Add countTrailingOnes member functions to APInt.

llvm-svn: 47086

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/Support/APInt.cpp b/llvm/lib/Support/APInt.cpp
index 88f32810d67..c8482e9c719 100644
--- a/llvm/lib/Support/APInt.cpp
+++ b/llvm/lib/Support/APInt.cpp
@@ -813,6 +813,18 @@ uint32_t APInt::countTrailingZeros() const {
   return std::min(Count, BitWidth);
 }
 
+uint32_t APInt::countTrailingOnes() const {
+  if (isSingleWord())
+    return std::min(uint32_t(CountTrailingOnes_64(VAL)), BitWidth);
+  uint32_t Count = 0;
+  uint32_t i = 0;
+  for (; i < getNumWords() && pVal[i] == -1; ++i)
+    Count += APINT_BITS_PER_WORD;
+  if (i < getNumWords())
+    Count += CountTrailingOnes_64(pVal[i]);
+  return std::min(Count, BitWidth);
+}
+
 uint32_t APInt::countPopulation() const {
   if (isSingleWord())
     return CountPopulation_64(VAL);