1 files changed, 14 insertions, 1 deletions
diff --git a/llvm/include/llvm/Support/KnownBits.h b/llvm/include/llvm/Support/KnownBits.h
index 1f32760a6fd1..5ef0ba31f785 100644
--- a/llvm/include/llvm/Support/KnownBits.h
+++ b/llvm/include/llvm/Support/KnownBits.h
@@ -249,7 +249,17 @@ public:
       return countMinLeadingZeros();
     if (isNegative())
       return countMinLeadingOnes();
-    return 0;
+    // Every value has at least 1 sign bit.
+    return 1;
+  }
+
+  /// Returns the maximum number of bits needed to represent all possible
+  /// signed values with these known bits. This is the inverse of the minimum
+  /// number of known sign bits. Examples for bitwidth 5:
+  /// 110?? --> 4
+  /// 0000? --> 2
+  unsigned countMaxSignificantBits() const {
+    return getBitWidth() - countMinSignBits() + 1;
   }
 
   /// Returns the maximum number of trailing zero bits possible.
@@ -282,6 +292,9 @@ public:
     return getBitWidth() - Zero.countPopulation();
   }
 
+  /// Returns the maximum number of bits needed to represent all possible
+  /// unsigned values with these known bits. This is the inverse of the
+  /// minimum number of leading zeros.
   unsigned countMaxActiveBits() const {
     return getBitWidth() - countMinLeadingZeros();
   }