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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35313 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h
index b524b56e9b40be15d46f5ed7bf11bf733bd5fd1f..8f3b2f6a6d4421683a3925b2b4d8cbc78e82df83 100644 (file)
--- a/include/llvm/ADT/APInt.h
+++ b/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)