From 6a5f3c2b82fcbf5714eaf95661ac4dd4bff46259 Mon Sep 17 00:00:00 2001
From: Nathaniel Wesley Filardo <nfilardo@microsoft.com>
Date: Tue, 31 May 2022 13:39:11 +0100
Subject: [PATCH] NFC: backend_helper: generalize chunk bounds

Most ranges just deal with whatever kinds of ranges their parent deal with, but
that might be Chunk- or (soon) Arena-bounded.  This commit does not yet
introduce nuance, but just sets the stage.
---
 src/snmalloc/backend/standard_range.h               | 2 +-
 src/snmalloc/backend_helpers/commitrange.h          | 9 +++++++--
 src/snmalloc/backend_helpers/empty_range.h          | 5 ++++-
 src/snmalloc/backend_helpers/globalrange.h          | 8 +++++---
 src/snmalloc/backend_helpers/largebuddyrange.h      | 4 +++-
 src/snmalloc/backend_helpers/logrange.h             | 8 +++++---
 src/snmalloc/backend_helpers/pagemapregisterrange.h | 6 ++++--
 src/snmalloc/backend_helpers/palrange.h             | 2 ++
 src/snmalloc/backend_helpers/smallbuddyrange.h      | 4 +++-
 src/snmalloc/backend_helpers/statsrange.h           | 8 +++++---
 src/snmalloc/backend_helpers/subrange.h             | 6 ++++--
 11 files changed, 43 insertions(+), 19 deletions(-)

diff --git a/src/snmalloc/backend/standard_range.h b/src/snmalloc/backend/standard_range.h
index d07c9a504..b9a2d5b79 100644
--- a/src/snmalloc/backend/standard_range.h
+++ b/src/snmalloc/backend/standard_range.h
@@ -22,7 +22,7 @@ namespace snmalloc
   template<
     typename PAL,
     typename Pagemap,
-    typename Base = EmptyRange,
+    typename Base = EmptyRange<>,
     size_t MinSizeBits = MinBaseSizeBits<PAL>()>
   struct StandardLocalState : BaseLocalStateConstants
   {
diff --git a/src/snmalloc/backend_helpers/commitrange.h b/src/snmalloc/backend_helpers/commitrange.h
index de67a1367..2bbd7a583 100644
--- a/src/snmalloc/backend_helpers/commitrange.h
+++ b/src/snmalloc/backend_helpers/commitrange.h
@@ -18,9 +18,14 @@ namespace snmalloc
 
       static constexpr bool ConcurrencySafe = ParentRange::ConcurrencySafe;
 
+      using ChunkBounds = typename ParentRange::ChunkBounds;
+      static_assert(
+        ChunkBounds::address_space_control ==
+        capptr::dimension::AddressSpaceControl::Full);
+
       constexpr Type() = default;
 
-      capptr::Chunk<void> alloc_range(size_t size)
+      CapPtr<void, ChunkBounds> alloc_range(size_t size)
       {
         SNMALLOC_ASSERT_MSG(
           (size % PAL::page_size) == 0,
@@ -33,7 +38,7 @@ namespace snmalloc
         return range;
       }
 
-      void dealloc_range(capptr::Chunk<void> base, size_t size)
+      void dealloc_range(CapPtr<void, ChunkBounds> base, size_t size)
       {
         SNMALLOC_ASSERT_MSG(
           (size % PAL::page_size) == 0,
diff --git a/src/snmalloc/backend_helpers/empty_range.h b/src/snmalloc/backend_helpers/empty_range.h
index 6507a01e3..c4eb16090 100644
--- a/src/snmalloc/backend_helpers/empty_range.h
+++ b/src/snmalloc/backend_helpers/empty_range.h
@@ -3,6 +3,7 @@
 
 namespace snmalloc
 {
+  template<SNMALLOC_CONCEPT(capptr::ConceptBound) B = capptr::bounds::Chunk>
   class EmptyRange
   {
   public:
@@ -10,9 +11,11 @@ namespace snmalloc
 
     static constexpr bool ConcurrencySafe = true;
 
+    using ChunkBounds = B;
+
     constexpr EmptyRange() = default;
 
