cursor, funs);
 
         bindings->varStart = cursor - start;
-        PodCopy(cursor, vars.begin(), vars.length());
+        cursor = FreshlyInitializeBindings(cursor, vars);
+
         bindings->length = numBindings;
     }
 
@@ -1719,18 +1727,17 @@ Parser<FullParseHandler>::newFunctionScopeData(ParseContext::Scope& scope, bool
             return Nothing();
 
         // The ordering here is important. See comments in FunctionScope.
-        BindingName* start = bindings->names;
+        BindingName* start = bindings->trailingNames.start();
         BindingName* cursor = start;
 
-        PodCopy(cursor, positionalFormals.begin(), positionalFormals.length());
-        cursor += positionalFormals.length();
+        cursor = FreshlyInitializeBindings(cursor, positionalFormals);
 
         bindings->nonPositionalFormalStart = cursor - start;
-        PodCopy(cursor, formals.begin(), formals.length());
-        cursor += formals.length();
+        cursor = FreshlyInitializeBindings(cursor, formals);
 
         bindings->varStart = cursor - start;
-        PodCopy(cursor, vars.begin(), vars.length());
+        cursor = FreshlyInitializeBindings(cursor, vars);
+
         bindings->length = numBindings;
     }
 
@@ -1760,10 +1767,11 @@ Parser<FullParseHandler>::newVarScopeData(ParseContext::Scope& scope)
             return Nothing();
 
         // The ordering here is important. See comments in FunctionScope.
-        BindingName* start = bindings->names;
+        BindingName* start = bindings->trailingNames.start();
         BindingName* cursor = start;
 
-        PodCopy(cursor, vars.begin(), vars.length());
+        cursor = FreshlyInitializeBindings(cursor, vars);
+
         bindings->length = numBindings;
     }
 
@@ -1808,14 +1816,14 @@ Parser<FullParseHandler>::newLexicalScopeData(ParseContext::Scope& scope)
             return Nothing();
 
         // The ordering here is important. See comments in LexicalScope.
-        BindingName* cursor = bindings->names;
+        BindingName* cursor = bindings->trailingNames.start();
         BindingName* start = cursor;
 
-        PodCopy(cursor, lets.begin(), lets.length());
-        cursor += lets.length();
+        cursor = FreshlyInitializeBindings(cursor, lets);
 
         bindings->constStart = cursor - start;
-        PodCopy(cursor, consts.begin(), consts.length());
+        cursor = FreshlyInitializeBindings(cursor, consts);
+
         bindings->length = numBindings;
     }
 
diff --git a/js/src/gc/GCInternals.h b/js/src/gc/GCInternals.h
index 4919b87a5..e8df0bb70 100644
--- a/js/src/gc/GCInternals.h
+++ b/js/src/gc/GCInternals.h
@@ -9,7 +9,6 @@
 
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/Maybe.h"
-#include "mozilla/PodOperations.h"
 
 #include "jscntxt.h"
 
@@ -102,9 +101,9 @@ struct TenureCountCache
     static const size_t EntryShift = 4;
     static const size_t EntryCount = 1 << EntryShift;
 
-    TenureCount entries[EntryCount];
+    TenureCount entries[EntryCount] = {}; // zeroes
 
-    TenureCountCache() { mozilla::PodZero(this); }
+    TenureCountCache() = default;
 
