Optimise Math.floor(x/y) to use integer division for specific divisor.

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
===================================================================
--- src/arm/macro-assembler-arm.cc	(revision 11426)
+++ src/arm/macro-assembler-arm.cc	(working copy)
@@ -3710,15 +3710,28 @@
 }
 
 
-bool AreAliased(Register r1, Register r2, Register r3, Register r4) {
-  if (r1.is(r2)) return true;
-  if (r1.is(r3)) return true;
-  if (r1.is(r4)) return true;
-  if (r2.is(r3)) return true;
-  if (r2.is(r4)) return true;
-  if (r3.is(r4)) return true;
-  return false;
+#ifdef DEBUG
+bool AreAliased(Register reg1,
+                Register reg2,
+                Register reg3,
+                Register reg4,
+                Register reg5,
+                Register reg6) {
+  int n_of_valid_regs = reg1.is_valid() + reg2.is_valid() +
+    reg3.is_valid() + reg4.is_valid() + reg5.is_valid() + reg6.is_valid();
+
+  RegList regs = 0;
+  if (reg1.is_valid()) regs |= reg1.bit();
+  if (reg2.is_valid()) regs |= reg2.bit();
+  if (reg3.is_valid()) regs |= reg3.bit();
+  if (reg4.is_valid()) regs |= reg4.bit();
+  if (reg5.is_valid()) regs |= reg5.bit();
+  if (reg6.is_valid()) regs |= reg6.bit();
+  int n_of_non_aliasing_regs = NumRegs(regs);
+
+  return n_of_valid_regs != n_of_non_aliasing_regs;
 }
+#endif
 
 
 CodePatcher::CodePatcher(byte* address, int instructions)