A64: Improve constraints on StoreKeyed instructions

src/a64/lithium-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 5041 matching lines @@
         UNREACHABLE();
         break;
     }
   }
 }
 
 
 void LCodeGen::DoStoreKeyedFixedDouble(LStoreKeyedFixedDouble* instr) {
   Register elements = ToRegister(instr->elements());
   DoubleRegister value = ToDoubleRegister(instr->value());
-  Register store_base = ToRegister(instr->temp());
+  Register store_base = no_reg;
   int offset = 0;
 
   if (instr->key()->IsConstantOperand()) {
     int constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
     if (constant_key & 0xf0000000) {
       Abort(kArrayIndexConstantValueTooBig);
     }
     offset = FixedDoubleArray::OffsetOfElementAt(constant_key +
                                                  instr->additional_index());
     store_base = elements;
   } else {
+    store_base = ToRegister(instr->temp());
     Register key = ToRegister(instr->key());
     bool key_is_tagged = instr->hydrogen()->key()->representation().IsSmi();
     CalcKeyedArrayBaseRegister(store_base, elements, key, key_is_tagged,
                                instr->hydrogen()->elements_kind());
     offset = FixedDoubleArray::OffsetOfElementAt(instr->additional_index());
   }
 
   if (instr->NeedsCanonicalization()) {
     DoubleRegister dbl_scratch = double_scratch();
     __ Fmov(dbl_scratch,
             FixedDoubleArray::canonical_not_the_hole_nan_as_double());
     __ Fmaxnm(dbl_scratch, dbl_scratch, value);
     __ Str(dbl_scratch, FieldMemOperand(store_base, offset));
   } else {
     __ Str(value, FieldMemOperand(store_base, offset));
   }
 }
 
 
 void LCodeGen::DoStoreKeyedFixed(LStoreKeyedFixed* instr) {
   Register value = ToRegister(instr->value());
   Register elements = ToRegister(instr->elements());
-  Register store_base = ToRegister(instr->temp());
+  Register scratch = no_reg;
+  Register store_base = no_reg;
   Register key = no_reg;
   int offset = 0;
 
+  if (!instr->key()->IsConstantOperand() ||
+      instr->hydrogen()->NeedsWriteBarrier()) {
+    scratch = ToRegister(instr->temp());
+  }
+
   if (instr->key()->IsConstantOperand()) {
-    ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
     LConstantOperand* const_operand = LConstantOperand::cast(instr->key());
     offset = FixedArray::OffsetOfElementAt(ToInteger32(const_operand) +
                                            instr->additional_index());
     store_base = elements;
   } else {
+    store_base = scratch;
     key = ToRegister(instr->key());
     bool key_is_tagged = instr->hydrogen()->key()->representation().IsSmi();
     CalcKeyedArrayBaseRegister(store_base, elements, key, key_is_tagged,
                                instr->hydrogen()->elements_kind());
     offset = FixedArray::OffsetOfElementAt(instr->additional_index());
   }
   Representation representation = instr->hydrogen()->value()->representation();
   if (representation.IsInteger32()) {
     ASSERT(instr->hydrogen()->store_mode() == STORE_TO_INITIALIZED_ENTRY);
     ASSERT(instr->hydrogen()->elements_kind() == FAST_SMI_ELEMENTS);
     STATIC_ASSERT(kSmiValueSize == 32 && kSmiShift == 32 && kSmiTag == 0);
     __ Store(value, UntagSmiFieldMemOperand(store_base, offset),
              Representation::Integer32());
   } else {
     __ Store(value, FieldMemOperand(store_base, offset), representation);
   }
 
   if (instr->hydrogen()->NeedsWriteBarrier()) {
+    ASSERT(representation.IsTagged());
+    // This assignment may cause element_addr to alias store_base.
+    Register element_addr = scratch;
     SmiCheck check_needed =
         instr->hydrogen()->value()->IsHeapObject()
             ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     // Compute address of modified element and store it into key register.
-    __ Add(key, store_base, offset - kHeapObjectTag);
-    __ RecordWrite(elements, key, value, GetLinkRegisterState(), kSaveFPRegs,
-                   EMIT_REMEMBERED_SET, check_needed);
+    __ Add(element_addr, store_base, offset - kHeapObjectTag);
+    __ RecordWrite(elements, element_addr, value, GetLinkRegisterState(),
+                   kSaveFPRegs, EMIT_REMEMBERED_SET, check_needed);
   }
 }
 
 
 void LCodeGen::DoStoreKeyedGeneric(LStoreKeyedGeneric* instr) {
   ASSERT(ToRegister(instr->context()).is(cp));
   ASSERT(ToRegister(instr->object()).Is(x2));
   ASSERT(ToRegister(instr->key()).Is(x1));
   ASSERT(ToRegister(instr->value()).Is(x0));
 
@@ skipping 659 matching lines @@
   __ Bind(&out_of_object);
   __ Ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
   // Index is equal to negated out of object property index plus 1.
   __ Sub(result, result, Operand::UntagSmiAndScale(index, kPointerSizeLog2));
   __ Ldr(result, FieldMemOperand(result,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ Bind(&done);
 }
 
 } }  // namespace v8::internal