[llvm] 7d0b1d7 - [Examples] Add IRTransformations directory to examples.
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 12 06:17:21 PST 2019
Author: Florian Hahn
Date: 2019-11-12T14:14:48Z
New Revision: 7d0b1d77b3d4d47df477519fd1bf099b3df6f899
URL: https://github.com/llvm/llvm-project/commit/7d0b1d77b3d4d47df477519fd1bf099b3df6f899
DIFF: https://github.com/llvm/llvm-project/commit/7d0b1d77b3d4d47df477519fd1bf099b3df6f899.diff
LOG: [Examples] Add IRTransformations directory to examples.
This patch adds a new IRTransformations directory to llvm/examples/. This is
intended to serve as a new home for example transformations/analysis
code used by various tutorials.
If LLVM_BUILD_EXAMPLES is enabled, the ExamplesIRTransforms library is
linked into the opt binary and the example passes become available.
To start off with, it contains the CFG simplifications used in the IR
part of the 'Getting Started With LLVM: Basics' tutorial at the US LLVM
Developers Meeting 2019.
Reviewers: paquette, jfb, meikeb, lhames, kbarton
Reviewed By: paquette
Differential Revision: https://reviews.llvm.org/D69416
Added:
llvm/examples/IRTransforms/CMakeLists.txt
llvm/examples/IRTransforms/InitializePasses.cpp
llvm/examples/IRTransforms/InitializePasses.h
llvm/examples/IRTransforms/SimplifyCFG.cpp
llvm/examples/IRTransforms/SimplifyCFG.h
llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg-blockaddress.ll
llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg1.ll
llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg2-dead-block-order.ll
llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg3-phis.ll
llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg4-multiple-duplicate-cfg-updates.ll
llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg5-del-phis-for-dead-block.ll
llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg6-dead-self-loop.ll
Modified:
llvm/CMakeLists.txt
llvm/examples/CMakeLists.txt
llvm/tools/opt/CMakeLists.txt
llvm/tools/opt/opt.cpp
Removed:
################################################################################
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index 290738699896..0aa22c6deb08 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -530,6 +530,10 @@ option(LLVM_BUILD_EXAMPLES
"Build the LLVM example programs. If OFF, just generate build targets." OFF)
option(LLVM_INCLUDE_EXAMPLES "Generate build targets for the LLVM examples" ON)
+if(LLVM_BUILD_EXAMPLES)
+ add_definitions(-DBUILD_EXAMPLES)
+endif(LLVM_BUILD_EXAMPLES)
+
option(LLVM_BUILD_TESTS
"Build LLVM unit tests. If OFF, just generate build targets." OFF)
option(LLVM_INCLUDE_TESTS "Generate build targets for the LLVM unit tests." ON)
diff --git a/llvm/examples/CMakeLists.txt b/llvm/examples/CMakeLists.txt
index ad99d4c7e312..1fbcbf793b2d 100644
--- a/llvm/examples/CMakeLists.txt
+++ b/llvm/examples/CMakeLists.txt
@@ -2,6 +2,7 @@ add_subdirectory(BrainF)
add_subdirectory(Fibonacci)
add_subdirectory(HowToUseJIT)
add_subdirectory(HowToUseLLJIT)
+add_subdirectory(IRTransforms)
add_subdirectory(LLJITExamples)
add_subdirectory(Kaleidoscope)
add_subdirectory(ModuleMaker)
diff --git a/llvm/examples/IRTransforms/CMakeLists.txt b/llvm/examples/IRTransforms/CMakeLists.txt
new file mode 100644
index 000000000000..bf135b92b204
--- /dev/null
+++ b/llvm/examples/IRTransforms/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_llvm_library(ExampleIRTransforms
+ InitializePasses.cpp
+ SimplifyCFG.cpp
+
+ ADDITIONAL_HEADER_DIRS
+
+ DEPENDS
+ intrinsics_gen
+ )
diff --git a/llvm/examples/IRTransforms/InitializePasses.cpp b/llvm/examples/IRTransforms/InitializePasses.cpp
new file mode 100644
index 000000000000..125180715cd4
--- /dev/null
+++ b/llvm/examples/IRTransforms/InitializePasses.cpp
@@ -0,0 +1,21 @@
+//===-- InitializePasses.cpp ----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements implements the initialization hook for the example
+// transforms.
