[heap] refactor inline allocation step code

Once I improved byte accounting done for incremental mark in [1], there is some
code duplication that becomes apparent. This commit refactors the duplicated
code into a private method on NewSpace. This also makes it easy to add new
consumers of inline allocation steps in the future.

[1] https://codereview.chromium.org/1274453002/

R=hpayer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1351983002

Cr-Commit-Position: refs/heads/master@{#30921}

diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index cd9d627b39a83e43a1cba90b5ac52f3e48d5f957..402a6c04b0591354879f1bdd68552e4bb0f192c8 100644 (file)
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -1400,12 +1400,7 @@ void NewSpace::ResetAllocationInfo() {
   while (it.has_next()) {
     Bitmap::Clear(it.next());
   }
-  if (top_on_previous_step_) {
-    int bytes_allocated = static_cast<int>(old_top - top_on_previous_step_);
-    heap()->incremental_marking()->Step(bytes_allocated,
-                                        IncrementalMarking::GC_VIA_STACK_GUARD);
-    top_on_previous_step_ = allocation_info_.top();
-  }
+  InlineAllocationStep(old_top, allocation_info_.top());
 }
 
 
@@ -1484,13 +1479,7 @@ bool NewSpace::EnsureAllocation(int size_in_bytes,
       return false;
     }
 
-    if (top_on_previous_step_) {
-      // Do a step for the bytes allocated on the last page.
-      int bytes_allocated = static_cast<int>(old_top - top_on_previous_step_);
-      heap()->incremental_marking()->Step(
-          bytes_allocated, IncrementalMarking::GC_VIA_STACK_GUARD);
-      top_on_previous_step_ = allocation_info_.top();
-    }
+    InlineAllocationStep(old_top, allocation_info_.top());
 
     old_top = allocation_info_.top();
     high = to_space_.page_high();
@@ -1504,19 +1493,23 @@ bool NewSpace::EnsureAllocation(int size_in_bytes,
     // Either the limit has been lowered because linear allocation was disabled
     // or because incremental marking wants to get a chance to do a step. Set
     // the new limit accordingly.
-    if (top_on_previous_step_) {
-      Address new_top = old_top + aligned_size_in_bytes;
-      int bytes_allocated = static_cast<int>(new_top - top_on_previous_step_);
-      heap()->incremental_marking()->Step(
-          bytes_allocated, IncrementalMarking::GC_VIA_STACK_GUARD);
-      top_on_previous_step_ = new_top;
-    }
+    Address new_top = old_top + aligned_size_in_bytes;
+    InlineAllocationStep(new_top, new_top);
     UpdateInlineAllocationLimit(aligned_size_in_bytes);
   }
   return true;
 }
 
 
+void NewSpace::InlineAllocationStep(Address top, Address new_top) {
+  if (top_on_previous_step_) {
+    int bytes_allocated = static_cast<int>(top - top_on_previous_step_);
+    heap()->incremental_marking()->Step(bytes_allocated,
+                                        IncrementalMarking::GC_VIA_STACK_GUARD);
+    top_on_previous_step_ = new_top;
+  }
+}
+
 #ifdef VERIFY_HEAP
 // We do not use the SemiSpaceIterator because verification doesn't assume
 // that it works (it depends on the invariants we are checking).

diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 029e5c6f15b56765bccc14c1e44f24e9c6be1240..2cea06673abf136a0e3b013680e2cc6d59418e71 100644 (file)
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -2721,6 +2721,15 @@ class NewSpace : public Space {
 
   bool EnsureAllocation(int size_in_bytes, AllocationAlignment alignment);
 
+  // If we are doing inline allocation in steps, this method performs the 'step'
+  // operation. Right now incremental marking is the only consumer of inline
+  // allocation steps. top is the memory address of the bump pointer at the last
+  // inline allocation (i.e. it determines the numbers of bytes actually
+  // allocated since the last step.) new_top is the address of the bump pointer
+  // where the next byte is going to be allocated from. top and new_top may be
+  // different when we cross a page boundary or reset the space.
+  void InlineAllocationStep(Address top, Address new_top);
+
   friend class SemiSpaceIterator;
 };