Make minAllocationSize constexpr

neildhar · facebook-github-bot · commit 22874567517e · 2021-02-17T22:28:40.000-08:00
Summary:
Make HadesGC::minAllocationSize and GCBase::minAllocationSize
constexpr, this allows us to use them in compile time checks.

Reviewed By: dulinriley

Differential Revision: D26478072

fbshipit-source-id: 9c75be352ef49f085518dd959354167139e0eb5a
diff --git a/include/hermes/VM/GCBase-inline.h b/include/hermes/VM/GCBase-inline.h
@@ -80,6 +80,11 @@ constexpr uint32_t GCBase::maxAllocationSize() {
   // Return the lesser of the two GC options' max allowed sizes.
   return min(HadesGC::maxAllocationSize(), GenGC::maxAllocationSize());
 }
+
+constexpr uint32_t GCBase::minAllocationSize() {
+  // Return the greater of the two GC options' min allowed sizes.
+  return max(HadesGC::minAllocationSize(), GenGC::minAllocationSize());
+}
 #endif
 
 template <typename Acceptor>
diff --git a/include/hermes/VM/GCBase.h b/include/hermes/VM/GCBase.h
@@ -1010,9 +1010,9 @@ class GCBase {
 #endif
 
 #ifdef HERMESVM_GC_RUNTIME
-  static uint32_t minAllocationSize();
+  inline static constexpr uint32_t minAllocationSize();
 
-  static constexpr uint32_t maxAllocationSize();
+  inline static constexpr uint32_t maxAllocationSize();
 #endif
 
   /// Dump detailed heap contents to the given output stream, \p os.
diff --git a/include/hermes/VM/HadesGC.h b/include/hermes/VM/HadesGC.h
@@ -10,6 +10,7 @@
 
 #include "hermes/ADT/BitArray.h"
 #include "hermes/ADT/ExponentialMovingAverage.h"
+#include "hermes/Support/Algorithms.h"
 #include "hermes/Support/SlowAssert.h"
 #include "hermes/VM/AlignedHeapSegment.h"
 #include "hermes/VM/GCBase.h"
@@ -76,14 +77,17 @@ class HadesGC final : public GCBase {
     return gc->getKind() == HeapKind::HADES;
   }
 
-  static uint32_t minAllocationSize();
-
   static constexpr uint32_t maxAllocationSize() {
     // The largest allocation allowable in Hades is the max size a single
     // segment supports.
     return HeapSegment::maxSize();
   }
 
+  static constexpr uint32_t minAllocationSize() {
+    return heapAlignSize(
+        max(sizeof(OldGen::FreelistCell), sizeof(CopyListCell)));
+  }
+
   /// \name GCBase overrides
   /// \{
 
@@ -234,14 +238,22 @@ class HadesGC final : public GCBase {
 
   class CollectionStats;
   class HeapMarkingAcceptor;
-  struct CopyListCell;
   template <bool CompactionEnabled>
   class EvacAcceptor;
   class MarkAcceptor;
   class MarkWeakRootsAcceptor;
   class OldGen;
   class Executor;
 
+  struct CopyListCell final : public GCCell {
+    // Linked list of cells pointing to the next cell that was copied.
+    CopyListCell *next_;
+    // If the cell was trimmed, this field will have the original size of the
+    // object stored. If the cell wasn't trimmed it'll have the same size as the
+    // forwarded pointer.
+    uint32_t originalSize_;
+  };
+
   /// Similar to AlignedHeapSegment except it uses a free list.
   class HeapSegment final : public AlignedHeapSegment {
    public:
diff --git a/lib/VM/GCBase.cpp b/lib/VM/GCBase.cpp
@@ -94,13 +94,6 @@ GCBase::GCBase(
 #endif
 }
 
-#ifdef HERMESVM_GC_RUNTIME
-/* static */
-uint32_t GCBase::minAllocationSize() {
-  return std::max({GenGC::minAllocationSize(), HadesGC::minAllocationSize()});
-}
-#endif
-
 GCBase::GCCycle::GCCycle(
     GCBase *gc,
     OptValue<GCCallbacks *> gcCallbacksOpt,
diff --git a/lib/VM/gcs/HadesGC.cpp b/lib/VM/gcs/HadesGC.cpp
@@ -39,15 +39,6 @@ HadesGC::HeapSegment::HeapSegment(AlignedStorage storage)
   growToLimit();
 }
 
-struct HadesGC::CopyListCell final : public GCCell {
-  // Linked list of cells pointing to the next cell that was copied.
-  CopyListCell *next_;
-  // If the cell was trimmed, this field will have the original size of the
-  // object stored. If the cell wasn't trimmed it'll have the same size as the
-  // forwarded pointer.
-  uint32_t originalSize_;
-};
-
 GCCell *
 HadesGC::OldGen::finishAlloc(GCCell *cell, uint32_t sz, uint16_t segmentIdx) {
   // Track the number of allocated bytes in a segment.
@@ -1301,11 +1292,6 @@ HadesGC::~HadesGC() {
       "Must call finalizeAll before destructor.");
 }
 
-uint32_t HadesGC::minAllocationSize() {
-  return heapAlignSize(
-      std::max(sizeof(OldGen::FreelistCell), sizeof(CopyListCell)));
-}
-
 void HadesGC::getHeapInfo(HeapInfo &info) {
   std::lock_guard<Mutex> lk{gcMutex_};
   GCBase::getHeapInfo(info);
