[heap] Introduce fast path in PagedSpace::AllocateRaw

Introduce explicit fast path for allocation in PagedSpace. The slow path
is moved into AllocateRawSlow which refills the LAB and retries the
allocation.

Bug: v8:10315
Change-Id: I807e56ccde833b0e9a42166b4883c1978d01e828
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2277808Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68653}

src/heap/paged-spaces-inl.h

@@ -5,6 +5,7 @@
 #ifndef V8_HEAP_PAGED_SPACES_INL_H_
 #define V8_HEAP_PAGED_SPACES_INL_H_
 
+#include "src/common/globals.h"
 #include "src/heap/incremental-marking.h"
 #include "src/heap/paged-spaces.h"
 #include "src/objects/code-inl.h"
@@ -96,31 +97,35 @@ bool PagedSpace::EnsureLinearAllocationArea(int size_in_bytes,
   return SlowRefillLinearAllocationArea(size_in_bytes, origin);
 }
 
-HeapObject PagedSpace::AllocateLinearly(int size_in_bytes) {
+AllocationResult PagedSpace::AllocateLinearly(int size_in_bytes) {
   Address current_top = allocation_info_.top();
   Address new_top = current_top + size_in_bytes;
+  if (new_top > allocation_info_.limit())
+    return AllocationResult::Retry(identity());
   DCHECK_LE(new_top, allocation_info_.limit());
   allocation_info_.set_top(new_top);
-  return HeapObject::FromAddress(current_top);
+  return AllocationResult(HeapObject::FromAddress(current_top));
 }
 
-HeapObject PagedSpace::TryAllocateLinearlyAligned(
+AllocationResult PagedSpace::TryAllocateLinearlyAligned(
     int* size_in_bytes, AllocationAlignment alignment) {
   Address current_top = allocation_info_.top();
   int filler_size = Heap::GetFillToAlign(current_top, alignment);
 
   Address new_top = current_top + filler_size + *size_in_bytes;
-  if (new_top > allocation_info_.limit()) return HeapObject();
+  if (new_top > allocation_info_.limit())
+    return AllocationResult::Retry(identity());
 
   allocation_info_.set_top(new_top);
   if (filler_size > 0) {
     *size_in_bytes += filler_size;
-    return Heap::PrecedeWithFiller(ReadOnlyRoots(heap()),
-                                   HeapObject::FromAddress(current_top),
+    HeapObject object = Heap::PrecedeWithFiller(
+        ReadOnlyRoots(heap()), HeapObject::FromAddress(current_top),
         filler_size);
+    return AllocationResult(object);
   }
 
-  return HeapObject::FromAddress(current_top);
+  return AllocationResult(HeapObject::FromAddress(current_top));
 }
 
 AllocationResult PagedSpace::AllocateRawUnaligned(int size_in_bytes,
@@ -128,15 +133,16 @@ AllocationResult PagedSpace::AllocateRawUnaligned(int size_in_bytes,
   if (!EnsureLinearAllocationArea(size_in_bytes, origin)) {
     return AllocationResult::Retry(identity());
   }
-  HeapObject object = AllocateLinearly(size_in_bytes);
-  DCHECK(!object.is_null());
-  MSAN_ALLOCATED_UNINITIALIZED_MEMORY(object.address(), size_in_bytes);
+  AllocationResult result = AllocateLinearly(size_in_bytes);
+  DCHECK(!result.IsRetry());
+  MSAN_ALLOCATED_UNINITIALIZED_MEMORY(result.ToObjectChecked().address(),
+                                      size_in_bytes);
 
   if (FLAG_trace_allocations_origins) {
     UpdateAllocationOrigins(origin);
   }
 
-  return object;
+  return result;
 }
 
 AllocationResult PagedSpace::AllocateRawAligned(int size_in_bytes,
@@ -144,8 +150,6 @@ AllocationResult PagedSpace::AllocateRawAligned(int size_in_bytes,
                                                 AllocationOrigin origin) {
   DCHECK_EQ(identity(), OLD_SPACE);
   int allocation_size = size_in_bytes;
-  HeapObject object = TryAllocateLinearlyAligned(&allocation_size, alignment);
-  if (object.is_null()) {
   // We don't know exactly how much filler we need to align until space is
   // allocated, so assume the worst case.
   int filler_size = Heap::GetMaximumFillToAlign(alignment);
@@ -154,52 +158,36 @@ AllocationResult PagedSpace::AllocateRawAligned(int size_in_bytes,
     return AllocationResult::Retry(identity());
   }
   allocation_size = size_in_bytes;
-    object = TryAllocateLinearlyAligned(&allocation_size, alignment);
-    DCHECK(!object.is_null());
-  }
-  MSAN_ALLOCATED_UNINITIALIZED_MEMORY(object.address(), size_in_bytes);
+  AllocationResult result =
+      TryAllocateLinearlyAligned(&allocation_size, alignment);
+  DCHECK(!result.IsRetry());
+  MSAN_ALLOCATED_UNINITIALIZED_MEMORY(result.ToObjectChecked().address(),
+                                      size_in_bytes);
 
   if (FLAG_trace_allocations_origins) {
     UpdateAllocationOrigins(origin);
   }
 
-  return object;
+  return result;
 }
 
 AllocationResult PagedSpace::AllocateRaw(int size_in_bytes,
                                          AllocationAlignment alignment,
                                          AllocationOrigin origin) {
-  if (top_on_previous_step_ && top() < top_on_previous_step_ &&
-      SupportsInlineAllocation()) {
-    // Generated code decreased the top() pointer to do folded allocations.
-    // The top_on_previous_step_ can be one byte beyond the current page.
-    DCHECK_NE(top(), kNullAddress);
-    DCHECK_EQ(Page::FromAllocationAreaAddress(top()),
-              Page::FromAllocationAreaAddress(top_on_previous_step_ - 1));
-    top_on_previous_step_ = top();
-  }
-  size_t bytes_since_last =
-      top_on_previous_step_ ? top() - top_on_previous_step_ : 0;
+  AllocationResult result;
 
