A64: Implement and use FillFields

src/a64/macro-assembler-a64.h

Index: src/a64/macro-assembler-a64.h
diff --git a/src/a64/macro-assembler-a64.h b/src/a64/macro-assembler-a64.h
index 02c4f54f6b4af68c5bd20ac7ad9e89a05e43fd4d..a77f5b2b3387dc6636d909f18ad5d2f9d3fcec72 100644
--- a/src/a64/macro-assembler-a64.h
+++ b/src/a64/macro-assembler-a64.h
@@ -948,6 +948,12 @@ class MacroAssembler : public Assembler {
   // MacroAssembler::TmpList().
   void CopyFields(Register dst, Register src, CPURegList temps, unsigned count);
 
+  // Starting at address in dst, initialize field_count 64-bit fields with
+  // 64-bit value in register filler. Register dst is corrupted.
+  void FillFields(Register dst,
+                  Register field_count,
+                  Register filler);
+
   // Copies a number of bytes from src to dst. All passed registers are
   // clobbered. On exit src and dst will point to the place just after where the
   // last byte was read or written and length will be zero. Hint may be used to
@@ -958,13 +964,6 @@ class MacroAssembler : public Assembler {
                  Register scratch,
                  CopyHint hint = kCopyUnknown);
 
-  // Initialize fields with filler values. Fields starting at start_offset not
-  // including end_offset are overwritten with the value in filler. At the end
-  // of the loop, start_offset takes the value of end_offset.
-  void InitializeFieldsWithFiller(Register start_offset,
-                                  Register end_offset,
-                                  Register filler);
-
   // ---- String Utilities ----