Fix a bug summing two full sets. The overflow checking doesn't handle sets as

large as the full set, only those one size smaller. Thanks to Daniel Dunbar
who found this bug using Klee!

llvm-svn: 75443

2 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/Support/ConstantRange.cpp b/llvm/lib/Support/ConstantRange.cpp
index 04a1b68e072..8bab5377952 100644
--- a/llvm/lib/Support/ConstantRange.cpp
+++ b/llvm/lib/Support/ConstantRange.cpp
@@ -533,6 +533,8 @@ ConstantRange
 ConstantRange::add(const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())
     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
+  if (isFullSet() || Other.isFullSet())
+    return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 
   APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
   APInt NewLower = getLower() + Other.getLower();
diff --git a/llvm/unittests/Support/ConstantRangeTest.cpp b/llvm/unittests/Support/ConstantRangeTest.cpp
index 891c209f11c..cd91a9e103c 100644
--- a/llvm/unittests/Support/ConstantRangeTest.cpp
+++ b/llvm/unittests/Support/ConstantRangeTest.cpp
@@ -239,6 +239,7 @@ TEST_F(ConstantRangeTest, SubtractAPInt) {
 
 TEST_F(ConstantRangeTest, Add) {
   EXPECT_TRUE(Full.add(APInt(16, 4)).isFullSet());
+  EXPECT_EQ(Full.add(Full), Full);
   EXPECT_EQ(Full.add(Empty), Empty);
   EXPECT_EQ(Full.add(One), Full);
   EXPECT_EQ(Full.add(Some), Full);