[vm, gc] New-space alignment is not configurable.

Change-Id: I6bb1c3dab0319ac5d827c947f38cb6396d2f7d81
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/134809
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

runtime/vm/heap/heap.cc

@@ -37,7 +37,7 @@ Heap::Heap(Isolate* isolate,
            intptr_t max_new_gen_semi_words,
            intptr_t max_old_gen_words)
     : isolate_(isolate),
-      new_space_(this, max_new_gen_semi_words, kNewObjectAlignmentOffset),
+      new_space_(this, max_new_gen_semi_words),
       old_space_(this, max_old_gen_words),
       barrier_(),
       barrier_done_(),

runtime/vm/heap/scavenger.cc

@@ -421,12 +421,9 @@ void SemiSpace::WriteProtect(bool read_only) {
 // on the device's actual speed.
 static const intptr_t kConservativeInitialScavengeSpeed = 40;
 
-Scavenger::Scavenger(Heap* heap,
-                     intptr_t max_semi_capacity_in_words,
-                     uword object_alignment)
+Scavenger::Scavenger(Heap* heap, intptr_t max_semi_capacity_in_words)
     : heap_(heap),
       max_semi_capacity_in_words_(max_semi_capacity_in_words),
-      object_alignment_(object_alignment),
       scavenging_(false),
       delayed_weak_properties_(NULL),
       gc_time_micros_(0),
@@ -1009,7 +1006,7 @@ uword Scavenger::TryAllocateNewTLAB(Thread* thread, intptr_t size) {
     return 0;
   }
   ASSERT(to_->Contains(result));
-  ASSERT((result & kObjectAlignmentMask) == object_alignment_);
+  ASSERT((result & kObjectAlignmentMask) == kNewObjectAlignmentOffset);
   top_ += size;
   ASSERT(to_->Contains(top_) || (top_ == to_->end()));
   ASSERT(result < top_);

runtime/vm/heap/scavenger.h

@@ -114,9 +114,7 @@ class ScavengeStats {
 
 class Scavenger {
  public:
-  Scavenger(Heap* heap,
-            intptr_t max_semi_capacity_in_words,
-            uword object_alignment);
+  Scavenger(Heap* heap, intptr_t max_semi_capacity_in_words);
   ~Scavenger();
 
   // Check whether this Scavenger contains this address.
@@ -140,7 +138,7 @@ class Scavenger {
     // the new to_ space. It must succeed.
     ASSERT(size <= remaining);
     ASSERT(to_->Contains(result));
-    ASSERT((result & kObjectAlignmentMask) == object_alignment_);
+    ASSERT((result & kObjectAlignmentMask) == kNewObjectAlignmentOffset);
     top_ += size;
     ASSERT((to_->Contains(top_)) || (top_ == to_->end()));
     return result;
@@ -157,7 +155,7 @@ class Scavenger {
       return 0;
     }
     ASSERT(to_->Contains(result));
-    ASSERT((result & kObjectAlignmentMask) == object_alignment_);
+    ASSERT((result & kObjectAlignmentMask) == kNewObjectAlignmentOffset);
     top += size;
     ASSERT((to_->Contains(top)) || (top == to_->end()));
     thread->set_top(top);
@@ -237,7 +235,9 @@ class Scavenger {
     kToKBAfterStoreBuffer = 3
   };
 
-  uword FirstObjectStart() const { return to_->start() | object_alignment_; }
+  uword FirstObjectStart() const {
+    return to_->start() + kNewObjectAlignmentOffset;
+  }
   SemiSpace* Prologue(Isolate* isolate);
   void IterateStoreBuffers(Isolate* isolate, ScavengerVisitor* visitor);
   void IterateObjectIdTable(Isolate* isolate, ScavengerVisitor* visitor);
@@ -298,9 +298,6 @@ class Scavenger {
 
   intptr_t max_semi_capacity_in_words_;
 
-  // All object are aligned to this value.
-  uword object_alignment_;
-
   // Keep track whether a scavenge is currently running.
   bool scavenging_;