// FIXME: THREADING will delete values that are just used to compute the
// branch, so they shouldn't count against the duplication cost.
+ unsigned Bonus = 0;
+ const TerminatorInst *BBTerm = BB->getTerminator();
+ // Threading through a switch statement is particularly profitable. If this
+ // block ends in a switch, decrease its cost to make it more likely to happen.
+ if (isa<SwitchInst>(BBTerm))
+ Bonus = 6;
+
+ // The same holds for indirect branches, but slightly more so.
+ if (isa<IndirectBrInst>(BBTerm))
+ Bonus = 8;
+
+ // Bump the threshold up so the early exit from the loop doesn't skip the
+ // terminator-based Size adjustment at the end.
+ Threshold += Bonus;
+
// Sum up the cost of each instruction until we get to the terminator. Don't
// include the terminator because the copy won't include it.
unsigned Size = 0;
}
}
- // Threading through a switch statement is particularly profitable. If this
- // block ends in a switch, decrease its cost to make it more likely to happen.
- if (isa<SwitchInst>(I))
- Size = Size > 6 ? Size-6 : 0;
-
- // The same holds for indirect branches, but slightly more so.
- if (isa<IndirectBrInst>(I))
- Size = Size > 8 ? Size-8 : 0;
-
- return Size;
+ return Size > Bonus ? Size - Bonus : 0;
}
/// FindLoopHeaders - We do not want jump threading to turn proper loop