+//
+//===----------------------------------------------------------------------===//
+
+#include "InitializePasses.h"
+#include "llvm/PassRegistry.h"
+
+using namespace llvm;
+
+void initializeExampleIRTransforms(PassRegistry &Registry) {
+ initializeSimplifyCFGLegacyPassPass(Registry);
+}
diff --git a/llvm/examples/IRTransforms/InitializePasses.h b/llvm/examples/IRTransforms/InitializePasses.h
new file mode 100644
index 000000000000..8b6673d518e6
--- /dev/null
+++ b/llvm/examples/IRTransforms/InitializePasses.h
@@ -0,0 +1,22 @@
+//===- InitializePasses.h - -------------------------------------*- C++ -*-===//
+//
+//
+// 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_EXAMPLES_IRTRANSFORMS_INITIALIZEPASSES__H
+#define LLVM_EXAMPLES_IRTRANSFORMS_INITIALIZEPASSES__H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+void initializeExampleIRTransforms(PassRegistry &Registry);
+void initializeSimplifyCFGLegacyPassPass(PassRegistry &Registry);
+
+} // end namespace llvm
+
+#endif
diff --git a/llvm/examples/IRTransforms/SimplifyCFG.cpp b/llvm/examples/IRTransforms/SimplifyCFG.cpp
new file mode 100644
index 000000000000..44bbedf4dc4f
--- /dev/null
+++ b/llvm/examples/IRTransforms/SimplifyCFG.cpp
@@ -0,0 +1,413 @@
+//===- SimplifyCFG.cpp ----------------------------------------------------===//
+//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the control flow graph (CFG) simplifications
+// presented as part of the 'Getting Started With LLVM: Basics' tutorial at the
+// US LLVM Developers Meeting 2019. It also contains additional material.
+//
+// The current file contains three
diff erent CFG simplifications. There are
+// multiple versions of each implementation (e.g. _v1 and _v2), which implement
+// additional functionality (e.g. preserving analysis like the DominatorTree) or
+// use additional utilities to simplify the code (e.g. LLVM's PatternMatch.h).
+// The available simplifications are:
+// 1. Trivially Dead block Removal (removeDeadBlocks_v[1,2]).
+// This simplifications removes all blocks without predecessors in the CFG
+// from a function.
+// 2. Conditional Branch Elimination (eliminateCondBranches_v[1,2,3])
+// This simplification replaces conditional branches with constant integer
+// conditions with unconditional branches.
+// 3. Single Predecessor Block Merging (mergeIntoSinglePredecessor_v[1,2])
+// This simplification merges blocks with a single predecessor into the
+// predecessor, if that block has a single successor.
+//
+// TODOs
+// * Hook up pass to the new pass manager.
+// * Preserve LoopInfo.
+// * Add fixed point iteration to delete all dead blocks
+// * Add implementation using reachability to discover dead blocks.
+//===----------------------------------------------------------------------===//
+
+#include "SimplifyCFG.h"
+#include "InitializePasses.h"
+#include "llvm/Analysis/DomTreeUpdater.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/Support/CommandLine.h"
+
+using namespace llvm;
+using namespace PatternMatch;
+
+enum TutorialVersion { V1, V2, V3 };
+static cl::opt<TutorialVersion>
+ Version("tut-simplifycfg-version", cl::desc("Select tutorial version"),
+ cl::Hidden, cl::ValueOptional, cl::init(V1),
+ cl::values(clEnumValN(V1, "v1", "version 1"),
+ clEnumValN(V2, "v2", "version 2"),
+ clEnumValN(V3, "v3", "version 3"),
+ // Sentinel value for unspecified option.
+ clEnumValN(V3, "", "")));
+
+#define DEBUG_TYPE "tut-simplifycfg"
+
+// Remove trivially dead blocks. First version, not preserving the
+// DominatorTree.
+static bool removeDeadBlocks_v1(Function &F) {
+ bool Changed = false;
+
+ // Remove trivially dead blocks.
+ for (BasicBlock &BB : make_early_inc_range(F)) {
+ // Skip blocks we know to not be trivially dead. We know a block is
+ // guaranteed to be dead, iff it is neither the entry block nor
+ // has any predecessors.
+ if (&F.getEntryBlock() == &BB || !pred_empty(&BB))
+ continue;
+
+ // Notify successors of BB that BB is going to be removed. This removes
+ // incoming values from BB from PHIs in the successors. Note that this will
+ // not actually remove BB from the predecessor lists of its successors.
+ for (BasicBlock *Succ : successors(&BB))
+ Succ->removePredecessor(&BB);
+ // TODO: Find a better place to put such small variations.
+ // Alternatively, we can update the PHI nodes manually:
+ // for (PHINode &PN : make_early_inc_range(Succ->phis()))
+ // PN.removeIncomingValue(&BB);
+
+ // Replace all instructions in BB with an undef constant. The block is
+ // unreachable, so the results of the instructions should never get used.
