[StructurizeCFG][NewPM] Port -structurizecfg to NPM

This doesn't support -structurizecfg-skip-uniform-regions since that
would require porting LegacyDivergenceAnalysis.

The NPM doesn't support adding a non-analysis pass as a dependency of
another, so I had to add -lowerswitch to some tests or pin them to the
legacy PM.

This is the only RegionPass in tree, so I simply copied the logic for
finding all Regions from the legacy PM's RGManager into
StructurizeCFG::run().

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D89026

Author: aeubanks

llvm/include/llvm/InitializePasses.h

@@ -418,7 +418,7 @@ void initializeStripGCRelocatesLegacyPass(PassRegistry &);
 void initializeStripNonDebugSymbolsPass(PassRegistry&);
 void initializeStripNonLineTableDebugLegacyPassPass(PassRegistry &);
 void initializeStripSymbolsPass(PassRegistry&);
-void initializeStructurizeCFGPass(PassRegistry&);
+void initializeStructurizeCFGLegacyPassPass(PassRegistry &);
 void initializeTailCallElimPass(PassRegistry&);
 void initializeTailDuplicatePass(PassRegistry&);
 void initializeTargetLibraryInfoWrapperPassPass(PassRegistry&);

llvm/include/llvm/Transforms/Scalar/StructurizeCFG.h

@@ -0,0 +1,20 @@
+//===- StructurizeCFG.h ---------------------------------------------------===//
+//
+// 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_SCALAR_STRUCTURIZECFG_H
+#define LLVM_TRANSFORMS_SCALAR_STRUCTURIZECFG_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+struct StructurizeCFGPass : PassInfoMixin<StructurizeCFGPass> {
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+} // namespace llvm
+
+#endif // LLVM_TRANSFORMS_SCALAR_STRUCTURIZECFG_H

llvm/lib/Passes/PassBuilder.cpp

@@ -191,6 +191,7 @@
 #include "llvm/Transforms/Scalar/Sink.h"
 #include "llvm/Transforms/Scalar/SpeculateAroundPHIs.h"
 #include "llvm/Transforms/Scalar/SpeculativeExecution.h"
+#include "llvm/Transforms/Scalar/StructurizeCFG.h"
 #include "llvm/Transforms/Scalar/TailRecursionElimination.h"
 #include "llvm/Transforms/Scalar/WarnMissedTransforms.h"
 #include "llvm/Transforms/Utils/AddDiscriminators.h"

llvm/lib/Passes/PassRegistry.def

@@ -287,6 +287,7 @@ FUNCTION_PASS("speculative-execution", SpeculativeExecutionPass())
 FUNCTION_PASS("spec-phis", SpeculateAroundPHIsPass())
 FUNCTION_PASS("sroa", SROA())
 FUNCTION_PASS("strip-gc-relocates", StripGCRelocates())
+FUNCTION_PASS("structurizecfg", StructurizeCFGPass())
 FUNCTION_PASS("tailcallelim", TailCallElimPass())
 FUNCTION_PASS("unify-loop-exits", UnifyLoopExitsPass())
 FUNCTION_PASS("vector-combine", VectorCombinePass())

llvm/lib/Transforms/Scalar/Scalar.cpp

@@ -97,7 +97,7 @@ void llvm::initializeScalarOpts(PassRegistry &Registry) {
   initializeSCCPLegacyPassPass(Registry);
   initializeSROALegacyPassPass(Registry);
   initializeCFGSimplifyPassPass(Registry);
-  initializeStructurizeCFGPass(Registry);
+  initializeStructurizeCFGLegacyPassPass(Registry);
   initializeSimpleLoopUnswitchLegacyPassPass(Registry);
   initializeSinkingLegacyPassPass(Registry);
   initializeTailCallElimPass(Registry);

llvm/lib/Transforms/Scalar/StructurizeCFG.cpp

@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/Scalar/StructurizeCFG.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/SCCIterator.h"
@@ -28,6 +29,7 @@
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Metadata.h"
+#include "llvm/IR/PassManager.h"
 #include "llvm/IR/PatternMatch.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Use.h"
@@ -233,9 +235,8 @@ class NearestCommonDominator {
 /// while the true side continues the general flow. So the loop condition
 /// consist of a network of PHI nodes where the true incoming values expresses
 /// breaks and the false values expresses continue states.
-class StructurizeCFG : public RegionPass {
-  bool SkipUniformRegions;
 
+class StructurizeCFG {
   Type *Boolean;
   ConstantInt *BoolTrue;
   ConstantInt *BoolFalse;
@@ -244,7 +245,7 @@ class StructurizeCFG : public RegionPass {
   Function *Func;
   Region *ParentRegion;
 
-  LegacyDivergenceAnalysis *DA;
+  LegacyDivergenceAnalysis *DA = nullptr;
   DominatorTree *DT;
 
   SmallVector<RegionNode *, 8> Order;
@@ -308,20 +309,36 @@ class StructurizeCFG : public RegionPass {
 
   void rebuildSSA();
 
