[ValueTracking] Remove unnecessary temporary APInt from computeNumSignBitsVectorConstant.

We can just use getNumSignBits instead of inverting negative numbers.

llvm-svn: 316266

1 files changed, 1 insertions, 5 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 244bc7d..182377d 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -2097,11 +2097,7 @@ static unsigned computeNumSignBitsVectorConstant(const Value *V,
     if (!Elt)
       return 0;
 
-    // If the sign bit is 1, flip the bits, so we always count leading zeros.
-    APInt EltVal = Elt->getValue();
-    if (EltVal.isNegative())
-      EltVal = ~EltVal;
-    MinSignBits = std::min(MinSignBits, EltVal.countLeadingZeros());
+    MinSignBits = std::min(MinSignBits, Elt->getValue().getNumSignBits());
   }
 
   return MinSignBits;