     HashNumber hash(ObjectGroup* group) {
 #if JS_BITS_PER_WORD == 32
diff --git a/js/src/gc/Marking.cpp b/js/src/gc/Marking.cpp
index b2c105999..3ea4c9d29 100644
--- a/js/src/gc/Marking.cpp
+++ b/js/src/gc/Marking.cpp
@@ -1231,34 +1231,34 @@ BindingIter::trace(JSTracer* trc)
 void
 LexicalScope::Data::trace(JSTracer* trc)
 {
-    TraceBindingNames(trc, names, length);
+    TraceBindingNames(trc, trailingNames.start(), length);
 }
 void
 FunctionScope::Data::trace(JSTracer* trc)
 {
     TraceNullableEdge(trc, &canonicalFunction, "scope canonical function");
-    TraceNullableBindingNames(trc, names, length);
+    TraceNullableBindingNames(trc, trailingNames.start(), length);
 }
 void
 VarScope::Data::trace(JSTracer* trc)
 {
-    TraceBindingNames(trc, names, length);
+    TraceBindingNames(trc, trailingNames.start(), length);
 }
 void
 GlobalScope::Data::trace(JSTracer* trc)
 {
-    TraceBindingNames(trc, names, length);
+    TraceBindingNames(trc, trailingNames.start(), length);
 }
 void
 EvalScope::Data::trace(JSTracer* trc)
 {
-    TraceBindingNames(trc, names, length);
+    TraceBindingNames(trc, trailingNames.start(), length);
 }
 void
 ModuleScope::Data::trace(JSTracer* trc)
 {
     TraceNullableEdge(trc, &module, "scope module");
-    TraceBindingNames(trc, names, length);
+    TraceBindingNames(trc, trailingNames.start(), length);
 }
 void
 Scope::traceChildren(JSTracer* trc)
@@ -1302,13 +1302,13 @@ js::GCMarker::eagerlyMarkChildren(Scope* scope)
         traverseEdge(scope, static_cast<Scope*>(scope->enclosing_));
     if (scope->environmentShape_)
         traverseEdge(scope, static_cast<Shape*>(scope->environmentShape_));
-    BindingName* names = nullptr;
+    TrailingNamesArray* names = nullptr;
     uint32_t length = 0;
     switch (scope->kind_) {
       case ScopeKind::Function: {
         FunctionScope::Data* data = reinterpret_cast<FunctionScope::Data*>(scope->data_);
         traverseEdge(scope, static_cast<JSObject*>(data->canonicalFunction));
-        names = data->names;
+        names = &data->trailingNames;
         length = data->length;
         break;
       }
@@ -1316,7 +1316,7 @@ js::GCMarker::eagerlyMarkChildren(Scope* scope)
       case ScopeKind::FunctionBodyVar:
       case ScopeKind::ParameterExpressionVar: {
         VarScope::Data* data = reinterpret_cast<VarScope::Data*>(scope->data_);
-        names = data->names;
+        names = &data->trailingNames;
         length = data->length;
         break;
       }
@@ -1327,7 +1327,7 @@ js::GCMarker::eagerlyMarkChildren(Scope* scope)
       case ScopeKind::NamedLambda:
       case ScopeKind::StrictNamedLambda: {
         LexicalScope::Data* data = reinterpret_cast<LexicalScope::Data*>(scope->data_);
-        names = data->names;
+        names = &data->trailingNames;
         length = data->length;
         break;
       }
@@ -1335,7 +1335,7 @@ js::GCMarker::eagerlyMarkChildren(Scope* scope)
       case ScopeKind::Global:
       case ScopeKind::NonSyntactic: {
         GlobalScope::Data* data = reinterpret_cast<GlobalScope::Data*>(scope->data_);
-        names = data->names;
+        names = &data->trailingNames;
         length = data->length;
         break;
       }
@@ -1343,7 +1343,7 @@ js::GCMarker::eagerlyMarkChildren(Scope* scope)
       case ScopeKind::Eval:
       case ScopeKind::StrictEval: {
         EvalScope::Data* data = reinterpret_cast<EvalScope::Data*>(scope->data_);
-        names = data->names;
+        names = &data->trailingNames;
         length = data->length;
         break;
       }
@@ -1351,7 +1351,7 @@ js::GCMarker::eagerlyMarkChildren(Scope* scope)
       case ScopeKind::Module: {
         ModuleScope::Data* data = reinterpret_cast<ModuleScope::Data*>(scope->data_);
         traverseEdge(scope, static_cast<JSObject*>(data->module));
-        names = data->names;
+        names = &data->trailingNames;
         length = data->length;
         break;
       }
@@ -1361,12 +1361,12 @@ js::GCMarker::eagerlyMarkChildren(Scope* scope)
     }
     if (scope->kind_ == ScopeKind::Function) {
         for (uint32_t i = 0; i < length; i++) {
-            if (JSAtom* name = names[i].name())
+            if (JSAtom* name = names->operator[](i).name())
                 traverseEdge(scope, static_cast<JSString*>(name));
         }
     } else {
         for (uint32_t i = 0; i < length; i++)
-            traverseEdge(scope, static_cast<JSString*>(names[i].name()));
+            traverseEdge(scope, static_cast<JSString*>(names->operator[](i).name()));
     }
 }
 
diff --git a/js/src/gc/Statistics.h b/js/src/gc/Statistics.h
index ca1969b2c..08a2810cf 100644
--- a/js/src/gc/Statistics.h
+++ b/js/src/gc/Statistics.h
@@ -10,7 +10,6 @@
 #include "mozilla/EnumeratedArray.h"
 #include "mozilla/IntegerRange.h"
 #include "mozilla/Maybe.h"
-#include "mozilla/PodOperations.h"
 
 #include "jsalloc.h"
 #include "jsgc.h"
@@ -112,29 +111,26 @@ enum Stat {
 struct ZoneGCStats
 {
     /* Number of zones collected in this GC. */
-    int collectedZoneCount;
+    int collectedZoneCount = 0;
 
     /* Total number of zones in the Runtime at the start of this GC. */
-    int zoneCount;
+    int zoneCount = 0;
 
     /* Number of zones swept in this GC. */
-    int sweptZoneCount;
+    int sweptZoneCount = 0;
 
     /* Total number of compartments in all zones collected. */
-    int collectedCompartmentCount;
+    int collectedCompartmentCount = 0;
 
     /* Total number of compartments in the Runtime at the start of this GC. */
-    int compartmentCount;
+    int compartmentCount = 0;
 
     /* Total number of compartments swept by this GC. */
-    int sweptCompartmentCount;
+    int sweptCompartmentCount = 0;
 
     bool isCollectingAllZones() const { return collectedZoneCount == zoneCount; }
 
-    ZoneGCStats()
-      : collectedZoneCount(0), zoneCount(0), sweptZoneCount(0),
-        collectedCompartmentCount(0), compartmentCount(0), sweptCompartmentCount(0)
-    {}
+    ZoneGCStats() = default;
 };
 
 #define FOR_EACH_GC_PROFILE_TIME(_)                                           \
diff --git a/js/src/jit/BacktrackingAllocator.cpp b/js/src/jit/BacktrackingAllocator.cpp
index 94ef25785..73aceeccb 100644
--- a/js/src/jit/BacktrackingAllocator.cpp
+++ b/js/src/jit/BacktrackingAllocator.cpp
@@ -378,7 +378,6 @@ BacktrackingAllocator::init()
     size_t numVregs = graph.numVirtualRegisters();
     if (!vregs.init(mir->alloc(), numVregs))
         return false;
-    memset(&vregs[0], 0, sizeof(VirtualRegister) * numVregs);
     for (uint32_t i = 0; i < numVregs; i++)
         new(&vregs[i]) VirtualRegister();
 