+public:
+  void init(Region *R);
+  bool run(Region *R, DominatorTree *DT);
+  bool makeUniformRegion(Region *R, LegacyDivergenceAnalysis *DA);
+};
+
+class StructurizeCFGLegacyPass : public RegionPass {
+  bool SkipUniformRegions;
+
 public:
   static char ID;
 
-  explicit StructurizeCFG(bool SkipUniformRegions_ = false)
-      : RegionPass(ID),
-        SkipUniformRegions(SkipUniformRegions_) {
+  explicit StructurizeCFGLegacyPass(bool SkipUniformRegions_ = false)
+      : RegionPass(ID), SkipUniformRegions(SkipUniformRegions_) {
     if (ForceSkipUniformRegions.getNumOccurrences())
       SkipUniformRegions = ForceSkipUniformRegions.getValue();
-    initializeStructurizeCFGPass(*PassRegistry::getPassRegistry());
+    initializeStructurizeCFGLegacyPassPass(*PassRegistry::getPassRegistry());
   }
 
-  bool doInitialization(Region *R, RGPassManager &RGM) override;
-
-  bool runOnRegion(Region *R, RGPassManager &RGM) override;
+  bool runOnRegion(Region *R, RGPassManager &RGM) override {
+    StructurizeCFG SCFG;
+    SCFG.init(R);
+    if (SkipUniformRegions) {
+      LegacyDivergenceAnalysis *DA = &getAnalysis<LegacyDivergenceAnalysis>();
+      if (SCFG.makeUniformRegion(R, DA))
+        return false;
+    }
+    DominatorTree *DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+    return SCFG.run(R, DT);
+  }
 
   StringRef getPassName() const override { return "Structurize control flow"; }
 
@@ -338,28 +355,16 @@ class StructurizeCFG : public RegionPass {
 
 } // end anonymous namespace
 
-char StructurizeCFG::ID = 0;
+char StructurizeCFGLegacyPass::ID = 0;
 
-INITIALIZE_PASS_BEGIN(StructurizeCFG, "structurizecfg", "Structurize the CFG",
-                      false, false)
+INITIALIZE_PASS_BEGIN(StructurizeCFGLegacyPass, "structurizecfg",
+                      "Structurize the CFG", false, false)
 INITIALIZE_PASS_DEPENDENCY(LegacyDivergenceAnalysis)
 INITIALIZE_PASS_DEPENDENCY(LowerSwitchLegacyPass)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(RegionInfoPass)
-INITIALIZE_PASS_END(StructurizeCFG, "structurizecfg", "Structurize the CFG",
-                    false, false)
-
-/// Initialize the types and constants used in the pass
-bool StructurizeCFG::doInitialization(Region *R, RGPassManager &RGM) {
-  LLVMContext &Context = R->getEntry()->getContext();
-
-  Boolean = Type::getInt1Ty(Context);
-  BoolTrue = ConstantInt::getTrue(Context);
-  BoolFalse = ConstantInt::getFalse(Context);
-  BoolUndef = UndefValue::get(Boolean);
-
-  return false;
-}
+INITIALIZE_PASS_END(StructurizeCFGLegacyPass, "structurizecfg",
+                    "Structurize the CFG", false, false)
 
 /// Build up the general order of nodes, by performing a topological sort of the
 /// parent region's nodes, while ensuring that there is no outer cycle node
@@ -1003,48 +1008,62 @@ static bool hasOnlyUniformBranches(Region *R, unsigned UniformMDKindID,
   return SubRegionsAreUniform || (ConditionalDirectChildren <= 1);
 }
 
-/// Run the transformation for each region found
-bool StructurizeCFG::runOnRegion(Region *R, RGPassManager &RGM) {
+void StructurizeCFG::init(Region *R) {
+  LLVMContext &Context = R->getEntry()->getContext();
+
+  Boolean = Type::getInt1Ty(Context);
+  BoolTrue = ConstantInt::getTrue(Context);
+  BoolFalse = ConstantInt::getFalse(Context);
+  BoolUndef = UndefValue::get(Boolean);
+
+  this->DA = nullptr;
+}
+
+bool StructurizeCFG::makeUniformRegion(Region *R,
+                                       LegacyDivergenceAnalysis *DA) {
   if (R->isTopLevelRegion())
     return false;
 