+ while (!BB.empty()) {
+ Instruction &I = BB.back();
+ I.replaceAllUsesWith(UndefValue::get(I.getType()));
+ I.eraseFromParent();
+ }
+
+ // Finally remove the basic block.
+ BB.eraseFromParent();
+ Changed = true;
+ }
+
+ return Changed;
+}
+
+// Remove trivially dead blocks. This is the second version and preserves the
+// dominator tree.
+static bool removeDeadBlocks_v2(Function &F, DominatorTree &DT) {
+ bool Changed = false;
+ DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+ SmallVector<DominatorTree::UpdateType, 8> DTUpdates;
+
+ // Remove trivially dead blocks.
+ for (BasicBlock &BB : make_early_inc_range(F)) {
+ // Skip blocks we know to not be trivially dead. We know a block is
+ // guaranteed to be dead, iff it is neither the entry block nor
+ // has any predecessors.
+ if (&F.getEntryBlock() == &BB || !pred_empty(&BB))
+ continue;
+
+ // Notify successors of BB that BB is going to be removed. This removes
+ // incoming values from BB from PHIs in the successors. Note that this will
+ // not actually remove BB from the predecessor lists of its successors.
+ for (BasicBlock *Succ : successors(&BB)) {
+ Succ->removePredecessor(&BB);
+
+ // Collect updates that need to be applied to the dominator tree.
+ DTUpdates.push_back({DominatorTree::Delete, &BB, Succ});
+ }
+
+ // Remove BB via the DomTreeUpdater. DomTreeUpdater::deleteBB conveniently
+ // removes the instructions in BB as well.
+ DTU.deleteBB(&BB);
+ Changed = true;
+ }
+
+ // Apply updates permissively, to remove duplicates.
+ DTU.applyUpdatesPermissive(DTUpdates);
+
+ return Changed;
+}
+
+// Eliminate branches with constant conditionals. This is the first version,
+// which *does not* preserve the dominator tree.
+static bool eliminateCondBranches_v1(Function &F) {
+ bool Changed = false;
+
+ // Eliminate branches with constant conditionals.
+ for (BasicBlock &BB : F) {
+ // Skip blocks without conditional branches as terminators.
+ BranchInst *BI = dyn_cast<BranchInst>(BB.getTerminator());
+ if (!BI || !BI->isConditional())
+ continue;
+
+ // Skip blocks with conditional branches without ConstantInt conditions.
+ ConstantInt *CI = dyn_cast<ConstantInt>(BI->getCondition());
+ if (!CI)
+ continue;
+
+ // We use the branch condition (CI), to select the successor we remove:
+ // if CI == 1 (true), we remove the second successor, otherwise the first.
+ BasicBlock *RemovedSucc = BI->getSuccessor(CI->isOne());
+ // Tell RemovedSucc we will remove BB from its predecessors.
+ RemovedSucc->removePredecessor(&BB);
+
+ // Replace the conditional branch with an unconditional one, by creating
+ // a new unconditional branch to the selected successor and removing the
+ // conditional one.
+ BranchInst::Create(BI->getSuccessor(CI->isZero()), BI);
+ BI->eraseFromParent();
+ Changed = true;
+ }
+
+ return Changed;
+}
+
+// Eliminate branches with constant conditionals. This is the second
+// version, which *does* preserve the dominator tree.
+static bool eliminateCondBranches_v2(Function &F, DominatorTree &DT) {
+ bool Changed = false;
+
+ DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+ SmallVector<DominatorTree::UpdateType, 8> DTUpdates;
+ // Eliminate branches with constant conditionals.
+ for (BasicBlock &BB : F) {
+ // Skip blocks without conditional branches as terminators.
+ BranchInst *BI = dyn_cast<BranchInst>(BB.getTerminator());
+ if (!BI || !BI->isConditional())
+ continue;
+
+ // Skip blocks with conditional branches without ConstantInt conditions.
+ ConstantInt *CI = dyn_cast<ConstantInt>(BI->getCondition());
+ if (!CI)
+ continue;
+
+ // We use the branch condition (CI), to select the successor we remove:
+ // if CI == 1 (true), we remove the second successor, otherwise the first.
+ BasicBlock *RemovedSucc = BI->getSuccessor(CI->isOne());
+ // Tell RemovedSucc we will remove BB from its predecessors.
+ RemovedSucc->removePredecessor(&BB);
+
+ // Replace the conditional branch with an unconditional one, by creating
+ // a new unconditional branch to the selected successor and removing the
+ // conditional one.