@@ -1101,9 +1100,9 @@ BacktrackingAllocator::mergeAndQueueRegisters()
             if (iter->isParameter()) {
                 for (size_t i = 0; i < iter->numDefs(); i++) {
                     DebugOnly<bool> found = false;
-                    VirtualRegister &paramVreg = vreg(iter->getDef(i));
+                    VirtualRegister& paramVreg = vreg(iter->getDef(i));
                     for (; original < paramVreg.vreg(); original++) {
-                        VirtualRegister &originalVreg = vregs[original];
+                        VirtualRegister& originalVreg = vregs[original];
                         if (*originalVreg.def()->output() == *iter->getDef(i)->output()) {
                             MOZ_ASSERT(originalVreg.ins()->isParameter());
                             if (!tryMergeBundles(originalVreg.firstBundle(), paramVreg.firstBundle()))
@@ -1136,7 +1135,7 @@ BacktrackingAllocator::mergeAndQueueRegisters()
         LBlock* block = graph.getBlock(i);
         for (size_t j = 0; j < block->numPhis(); j++) {
             LPhi* phi = block->getPhi(j);
-            VirtualRegister &outputVreg = vreg(phi->getDef(0));
+            VirtualRegister& outputVreg = vreg(phi->getDef(0));
             for (size_t k = 0, kend = phi->numOperands(); k < kend; k++) {
                 VirtualRegister& inputVreg = vreg(phi->getOperand(k)->toUse());
                 if (!tryMergeBundles(inputVreg.firstBundle(), outputVreg.firstBundle()))
@@ -1334,7 +1333,7 @@ BacktrackingAllocator::computeRequirement(LiveBundle* bundle,
 
     for (LiveRange::BundleLinkIterator iter = bundle->rangesBegin(); iter; iter++) {
         LiveRange* range = LiveRange::get(*iter);
-        VirtualRegister &reg = vregs[range->vreg()];
+        VirtualRegister& reg = vregs[range->vreg()];
 
         if (range->hasDefinition()) {
             // Deal with any definition constraints/hints.
@@ -1396,7 +1395,7 @@ BacktrackingAllocator::tryAllocateRegister(PhysicalRegister& r, LiveBundle* bund
 
     for (LiveRange::BundleLinkIterator iter = bundle->rangesBegin(); iter; iter++) {
         LiveRange* range = LiveRange::get(*iter);
-        VirtualRegister &reg = vregs[range->vreg()];
+        VirtualRegister& reg = vregs[range->vreg()];
 
         if (!reg.isCompatible(r.reg))
             return true;
diff --git a/js/src/jit/BacktrackingAllocator.h b/js/src/jit/BacktrackingAllocator.h
index 6d14ffacd..9910498fb 100644
--- a/js/src/jit/BacktrackingAllocator.h
+++ b/js/src/jit/BacktrackingAllocator.h
@@ -478,34 +478,31 @@ class LiveBundle : public TempObject
 class VirtualRegister
 {
     // Instruction which defines this register.
-    LNode* ins_;
+    LNode* ins_ = nullptr;
 
     // Definition in the instruction for this register.
-    LDefinition* def_;
+    LDefinition* def_ = nullptr;
 
     // All live ranges for this register. These may overlap each other, and are
     // ordered by their start position.
     InlineForwardList<LiveRange::RegisterLink> ranges_;
 
     // Whether def_ is a temp or an output.
-    bool isTemp_;
+    bool isTemp_ = false;
 
     // Whether this vreg is an input for some phi. This use is not reflected in
     // any range on the vreg.
-    bool usedByPhi_;
+    bool usedByPhi_ = false;
 
     // If this register's definition is MUST_REUSE_INPUT, whether a copy must
     // be introduced before the definition that relaxes the policy.
-    bool mustCopyInput_;
+    bool mustCopyInput_ = false;
 
     void operator=(const VirtualRegister&) = delete;
     VirtualRegister(const VirtualRegister&) = delete;
 
   public:
-    explicit VirtualRegister()
-    {
-        // Note: This class is zeroed before it is constructed.
-    }
+    VirtualRegister() = default;
 
     void init(LNode* ins, LDefinition* def, bool isTemp) {
         MOZ_ASSERT(!ins_);
diff --git a/js/src/jit/IonCode.h b/js/src/jit/IonCode.h
index c581aa62e..55c3d4dad 100644
--- a/js/src/jit/IonCode.h
+++ b/js/src/jit/IonCode.h
@@ -9,7 +9,6 @@
 
 #include "mozilla/Atomics.h"
 #include "mozilla/MemoryReporting.h"
-#include "mozilla/PodOperations.h"
 
 #include "jstypes.h"
 
@@ -692,17 +691,15 @@ struct IonScriptCounts
 {
   private:
     // Any previous invalidated compilation(s) for the script.
-    IonScriptCounts* previous_;
+    IonScriptCounts* previous_ = nullptr;
 
     // Information about basic blocks in this script.
-    size_t numBlocks_;
-    IonBlockCounts* blocks_;
+    size_t numBlocks_ = 0;
+    IonBlockCounts* blocks_ = nullptr;
 
   public:
 
-    IonScriptCounts() {
-        mozilla::PodZero(this);
-    }
+    IonScriptCounts() = default;
 
     ~IonScriptCounts() {
         for (size_t i = 0; i < numBlocks_; i++)
diff --git a/js/src/jit/shared/Assembler-shared.h b/js/src/jit/shared/Assembler-shared.h
index aac9687b8..8044e75cb 100644
--- a/js/src/jit/shared/Assembler-shared.h
+++ b/js/src/jit/shared/Assembler-shared.h
@@ -7,8 +7,6 @@
 #ifndef jit_shared_Assembler_shared_h
 #define jit_shared_Assembler_shared_h
 
-#include "mozilla/PodOperations.h"
-
 #include <limits.h>
 
 #include "jit/AtomicOp.h"
@@ -491,10 +489,10 @@ class CodeLabel
 
 class CodeOffsetJump
 {
-    size_t offset_;
+    size_t offset_ = 0;
 
 #ifdef JS_SMALL_BRANCH
-    size_t jumpTableIndex_;
+    size_t jumpTableIndex_ = 0;
 #endif
 
   public:
@@ -510,9 +508,7 @@ class CodeOffsetJump
     explicit CodeOffsetJump(size_t offset) : offset_(offset) {}
 #endif
 
