Simplify [su]max(MAX, n) to MAX. This comes up in loop tripcount
computations in loops with multiple exits.
Adjust the testcase for PR4436 so that the relevant portion isn't
optimized away.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74073 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 3bbeb95..6ac6efa 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -1690,10 +1690,14 @@
LHSC = cast<SCEVConstant>(Ops[0]);
}
- // If we are left with a constant -inf, strip it off.
+ // If we are left with a constant minimum-int, strip it off.
if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) {
Ops.erase(Ops.begin());
--Idx;
+ } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(true)) {
+ // If we have an smax with a constant maximum-int, it will always be
+ // maximum-int.
+ return Ops[0];
}
}
@@ -1777,10 +1781,14 @@
LHSC = cast<SCEVConstant>(Ops[0]);
}
- // If we are left with a constant zero, strip it off.
+ // If we are left with a constant minimum-int, strip it off.
if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) {
Ops.erase(Ops.begin());
--Idx;
+ } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(false)) {
+ // If we have an umax with a constant maximum-int, it will always be
+ // maximum-int.
+ return Ops[0];
}
}