-  DA = nullptr;
-
-  if (SkipUniformRegions) {
-    // TODO: We could probably be smarter here with how we handle sub-regions.
-    // We currently rely on the fact that metadata is set by earlier invocations
-    // of the pass on sub-regions, and that this metadata doesn't get lost --
-    // but we shouldn't rely on metadata for correctness!
-    unsigned UniformMDKindID =
-        R->getEntry()->getContext().getMDKindID("structurizecfg.uniform");
-    DA = &getAnalysis<LegacyDivergenceAnalysis>();
-
-    if (hasOnlyUniformBranches(R, UniformMDKindID, *DA)) {
-      LLVM_DEBUG(dbgs() << "Skipping region with uniform control flow: " << *R
-                        << '\n');
-
-      // Mark all direct child block terminators as having been treated as
-      // uniform. To account for a possible future in which non-uniform
-      // sub-regions are treated more cleverly, indirect children are not
-      // marked as uniform.
-      MDNode *MD = MDNode::get(R->getEntry()->getParent()->getContext(), {});
-      for (RegionNode *E : R->elements()) {
-        if (E->isSubRegion())
-          continue;
-
-        if (Instruction *Term = E->getEntry()->getTerminator())
-          Term->setMetadata(UniformMDKindID, MD);
-      }
+  this->DA = DA;
+  // TODO: We could probably be smarter here with how we handle sub-regions.
+  // We currently rely on the fact that metadata is set by earlier invocations
+  // of the pass on sub-regions, and that this metadata doesn't get lost --
+  // but we shouldn't rely on metadata for correctness!
+  unsigned UniformMDKindID =
+      R->getEntry()->getContext().getMDKindID("structurizecfg.uniform");
+
+  if (hasOnlyUniformBranches(R, UniformMDKindID, *DA)) {
+    LLVM_DEBUG(dbgs() << "Skipping region with uniform control flow: " << *R
+                      << '\n');
+
+    // Mark all direct child block terminators as having been treated as
+    // uniform. To account for a possible future in which non-uniform
+    // sub-regions are treated more cleverly, indirect children are not
+    // marked as uniform.
+    MDNode *MD = MDNode::get(R->getEntry()->getParent()->getContext(), {});
+    for (RegionNode *E : R->elements()) {
+      if (E->isSubRegion())
+        continue;
 
-      return false;
+      if (Instruction *Term = E->getEntry()->getTerminator())
+        Term->setMetadata(UniformMDKindID, MD);
     }
+
+    return true;
   }
+  return false;
+}
+
+/// Run the transformation for each region found
+bool StructurizeCFG::run(Region *R, DominatorTree *DT) {
+  if (R->isTopLevelRegion())
+    return false;
+
+  this->DT = DT;
 
   Func = R->getEntry()->getParent();
   ParentRegion = R;
 
-  DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
-
   orderNodes();
   collectInfos();
   createFlow();
@@ -1069,5 +1088,33 @@ bool StructurizeCFG::runOnRegion(Region *R, RGPassManager &RGM) {
 }
 
 Pass *llvm::createStructurizeCFGPass(bool SkipUniformRegions) {
-  return new StructurizeCFG(SkipUniformRegions);
+  return new StructurizeCFGLegacyPass(SkipUniformRegions);
+}
+
+static void addRegionIntoQueue(Region &R, std::vector<Region *> &Regions) {
+  Regions.push_back(&R);
+  for (const auto &E : R)
+    addRegionIntoQueue(*E, Regions);
+}
+
+PreservedAnalyses StructurizeCFGPass::run(Function &F,
+                                          FunctionAnalysisManager &AM) {
+
+  bool Changed = false;
+  DominatorTree *DT = &AM.getResult<DominatorTreeAnalysis>(F);
+  auto &RI = AM.getResult<RegionInfoAnalysis>(F);
+  std::vector<Region *> Regions;
+  addRegionIntoQueue(*RI.getTopLevelRegion(), Regions);
+  while (!Regions.empty()) {
+    Region *R = Regions.back();
+    StructurizeCFG SCFG;
+    SCFG.init(R);
+    Changed |= SCFG.run(R, DT);
+    Regions.pop_back();
+  }
+  if (!Changed)
+    return PreservedAnalyses::all();
+  PreservedAnalyses PA;
+  PA.preserve<DominatorTreeAnalysis>();
+  return PA;
 }

llvm/test/Transforms/StructurizeCFG/AMDGPU/uniform-regions.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -mtriple=amdgcn-- -S -o - -structurizecfg -structurizecfg-skip-uniform-regions -structurizecfg-relaxed-uniform-regions < %s | FileCheck %s
+; RUN: opt -mtriple=amdgcn-- -S -o - -structurizecfg -structurizecfg-skip-uniform-regions -structurizecfg-relaxed-uniform-regions -enable-new-pm=0 < %s | FileCheck %s
 
 define amdgpu_cs void @uniform(i32 inreg %v) {
 ; CHECK-LABEL: @uniform(

llvm/test/Transforms/StructurizeCFG/interleaved-loop-order.ll

@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -structurizecfg %s -o - | FileCheck %s
+; RUN: opt -S -lowerswitch -structurizecfg %s -o - | FileCheck %s
 
 ; This test have an outer loop containing an inner loop,
 ; for which there is an interleaved post-order traversal.

llvm/test/Transforms/StructurizeCFG/nested-loop-order.ll

@@ -1,4 +1,5 @@
 ; RUN: opt -S -structurizecfg %s -o - | FileCheck %s
+; RUN: opt -S -passes=structurizecfg %s -o - | FileCheck %s
 
 define void @main(float addrspace(1)* %out) {
 

llvm/test/Transforms/StructurizeCFG/switch.ll

@@ -1,4 +1,4 @@
-; RUN: opt -S -structurizecfg %s -o - | FileCheck %s
+; RUN: opt -S -structurizecfg %s -o - -enable-new-pm=0 | FileCheck %s
 
 ; The structurizecfg pass cannot handle switch instructions, so we need to
 ; make sure the lower switch pass is always run before structurizecfg.