-    CodeOffsetJump() {
-        mozilla::PodZero(this);
-    }
+    CodeOffsetJump() = default;
 
     size_t offset() const {
         return offset_;
diff --git a/js/src/vm/ArrayBufferObject.h b/js/src/vm/ArrayBufferObject.h
index 6614f5220..e9c9bc0e0 100644
--- a/js/src/vm/ArrayBufferObject.h
+++ b/js/src/vm/ArrayBufferObject.h
@@ -457,8 +457,8 @@ ClampDoubleToUint8(const double x);
 struct uint8_clamped {
     uint8_t val;
 
-    uint8_clamped() { }
-    uint8_clamped(const uint8_clamped& other) : val(other.val) { }
+    uint8_clamped() = default;
+    uint8_clamped(const uint8_clamped& other) = default;
 
     // invoke our assignment helpers for constructor conversion
     explicit uint8_clamped(uint8_t x)    { *this = x; }
@@ -469,10 +469,7 @@ struct uint8_clamped {
     explicit uint8_clamped(int32_t x)    { *this = x; }
     explicit uint8_clamped(double x)     { *this = x; }
 
-    uint8_clamped& operator=(const uint8_clamped& x) {
-        val = x.val;
-        return *this;
-    }
+    uint8_clamped& operator=(const uint8_clamped& x) = default;
 
     uint8_clamped& operator=(uint8_t x) {
         val = x;
diff --git a/js/src/vm/Caches.h b/js/src/vm/Caches.h
index 91a78bdc8..b11dd9dcb 100644
--- a/js/src/vm/Caches.h
+++ b/js/src/vm/Caches.h
@@ -7,6 +7,8 @@
 #ifndef vm_Caches_h
 #define vm_Caches_h
 
+#include <new>
+
 #include "jsatom.h"
 #include "jsbytecode.h"
 #include "jsobj.h"
@@ -191,14 +193,20 @@ class NewObjectCache
         char templateObject[MAX_OBJ_SIZE];
     };
 
-    Entry entries[41];  // TODO: reconsider size
+    using EntryArray = Entry[41]; // TODO: reconsider size;
+    EntryArray entries;
 
   public:
 
-    typedef int EntryIndex;
+    using EntryIndex = int;
+
+    NewObjectCache()
+      : entries{} // zeroes out the array
+    {}
 
-    NewObjectCache() { mozilla::PodZero(this); }
-    void purge() { mozilla::PodZero(this); }
+    void purge() {
+        new (&entries) EntryArray{}; // zeroes out the array
+    }
 
     /* Remove any cached items keyed on moved objects. */
     void clearNurseryObjects(JSRuntime* rt);
diff --git a/js/src/vm/Runtime.h b/js/src/vm/Runtime.h
index 735adadf2..f354d2069 100644
--- a/js/src/vm/Runtime.h
+++ b/js/src/vm/Runtime.h
@@ -11,11 +11,11 @@
 #include "mozilla/Attributes.h"
 #include "mozilla/LinkedList.h"
 #include "mozilla/MemoryReporting.h"
-#include "mozilla/PodOperations.h"
 #include "mozilla/Scoped.h"
 #include "mozilla/ThreadLocal.h"
 #include "mozilla/Vector.h"
 
+#include <algorithm>
 #include <setjmp.h>
 
 #include "jsatom.h"
@@ -1504,20 +1504,21 @@ PerThreadData::exclusiveThreadsPresent()
 static MOZ_ALWAYS_INLINE void
 MakeRangeGCSafe(Value* vec, size_t len)
 {
-    mozilla::PodZero(vec, len);
+    // Don't PodZero here because JS::Value is non-trivial.
+    for (size_t i = 0; i < len; i++)
+        vec[i].setDouble(+0.0);
 }
 
 static MOZ_ALWAYS_INLINE void
 MakeRangeGCSafe(Value* beg, Value* end)
 {
-    mozilla::PodZero(beg, end - beg);
+    MakeRangeGCSafe(beg, end - beg);
 }
 
 static MOZ_ALWAYS_INLINE void
 MakeRangeGCSafe(jsid* beg, jsid* end)
 {
-    for (jsid* id = beg; id != end; ++id)
-        *id = INT_TO_JSID(0);
+    std::fill(beg, end, INT_TO_JSID(0));
 }
 
 static MOZ_ALWAYS_INLINE void
@@ -1529,13 +1530,13 @@ MakeRangeGCSafe(jsid* vec, size_t len)
 static MOZ_ALWAYS_INLINE void
 MakeRangeGCSafe(Shape** beg, Shape** end)
 {
-    mozilla::PodZero(beg, end - beg);
+    std::fill(beg, end, nullptr);
 }
 
 static MOZ_ALWAYS_INLINE void
 MakeRangeGCSafe(Shape** vec, size_t len)
 {
-    mozilla::PodZero(vec, len);
+    MakeRangeGCSafe(vec, vec + len);
 }
 
 static MOZ_ALWAYS_INLINE void
diff --git a/js/src/vm/Scope.cpp b/js/src/vm/Scope.cpp
index 112b34586..a71c03695 100644
--- a/js/src/vm/Scope.cpp
+++ b/js/src/vm/Scope.cpp
@@ -191,12 +191,12 @@ template <typename ConcreteScope>
 static UniquePtr<typename ConcreteScope::Data>
 NewEmptyScopeData(ExclusiveContext* cx, uint32_t length = 0)
 {
-    uint8_t* bytes = cx->zone()->pod_calloc<uint8_t>(ConcreteScope::sizeOfData(length));
+    uint8_t* bytes = cx->zone()->pod_malloc<uint8_t>(ConcreteScope::sizeOfData(length));
     if (!bytes)
         ReportOutOfMemory(cx);
     auto data = reinterpret_cast<typename ConcreteScope::Data*>(bytes);
     if (data)
-        new (data) typename ConcreteScope::Data();
+        new (data) typename ConcreteScope::Data(length);
     return UniquePtr<typename ConcreteScope::Data>(data);
 }
 