+ BranchInst *NewBranch =
+ BranchInst::Create(BI->getSuccessor(CI->isZero()), BI);
+ BI->eraseFromParent();
+
+ // Delete the edge between BB and RemovedSucc in the DominatorTree, iff
+ // the conditional branch did not use RemovedSucc as both the true and false
+ // branches.
+ if (NewBranch->getSuccessor(0) != RemovedSucc)
+ DTUpdates.push_back({DominatorTree::Delete, &BB, RemovedSucc});
+ Changed = true;
+ }
+
+ // Apply updates permissively, to remove duplicates.
+ DTU.applyUpdatesPermissive(DTUpdates);
+
+ return Changed;
+}
+
+// Eliminate branches with constant conditionals. This is the third
+// version, which uses PatternMatch.h.
+static bool eliminateCondBranches_v3(Function &F, DominatorTree &DT) {
+ bool Changed = false;
+ DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+ SmallVector<DominatorTree::UpdateType, 8> DTUpdates;
+
+ // Eliminate branches with constant conditionals.
+ for (BasicBlock &BB : F) {
+ ConstantInt *CI = nullptr;
+ BasicBlock *TakenSucc, *RemovedSucc;
+ // Check if the terminator is a conditional branch, with constant integer
+ // condition and also capture the successor blocks as TakenSucc and
+ // RemovedSucc.
+ if (!match(BB.getTerminator(),
+ m_Br(m_ConstantInt(CI), m_BasicBlock(TakenSucc),
+ m_BasicBlock(RemovedSucc))))
+ continue;
+
+ // If the condition is false, swap TakenSucc and RemovedSucc.
+ if (CI->isZero())
+ std::swap(TakenSucc, RemovedSucc);
+
+ // Tell RemovedSucc we will remove BB from its predecessors.
+ RemovedSucc->removePredecessor(&BB);
+
+ // Replace the conditional branch with an unconditional one, by creating
+ // a new unconditional branch to the selected successor and removing the
+ // conditional one.
+
+ BranchInst *NewBranch = BranchInst::Create(TakenSucc, BB.getTerminator());
+ BB.getTerminator()->eraseFromParent();
+
+ // Delete the edge between BB and RemovedSucc in the DominatorTree, iff
+ // the conditional branch did not use RemovedSucc as both the true and false
+ // branches.
+ if (NewBranch->getSuccessor(0) != RemovedSucc)
+ DTUpdates.push_back({DominatorTree::Delete, &BB, RemovedSucc});
+ Changed = true;
+ }
+
+ // Apply updates permissively, to remove duplicates.
+ DTU.applyUpdatesPermissive(DTUpdates);
+ return Changed;
+}
+
+// Merge basic blocks into their single predecessor, if their predecessor has a
+// single successor. This is the first version and does not preserve the
+// DominatorTree.
+static bool mergeIntoSinglePredecessor_v1(Function &F) {
+ bool Changed = false;
+
+ // Merge blocks with single predecessors.
+ for (BasicBlock &BB : make_early_inc_range(F)) {
+ BasicBlock *Pred = BB.getSinglePredecessor();
+ // Make sure BB has a single predecessor Pred and BB is the single
+ // successor of Pred.
+ if (!Pred || Pred->getSingleSuccessor() != &BB)
+ continue;
+
+ // Do not try to merge self loops. That can happen in dead blocks.
+ if (Pred == &BB)
+ continue;
+
+ // Need to replace it before nuking the branch.
+ BB.replaceAllUsesWith(Pred);
+ // PHI nodes in BB can only have a single incoming value. Remove them.
+ for (PHINode &PN : make_early_inc_range(BB.phis())) {
+ PN.replaceAllUsesWith(PN.getIncomingValue(0));
+ PN.eraseFromParent();
+ }
+ // Move all instructions from BB to Pred.
+ for (Instruction &I : make_early_inc_range(BB))
+ I.moveBefore(Pred->getTerminator());
+
+ // Remove the Pred's terminator (which jumped to BB). BB's terminator
+ // will become Pred's terminator.
+ Pred->getTerminator()->eraseFromParent();
+ BB.eraseFromParent();
+
+ Changed = true;
+ }
+
+ return Changed;
+}
+
+// Merge basic blocks into their single predecessor, if their predecessor has a
+// single successor. This is the second version and does preserve the
+// DominatorTree.
+static bool mergeIntoSinglePredecessor_v2(Function &F, DominatorTree &DT) {
+ bool Changed = false;
+ DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+ SmallVector<DominatorTree::UpdateType, 8> DTUpdates;
+
+ // Merge blocks with single predecessors.
