[SimplifyCFG] Make use of ComputeMinSignedBits and KnownBits::getBitWidth. NFC

1 files changed, 3 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 1046998..02bd0bd 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -4935,14 +4935,12 @@ static bool eliminateDeadSwitchCases(SwitchInst *SI, DomTreeUpdater *DTU,
                                      AssumptionCache *AC,
                                      const DataLayout &DL) {
   Value *Cond = SI->getCondition();
-  unsigned Bits = Cond->getType()->getIntegerBitWidth();
   KnownBits Known = computeKnownBits(Cond, DL, 0, AC, SI);
 
   // We can also eliminate cases by determining that their values are outside of
   // the limited range of the condition based on how many significant (non-sign)
   // bits are in the condition value.
-  unsigned ExtraSignBits = ComputeNumSignBits(Cond, DL, 0, AC, SI) - 1;
-  unsigned MaxSignificantBitsInCond = Bits - ExtraSignBits;
+  unsigned MaxSignificantBitsInCond = ComputeMinSignedBits(Cond, DL, 0, AC, SI);
 
   // Gather dead cases.
   SmallVector<ConstantInt *, 8> DeadCases;
@@ -4973,8 +4971,8 @@ static bool eliminateDeadSwitchCases(SwitchInst *SI, DomTreeUpdater *DTU,
   bool HasDefault =
       !isa<UnreachableInst>(SI->getDefaultDest()->getFirstNonPHIOrDbg());
   const unsigned NumUnknownBits =
-      Bits - (Known.Zero | Known.One).countPopulation();
-  assert(NumUnknownBits <= Bits);
+      Known.getBitWidth() - (Known.Zero | Known.One).countPopulation();
+  assert(NumUnknownBits <= Known.getBitWidth());
   if (HasDefault && DeadCases.empty() &&
       NumUnknownBits < 64 /* avoid overflow */ &&
       SI->getNumCases() == (1ULL << NumUnknownBits)) {