Recognize for (int i = 0; i != x.length; i++) loops
Rationale:
Idiom occurs in real-life and is very straightforwardly
recognized by existing induction/range machinery.
Change-Id: I965a16e9de72f3523ea5023d30ed1c4e47ed5010
diff --git a/compiler/optimizing/induction_var_range.cc b/compiler/optimizing/induction_var_range.cc
index b162696..f9b6910 100644
--- a/compiler/optimizing/induction_var_range.cc
+++ b/compiler/optimizing/induction_var_range.cc
@@ -216,6 +216,14 @@
}
}
} while (RefineOuter(&v_min, &v_max));
+ // Exploit array length + c >= c, with c <= 0 to avoid arithmetic wrap-around anomalies
+ // (e.g. array length == maxint and c == 1 would yield minint).
+ if (request == kAtLeast) {
+ if (v_min.a_constant == 1 && v_min.b_constant <= 0 && v_min.instruction->IsArrayLength()) {
+ *value = v_min.b_constant;
+ return true;
+ }
+ }
}
return false;
}