Refactor implied condition logic from ValueTracking directly into CmpInst. NFC.
Differential Revision: http://reviews.llvm.org/D19330
llvm-svn: 266987
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index ac43eef..02005cf 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -3597,6 +3597,58 @@
}
}
+bool CmpInst::isTrueWhenOperandsMatch(Predicate Pred1, Predicate Pred2) {
+ // If the predicates match, then we know the first condition implies the
+ // second is true.
+ if (Pred1 == Pred2)
+ return true;
+
+ switch (Pred1) {
+ default:
+ break;
+ case ICMP_UGT: // A >u B implies A != B is true.
+ case ICMP_ULT: // A <u B implies A != B is true.
+ case ICMP_SGT: // A >s B implies A != B is true.
+ case ICMP_SLT: // A <s B implies A != B is true.
+ return Pred2 == ICMP_NE;
+ }
+ return false;
+}
+
+bool CmpInst::isFalseWhenOperandsMatch(Predicate Pred1, Predicate Pred2) {
+ // If an inverted Pred1 matches Pred2, we can infer the second condition is
+ // false.
+ if (getInversePredicate(Pred1) == Pred2)
+ return true;
+
+ // If a swapped Pred1 matches Pred2, we can infer the second condition is
+ // false in many cases.
+ if (getSwappedPredicate(Pred1) == Pred2) {
+ switch (Pred1) {
+ default:
+ break;
+ case ICMP_UGT: // A >u B implies A <u B is false.
+ case ICMP_ULT: // A <u B implies A >u B is false.
+ case ICMP_SGT: // A >s B implies A <s B is false.
+ case ICMP_SLT: // A <s B implies A >s B is false.
+ return true;
+ }
+ }
+ // A == B implies A > B and A < B are false.
+ if (Pred1 == ICMP_EQ && isFalseWhenEqual(Pred2))
+ return true;
+
+ switch (Pred1) {
+ default:
+ break;
+ case ICMP_UGT: // A >u B implies A == B is false.
+ case ICMP_ULT: // A <u B implies A == B is false.
+ case ICMP_SGT: // A >s B implies A == B is false.
+ case ICMP_SLT: // A <s B implies A == B is false.
+ return Pred2 == ICMP_EQ;
+ }
+ return false;
+}
//===----------------------------------------------------------------------===//
// SwitchInst Implementation