Bug 1240055: IonMonkey: When spewing info about range analysis, also spew truncation info, r=nbp

js/src/jit/MIR.h

@@ -565,6 +565,21 @@ class MDefinition : public MNode
         Truncate = 3
     };
 
+    static const char * TruncateKindString(TruncateKind kind) {
+        switch(kind) {
+          case NoTruncate:
+            return "NoTruncate";
+          case TruncateAfterBailouts:
+            return "TruncateAfterBailouts";
+          case IndirectTruncate:
+            return "IndirectTruncate";
+          case Truncate:
+            return "Truncate";
+          default:
+            MOZ_CRASH("Unknown truncate kind.");
+        }
+    }
+
     // |needTruncation| records the truncation kind of the results, such that it
     // can be used to truncate the operands of this instruction.  If
     // |needTruncation| function returns true, then the |truncate| function is

js/src/jit/RangeAnalysis.cpp

@@ -123,6 +123,20 @@ SpewRange(MDefinition* def)
 #endif
 }
 
+static inline void
+SpewTruncate(MDefinition* def, MDefinition::TruncateKind kind, bool shouldClone)
+{
+#ifdef JS_JITSPEW
+    if (JitSpewEnabled(JitSpew_Range)) {
+        JitSpewHeader(JitSpew_Range);
+        Fprinter& out = JitSpewPrinter();
+        out.printf("truncating ");
+        def->printName(out);
+        out.printf(" (kind: %s, clone: %d)\n", MDefinition::TruncateKindString(kind), shouldClone);
+    }
+#endif
+}
+
 TempAllocator&
 RangeAnalysis::alloc() const
 {
@@ -3033,6 +3047,8 @@ RangeAnalysis::truncate()
             if (!iter->needTruncation(kind))
                 continue;
 
+            SpewTruncate(*iter, kind, shouldClone);
+
             // If needed, clone the current instruction for keeping it for the
             // bailout path.  This give us the ability to truncate instructions
             // even after the removal of branches.
@@ -3056,6 +3072,9 @@ RangeAnalysis::truncate()
             // Truncate this phi if possible.
             if (shouldClone || !iter->needTruncation(kind))
                 continue;
+
+            SpewTruncate(*iter, kind, shouldClone);
+
             iter->truncate();
 
             // Delay updates of inputs/outputs to avoid creating node which