[vm, gc] Assert the whole object is in to-space, not just its beginning.

TEST=ci
Bug: https://github.com/dart-lang/sdk/issues/50564
Change-Id: I60e7637600a1a7a99d546e8c674901175a119ba5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/272863
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>

runtime/vm/heap/page.h

@@ -72,7 +72,9 @@ class Page {
 
   uword start() const { return memory_->start(); }
   uword end() const { return memory_->end(); }
-  bool Contains(uword addr) const { return memory_->Contains(addr); }
+  bool Contains(uword addr, intptr_t size = 1) const {
+    return memory_->Contains(addr, size);
+  }
   intptr_t AliasOffset() const { return memory_->AliasOffset(); }
 
   uword object_start() const {

runtime/vm/heap/scavenger.cc

@@ -711,9 +711,9 @@ Page* SemiSpace::TryAllocatePageLocked(bool link) {
   return page;
 }
 
-bool SemiSpace::Contains(uword addr) const {
+bool SemiSpace::Contains(uword addr, intptr_t size) const {
   for (Page* page = head_; page != nullptr; page = page->next()) {
-    if (page->Contains(addr)) return true;
+    if (page->Contains(addr, size)) return true;
   }
   return false;
 }

runtime/vm/heap/scavenger.h

@@ -37,7 +37,7 @@ class SemiSpace {
 
   Page* TryAllocatePageLocked(bool link);
 
-  bool Contains(uword addr) const;
+  bool Contains(uword addr, intptr_t size = 1) const;
   void WriteProtect(bool read_only);
 
   intptr_t used_in_words() const {
@@ -128,7 +128,9 @@ class Scavenger {
   // During scavenging both the to and from spaces contain "legal" objects.
   // During a scavenge this function only returns true for addresses that will
   // be part of the surviving objects.
-  bool Contains(uword addr) const { return to_->Contains(addr); }
+  bool Contains(uword addr, intptr_t size = 1) const {
+    return to_->Contains(addr, size);
+  }
 
   ObjectPtr FindObject(FindObjectVisitor* visitor);
 
@@ -255,7 +257,7 @@ class Scavenger {
     if (UNLIKELY(remaining < size)) {
       return 0;
     }
-    ASSERT(to_->Contains(result));
+    ASSERT(to_->Contains(result, size));
     ASSERT((result & kObjectAlignmentMask) == kNewObjectAlignmentOffset);
     thread->set_top(result + size);
     return result;

runtime/vm/memory_region.h

@@ -53,8 +53,8 @@ class MemoryRegion : public ValueObject {
     return ComputeInternalPointer<T>(offset);
   }
 
-  bool Contains(uword address) const {
-    return (address >= start()) && (address < end());
+  bool Contains(uword address, intptr_t size = 1) const {
+    return (address >= start()) && (address <= (end() - size));
   }
 
   void CopyFrom(uword offset, const MemoryRegion& from) const;

runtime/vm/virtual_memory.h

@@ -37,9 +37,11 @@ class VirtualMemory {
   // Returns true if dual mapping is enabled.
   static bool DualMappingEnabled();
 
-  bool Contains(uword addr) const { return region_.Contains(addr); }
-  bool ContainsAlias(uword addr) const {
-    return (AliasOffset() != 0) && alias_.Contains(addr);
+  bool Contains(uword addr, intptr_t size = 1) const {
+    return region_.Contains(addr, size);
+  }
+  bool ContainsAlias(uword addr, intptr_t size = 1) const {
+    return (AliasOffset() != 0) && alias_.Contains(addr, size);
   }
 
   // Changes the protection of the virtual memory area.

runtime/vm/virtual_memory_compressed.h

@@ -47,7 +47,7 @@ class VirtualMemoryCompressedHeap : public AllStatic {
   static void Free(void* address, intptr_t size);
 
   // Returns whether the address is within the compressed heap.
-  static bool Contains(void* address);
+  static bool Contains(void* address, intptr_t size = 1);
 
   // Returns a pointer to the compressed heap region.
   static void* GetRegion();