Fix APInt value initialization to give a zero value as any sane integer type

should, rather than giving a broken value that doesn't even zero/sign-extend
properly.

llvm-svn: 246836

2 files changed, 10 insertions, 2 deletions

diff --git a/llvm/include/llvm/ADT/APInt.h b/llvm/include/llvm/ADT/APInt.h
index ea67e7928a7..e2a0cb5e69d 100644
--- a/llvm/include/llvm/ADT/APInt.h
+++ b/llvm/include/llvm/ADT/APInt.h
@@ -294,11 +294,12 @@ public:
       delete[] pVal;
   }
 
-  /// \brief Default constructor that creates an uninitialized APInt.
+  /// \brief Default constructor that creates an uninteresting APInt
+  /// representing a 1-bit zero value.
   ///
   /// This is useful for object deserialization (pair this with the static
   ///  method Read).
-  explicit APInt() : BitWidth(1) {}
+  explicit APInt() : BitWidth(1), VAL(0) {}
 
   /// \brief Returns whether this instance allocated memory.
   bool needsCleanup() const { return !isSingleWord(); }
diff --git a/llvm/unittests/ADT/APIntTest.cpp b/llvm/unittests/ADT/APIntTest.cpp
index ffba7b16336..0002dad8555 100644
--- a/llvm/unittests/ADT/APIntTest.cpp
+++ b/llvm/unittests/ADT/APIntTest.cpp
@@ -17,6 +17,13 @@ using namespace llvm;
 
 namespace {
 
+TEST(APIntTest, ValueInit) {
+  APInt Zero = APInt();
+  EXPECT_TRUE(!Zero);
+  EXPECT_TRUE(!Zero.zext(64));
+  EXPECT_TRUE(!Zero.sext(64));
+}
+
 // Test that APInt shift left works when bitwidth > 64 and shiftamt == 0
 TEST(APIntTest, ShiftLeftByZero) {
   APInt One = APInt::getNullValue(65) + 1;