ADT: Correct APInt::getActiveWords for zero values
PR15138 was opened because of a segfault in the Bitcode writer.
The actual issue ended up being a bug in APInt where calls to
APInt::getActiveWords returns a bogus value when the APInt value
is 0. This patch fixes the problem by ensuring that getActiveWords
returns 1 for 0 valued APInts.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174641 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h
index e67e032..2e623a1 100644
--- a/include/llvm/ADT/APInt.h
+++ b/include/llvm/ADT/APInt.h
@@ -1191,7 +1191,8 @@
/// APInt. This is used in conjunction with getActiveData to extract the raw
/// value of the APInt.
unsigned getActiveWords() const {
- return whichWord(getActiveBits()-1) + 1;
+ unsigned numActiveBits = getActiveBits();
+ return numActiveBits ? whichWord(numActiveBits - 1) + 1 : 1;
}
/// Computes the minimum bit width for this APInt while considering it to be
diff --git a/unittests/ADT/APIntTest.cpp b/unittests/ADT/APIntTest.cpp
index 2a4c5b4..2510bc7 100644
--- a/unittests/ADT/APIntTest.cpp
+++ b/unittests/ADT/APIntTest.cpp
@@ -56,6 +56,14 @@
#endif
TEST(APIntTest, i65_Count) {
+ APInt i65(65, 0, true);
+ EXPECT_EQ(65u, i65.countLeadingZeros());
+ EXPECT_EQ(0u, i65.countLeadingOnes());
+ EXPECT_EQ(0u, i65.getActiveBits());
+ EXPECT_EQ(1u, i65.getActiveWords());
+ EXPECT_EQ(65u, i65.countTrailingZeros());
+ EXPECT_EQ(0u, i65.countPopulation());
+
APInt i65minus(65, 0, true);
i65minus.setBit(64);
EXPECT_EQ(0u, i65minus.countLeadingZeros());