[turbofan] Change TruncateFloat64ToUint64 to TryTruncateFloatToUint64.

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

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index 43907951896b6d640c1d041a16320d026dc01890..b98b8b00e7b6c10e798626a07dc105275234a9d5 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -1052,6 +1052,15 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       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));