ARM64: Small optimisations

src/arm64/macro-assembler-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "bootstrapper.h"
 #include "codegen.h"
@@ skipping 2325 matching lines @@
 }
 
 
 void MacroAssembler::JumpIfMinusZero(DoubleRegister input,
                                      Label* on_negative_zero) {
   TestForMinusZero(input);
   B(vs, on_negative_zero);
 }
 
 
+void MacroAssembler::JumpIfMinusZero(Register input,
+                                     Label* on_negative_zero) {
+  ASSERT(input.Is64Bits());
+  // Floating point value is in an integer register. Detect -0.0 by subtracting
+  // 1 (cmp), which will cause overflow.
+  Cmp(input, 1);
+  B(vs, on_negative_zero);
+}
+
+
 void MacroAssembler::ClampInt32ToUint8(Register output, Register input) {
   // Clamp the value to [0..255].
   Cmp(input.W(), Operand(input.W(), UXTB));
   // If input < input & 0xff, it must be < 0, so saturate to 0.
   Csel(output.W(), wzr, input.W(), lt);
   // If input <= input & 0xff, it must be <= 255. Otherwise, saturate to 255.
   Csel(output.W(), output.W(), 255, le);
 }
 
 
@@ skipping 2906 matching lines @@
   }
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64