[crankshaft][arm][mips] Fix Math.min(0, 0)

src/crankshaft/mips64/lithium-codegen-mips64.cc

 // Copyright 2012 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 "src/crankshaft/mips64/lithium-codegen-mips64.h"
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/crankshaft/hydrogen-osr.h"
 #include "src/crankshaft/mips64/lithium-gap-resolver-mips64.h"
@@ skipping 1888 matching lines @@
     Label check_nan_left, check_zero, return_left, return_right, done;
     __ BranchF(&check_zero, &check_nan_left, eq, left_reg, right_reg);
     __ BranchF(&return_left, NULL, condition, left_reg, right_reg);
     __ Branch(&return_right);
 
     __ bind(&check_zero);
     // left == right != 0.
     __ BranchF(&return_left, NULL, ne, left_reg, kDoubleRegZero);
     // At this point, both left and right are either 0 or -0.
     if (operation == HMathMinMax::kMathMin) {
+      // The algorithm is: -((-L) + (-R)), which in case of L and R being
+      // different registers is most efficiently expressed as -((-L) - R).
       __ neg_d(left_reg, left_reg);
-      __ sub_d(result_reg, left_reg, right_reg);
+      if (left_reg.is(right_reg)) {
+        __ add_d(result_reg, left_reg, right_reg);
+      } else {
+        __ sub_d(result_reg, left_reg, right_reg);
+      }
       __ neg_d(result_reg, result_reg);
     } else {
       __ add_d(result_reg, left_reg, right_reg);
     }
     __ Branch(&done);
 
     __ bind(&check_nan_left);
     // left == NaN.
     __ BranchF(NULL, &return_left, eq, left_reg, left_reg);
     __ bind(&return_right);
@@ skipping 3852 matching lines @@
   __ Push(at, ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8