[crankshaft] Fragmentation-free allocation folding.

src/arm64/macro-assembler-arm64.h

Index: src/arm64/macro-assembler-arm64.h
diff --git a/src/arm64/macro-assembler-arm64.h b/src/arm64/macro-assembler-arm64.h
index ad28133cb0c6c30649fedcb74a6c60e8d765332d..67e64f4d672fb451cee506f7e7df151321f07d45 100644
--- a/src/arm64/macro-assembler-arm64.h
+++ b/src/arm64/macro-assembler-arm64.h
@@ -1312,7 +1312,6 @@ class MacroAssembler : public Assembler {
   //
   // If the new space is exhausted control continues at the gc_required label.
   // In this case, the result and scratch registers may still be clobbered.
-  // If flags includes TAG_OBJECT, the result is tagged as as a heap object.
   void Allocate(Register object_size, Register result, Register result_end,
                 Register scratch, Label* gc_required, AllocationFlags flags);
 
@@ -1323,6 +1322,15 @@ class MacroAssembler : public Assembler {
                 Label* gc_required,
                 AllocationFlags flags);
 
+  // FastAllocate is right now only used for folded allocations. It just
+  // increments the top pointer without checking against limit. This can only
+  // be done if it was proved earlier that the allocation will succeed.
+  void FastAllocate(Register object_size, Register result, Register result_end,
+                    Register scratch, AllocationFlags flags);
+
+  void FastAllocate(int object_size, Register result, Register scratch1,
+                    Register scratch2, AllocationFlags flags);
+
   void AllocateTwoByteString(Register result,
                              Register length,
                              Register scratch1,