Fix optimized Math.pow on x64 with NaN exponents.

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2013, 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"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 4210 matching lines @@
     // if (base == 1.0) return 1.0;
     // if (base.isNaN || exponent.isNaN) {
     //    return double.NAN;
     // }
     XmmRegister base = locs()->in(0).fpu_reg();
     XmmRegister exp = locs()->in(1).fpu_reg();
     XmmRegister result = locs()->out().fpu_reg();
     Register temp = locs()->temp(0).reg();
     XmmRegister zero_temp = locs()->temp(1).fpu_reg();
 
-    Label check_base_is_one;
     // Check if exponent is 0.0 -> return 1.0;
     __ LoadObject(temp, Double::ZoneHandle(Double::NewCanonical(0)), PP);
     __ movsd(zero_temp, FieldAddress(temp, Double::value_offset()));
     __ LoadObject(temp, Double::ZoneHandle(Double::NewCanonical(1)), PP);
     __ movsd(result, FieldAddress(temp, Double::value_offset()));
     // 'result' contains 1.0.
+    Label exp_is_nan;
     __ comisd(exp, zero_temp);
-    __ j(PARITY_EVEN, &check_base_is_one, Assembler::kNearJump);  // NaN.
+    __ j(PARITY_EVEN, &exp_is_nan, Assembler::kNearJump);  // NaN.
     __ j(EQUAL, &skip_call, Assembler::kNearJump);  // exp is 0, result is 1.0.
 
     Label base_is_nan;
-    __ Bind(&check_base_is_one);
     // Checks if base == 1.0.
     __ comisd(base, result);
     __ j(PARITY_EVEN, &base_is_nan, Assembler::kNearJump);
     __ j(EQUAL, &skip_call, Assembler::kNearJump);  // base and result are 1.0
     __ jmp(&do_call, Assembler::kNearJump);
 
     __ Bind(&base_is_nan);
     // Returns NaN.
     __ movsd(result, base);
     __ jmp(&skip_call, Assembler::kNearJump);
-    // exp is Nan case is handled correctly in the C-library.
+
+    __ Bind(&exp_is_nan);
+    // Checks if base == 1.0.
+    __ comisd(base, result);
+    __ j(PARITY_EVEN, &base_is_nan, Assembler::kNearJump);
+    __ j(EQUAL, &skip_call, Assembler::kNearJump);  // base and result are 1.0
+    __ movsd(result, exp);  // result is NaN
+    __ jmp(&skip_call, Assembler::kNearJump);
   }
   __ Bind(&do_call);
   __ CallRuntime(TargetFunction(), InputCount());
   __ movaps(locs()->out().fpu_reg(), XMM0);
   __ Bind(&skip_call);
   __ leave();
 }
 
 
 LocationSummary* PolymorphicInstanceCallInstr::MakeLocationSummary() const {
@@ skipping 571 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64