[FixIrreducible][NewPM] Port -fix-irreducible to NPM

[aeubanks]

Summary

In the NPM, a pass cannot depend on another non-analysis pass. So pin
the test that tests that -lowerswitch is run automatically to legacy PM.

[sameerds]

LGTM. Thanks!

llvm/include/llvm/Transforms/Utils/FixIrreducible.h

+//===- FixIrreducible.h - Convert irreducible control-flow into loops -----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_FIXIRREDUCIBLE_H
+#define LLVM_TRANSFORMS_UTILS_FIXIRREDUCIBLE_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+struct FixIrreduciblePass : PassInfoMixin<FixIrreduciblePass> {
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+} // namespace llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_FIXIRREDUCIBLE_H

llvm/lib/Passes/PassBuilder.cpp

 #include "llvm/Transforms/Scalar/TailRecursionElimination.h"
 #include "llvm/Transforms/Scalar/WarnMissedTransforms.h"
 #include "llvm/Transforms/Utils/AddDiscriminators.h"
 #include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
 #include "llvm/Transforms/Utils/BreakCriticalEdges.h"
 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
 #include "llvm/Transforms/Utils/CanonicalizeFreezeInLoops.h"
 #include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
+#include "llvm/Transforms/Utils/FixIrreducible.h"
 #include "llvm/Transforms/Utils/InjectTLIMappings.h"
 #include "llvm/Transforms/Utils/LCSSA.h"
 #include "llvm/Transforms/Utils/LibCallsShrinkWrap.h"
 #include "llvm/Transforms/Utils/LoopSimplify.h"
 #include "llvm/Transforms/Utils/LoopVersioning.h"
 #include "llvm/Transforms/Utils/LowerInvoke.h"
 #include "llvm/Transforms/Utils/LowerSwitch.h"
 #include "llvm/Transforms/Utils/Mem2Reg.h"

llvm/lib/Passes/PassRegistry.def

 FUNCTION_PASS("dce", DCEPass())
 FUNCTION_PASS("div-rem-pairs", DivRemPairsPass())
 FUNCTION_PASS("dse", DSEPass())
 FUNCTION_PASS("dot-cfg", CFGPrinterPass())
 FUNCTION_PASS("dot-cfg-only", CFGOnlyPrinterPass())
 FUNCTION_PASS("early-cse", EarlyCSEPass(/*UseMemorySSA=*/false))
 FUNCTION_PASS("early-cse-memssa", EarlyCSEPass(/*UseMemorySSA=*/true))
 FUNCTION_PASS("ee-instrument", EntryExitInstrumenterPass(/*PostInlining=*/false))
+FUNCTION_PASS("fix-irreducible", FixIrreduciblePass())
 FUNCTION_PASS("make-guards-explicit", MakeGuardsExplicitPass())
 FUNCTION_PASS("post-inline-ee-instrument", EntryExitInstrumenterPass(/*PostInlining=*/true))
 FUNCTION_PASS("gvn-hoist", GVNHoistPass())
 FUNCTION_PASS("gvn-sink", GVNSinkPass())
 FUNCTION_PASS("helloworld", HelloWorldPass())
 FUNCTION_PASS("instcombine", InstCombinePass())
 FUNCTION_PASS("instcount", InstCountPass())
 FUNCTION_PASS("instsimplify", InstSimplifyPass())

llvm/lib/Transforms/Utils/FixIrreducible.cpp

 // above handling of PHINodes is sufficient and no further processing is
 // required to restore SSA.
 //
 // Limitation: The pass cannot handle switch statements and indirect
 //             branches. Both must be lowered to plain branches first.
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/Utils/FixIrreducible.h"
 #include "llvm/ADT/SCCIterator.h"
 #include "llvm/Analysis/LoopIterator.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
 #include "llvm/Transforms/Utils.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 
 #define DEBUG_TYPE "fix-irreducible"
if (Headers.size() == 1) {
       continue;
     }
     createNaturalLoop(LI, DT, G, Blocks, Headers);
     Changed = true;
   }
   return Changed;
 }
 
-bool FixIrreducible::runOnFunction(Function &F) {
+static bool FixIrreducibleImpl(Function &F, LoopInfo &LI, DominatorTree &DT) {
   LLVM_DEBUG(dbgs() << "===== Fix irreducible control-flow in function: "
                     << F.getName() << "\n");
-  auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
-  auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
 
   bool Changed = false;
   SmallVector<Loop *, 8> WorkList;
 
   LLVM_DEBUG(dbgs() << "visiting top-level\n");
   Changed |= makeReducible(LI, DT, &F);
 
   // Any SCCs reduced are now already in the list of top-level loops, so simply
while (!WorkList.empty()) {
     Changed |= makeReducible(LI, DT, *L);
     // Any SCCs reduced are now already in the list of child loops, so simply
     // add them all to the worklist.
     WorkList.append(L->begin(), L->end());
   }
 
   return Changed;
 }
+
+bool FixIrreducible::runOnFunction(Function &F) {
+  auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+  auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+  return FixIrreducibleImpl(F, LI, DT);
+}
+
+PreservedAnalyses FixIrreduciblePass::run(Function &F,
+                                          FunctionAnalysisManager &AM) {
+  auto &LI = AM.getResult<LoopAnalysis>(F);
+  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
+  if (!FixIrreducibleImpl(F, LI, DT))
+    return PreservedAnalyses::all();
+  PreservedAnalyses PA;
+  PA.preserve<LoopAnalysis>();
+  PA.preserve<DominatorTreeAnalysis>();
+  return PA;
+}

llvm/test/Transforms/FixIrreducible/basic.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -fix-irreducible -S | FileCheck %s -check-prefix=CHECK
+; RUN: opt < %s -passes=fix-irreducible -S | FileCheck %s -check-prefix=CHECK
 
 define i32 @basic(i1 %PredEntry, i1 %PredLeft, i1 %PredRight, i32 %X, i32 %Y) {
 ; CHECK-LABEL: @basic(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[IRR_GUARD:%.*]]
 ; CHECK:       left:
 ; CHECK-NEXT:    [[L:%.*]] = add i32 [[L_PHI_MOVED:%.*]], 1
 ; CHECK-NEXT:    br i1 [[PREDLEFT:%.*]], label [[IRR_GUARD]], label [[EXIT:%.*]]

llvm/test/Transforms/FixIrreducible/switch.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -fix-irreducible -S | FileCheck %s
+; RUN: opt < %s -fix-irreducible -enable-new-pm=0 -S | FileCheck %s
 
 define void @loop_1(i32 %Value, i1 %PredEntry, i1 %PredD) {
 ; CHECK-LABEL: @loop_1(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[IRR_GUARD:%.*]]
 ; CHECK:       A:
 ; CHECK-NEXT:    br label [[IRR_GUARD]]
 ; CHECK:       B: