[LegacyPM] Remove LowerGuardIntrinsicLegacyPass

[nikic]

@anna @apilipenko Do you need this legacy pass (i.e. used in codegen pipeline rather than late opt pipeline)?

[anna]

LGTM - we don't use the legacy pass pipeline. In fact, we're moving away from guard representation completely (not sure if anyone else downstream uses it though).

llvm/include/llvm/InitializePasses.h

 void initializeLoopSimplifyPass(PassRegistry&);
 void initializeLoopStrengthReducePass(PassRegistry&);
 void initializeLoopUnrollPass(PassRegistry&);
 void initializeLowerAtomicLegacyPassPass(PassRegistry&);
 void initializeLowerConstantIntrinsicsPass(PassRegistry&);
 void initializeLowerEmuTLSPass(PassRegistry&);
 void initializeLowerExpectIntrinsicPass(PassRegistry&);
 void initializeLowerGlobalDtorsLegacyPassPass(PassRegistry &);
-void initializeLowerGuardIntrinsicLegacyPassPass(PassRegistry&);
 void initializeLowerWidenableConditionLegacyPassPass(PassRegistry&);
 void initializeLowerIntrinsicsPass(PassRegistry&);
 void initializeLowerInvokeLegacyPassPass(PassRegistry&);
 void initializeLowerSwitchLegacyPassPass(PassRegistry &);
 void initializeKCFIPass(PassRegistry &);
 void initializeMIRAddFSDiscriminatorsPass(PassRegistry &);
 void initializeMIRCanonicalizerPass(PassRegistry &);
 void initializeMIRNamerPass(PassRegistry &);

llvm/include/llvm/Transforms/Scalar.h

 //===----------------------------------------------------------------------===//
 //
 // LowerAtomic - Lower atomic intrinsics to non-atomic form
 //
 Pass *createLowerAtomicPass();
 
 //===----------------------------------------------------------------------===//
 //
-// LowerGuardIntrinsic - Lower guard intrinsics to normal control flow.
-//
-Pass *createLowerGuardIntrinsicPass();
-
-//===----------------------------------------------------------------------===//
-//
 // LowerWidenableCondition - Lower widenable condition to i1 true.
 //
 Pass *createLowerWidenableConditionPass();
 
 //===----------------------------------------------------------------------===//
 //
 // MergeICmps - Merge integer comparison chains into a memcmp
 //

llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp

 #include "llvm/IR/Module.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/GuardUtils.h"
 
 using namespace llvm;
 
-namespace {
-struct LowerGuardIntrinsicLegacyPass : public FunctionPass {
-  static char ID;
-  LowerGuardIntrinsicLegacyPass() : FunctionPass(ID) {
-    initializeLowerGuardIntrinsicLegacyPassPass(
-        *PassRegistry::getPassRegistry());
-  }
-
-  bool runOnFunction(Function &F) override;
-};
-}
-
 static bool lowerGuardIntrinsic(Function &F) {
   // Check if we can cheaply rule out the possibility of not having any work to
   // do.
   auto *GuardDecl = F.getParent()->getFunction(
       Intrinsic::getName(Intrinsic::experimental_guard));
   if (!GuardDecl || GuardDecl->use_empty())
     return false;
 
static bool lowerGuardIntrinsic(Function &F) {
   for (auto *CI : ToLower) {
     makeGuardControlFlowExplicit(DeoptIntrinsic, CI, false);
     CI->eraseFromParent();
   }
 
   return true;
 }
 
-bool LowerGuardIntrinsicLegacyPass::runOnFunction(Function &F) {
-  return lowerGuardIntrinsic(F);
-}
-
-char LowerGuardIntrinsicLegacyPass::ID = 0;
-INITIALIZE_PASS(LowerGuardIntrinsicLegacyPass, "lower-guard-intrinsic",
-                "Lower the guard intrinsic to normal control flow", false,
-                false)
-
-Pass *llvm::createLowerGuardIntrinsicPass() {
-  return new LowerGuardIntrinsicLegacyPass();
-}
-
 PreservedAnalyses LowerGuardIntrinsicPass::run(Function &F,
                                                FunctionAnalysisManager &AM) {
   if (lowerGuardIntrinsic(F))
     return PreservedAnalyses::none();
 
   return PreservedAnalyses::all();
 }

llvm/lib/Transforms/Scalar/Scalar.cpp

void llvm::initializeScalarOpts(PassRegistry &Registry) {
   initializeLoopInstSimplifyLegacyPassPass(Registry);
   initializeLoopPredicationLegacyPassPass(Registry);
   initializeLoopRotateLegacyPassPass(Registry);
   initializeLoopStrengthReducePass(Registry);
   initializeLoopUnrollPass(Registry);
   initializeLowerAtomicLegacyPassPass(Registry);
   initializeLowerConstantIntrinsicsPass(Registry);
   initializeLowerExpectIntrinsicPass(Registry);
-  initializeLowerGuardIntrinsicLegacyPassPass(Registry);
   initializeLowerWidenableConditionLegacyPassPass(Registry);
   initializeMergeICmpsLegacyPassPass(Registry);
   initializeMergedLoadStoreMotionLegacyPassPass(Registry);
   initializeNaryReassociateLegacyPassPass(Registry);
   initializePartiallyInlineLibCallsLegacyPassPass(Registry);
   initializeReassociateLegacyPassPass(Registry);
   initializeRedundantDbgInstEliminationPass(Registry);
   initializeRegToMemLegacyPass(Registry);