Optimize truncated divide (intrinsics and inline).

vm/opt_code_generator_ia32.cc

Index: vm/opt_code_generator_ia32.cc
===================================================================
--- vm/opt_code_generator_ia32.cc	(revision 2388)
+++ vm/opt_code_generator_ia32.cc	(working copy)
@@ -755,6 +755,7 @@
   if ((kind == Token::kADD) ||
       (kind == Token::kSUB) ||
       (kind == Token::kMUL) ||
+      (kind == Token::kTRUNCDIV) ||
       (kind == Token::kBIT_AND) ||
       (kind == Token::kBIT_OR) ||
       (kind == Token::kBIT_XOR)) {
@@ -858,6 +859,20 @@
         __ xorl(EAX, EDX);
         break;
       }
+      case Token::kTRUNCDIV: {
+        // Handle Divide by Zero elsewhere
+        __ cmpl(EDX, Immediate(0));
+        __ j(EQUAL, overflow_label);
+        // Move right to ECX, left is in EAX.
+        __ movl(ECX, EDX);
+        __ SmiUntag(ECX);
+        __ SmiUntag(EAX);
+        // Sign extend EAX -> EDX:EAX.
+        __ cdq();
+        __ idivl(ECX);
+        __ SmiTag(EAX);

[sra1, 2011/12/13 21:12:08]

MIN_SMI / -1 is not a Smi.

+        break;
+      }
       default:
         UNREACHABLE();
     }