[llvm] [SelectionDAG] Optimize BSWAP yet again once more (PR #165292)

[via llvm-commits]

================
@@ -20157,28 +20174,28 @@ bool ARMTargetLowering::targetShrinkDemandedConstant(
 
   assert(VT == MVT::i32 && "Unexpected integer type");
 
+  // Exit early if we demand all bits.
+  if (DemandedBits.popcount() == 32)
----------------
AZero13 wrote:

@topperc is it literally a one line change: if I say it's not working it's because it doesn't compile.

I tried. With all due respect, I'm not dragging my feet for no reason.

https://github.com/llvm/llvm-project/pull/165292