+ for (BasicBlock &BB : make_early_inc_range(F)) {
+ BasicBlock *Pred = BB.getSinglePredecessor();
+ // Make sure BB has a single predecessor Pred and BB is the single
+ // successor of Pred.
+ if (!Pred || Pred->getSingleSuccessor() != &BB)
+ continue;
+
+ // Do not try to merge self loops. That can happen in dead blocks.
+ if (Pred == &BB)
+ continue;
+
+ // Tell DTU about the changes to the CFG: All edges from BB to its
+ // successors get removed and we add edges between Pred and BB's successors.
+ for (BasicBlock *Succ : successors(&BB)) {
+ DTUpdates.push_back({DominatorTree::Delete, &BB, Succ});
+ DTUpdates.push_back({DominatorTree::Insert, Pred, Succ});
+ }
+ // Also remove the edge between Pred and BB.
+ DTUpdates.push_back({DominatorTree::Delete, Pred, &BB});
+
+ // Need to replace it before nuking the branch.
+ BB.replaceAllUsesWith(Pred);
+ // PHI nodes in BB can only have a single incoming value. Remove them.
+ for (PHINode &PN : make_early_inc_range(BB.phis())) {
+ PN.replaceAllUsesWith(PN.getIncomingValue(0));
+ PN.eraseFromParent();
+ }
+ // Move all instructions from BB to Pred.
+ for (Instruction &I : make_early_inc_range(BB))
+ I.moveBefore(Pred->getTerminator());
+
+ // Remove the Pred's terminator (which jumped to BB). BB's terminator
+ // will become Pred's terminator.
+ Pred->getTerminator()->eraseFromParent();
+ DTU.deleteBB(&BB);
+
+ Changed = true;
+ }
+
+ // Apply updates permissively, to remove duplicates.
+ DTU.applyUpdatesPermissive(DTUpdates);
+ return Changed;
+}
+
+static bool doSimplify_v1(Function &F) {
+ return eliminateCondBranches_v1(F) & mergeIntoSinglePredecessor_v1(F) &
+ removeDeadBlocks_v1(F);
+}
+
+static bool doSimplify_v2(Function &F, DominatorTree &DT) {
+ return eliminateCondBranches_v2(F, DT) &
+ mergeIntoSinglePredecessor_v2(F, DT) & removeDeadBlocks_v2(F, DT);
+}
+
+static bool doSimplify_v3(Function &F, DominatorTree &DT) {
+ return eliminateCondBranches_v3(F, DT) &
+ mergeIntoSinglePredecessor_v2(F, DT) & removeDeadBlocks_v2(F, DT);
+}
+
+namespace {
+struct SimplifyCFGLegacyPass : public FunctionPass {
+ static char ID;
+ SimplifyCFGLegacyPass() : FunctionPass(ID) {
+ initializeSimplifyCFGLegacyPassPass(*PassRegistry::getPassRegistry());
+ }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<DominatorTreeWrapperPass>();
+ // Version 1 of the implementation does not preserve the dominator tree.
+ if (Version != V1)
+ AU.addPreserved<DominatorTreeWrapperPass>();
+
+ FunctionPass::getAnalysisUsage(AU);
+ }
+
+ bool runOnFunction(Function &F) override {
+ if (skipFunction(F))
+ return false;
+
+ switch (Version) {
+ case V1:
+ return doSimplify_v1(F);
+ case V2: {
+ auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ return doSimplify_v2(F, DT);
+ }
+ case V3: {
+ auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ return doSimplify_v3(F, DT);
+ }
+ }
+
+ llvm_unreachable("Unsupported version");
+ }
+};
+} // namespace
+
+char SimplifyCFGLegacyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(SimplifyCFGLegacyPass, DEBUG_TYPE,
+ "Tutorial CFG simplification", false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_END(SimplifyCFGLegacyPass, DEBUG_TYPE,
+ "Tutorial CFG simplifications", false, false)
diff --git a/llvm/examples/IRTransforms/SimplifyCFG.h b/llvm/examples/IRTransforms/SimplifyCFG.h
new file mode 100644
index 000000000000..09328afb01d3
--- /dev/null
+++ b/llvm/examples/IRTransforms/SimplifyCFG.h
@@ -0,0 +1,24 @@
+//===- SimplifyCFG.h - Tutorial SimplifyCFG ---------------------*- C++ -*-===//
+//
+//
+// 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_EXAMPLES_IRTRANSFORMS_SIMPLIFYCFG__H
+#define LLVM_EXAMPLES_IRTRANSFORMS_SIMPLIFYCFG__H
+
+#include "llvm/Pass.h"
+#include "llvm/PassRegistry.h"
+
+namespace llvm {
+
+FunctionPass *createSimplifyCFGPass();