@@ -273,7 +273,7 @@ Scope::XDRSizedBindingNames(XDRState<mode>* xdr, Handle<ConcreteScope*> scope,
     }
 
     for (uint32_t i = 0; i < length; i++) {
-        if (!XDRBindingName(xdr, &data->names[i])) {
+        if (!XDRBindingName(xdr, &data->trailingNames[i])) {
             if (mode == XDR_DECODE) {
                 DeleteScopeData(data.get());
                 data.set(nullptr);
@@ -1250,7 +1250,7 @@ BindingIter::init(LexicalScope::Data& data, uint32_t firstFrameSlot, uint8_t fla
         init(0, 0, 0, 0, 0, 0,
              CanHaveEnvironmentSlots | flags,
              firstFrameSlot, JSSLOT_FREE(&LexicalEnvironmentObject::class_),
-             data.names, data.length);
+             data.trailingNames.start(), data.length);
     } else {
         //            imports - [0, 0)
         // positional formals - [0, 0)
@@ -1262,7 +1262,7 @@ BindingIter::init(LexicalScope::Data& data, uint32_t firstFrameSlot, uint8_t fla
         init(0, 0, 0, 0, 0, data.constStart,
              CanHaveFrameSlots | CanHaveEnvironmentSlots | flags,
              firstFrameSlot, JSSLOT_FREE(&LexicalEnvironmentObject::class_),
-             data.names, data.length);
+             data.trailingNames.start(), data.length);
     }
 }
 
@@ -1283,7 +1283,7 @@ BindingIter::init(FunctionScope::Data& data, uint8_t flags)
     init(0, data.nonPositionalFormalStart, data.varStart, data.varStart, data.length, data.length,
          flags,
          0, JSSLOT_FREE(&CallObject::class_),
-         data.names, data.length);
+         data.trailingNames.start(), data.length);
 }
 
 void
@@ -1299,7 +1299,7 @@ BindingIter::init(VarScope::Data& data, uint32_t firstFrameSlot)
     init(0, 0, 0, 0, data.length, data.length,
          CanHaveFrameSlots | CanHaveEnvironmentSlots,
          firstFrameSlot, JSSLOT_FREE(&VarEnvironmentObject::class_),
-         data.names, data.length);
+         data.trailingNames.start(), data.length);
 }
 
 void
@@ -1315,7 +1315,7 @@ BindingIter::init(GlobalScope::Data& data)
     init(0, 0, 0, data.varStart, data.letStart, data.constStart,
          CannotHaveSlots,
          UINT32_MAX, UINT32_MAX,
-         data.names, data.length);
+         data.trailingNames.start(), data.length);
 }
 
 void
@@ -1343,7 +1343,7 @@ BindingIter::init(EvalScope::Data& data, bool strict)
     //             consts - [data.length, data.length)
     init(0, 0, 0, data.varStart, data.length, data.length,
          flags, firstFrameSlot, firstEnvironmentSlot,
-         data.names, data.length);
+         data.trailingNames.start(), data.length);
 }
 
 void
@@ -1359,7 +1359,7 @@ BindingIter::init(ModuleScope::Data& data)
     init(data.varStart, data.varStart, data.varStart, data.varStart, data.letStart, data.constStart,
          CanHaveFrameSlots | CanHaveEnvironmentSlots,
          0, JSSLOT_FREE(&ModuleEnvironmentObject::class_),
-         data.names, data.length);
+         data.trailingNames.start(), data.length);
 }
 
 PositionalFormalParameterIter::PositionalFormalParameterIter(JSScript* script)
diff --git a/js/src/vm/Scope.h b/js/src/vm/Scope.h
index 5304d6713..1d04fd9f6 100644
--- a/js/src/vm/Scope.h
+++ b/js/src/vm/Scope.h
@@ -12,6 +12,7 @@
 
 #include "jsobj.h"
 #include "jsopcode.h"
+#include "jsutil.h"
 
 #include "gc/Heap.h"
 #include "gc/Policy.h"
@@ -111,6 +112,47 @@ class BindingName
     void trace(JSTracer* trc);
 };
 
+/**
+ * The various {Global,Module,...}Scope::Data classes consist of always-present
+ * bits, then a trailing array of BindingNames.  The various Data classes all
+ * end in a TrailingNamesArray that contains sized/aligned space for *one*
+ * BindingName.  Data instances that contain N BindingNames, are then allocated
+ * in sizeof(Data) + (space for (N - 1) BindingNames).  Because this class's
+ * |data_| field is properly sized/aligned, the N-BindingName array can start
+ * at |data_|.
+ *
+ * This is concededly a very low-level representation, but we want to only
+ * allocate once for data+bindings both, and this does so approximately as
+ * elegantly as C++ allows.
+ */
+class TrailingNamesArray
+{
+  private:
+    alignas(BindingName) unsigned char data_[sizeof(BindingName)];
+
+  private:
+    // Some versions of GCC treat it as a -Wstrict-aliasing violation (ergo a
+    // -Werror compile error) to reinterpret_cast<> |data_| to |T*|, even
+    // through |void*|.  Placing the latter cast in these separate functions
+    // breaks the chain such that affected GCC versions no longer warn/error.
+    void* ptr() {
+        return data_;
+    }
+
+  public:
+    // Explicitly ensure no one accidentally allocates scope data without
+    // poisoning its trailing names.
+    TrailingNamesArray() = delete;
+
+    explicit TrailingNamesArray(size_t nameCount) {
+        if (nameCount)
+            JS_POISON(&data_, 0xCC, sizeof(BindingName) * nameCount);
+    }
+    BindingName* start() { return reinterpret_cast<BindingName*>(ptr()); }
+
+    BindingName& operator[](size_t i) { return start()[i]; }
+};
+
 class BindingLocation
 {
   public:
@@ -337,16 +379,19 @@ class LexicalScope : public Scope
         //
         //   lets - [0, constStart)
         // consts - [constStart, length)
-        uint32_t constStart;
-        uint32_t length;
+        uint32_t constStart = 0;
+        uint32_t length = 0;
 
