[ConstantRange] Split makeICmpRegion in two.
Summary:
This change splits `makeICmpRegion` into `makeAllowedICmpRegion` and
`makeSatisfyingICmpRegion` with slightly different contracts. The first
one is useful for determining what values some expression //may// take,
given that a certain `icmp` evaluates to true. The second one is useful
for determining what values are guaranteed to //satisfy// a given
`icmp`.
Reviewers: nlewycky
Reviewed By: nlewycky
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D8345
llvm-svn: 232575
diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index eec18b9..91095cf 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -49,14 +49,15 @@
"Lower == Upper, but they aren't min or max value!");
}
-ConstantRange ConstantRange::makeICmpRegion(unsigned Pred,
- const ConstantRange &CR) {
+ConstantRange ConstantRange::makeAllowedICmpRegion(CmpInst::Predicate Pred,
+ const ConstantRange &CR) {
if (CR.isEmptySet())
return CR;
uint32_t W = CR.getBitWidth();
switch (Pred) {
- default: llvm_unreachable("Invalid ICmp predicate to makeICmpRegion()");
+ default:
+ llvm_unreachable("Invalid ICmp predicate to makeAllowedICmpRegion()");
case CmpInst::ICMP_EQ:
return CR;
case CmpInst::ICMP_NE:
@@ -114,6 +115,16 @@
}
}
+ConstantRange ConstantRange::makeSatisfyingICmpRegion(CmpInst::Predicate Pred,
+ const ConstantRange &CR) {
+ // Follows from De-Morgan's laws:
+ //
+ // ~(~A union ~B) == A intersect B.
+ //
+ return makeAllowedICmpRegion(CmpInst::getInversePredicate(Pred), CR)
+ .inverse();
+}
+
/// isFullSet - Return true if this set contains all of the elements possible
/// for this data-type
bool ConstantRange::isFullSet() const {