[llvm] Use llvm::bit_ceil instead of PowerOf2Ceil (NFC)

The arguments to PowerOf2Ceil in this patch are all known to be
nonzero, so we can safely use llvm::bit_ceil here.

Author: kazutakahirata

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -1040,7 +1040,7 @@ static SDValue combineShiftToAVG(SDValue Op, SelectionDAG &DAG,
   EVT VT = Op.getValueType();
   unsigned MinWidth =
       std::max<unsigned>(VT.getScalarSizeInBits() - KnownBits, 8);
-  EVT NVT = EVT::getIntegerVT(*DAG.getContext(), PowerOf2Ceil(MinWidth));
+  EVT NVT = EVT::getIntegerVT(*DAG.getContext(), llvm::bit_ceil(MinWidth));
   if (VT.isVector())
     NVT = EVT::getVectorVT(*DAG.getContext(), NVT, VT.getVectorElementCount());
   if (!TLI.isOperationLegalOrCustom(AVGOpc, NVT))

llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp

@@ -2137,7 +2137,7 @@ static int sizeToSubRegIndex(unsigned Size) {
       return AMDGPU::sub0;
     if (Size > 256)
       return -1;
-    return sizeToSubRegIndex(PowerOf2Ceil(Size));
+    return sizeToSubRegIndex(llvm::bit_ceil(Size));
   }
 }
 

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -37707,7 +37707,7 @@ X86TargetLowering::targetShrinkDemandedConstant(SDValue Op,
     return false;
 
   // Find the next power of 2 width, rounding up to a byte.
-  Width = PowerOf2Ceil(std::max(Width, 8U));
+  Width = llvm::bit_ceil(std::max(Width, 8U));
   // Truncate the width to size to handle illegal types.
   Width = std::min(Width, EltSize);