Teach ScalarEvolution to simplify smax and umax when it can prove
that one operand is always greater than another.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101142 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 307c83a..a9a444f 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -2117,7 +2117,13 @@
// so, delete one. Since we sorted the list, these values are required to
// be adjacent.
for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
- if (Ops[i] == Ops[i+1]) { // X smax Y smax Y --> X smax Y
+ // X smax Y smax Y --> X smax Y
+ // X smax Y --> X, if X is always greater than Y
+ if (Ops[i] == Ops[i+1] ||
+ isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) {
+ Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
+ --i; --e;
+ } else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) {
Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
--i; --e;
}
@@ -2216,7 +2222,13 @@
// so, delete one. Since we sorted the list, these values are required to
// be adjacent.
for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
- if (Ops[i] == Ops[i+1]) { // X umax Y umax Y --> X umax Y
+ // X umax Y umax Y --> X umax Y
+ // X umax Y --> X, if X is always greater than Y
+ if (Ops[i] == Ops[i+1] ||
+ isKnownPredicate(ICmpInst::ICMP_UGE, Ops[i], Ops[i+1])) {
+ Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
+ --i; --e;
+ } else if (isKnownPredicate(ICmpInst::ICMP_ULE, Ops[i], Ops[i+1])) {
Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
--i; --e;
}