-    capptr::Chunk<void> alloc_range(size_t)
+    CapPtr<void, ChunkBounds> alloc_range(size_t)
     {
       return nullptr;
     }
diff --git a/src/snmalloc/backend_helpers/globalrange.h b/src/snmalloc/backend_helpers/globalrange.h
index 3e01c3d09..760ad21d7 100644
--- a/src/snmalloc/backend_helpers/globalrange.h
+++ b/src/snmalloc/backend_helpers/globalrange.h
@@ -11,7 +11,7 @@ namespace snmalloc
    */
   struct GlobalRange
   {
-    template<typename ParentRange = EmptyRange>
+    template<typename ParentRange = EmptyRange<>>
     class Type : public StaticParent<ParentRange>
     {
       using StaticParent<ParentRange>::parent;
@@ -27,15 +27,17 @@ namespace snmalloc
 
       static constexpr bool ConcurrencySafe = true;
 
+      using ChunkBounds = typename ParentRange::ChunkBounds;
+
       constexpr Type() = default;
 
-      capptr::Chunk<void> alloc_range(size_t size)
+      CapPtr<void, ChunkBounds> alloc_range(size_t size)
       {
         FlagLock lock(spin_lock);
         return parent.alloc_range(size);
       }
 
-      void dealloc_range(capptr::Chunk<void> base, size_t size)
+      void dealloc_range(CapPtr<void, ChunkBounds> base, size_t size)
       {
         FlagLock lock(spin_lock);
         parent.dealloc_range(base, size);
diff --git a/src/snmalloc/backend_helpers/largebuddyrange.h b/src/snmalloc/backend_helpers/largebuddyrange.h
index 7d315973f..379cb5d46 100644
--- a/src/snmalloc/backend_helpers/largebuddyrange.h
+++ b/src/snmalloc/backend_helpers/largebuddyrange.h
@@ -208,7 +208,7 @@ namespace snmalloc
       bits::one_at_bit(MIN_REFILL_SIZE_BITS);
 
   public:
-    template<typename ParentRange = EmptyRange>
+    template<typename ParentRange = EmptyRange<>>
     class Type : public ContainsParent<ParentRange>
     {
       using ContainsParent<ParentRange>::parent;
@@ -341,6 +341,8 @@ namespace snmalloc
 
       static constexpr bool ConcurrencySafe = false;
 
+      using ChunkBounds = capptr::bounds::Chunk;
+
       constexpr Type() = default;
 
       capptr::Chunk<void> alloc_range(size_t size)
diff --git a/src/snmalloc/backend_helpers/logrange.h b/src/snmalloc/backend_helpers/logrange.h
index 9bc1d4731..0a3f907de 100644
--- a/src/snmalloc/backend_helpers/logrange.h
+++ b/src/snmalloc/backend_helpers/logrange.h
@@ -14,7 +14,7 @@ namespace snmalloc
   template<size_t RangeName>
   struct LogRange
   {
-    template<typename ParentRange = EmptyRange>
+    template<typename ParentRange = EmptyRange<>>
     class Type : public ContainsParent<ParentRange>
     {
       using ContainsParent<ParentRange>::parent;
@@ -24,9 +24,11 @@ namespace snmalloc
 
       static constexpr bool ConcurrencySafe = ParentRange::ConcurrencySafe;
 
+      using ChunkBounds = typename ParentRange::ChunkBounds;
+
       constexpr Type() = default;
 
-      capptr::Chunk<void> alloc_range(size_t size)
+      CapPtr<void, ChunkBounds> alloc_range(size_t size)
       {
 #ifdef SNMALLOC_TRACING
         message<1024>("Call alloc_range({}) on {}", size, RangeName);
@@ -39,7 +41,7 @@ namespace snmalloc
         return range;
       }
 
-      void dealloc_range(capptr::Chunk<void> base, size_t size)
+      void dealloc_range(CapPtr<void, ChunkBounds> base, size_t size)
       {
 #ifdef SNMALLOC_TRACING
         message<1024>(
diff --git a/src/snmalloc/backend_helpers/pagemapregisterrange.h b/src/snmalloc/backend_helpers/pagemapregisterrange.h
index 7201f8ff9..9a0019e33 100644
--- a/src/snmalloc/backend_helpers/pagemapregisterrange.h
+++ b/src/snmalloc/backend_helpers/pagemapregisterrange.h
@@ -11,7 +11,7 @@ namespace snmalloc
     bool CanConsolidate = true>
   struct PagemapRegisterRange
   {
-    template<typename ParentRange = EmptyRange>
+    template<typename ParentRange = EmptyRange<>>
     class Type : public ContainsParent<ParentRange>
     {
       using ContainsParent<ParentRange>::parent;
@@ -23,7 +23,9 @@ namespace snmalloc
 
       static constexpr bool ConcurrencySafe = ParentRange::ConcurrencySafe;
 
