Actually, for getHighBitsSet and getLowBitsSet, don't make a 0 bit size

illegal. Instead do the 0 valued construction for the user. This is because
the caller may not know (or care to check) that the number of bits set is
zero.

llvm-svn: 35315

1 files changed, 6 insertions, 2 deletions

diff --git a/llvm/include/llvm/ADT/APInt.h b/llvm/include/llvm/ADT/APInt.h
index 8f3b2f6a6d4..7e5132f0d02 100644
--- a/llvm/include/llvm/ADT/APInt.h
+++ b/llvm/include/llvm/ADT/APInt.h
@@ -355,7 +355,9 @@ 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");
+    // Handle a degenerate case, to avoid shifting by word size
+    if (hiBitsSet == 0)
+      return APInt(numBits, 0);
     uint32_t shiftAmt = numBits - hiBitsSet;
     // For small values, return quickly
     if (numBits <= APINT_BITS_PER_WORD)
@@ -369,7 +371,9 @@ 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");
+    // Handle a degenerate case, to avoid shifting by word size
+    if (loBitsSet == 0)
+      return APInt(numBits, 0);
     uint32_t shiftAmt = numBits - loBitsSet;
     // For small values, return quickly
     if (numBits <= APINT_BITS_PER_WORD)