Add needsWriteBarriers for constructors and large objects

Differential Revision: D67556001
lavenzg · Dec 26, 2024 · d81ba7d · d81ba7d
1 parent 2d92eeb
commit d81ba7d
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diff --git a/include/hermes/VM/GCBase.h b/include/hermes/VM/GCBase.h
@@ -1084,6 +1084,18 @@ class GCBase {
       SmallHermesValue value) const = 0;
   virtual bool needsWriteBarrier(const GCPointerBase *loc, GCCell *value)
       const = 0;
+  virtual bool needsWriteBarrierInCtor(
+      const GCHermesValue *loc,
+      HermesValue value) const = 0;
+  virtual bool needsWriteBarrierInCtor(
+      const GCSmallHermesValue *loc,
+      SmallHermesValue value) const = 0;
+  virtual bool needsWriteBarrierForLargeObj(
+      const GCHermesValue *loc,
+      HermesValue value) const = 0;
+  virtual bool needsWriteBarrierForLargeObj(
+      const GCSmallHermesValue *loc,
+      SmallHermesValue value) const = 0;
   /// \}
 #endif
 

diff --git a/include/hermes/VM/HadesGC.h b/include/hermes/VM/HadesGC.h
@@ -489,6 +489,16 @@ class HadesGC final : public GCBase {
       const override;
   bool needsWriteBarrier(const GCPointerBase *loc, GCCell *value)
       const override;
+  bool needsWriteBarrierInCtor(const GCHermesValue *loc, HermesValue value)
+      const override;
+  bool needsWriteBarrierInCtor(
+      const GCSmallHermesValue *loc,
+      SmallHermesValue value) const override;
+  bool needsWriteBarrierForLargeObj(const GCHermesValue *loc, HermesValue value)
+      const override;
+  bool needsWriteBarrierForLargeObj(
+      const GCSmallHermesValue *loc,
+      SmallHermesValue value) const override;
   /// \}
 #endif
 

diff --git a/include/hermes/VM/MallocGC.h b/include/hermes/VM/MallocGC.h
@@ -222,6 +222,16 @@ class MallocGC final : public GCBase {
       const override;
   bool needsWriteBarrier(const GCPointerBase *loc, GCCell *value)
       const override;
+  bool needsWriteBarrierInCtor(const GCHermesValue *loc, HermesValue value)
+      const override;
+  bool needsWriteBarrierInCtor(
+      const GCSmallHermesValue *loc,
+      SmallHermesValue value) const override;
+  bool needsWriteBarrierForLargeObj(const GCHermesValue *loc, HermesValue value)
+      const override;
+  bool needsWriteBarrierForLargeObj(
+      const GCSmallHermesValue *loc,
+      SmallHermesValue value) const override;
 #endif
 
 #ifdef HERMES_MEMORY_INSTRUMENTATION

diff --git a/lib/VM/gcs/HadesGC.cpp b/lib/VM/gcs/HadesGC.cpp
@@ -2289,6 +2289,17 @@ bool HadesGC::needsWriteBarrier(const GCHermesValue *loc, HermesValue value)
     return true;
   return false;
 }
+bool HadesGC::needsWriteBarrierInCtor(
+    const GCHermesValue *loc,
+    HermesValue value) const {
+  // Values in the YG never need a barrier.
+  if (inYoungGen(loc))
+    return false;
+  // If the new value is a pointer, a relocation barrier is needed.
+  if (value.isPointer())
+    return true;
+  return false;
+}
 bool HadesGC::needsWriteBarrier(
     const GCSmallHermesValue *loc,
     SmallHermesValue value) const {
@@ -2303,6 +2314,41 @@ bool HadesGC::needsWriteBarrier(
     return true;
   return false;
 }
+bool HadesGC::needsWriteBarrierInCtor(
+    const GCSmallHermesValue *loc,
+    SmallHermesValue value) const {
+  // Values in the YG never need a barrier.
+  if (inYoungGen(loc))
+    return false;
+  // If the new value is a pointer, a relocation barrier is needed.
+  if (value.isPointer())
+    return true;
+  return false;
+}
+bool HadesGC::needsWriteBarrierForLargeObj(
+    const GCHermesValue *loc,
+    HermesValue value) const {
+  // For large allocation, we don't allow skipping barriers if the pointer lives
+  // in YG. We may revisit this if there is a case that we really want to skip
+  // barriers (by ensuring that the owning object always lives in YG).
+  if (loc->isPointer() || loc->isSymbol())
+    return true;
+  if (value.isPointer())
+    return true;
+  return false;
+}
+bool HadesGC::needsWriteBarrierForLargeObj(
+    const GCSmallHermesValue *loc,
+    SmallHermesValue value) const {
+  // For large allocation, we don't allow skipping barriers if the pointer lives
+  // in YG. We may revisit this if there is a case that we really want to skip
+  // barriers (by ensuring that the owning object always lives in YG).
+  if (loc->isPointer() || loc->isSymbol())
+    return true;
+  if (value.isPointer())
+    return true;
+  return false;
+}
 bool HadesGC::needsWriteBarrier(const GCPointerBase *loc, GCCell *value) const {
   return !inYoungGen(loc);
 }

diff --git a/lib/VM/gcs/MallocGC.cpp b/lib/VM/gcs/MallocGC.cpp
@@ -515,15 +515,35 @@ bool MallocGC::needsWriteBarrier(const GCHermesValue *loc, HermesValue value)
     const {
   return false;
 }
+bool MallocGC::needsWriteBarrierInCtor(
+    const GCHermesValue *loc,
+    HermesValue value) const {
+  return false;
+}
 bool MallocGC::needsWriteBarrier(
     const GCSmallHermesValue *loc,
     SmallHermesValue value) const {
   return false;
 }
+bool MallocGC::needsWriteBarrierInCtor(
+    const GCSmallHermesValue *loc,
+    SmallHermesValue value) const {
+  return false;
+}
 bool MallocGC::needsWriteBarrier(const GCPointerBase *loc, GCCell *value)
     const {
   return false;
 }
+bool MallocGC::needsWriteBarrierForLargeObj(
+    const GCHermesValue *loc,
+    HermesValue value) const {
+  return false;
+}
+bool MallocGC::needsWriteBarrierForLargeObj(
+    const GCSmallHermesValue *loc,
+    SmallHermesValue value) const {
+  return false;
+}
 #endif
 
 #ifdef HERMES_MEMORY_INSTRUMENTATION