[turbofan] Change TruncateFloat64ToUint64 to TryTruncateFloatToUint64.

src/compiler/arm64/code-generator-arm64.cc

 // Copyright 2014 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/compiler/code-generator.h"
 
 #include "src/arm64/frames-arm64.h"
 #include "src/arm64/macro-assembler-arm64.h"
 #include "src/ast/scopes.h"
 #include "src/compiler/code-generator-impl.h"
@@ skipping 1034 matching lines @@
         __ Ccmp(i.OutputRegister(0), -1, VFlag, vc);
         __ Fccmp(i.InputDoubleRegister(0), i.InputDoubleRegister(0), VFlag, vc);
         __ Cset(i.OutputRegister(1), vc);
       }
       break;
     case kArm64Float32ToUint64:
       __ Fcvtzu(i.OutputRegister64(), i.InputFloat32Register(0));
       break;
     case kArm64Float64ToUint64:
       __ Fcvtzu(i.OutputRegister64(), i.InputDoubleRegister(0));
+      if (i.OutputCount() > 1) {
+        Label done;
+        __ Fcmp(i.InputDoubleRegister(0), 0.0);
+        __ Cset(i.OutputRegister(1), ge);

[martyn.capewell, 2015/12/07 16:10:34]

You should be able to use conditional compare again here:

if (i.OutputCount() > 1) {
  __ Fcmp(i.InputDoubleRegister(0), 0.0);
  __ CCmp(i.OutputRegister(0), -1, ZFlag, ge);
  __ Cset(i.OutputRegister(1), ne);
}

[ahaas, 2015/12/07 17:03:03]

Done

+        __ B(lt, &done);
+        __ Cmp(i.OutputRegister(0), -1);
+        __ Cset(i.OutputRegister(1), ne);
+        __ Bind(&done);
+      }
       break;
     case kArm64Int32ToFloat64:
       __ Scvtf(i.OutputDoubleRegister(), i.InputRegister32(0));
       break;
     case kArm64Int64ToFloat32:
       __ Scvtf(i.OutputDoubleRegister().S(), i.InputRegister64(0));
       break;
     case kArm64Int64ToFloat64:
       __ Scvtf(i.OutputDoubleRegister(), i.InputRegister64(0));
       break;
@@ skipping 536 matching lines @@
       padding_size -= kInstructionSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8