-  DCHECK_IMPLIES(!SupportsInlineAllocation(), bytes_since_last == 0);
-#ifdef V8_HOST_ARCH_32_BIT
-  AllocationResult result =
-      alignment != kWordAligned
-          ? AllocateRawAligned(size_in_bytes, alignment, origin)
-          : AllocateRawUnaligned(size_in_bytes, origin);
-#else
-  AllocationResult result = AllocateRawUnaligned(size_in_bytes, origin);
-#endif
-  HeapObject heap_obj;
-  if (!result.IsRetry() && result.To(&heap_obj) && !is_local_space()) {
-    AllocationStep(static_cast<int>(size_in_bytes + bytes_since_last),
-                   heap_obj.address(), size_in_bytes);
-    StartNextInlineAllocationStep();
-    DCHECK_IMPLIES(
-        heap()->incremental_marking()->black_allocation(),
-        heap()->incremental_marking()->marking_state()->IsBlack(heap_obj));
+  if (alignment != kWordAligned) {
+    int allocation_size = size_in_bytes;
+    result = TryAllocateLinearlyAligned(&allocation_size, alignment);
+  } else {
+    result = AllocateLinearly(size_in_bytes);
   }
+
+  if (!result.IsRetry()) {
     return result;
+  } else {
+    return AllocateRawSlow(size_in_bytes, alignment, origin);
+  }
 }
 
 }  // namespace internal

src/heap/paged-spaces.cc

@@ -1004,6 +1004,43 @@ bool PagedSpace::SweepAndRetryAllocation(int required_freed_bytes,
   return false;
 }
 
+AllocationResult PagedSpace::AllocateRawSlow(int size_in_bytes,
+                                             AllocationAlignment alignment,
+                                             AllocationOrigin origin) {
+  if (top_on_previous_step_ && top() < top_on_previous_step_ &&
+      SupportsInlineAllocation()) {
+    // Generated code decreased the top() pointer to do folded allocations.
+    // The top_on_previous_step_ can be one byte beyond the current page.
+    DCHECK_NE(top(), kNullAddress);
+    DCHECK_EQ(Page::FromAllocationAreaAddress(top()),
+              Page::FromAllocationAreaAddress(top_on_previous_step_ - 1));
+    top_on_previous_step_ = top();
+  }
+
+  size_t bytes_since_last =
+      top_on_previous_step_ ? top() - top_on_previous_step_ : 0;
+  DCHECK_IMPLIES(!SupportsInlineAllocation(), bytes_since_last == 0);
+
+#ifdef V8_HOST_ARCH_32_BIT
+  AllocationResult result =
+      alignment != kWordAligned
+          ? AllocateRawAligned(size_in_bytes, alignment, origin)
+          : AllocateRawUnaligned(size_in_bytes, origin);
+#else
+  AllocationResult result = AllocateRawUnaligned(size_in_bytes, origin);
+#endif
+  HeapObject heap_obj;
+  if (!result.IsRetry() && result.To(&heap_obj) && !is_local_space()) {
+    AllocationStep(static_cast<int>(size_in_bytes + bytes_since_last),
+                   heap_obj.address(), size_in_bytes);
+    StartNextInlineAllocationStep();
+    DCHECK_IMPLIES(
+        heap()->incremental_marking()->black_allocation(),
+        heap()->incremental_marking()->marking_state()->IsBlack(heap_obj));
+  }
+  return result;
+}
+
 // -----------------------------------------------------------------------------
 // MapSpace implementation
 

src/heap/paged-spaces.h

@@ -327,6 +327,11 @@ class V8_EXPORT_PRIVATE PagedSpace
     return identity() == OLD_SPACE && !is_local_space();
   }
 
+  // Slow path of allocation function
+  V8_WARN_UNUSED_RESULT AllocationResult
+  AllocateRawSlow(int size_in_bytes, AllocationAlignment alignment,
+                  AllocationOrigin origin);
+
  protected:
   // PagedSpaces that should be included in snapshots have different, i.e.,
   // smaller, initial pages.
@@ -352,13 +357,13 @@ class V8_EXPORT_PRIVATE PagedSpace
                                          AllocationOrigin origin);
   // Allocates an object from the linear allocation area. Assumes that the
   // linear allocation area is large enought to fit the object.
-  inline HeapObject AllocateLinearly(int size_in_bytes);
+  inline AllocationResult AllocateLinearly(int size_in_bytes);
   // Tries to allocate an aligned object from the linear allocation area.
   // Returns nullptr if the linear allocation area does not fit the object.
   // Otherwise, returns the object pointer and writes the allocation size
   // (object size + alignment filler size) to the size_in_bytes.
-  inline HeapObject TryAllocateLinearlyAligned(int* size_in_bytes,
-                                               AllocationAlignment alignment);
+  inline AllocationResult TryAllocateLinearlyAligned(
+      int* size_in_bytes, AllocationAlignment alignment);
 
   V8_WARN_UNUSED_RESULT bool RefillLinearAllocationAreaFromFreeList(
       size_t size_in_bytes, AllocationOrigin origin);