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

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.

Reviewed By: sameerds

Differential Revision: https://reviews.llvm.org/D89051

include/llvm/Transforms/Utils/FixIrreducible.h

@@ -0,0 +1,20 @@
+//===- 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

lib/Passes/PassBuilder.cpp

@@ -196,6 +196,7 @@
 #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"

lib/Passes/PassRegistry.def

@@ -205,6 +205,7 @@ 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())

lib/Transforms/Utils/FixIrreducible.cpp

@@ -66,6 +66,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/Utils/FixIrreducible.h"
 #include "llvm/ADT/SCCIterator.h"
 #include "llvm/Analysis/LoopIterator.h"
 #include "llvm/InitializePasses.h"
@@ -304,11 +305,9 @@ static bool makeReducible(LoopInfo &LI, DominatorTree &DT, Graph &&G) {
   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;
@@ -335,3 +334,21 @@ bool FixIrreducible::runOnFunction(Function &F) {
 
   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;
+}

test/Transforms/FixIrreducible/basic.ll

@@ -1,5 +1,6 @@
 ; 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(

test/Transforms/FixIrreducible/switch.ll

@@ -1,5 +1,5 @@
 ; 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(