Add signed/unsigned 8-bit and 16-bit Representations

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 206ab7e2accf5e496b6cd814eb1071c511cb21e7..fcbde391e47c65b7d74a997445a08c0c3ce88e22 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -2856,9 +2856,18 @@ Range* HShl::InferRange(Zone* zone) {
 
 
 Range* HLoadNamedField::InferRange(Zone* zone) {
-  if (access().representation().IsByte()) {
+  if (access().representation().IsInteger8()) {
+    return new(zone) Range(-128, 127);
+  }
+  if (access().representation().IsUInteger8()) {
     return new(zone) Range(0, 255);
   }
+  if (access().representation().IsInteger16()) {
+    return new(zone) Range(-16384, 16383);

[Yang, 2013/11/07 09:32:43]

Afaik signed integer goes from -2^15 to 2^15-1, which is -32768 to 32767.

I suggest introducing kMaxInt8, kMinInt8, etc. to globals.h and define them
either as -(1<<7) and (1<<7)-1 or -0x80 and 0x7f. 

[danno, 2013/11/07 13:19:57]

Done.

+  }
+  if (access().representation().IsUInteger16()) {
+    return new(zone) Range(0, 65535);

[Yang, 2013/11/07 09:32:43]

Same here. Using a constant would be better.

[danno, 2013/11/07 13:19:57]

Done.

+  }
   if (access().IsStringLength()) {
     return new(zone) Range(0, String::kMaxLength);
   }