+
+void initializeSimplifyCFGLegacyPassPass(PassRegistry &);
+
+} // end namespace llvm
+
+#endif // LLVM_EXAMPLES_IRTRANSFORMS_SIMPLIFYCFG__H
diff --git a/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg-blockaddress.ll b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg-blockaddress.ll
new file mode 100644
index 000000000000..faf60f3acdb3
--- /dev/null
+++ b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg-blockaddress.ll
@@ -0,0 +1,23 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 -S < %s | FileCheck %s
+
+define i8* @simp1(i32 %x) {
+; CHECK-LABEL: @simp1(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 42
+; CHECK-NEXT: [[ADDR:%.*]] = select i1 [[CMP]], i8* inttoptr (i32 1 to i8*), i8* inttoptr (i32 1 to i8*)
+; CHECK-NEXT: ret i8* [[ADDR]]
+;
+entry:
+ %cmp = icmp slt i32 %x, 42
+ %addr = select i1 %cmp, i8* blockaddress(@simp1, %bb1), i8* blockaddress(@simp1, %bb2)
+ ret i8* %addr
+
+bb1:
+ ret i8* null
+
+bb2:
+ ret i8* null
+}
diff --git a/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg1.ll b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg1.ll
new file mode 100644
index 000000000000..cb0f82e37573
--- /dev/null
+++ b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg1.ll
@@ -0,0 +1,90 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 -S < %s | FileCheck %s
+
+define i32 @simp1() {
+; CHECK-LABEL: @simp1(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 10
+;
+entry:
+ br i1 true, label %if.then, label %if.else
+
+if.then:
+ ret i32 10
+
+if.else:
+ ret i32 12
+}
+
+define i32 @simp2() {
+; CHECK-LABEL: @simp2(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 200
+;
+entry:
+ br i1 false, label %if.then, label %if.else
+
+if.then:
+ ret i32 99
+
+if.else:
+ ret i32 200
+}
+
+declare void @foo(i64)
+
+define i64 @merge_into_predecessor(i64 %a, i64 %b) {
+; CHECK-LABEL: @merge_into_predecessor(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[R:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
+; CHECK-NEXT: call void @foo(i64 [[R]])
+; CHECK-NEXT: call void @foo(i64 [[A]])
+; CHECK-NEXT: ret i64 [[R]]
+;
+entry:
+ br label %bb.next
+
+bb.next:
+ %r = add i64 %a, %b
+ call void @foo(i64 %r)
+ call void @foo(i64 %a)
+ br label %bb.next.next
+
+bb.next.next:
+ ret i64 %r
+}
+
+define i64 @merge_into_predecessor_with_phi(i64 %a, i64 %b, i1 %c) {
+; CHECK-LABEL: @merge_into_predecessor_with_phi(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: call void @foo(i64 [[B:%.*]])
+; CHECK-NEXT: [[R:%.*]] = add i64 [[A:%.*]], [[B]]
+; CHECK-NEXT: call void @foo(i64 [[R]])
+; CHECK-NEXT: call void @foo(i64 [[A]])
+; CHECK-NEXT: br i1 [[C:%.*]], label [[BB_NEXT_NEXT:%.*]], label [[BB_EXIT:%.*]]
+; CHECK: bb.next.next:
+; CHECK-NEXT: br label [[BB_EXIT]]
+; CHECK: bb.exit:
+; CHECK-NEXT: [[RET:%.*]] = phi i64 [ [[R]], [[ENTRY:%.*]] ], [ 10, [[BB_NEXT_NEXT]] ]
+; CHECK-NEXT: ret i64 [[RET]]
+;
+entry:
+ call void @foo(i64 %b)
+ br label %bb.next
+
+bb.next:
+ %r = add i64 %a, %b
+ call void @foo(i64 %r)
+ call void @foo(i64 %a)
+ br i1 %c, label %bb.next.next, label %bb.exit
+
+bb.next.next:
+ br label %bb.exit
+
+bb.exit:
+ %ret = phi i64 [ %r, %bb.next], [ 10, %bb.next.next]
+ ret i64 %ret
+
+}
diff --git a/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg2-dead-block-order.ll b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg2-dead-block-order.ll
new file mode 100644
index 000000000000..11b70fa52677
--- /dev/null
+++ b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg2-dead-block-order.ll
@@ -0,0 +1,109 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 -S < %s | FileCheck %s
+
+define i32 @remove_dead_blocks() {
+; CHECK-LABEL: @remove_dead_blocks(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 1
+; CHECK-NEXT: }
+;
+entry:
+ ret i32 1
+
+bb.1:
+ ret i32 2
+
+bb.2:
+ ret i32 3
+}
+
+define i32 @simp1() {
+; CHECK-LABEL: @simp1(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 1
+; CHECK: bb.1:
+; CHECK-NEXT: ret i32 2
+; CHECK-NEXT: }
+;
+entry:
+ ret i32 1
+
+bb.1:
+ ret i32 2
+
+bb.2:
+ br i1 undef, label %bb.1, label %bb.3
+
+bb.3:
+ ret i32 3
+}
+
+define i32 @remove_dead_block_with_phi() {
+; CHECK-LABEL: @remove_dead_block_with_phi(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[BB_2:%.*]]
+; CHECK: bb.2:
+; CHECK-NEXT: ret i32 1
+; CHECK-NEXT: }
+;
+entry:
+ br label %bb.2
+
+bb.1:
+ br label %bb.2
+
+bb.2:
+ %rv = phi i32 [ 1, %entry ], [ 2, %bb.1 ]
+ ret i32 %rv
+}
+
+define i32 @remove_dead_blocks_remaining_uses(i32 %a) {
+; CHECK-LABEL: @remove_dead_blocks_remaining_uses(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 1
+; CHECK-NEXT: }
+;
+entry:
+ ret i32 1
+
+bb.2:
+ ret i32 %res
+
+bb.1:
+ %res = add i32 %a, 10
+ br label %bb.2
+}
+
+define i32 @remove_dead_blocks_remaining_uses2(i32 %a, i1 %cond) {
+; CHECK-LABEL: @remove_dead_blocks_remaining_uses2(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 1
+; CHECK: bb.2:
+; CHECK-NEXT: [[RES2:%.*]] = add i32 undef, 10
+; CHECK-NEXT: [[RES3:%.*]] = mul i32 [[RES2]], undef
+; CHECK-NEXT: ret i32 [[RES3]]
+; CHECK: bb.3:
+; CHECK-NEXT: ret i32 undef
+; CHECK-NEXT: }
+;
+entry:
+ ret i32 1
+
+bb.2:
+ %res2 = add i32 %res, 10
+ %res3 = mul i32 %res2, %res
+ ret i32 %res3
+
+bb.3:
+ br label %bb.4
+
+bb.4:
+ ret i32 %res
+
+bb.1:
+ %res = add i32 %a, 10
+ br i1 %cond, label %bb.2, label %bb.3
+ br label %bb.2
+}
diff --git a/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg3-phis.ll b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg3-phis.ll
new file mode 100644
index 000000000000..76db503faeb2
--- /dev/null
+++ b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg3-phis.ll
@@ -0,0 +1,70 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 -S < %s | FileCheck %s
+
+define i32 @phi_cond_branch_eliminated() {
+; CHECK-LABEL: @phi_cond_branch_eliminated(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 20
+;
+entry:
+ br i1 true, label %bb.2, label %bb.3
+
+bb.2:
+ br label %bb.3
+
+bb.3:
+ %ret = phi i32 [ 10, %entry ], [ 20, %bb.2 ]
+ ret i32 %ret
+}
+
+define i32 @phi_removed() {
+; CHECK-LABEL: @phi_removed(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[BB_3:%.*]]
+; CHECK: bb.3:
+; CHECK-NEXT: ret i32 0
+;
+entry:
+ br i1 false, label %bb.2, label %bb.3
+
+bb.2:
+ %pv = phi i32 [ 10, %entry ]
+ br label %bb.3
+
+bb.3:
+ ret i32 0
+}
+
+define i32 @phi_in_dead_region() {
+; CHECK-LABEL: @phi_in_dead_region(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 1
+;
+entry:
+ ret i32 1
+
+bb.1:
+ br i1 true, label %bb.2, label %bb.3
+
+bb.2:
+ br label %bb.3
+
+bb.3:
+ %ret = phi i32 [ 10, %bb.1 ], [ 20, %bb.2 ]
+ ret i32 %ret
+}
+
+define i32 @phi_in_mergable_blocks() {
+; CHECK-LABEL: @phi_in_mergable_blocks(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 10
+;
+entry:
+ br label %bb.1
+
+bb.1:
+ %pv = phi i32 [ 10, %entry ]
+ ret i32 %pv
+}
diff --git a/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg4-multiple-duplicate-cfg-updates.ll b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg4-multiple-duplicate-cfg-updates.ll
new file mode 100644
index 000000000000..82a0e0dac236
--- /dev/null
+++ b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg4-multiple-duplicate-cfg-updates.ll
@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 < %s -S -verify-dom-info | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 < %s -S -verify-dom-info | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 < %s -S -verify-dom-info | FileCheck %s
+
+; Check that we do not crash when we remove edges multiple times in
+; the DomTreeUpdater.
