Make it illegal to set 0 bits in getHighBitsSet and getLowBitsSet. For that

they should have used the uint64_t constructor. This avoids causing
undefined results via shifts by the word size when the bit width is an
exact multiple of the word size.

llvm-svn: 35313

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/include/llvm/ADT/APInt.h b/llvm/include/llvm/ADT/APInt.h
index b524b56e9b4..8f3b2f6a6d4 100644
--- a/llvm/include/llvm/ADT/APInt.h
+++ b/llvm/include/llvm/ADT/APInt.h
@@ -355,6 +355,7 @@ public:
   /// @brief Get a value with high bits set
   static APInt getHighBitsSet(uint32_t numBits, uint32_t hiBitsSet) {
     assert(hiBitsSet <= numBits && "Too many bits to set!");
+    assert(hiBitsSet > 0 && "You must set SOME bits");
     uint32_t shiftAmt = numBits - hiBitsSet;
     // For small values, return quickly
     if (numBits <= APINT_BITS_PER_WORD)
@@ -368,6 +369,7 @@ public:
   /// @brief Get a value with low bits set
   static APInt getLowBitsSet(uint32_t numBits, uint32_t loBitsSet) {
     assert(loBitsSet <= numBits && "Too many bits to set!");
+    assert(loBitsSet > 0 && "You must set SOME bits");
     uint32_t shiftAmt = numBits - loBitsSet;
     // For small values, return quickly
     if (numBits <= APINT_BITS_PER_WORD)