A64: Port LSeqStringSetChar optimizations from r16707 and r17521.

src/a64/full-codegen-a64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3237 matching lines @@
   VisitForStackValue(args->at(2));  // value
   VisitForAccumulatorValue(args->at(0));  // string
   __ Pop(value, index);
 
   if (FLAG_debug_code) {
     Label both_smis;
     __ JumpIfBothSmi(value, index, &both_smis);
     __ Throw(kNonSmiValue);
     __ Throw(kNonSmiIndex);
     __ Bind(&both_smis);
-
+    __ SmiUntag(index);
     static const uint32_t one_byte_seq_type = kSeqStringTag | kOneByteStringTag;
-    __ EmitSeqStringSetCharCheck(string, index, one_byte_seq_type);
+    __ EmitSeqStringSetCharCheck(string, index, scratch, one_byte_seq_type);
+    __ SmiTag(index);
   }
 
   __ Add(scratch, string, SeqOneByteString::kHeaderSize - kHeapObjectTag);
   __ SmiUntag(value);
   __ SmiUntag(index);
   __ Strb(value, MemOperand(scratch, index));
   context()->Plug(string);
 }
 
 
@@ skipping 10 matching lines @@
   VisitForStackValue(args->at(2));  // value
   VisitForAccumulatorValue(args->at(0));  // string
   __ Pop(value, index);
 
   if (FLAG_debug_code) {
     Label both_smis;
     __ JumpIfBothSmi(value, index, &both_smis);
     __ Throw(kNonSmiValue);
     __ Throw(kNonSmiIndex);
     __ Bind(&both_smis);
-
+    __ SmiUntag(index);
     static const uint32_t two_byte_seq_type = kSeqStringTag | kTwoByteStringTag;
-    __ EmitSeqStringSetCharCheck(string, index, two_byte_seq_type);
+    __ EmitSeqStringSetCharCheck(string, index, scratch, two_byte_seq_type);
+    __ SmiTag(index);
   }
 
   __ Add(scratch, string, SeqTwoByteString::kHeaderSize - kHeapObjectTag);
   __ SmiUntag(value);
   __ SmiUntag(index);
   __ Strh(value, MemOperand(scratch, index, LSL, 1));
   context()->Plug(string);
 }
 
 
@@ skipping 1753 matching lines @@
   return previous_;
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_A64