Fixed deopt reasons in TaggedToI.

src/mips64/lithium-codegen-mips64.cc

Index: src/mips64/lithium-codegen-mips64.cc
diff --git a/src/mips64/lithium-codegen-mips64.cc b/src/mips64/lithium-codegen-mips64.cc
index b50d7c266df5a1472ffda325b426054d2d226c04..1a3d8fb62812749419bca06a14f71aa0b6353a90 100644
--- a/src/mips64/lithium-codegen-mips64.cc
+++ b/src/mips64/lithium-codegen-mips64.cc
@@ -4973,11 +4973,12 @@ void LCodeGen::DoDeferredTaggedToI(LTaggedToI* instr) {
 
     __ bind(&check_false);
     __ LoadRoot(at, Heap::kFalseValueRootIndex);
+    __ RecordComment("Deferred TaggedToI: cannot truncate");
     DeoptimizeIf(ne, instr->environment(), scratch2, Operand(at));
     __ Branch(USE_DELAY_SLOT, &done);
     __ mov(input_reg, zero_reg);  // In delay slot.
   } else {
-    // Deoptimize if we don't have a heap number.
+    __ RecordComment("Deferred TaggedToI: not a heap number");
     DeoptimizeIf(ne, instr->environment(), scratch1, Operand(at));
 
     // Load the double value.
@@ -4993,7 +4994,7 @@ void LCodeGen::DoDeferredTaggedToI(LTaggedToI* instr) {
                        except_flag,
                        kCheckForInexactConversion);
 
-    // Deopt if the operation did not succeed.
+    __ RecordComment("Deferred TaggedToI: lost precision or NaN");
     DeoptimizeIf(ne, instr->environment(), except_flag, Operand(zero_reg));
 
     if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
@@ -5001,6 +5002,7 @@ void LCodeGen::DoDeferredTaggedToI(LTaggedToI* instr) {
 
       __ mfhc1(scratch1, double_scratch);  // Get exponent/sign bits.
       __ And(scratch1, scratch1, Operand(HeapNumber::kSignMask));
+      __ RecordComment("Deferred TaggedToI: minus zero");
       DeoptimizeIf(ne, instr->environment(), scratch1, Operand(zero_reg));
     }
   }