X87: Fixed flooring division by a power of 2, once again...

src/x87/lithium-codegen-x87.cc

Index: src/x87/lithium-codegen-x87.cc
===================================================================
--- src/x87/lithium-codegen-x87.cc	(revision 21827)
+++ src/x87/lithium-codegen-x87.cc	(working copy)
@@ -1546,14 +1546,17 @@
     DeoptimizeIf(zero, instr->environment());
   }
 
-  if (!instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
-    __ sar(dividend, shift);
+  // Dividing by -1 is basically negation, unless we overflow.
+  if (divisor == -1) {
+    if (instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
+      DeoptimizeIf(overflow, instr->environment());
+    }
     return;
   }
 
-  // Dividing by -1 is basically negation, unless we overflow.
-  if (divisor == -1) {
-    DeoptimizeIf(overflow, instr->environment());
+  // If the negation could not overflow, simply shifting is OK.
+  if (!instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
+    __ sar(dividend, shift);
     return;
   }