         // Frame slots [0, nextFrameSlot) are live when this is the innermost
         // scope.
-        uint32_t nextFrameSlot;
+        uint32_t nextFrameSlot = 0;
 
         // The array of tagged JSAtom* names, allocated beyond the end of the
         // struct.
-        BindingName names[1];
+        TrailingNamesArray trailingNames;
+
+        explicit Data(size_t nameCount) : trailingNames(nameCount) {}
+        Data() = delete;
 
         void trace(JSTracer* trc);
     };
@@ -433,11 +478,11 @@ class FunctionScope : public Scope
         // The canonical function of the scope, as during a scope walk we
         // often query properties of the JSFunction (e.g., is the function an
         // arrow).
-        GCPtrFunction canonicalFunction;
+        GCPtrFunction canonicalFunction = {};
 
         // If parameter expressions are present, parameters act like lexical
         // bindings.
-        bool hasParameterExprs;
+        bool hasParameterExprs = false;
 
         // Bindings are sorted by kind in both frames and environments.
         //
@@ -452,17 +497,20 @@ class FunctionScope : public Scope
         // positional formals - [0, nonPositionalFormalStart)
         //      other formals - [nonPositionalParamStart, varStart)
         //               vars - [varStart, length)
-        uint16_t nonPositionalFormalStart;
-        uint16_t varStart;
-        uint32_t length;
+        uint16_t nonPositionalFormalStart = 0;
+        uint16_t varStart = 0;
+        uint32_t length = 0;
 
         // Frame slots [0, nextFrameSlot) are live when this is the innermost
         // scope.
-        uint32_t nextFrameSlot;
+        uint32_t nextFrameSlot = 0;
 
         // The array of tagged JSAtom* names, allocated beyond the end of the
         // struct.
-        BindingName names[1];
+        TrailingNamesArray trailingNames;
+
+        explicit Data(size_t nameCount) : trailingNames(nameCount) {}
+        Data() = delete;
 
         void trace(JSTracer* trc);
     };
@@ -548,15 +596,18 @@ class VarScope : public Scope
     struct Data
     {
         // All bindings are vars.
-        uint32_t length;
+        uint32_t length = 0;
 
         // Frame slots [firstFrameSlot(), nextFrameSlot) are live when this is
         // the innermost scope.
-        uint32_t nextFrameSlot;
+        uint32_t nextFrameSlot = 0;
 
         // The array of tagged JSAtom* names, allocated beyond the end of the
         // struct.
-        BindingName names[1];
+        TrailingNamesArray trailingNames;
+
+        explicit Data(size_t nameCount) : trailingNames(nameCount) {}
+        Data() = delete;
 
         void trace(JSTracer* trc);
     };
@@ -638,14 +689,17 @@ class GlobalScope : public Scope
         //            vars - [varStart, letStart)
         //            lets - [letStart, constStart)
         //          consts - [constStart, length)
-        uint32_t varStart;
-        uint32_t letStart;
-        uint32_t constStart;
-        uint32_t length;
+        uint32_t varStart = 0;
+        uint32_t letStart = 0;
+        uint32_t constStart = 0;
+        uint32_t length = 0;
 
         // The array of tagged JSAtom* names, allocated beyond the end of the
         // struct.
-        BindingName names[1];
+        TrailingNamesArray trailingNames;
+
+        explicit Data(size_t nameCount) : trailingNames(nameCount) {}
+        Data() = delete;
 
         void trace(JSTracer* trc);
     };
@@ -736,16 +790,19 @@ class EvalScope : public Scope
         //
         // top-level funcs - [0, varStart)
         //            vars - [varStart, length)
-        uint32_t varStart;
-        uint32_t length;
+        uint32_t varStart = 0;
+        uint32_t length = 0;
 
         // Frame slots [0, nextFrameSlot) are live when this is the innermost
         // scope.
-        uint32_t nextFrameSlot;
+        uint32_t nextFrameSlot = 0;
 
         // The array of tagged JSAtom* names, allocated beyond the end of the
         // struct.
-        BindingName names[1];
+        TrailingNamesArray trailingNames;
+
+        explicit Data(size_t nameCount) : trailingNames(nameCount) {}
+        Data() = delete;
 
         void trace(JSTracer* trc);
     };
@@ -827,7 +884,7 @@ class ModuleScope : public Scope
     struct Data
     {
         // The module of the scope.
-        GCPtr<ModuleObject*> module;
+        GCPtr<ModuleObject*> module = {};
 
         // Bindings are sorted by kind.
         //
@@ -835,18 +892,21 @@ class ModuleScope : public Scope
         //    vars - [varStart, letStart)
         //    lets - [letStart, constStart)
         //  consts - [constStart, length)
-        uint32_t varStart;
-        uint32_t letStart;
-        uint32_t constStart;
-        uint32_t length;
+        uint32_t varStart = 0;
+        uint32_t letStart = 0;
+        uint32_t constStart = 0;
+        uint32_t length = 0;
 
         // Frame slots [0, nextFrameSlot) are live when this is the innermost
         // scope.
-        uint32_t nextFrameSlot;
+        uint32_t nextFrameSlot = 0;
 
