Cleanup of class id loading sequences.

runtime/vm/stub_code_arm64.cc

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 1356 matching lines @@
   __ AddImmediate(R6, R6, Array::data_offset() - kHeapObjectTag, kNoPP);
   // R6: points directly to the first ic data array element.
 
   // Get the receiver's class ID (first read number of arguments from
   // arguments descriptor array and then access the receiver from the stack).
   __ LoadFieldFromOffset(R7, R4, ArgumentsDescriptor::count_offset(), kNoPP);
   __ SmiUntag(R7);  // Untag so we can use the LSL 3 addressing mode.
   __ sub(R7, R7, Operand(1));
 
   // R0 <- [SP + (R7 << 3)]
-  __ ldr(R0, Address(SP, R7, UXTX, Address::Scaled));
-  __ LoadTaggedClassIdMayBeSmi(R0, R0);
+  __ ldr(R1, Address(SP, R7, UXTX, Address::Scaled));
+  __ LoadTaggedClassIdMayBeSmi(R0, R1);
 
   // R7: argument_count - 1 (untagged).
   // R0: receiver's class ID (smi).
   __ ldr(R1, Address(R6));  // First class id (smi) to check.
   __ b(&test);
 
   __ Bind(&loop);
   for (int i = 0; i < num_args; i++) {
     if (i > 0) {
       // If not the first, load the next argument's class ID.
       __ AddImmediate(R0, R7, -i, kNoPP);
       // R0 <- [SP + (R0 << 3)]
-      __ ldr(R0, Address(SP, R0, UXTX, Address::Scaled));
-      __ LoadTaggedClassIdMayBeSmi(R0, R0);
+      __ ldr(R1, Address(SP, R0, UXTX, Address::Scaled));
+      __ LoadTaggedClassIdMayBeSmi(R0, R1);
       // R0: next argument class ID (smi).
       __ LoadFromOffset(R1, R6, i * kWordSize, kNoPP);
       // R1: next class ID to check (smi).
     }
     __ CompareRegisters(R0, R1);  // Class id match?
     if (i < (num_args - 1)) {
       __ b(&update, NE);  // Continue.
     } else {
       // Last check, all checks before matched.
       __ b(&found, EQ);  // Break.
     }
   }
   __ Bind(&update);
   // Reload receiver class ID.  It has not been destroyed when num_args == 1.
   if (num_args > 1) {
-    __ ldr(R0, Address(SP, R7, UXTX, Address::Scaled));
-    __ LoadTaggedClassIdMayBeSmi(R0, R0);
+    __ ldr(R1, Address(SP, R7, UXTX, Address::Scaled));
+    __ LoadTaggedClassIdMayBeSmi(R0, R1);
   }
 
   const intptr_t entry_size = ICData::TestEntryLengthFor(num_args) * kWordSize;
   __ AddImmediate(R6, R6, entry_size, kNoPP);  // Next entry.
   __ ldr(R1, Address(R6));  // Next class ID.
 
   __ Bind(&test);
   __ CompareImmediate(R1, Smi::RawValue(kIllegalCid), kNoPP);  // Done?
   __ b(&loop, NE);
 
@@ skipping 541 matching lines @@
   const Register right = R0;
   __ LoadFromOffset(left, SP, 1 * kWordSize, kNoPP);
   __ LoadFromOffset(right, SP, 0 * kWordSize, kNoPP);
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64