Revert "[WebAssembly] Remove FAKE_USEs before ExplicitLocals" (llvm#160553)

Reverts llvm#160228
See
llvm#160228 (comment)

Author: dschuff

llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp

@@ -216,18 +216,6 @@ static MachineInstr *findStartOfTree(MachineOperand &MO,
   return Def;
 }
 
-// FAKE_USEs are no-ops, so remove them here so that the values used by them
-// will be correctly dropped later.
-static void removeFakeUses(MachineFunction &MF) {
-  SmallVector<MachineInstr *> ToDelete;
-  for (auto &MBB : MF)
-    for (auto &MI : MBB)
-      if (MI.isFakeUse())
-        ToDelete.push_back(&MI);
-  for (auto *MI : ToDelete)
-    MI->eraseFromParent();
-}
-
 bool WebAssemblyExplicitLocals::runOnMachineFunction(MachineFunction &MF) {
   LLVM_DEBUG(dbgs() << "********** Make Locals Explicit **********\n"
                        "********** Function: "
@@ -238,8 +226,6 @@ bool WebAssemblyExplicitLocals::runOnMachineFunction(MachineFunction &MF) {
   WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();
   const auto *TII = MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
 
-  removeFakeUses(MF);
-
   // Map non-stackified virtual registers to their local ids.
   DenseMap<unsigned, unsigned> Reg2Local;