-      capptr::Chunk<void> alloc_range(size_t size)
+      using ChunkBounds = typename ParentRange::ChunkBounds;
+
+      CapPtr<void, ChunkBounds> alloc_range(size_t size)
       {
         auto base = parent.alloc_range(size);
 
diff --git a/src/snmalloc/backend_helpers/palrange.h b/src/snmalloc/backend_helpers/palrange.h
index 0962e00bf..efa324ee1 100644
--- a/src/snmalloc/backend_helpers/palrange.h
+++ b/src/snmalloc/backend_helpers/palrange.h
@@ -14,6 +14,8 @@ namespace snmalloc
     // need to be changed.
     static constexpr bool ConcurrencySafe = true;
 
+    using ChunkBounds = capptr::bounds::Chunk;
+
     constexpr PalRange() = default;
 
     capptr::Chunk<void> alloc_range(size_t size)
diff --git a/src/snmalloc/backend_helpers/smallbuddyrange.h b/src/snmalloc/backend_helpers/smallbuddyrange.h
index fc42d6f7d..8e7de038e 100644
--- a/src/snmalloc/backend_helpers/smallbuddyrange.h
+++ b/src/snmalloc/backend_helpers/smallbuddyrange.h
@@ -145,7 +145,7 @@ namespace snmalloc
 
   struct SmallBuddyRange
   {
-    template<typename ParentRange = EmptyRange>
+    template<typename ParentRange = EmptyRange<>>
     class Type : public ContainsParent<ParentRange>
     {
       using ContainsParent<ParentRange>::parent;
@@ -187,6 +187,8 @@ namespace snmalloc
 
       static constexpr bool ConcurrencySafe = false;
 
+      using ChunkBounds = capptr::bounds::Chunk;
+
       constexpr Type() = default;
 
       capptr::Chunk<void> alloc_range(size_t size)
diff --git a/src/snmalloc/backend_helpers/statsrange.h b/src/snmalloc/backend_helpers/statsrange.h
index f38f6e999..8548be9cb 100644
--- a/src/snmalloc/backend_helpers/statsrange.h
+++ b/src/snmalloc/backend_helpers/statsrange.h
@@ -12,7 +12,7 @@ namespace snmalloc
    */
   struct StatsRange
   {
-    template<typename ParentRange = EmptyRange>
+    template<typename ParentRange = EmptyRange<>>
     class Type : public ContainsParent<ParentRange>
     {
       using ContainsParent<ParentRange>::parent;
@@ -25,9 +25,11 @@ namespace snmalloc
 
       static constexpr bool ConcurrencySafe = ParentRange::ConcurrencySafe;
 
+      using ChunkBounds = typename ParentRange::ChunkBounds;
+
       constexpr Type() = default;
 
-      capptr::Chunk<void> alloc_range(size_t size)
+      CapPtr<void, ChunkBounds> alloc_range(size_t size)
       {
         auto result = parent.alloc_range(size);
         if (result != nullptr)
@@ -43,7 +45,7 @@ namespace snmalloc
         return result;
       }
 
-      void dealloc_range(capptr::Chunk<void> base, size_t size)
+      void dealloc_range(CapPtr<void, ChunkBounds> base, size_t size)
       {
         current_usage -= size;
         parent.dealloc_range(base, size);
diff --git a/src/snmalloc/backend_helpers/subrange.h b/src/snmalloc/backend_helpers/subrange.h
index 03c782539..8d886a2b8 100644
--- a/src/snmalloc/backend_helpers/subrange.h
+++ b/src/snmalloc/backend_helpers/subrange.h
@@ -12,7 +12,7 @@ namespace snmalloc
   template<typename PAL, size_t RATIO_BITS>
   struct SubRange
   {
-    template<typename ParentRange = EmptyRange>
+    template<typename ParentRange = EmptyRange<>>
     class Type : public ContainsParent<ParentRange>
     {
       using ContainsParent<ParentRange>::parent;
@@ -24,7 +24,9 @@ namespace snmalloc
 
       static constexpr bool ConcurrencySafe = ParentRange::ConcurrencySafe;
 
-      capptr::Chunk<void> alloc_range(size_t sub_size)
+      using ChunkBounds = typename ParentRange::ChunkBounds;
+
+      CapPtr<void, ChunkBounds> alloc_range(size_t sub_size)
       {
         SNMALLOC_ASSERT(bits::is_pow2(sub_size));