         // The array of tagged JSAtom* names, allocated beyond the end of the
         // struct.
-        BindingName names[1];
+        TrailingNamesArray trailingNames;
+
+        explicit Data(size_t nameCount) : trailingNames(nameCount) {}
+        Data() = delete;
 
         void trace(JSTracer* trc);
     };
diff --git a/js/src/vm/String.h b/js/src/vm/String.h
index 1a0c58575..514e2c205 100644
--- a/js/src/vm/String.h
+++ b/js/src/vm/String.h
@@ -8,7 +8,6 @@
 #define vm_String_h
 
 #include "mozilla/MemoryReporting.h"
-#include "mozilla/PodOperations.h"
 #include "mozilla/Range.h"
 
 #include "jsapi.h"
@@ -1087,19 +1086,17 @@ class StaticStrings
     static const size_t SMALL_CHAR_LIMIT    = 128U;
     static const size_t NUM_SMALL_CHARS     = 64U;
 
-    JSAtom* length2StaticTable[NUM_SMALL_CHARS * NUM_SMALL_CHARS];
+    JSAtom* length2StaticTable[NUM_SMALL_CHARS * NUM_SMALL_CHARS] = {}; // zeroes
 
   public:
     /* We keep these public for the JITs. */
     static const size_t UNIT_STATIC_LIMIT   = 256U;
-    JSAtom* unitStaticTable[UNIT_STATIC_LIMIT];
+    JSAtom* unitStaticTable[UNIT_STATIC_LIMIT] = {}; // zeroes
 
     static const size_t INT_STATIC_LIMIT    = 256U;
-    JSAtom* intStaticTable[INT_STATIC_LIMIT];
+    JSAtom* intStaticTable[INT_STATIC_LIMIT] = {}; // zeroes
 
-    StaticStrings() {
-        mozilla::PodZero(this);
-    }
+    StaticStrings() = default;
 
     bool init(JSContext* cx);
     void trace(JSTracer* trc);
diff --git a/js/src/vm/TypeInference.cpp b/js/src/vm/TypeInference.cpp
index 3d09c7464..c86345d9c 100644
--- a/js/src/vm/TypeInference.cpp
+++ b/js/src/vm/TypeInference.cpp
@@ -12,6 +12,8 @@
 #include "mozilla/SizePrintfMacros.h"
 #include "mozilla/Sprintf.h"
 
+#include <new>
+
 #include "jsapi.h"
 #include "jscntxt.h"
 #include "jsgc.h"
@@ -859,10 +861,8 @@ TypeSet::IsTypeAboutToBeFinalized(TypeSet::Type* v)
 }
 
 bool
-TypeSet::clone(LifoAlloc* alloc, TemporaryTypeSet* result) const
+TypeSet::cloneIntoUninitialized(LifoAlloc* alloc, TemporaryTypeSet* result) const
 {
-    MOZ_ASSERT(result->empty());
-
     unsigned objectCount = baseObjectCount();
     unsigned capacity = (objectCount >= 2) ? TypeHashSet::Capacity(objectCount) : 0;
 
@@ -874,15 +874,15 @@ TypeSet::clone(LifoAlloc* alloc, TemporaryTypeSet* result) const
         PodCopy(newSet, objectSet, capacity);
     }
 
-    new(result) TemporaryTypeSet(flags, capacity ? newSet : objectSet);
+    new (result) TemporaryTypeSet(flags, capacity ? newSet : objectSet);
     return true;
 }
 
 TemporaryTypeSet*
 TypeSet::clone(LifoAlloc* alloc) const
 {
-    TemporaryTypeSet* res = alloc->new_<TemporaryTypeSet>();
-    if (!res || !clone(alloc, res))
+    TemporaryTypeSet* res = alloc->pod_malloc<TemporaryTypeSet>();
+    if (!res || !cloneIntoUninitialized(alloc, res))
         return nullptr;
     return res;
 }
@@ -1150,10 +1150,9 @@ TypeScript::FreezeTypeSets(CompilerConstraintList* constraints, JSScript* script
     TemporaryTypeSet* types = alloc->newArrayUninitialized<TemporaryTypeSet>(count);
     if (!types)
         return false;
-    PodZero(types, count);
 
     for (size_t i = 0; i < count; i++) {
-        if (!existing[i].clone(alloc, &types[i]))
+        if (!existing[i].cloneIntoUninitialized(alloc, &types[i]))
             return false;
     }
 
diff --git a/js/src/vm/TypeInference.h b/js/src/vm/TypeInference.h
index 9ba1c3cc8..0f1cd4936 100644
--- a/js/src/vm/TypeInference.h
+++ b/js/src/vm/TypeInference.h
@@ -498,7 +498,10 @@ class TypeSet
 
     // Clone a type set into an arbitrary allocator.
     TemporaryTypeSet* clone(LifoAlloc* alloc) const;
-    bool clone(LifoAlloc* alloc, TemporaryTypeSet* result) const;
+
+    // |*result| is not even partly initialized when this function is called:
+    // this function placement-new's its contents into existence.
+    bool cloneIntoUninitialized(LifoAlloc* alloc, TemporaryTypeSet* result) const;
 
     // Create a new TemporaryTypeSet where undefined and/or null has been filtered out.
     TemporaryTypeSet* filter(LifoAlloc* alloc, bool filterUndefined, bool filterNull) const;
@@ -807,12 +810,10 @@ class PreliminaryObjectArray
   private:
     // All objects with the type which have been allocated. The pointers in
     // this array are weak.
-    JSObject* objects[COUNT];
+    JSObject* objects[COUNT] = {}; // zeroes
 
   public:
-    PreliminaryObjectArray() {
-        mozilla::PodZero(this);
-    }
+    PreliminaryObjectArray() = default;
 
     void registerNewObject(JSObject* res);
     void unregisterObject(JSObject* obj);
@@ -906,11 +907,11 @@ class TypeNewScript
 
   private:
     // Scripted function which this information was computed for.
-    HeapPtr<JSFunction*> function_;
+    HeapPtr<JSFunction*> function_ = {};
 
     // Any preliminary objects with the type. The analyses are not performed
     // until this array is cleared.
-    PreliminaryObjectArray* preliminaryObjects;
+    PreliminaryObjectArray* preliminaryObjects = nullptr;
 
     // After the new script properties analyses have been performed, a template
     // object to use for newly constructed objects. The shape of this object
@@ -918,7 +919,7 @@ class TypeNewScript
     // allocation kind to use. This is null if the new objects have an unboxed
     // layout, in which case the UnboxedLayout provides the initial structure
     // of the object.
-    HeapPtr<PlainObject*> templateObject_;
+    HeapPtr<PlainObject*> templateObject_ = {};
 
     // Order in which definite properties become initialized. We need this in
     // case the definite properties are invalidated (such as by adding a setter
@@ -928,21 +929,21 @@ class TypeNewScript
     // shape. Property assignments in inner frames are preceded by a series of
     // SETPROP_FRAME entries specifying the stack down to the frame containing
     // the write.
-    Initializer* initializerList;
+    Initializer* initializerList = nullptr;
 
     // If there are additional properties found by the acquired properties
     // analysis which were not found by the definite properties analysis, this
     // shape contains all such additional properties (plus the definite
     // properties). When an object of this group acquires this shape, it is
     // fully initialized and its group can be changed to initializedGroup.
-    HeapPtr<Shape*> initializedShape_;
+    HeapPtr<Shape*> initializedShape_ = {};
 
     // Group with definite properties set for all properties found by
     // both the definite and acquired properties analyses.
-    HeapPtr<ObjectGroup*> initializedGroup_;
+    HeapPtr<ObjectGroup*> initializedGroup_ = {};
 
   public:
-    TypeNewScript() { mozilla::PodZero(this); }
+    TypeNewScript() = default;
     ~TypeNewScript() {
         js_delete(preliminaryObjects);
         js_free(initializerList);
diff --git a/js/src/vm/TypedArrayCommon.h b/js/src/vm/TypedArrayCommon.h
index d29c93a65..f59419b28 100644
--- a/js/src/vm/TypedArrayCommon.h
+++ b/js/src/vm/TypedArrayCommon.h
@@ -11,7 +11,8 @@
 
 #include "mozilla/Assertions.h"
 #include "mozilla/FloatingPoint.h"
-#include "mozilla/PodOperations.h"
+
+#include <algorithm>
 
 #include "jsarray.h"
 #include "jscntxt.h"
@@ -245,12 +246,24 @@ class UnsharedOps
 
     template<typename T>
     static void podCopy(SharedMem<T*> dest, SharedMem<T*> src, size_t nelem) {
-        mozilla::PodCopy(dest.unwrapUnshared(), src.unwrapUnshared(), nelem);
+        // std::copy_n better matches the argument values/types of this
+        // function, but as noted below it allows the input/output ranges to
+        // overlap.  std::copy does not, so use it so the compiler has extra
+        // ability to optimize.
+        const auto* first = src.unwrapUnshared();
+        const auto* last = first + nelem;
+        auto* result = dest.unwrapUnshared();
+        std::copy(first, last, result);
     }
 
     template<typename T>
-    static void podMove(SharedMem<T*> dest, SharedMem<T*> src, size_t nelem) {
-        mozilla::PodMove(dest.unwrapUnshared(), src.unwrapUnshared(), nelem);
+    static void podMove(SharedMem<T*> dest, SharedMem<T*> src, size_t n) {
+        // std::copy_n copies from |src| to |dest| starting from |src|, so
+        // input/output ranges *may* permissibly overlap, as this function
+        // allows.
+        const auto* start = src.unwrapUnshared();
+        auto* result = dest.unwrapUnshared();
+        std::copy_n(start, n, result);
     }
 
     static SharedMem<void*> extract(TypedArrayObject* obj) {
diff --git a/js/src/wasm/AsmJS.cpp b/js/src/wasm/AsmJS.cpp
index 7fade24fb..2237d1d7f 100644
--- a/js/src/wasm/AsmJS.cpp
+++ b/js/src/wasm/AsmJS.cpp
@@ -249,14 +249,14 @@ typedef Vector<AsmJSImport, 0, SystemAllocPolicy> AsmJSImportVector;
 // case the function is toString()ed.
 class AsmJSExport
 {
-    uint32_t funcIndex_;
+    uint32_t funcIndex_ = 0;
 
     // All fields are treated as cacheable POD:
-    uint32_t startOffsetInModule_;  // Store module-start-relative offsets
-    uint32_t endOffsetInModule_;    // so preserved by serialization.
+    uint32_t startOffsetInModule_ = 0;  // Store module-start-relative offsets
+    uint32_t endOffsetInModule_ = 0;    // so preserved by serialization.
 
   public:
-    AsmJSExport() { PodZero(this); }
+    AsmJSExport() = default;
     AsmJSExport(uint32_t funcIndex, uint32_t startOffsetInModule, uint32_t endOffsetInModule)
       : funcIndex_(funcIndex),
         startOffsetInModule_(startOffsetInModule),
@@ -288,12 +288,12 @@ enum class CacheResult
 
 struct AsmJSMetadataCacheablePod
 {
-    uint32_t                numFFIs;
-    uint32_t                srcLength;
-    uint32_t                srcLengthWithRightBrace;
-    bool                    usesSimd;
+    uint32_t                numFFIs = 0;
+    uint32_t                srcLength = 0;
+    uint32_t                srcLengthWithRightBrace = 0;
+    bool                    usesSimd = false;
 
-    AsmJSMetadataCacheablePod() { PodZero(this); }
+    AsmJSMetadataCacheablePod() = default;
 };
 
 struct js::AsmJSMetadata : Metadata, AsmJSMetadataCacheablePod