+define void @test() {
+; CHECK-LABEL: @test(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: switch i8 undef, label [[IF_THEN_EPIL:%.*]] [
+; CHECK-NEXT: i8 32, label [[FOR_INC_EPIL:%.*]]
+; CHECK-NEXT: i8 46, label [[FOR_INC_EPIL]]
+; CHECK-NEXT: i8 95, label [[FOR_INC_EPIL]]
+; CHECK-NEXT: i8 45, label [[FOR_INC_EPIL]]
+; CHECK-NEXT: i8 126, label [[FOR_INC_EPIL]]
+; CHECK-NEXT: ]
+; CHECK: if.then.epil:
+; CHECK-NEXT: unreachable
+; CHECK: for.inc.epil:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %for.body.epil
+
+for.body.epil: ; preds = %entry
+ switch i8 undef, label %if.then.epil [
+ i8 32, label %for.inc.epil
+ i8 46, label %for.inc.epil
+ i8 95, label %for.inc.epil
+ i8 45, label %for.inc.epil
+ i8 126, label %for.inc.epil
+ ]
+
+if.then.epil: ; preds = %for.body.epil
+ unreachable
+
+for.inc.epil: ; preds = %for.body.epil, %for.body.epil, %for.body.epil, %for.body.epil, %for.body.epil
+ ret void
+}
diff --git a/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg5-del-phis-for-dead-block.ll b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg5-del-phis-for-dead-block.ll
new file mode 100644
index 000000000000..b3edd1aa5058
--- /dev/null
+++ b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg5-del-phis-for-dead-block.ll
@@ -0,0 +1,122 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 < %s -S -verify-dom-info | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 < %s -S -verify-dom-info | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 < %s -S -verify-dom-info | FileCheck %s
+
+define void @test() {
+; CHECK-LABEL: @test(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: switch i32 undef, label [[SW_DEFAULT23:%.*]] [
+; CHECK-NEXT: i32 129, label [[SW_BB:%.*]]
+; CHECK-NEXT: i32 215, label [[SW_BB1:%.*]]
+; CHECK-NEXT: i32 117, label [[SW_BB1]]
+; CHECK-NEXT: i32 207, label [[SW_BB1]]
+; CHECK-NEXT: i32 158, label [[SW_BB1]]
+; CHECK-NEXT: i32 94, label [[SW_BB1]]
+; CHECK-NEXT: i32 219, label [[SW_BB1]]
+; CHECK-NEXT: i32 88, label [[SW_BB1]]
+; CHECK-NEXT: i32 168, label [[SW_BB1]]
+; CHECK-NEXT: i32 295, label [[SW_BB1]]
+; CHECK-NEXT: i32 294, label [[SW_BB1]]
+; CHECK-NEXT: i32 296, label [[SW_BB1]]
+; CHECK-NEXT: i32 67, label [[SW_BB1]]
+; CHECK-NEXT: i32 293, label [[SW_BB1]]
+; CHECK-NEXT: i32 382, label [[SW_BB1]]
+; CHECK-NEXT: i32 335, label [[SW_BB1]]
+; CHECK-NEXT: i32 393, label [[SW_BB1]]
+; CHECK-NEXT: i32 415, label [[SW_BB1]]
+; CHECK-NEXT: i32 400, label [[SW_BB1]]
+; CHECK-NEXT: i32 383, label [[SW_BB1]]
+; CHECK-NEXT: i32 421, label [[SW_BB1]]
+; CHECK-NEXT: i32 422, label [[SW_BB1]]
+; CHECK-NEXT: i32 302, label [[SW_BB1]]
+; CHECK-NEXT: i32 303, label [[SW_BB1]]
+; CHECK-NEXT: i32 304, label [[SW_BB1]]
+; CHECK-NEXT: i32 420, label [[SW_BB1]]
+; CHECK-NEXT: i32 401, label [[SW_EPILOG24:%.*]]
+; CHECK-NEXT: i32 53, label [[SW_BB12:%.*]]
+; CHECK-NEXT: i32 44, label [[SW_BB12]]
+; CHECK-NEXT: ]
+; CHECK: sw.bb:
+; CHECK-NEXT: unreachable
+; CHECK: sw.bb1:
+; CHECK-NEXT: br label [[SW_EPILOG24]]
+; CHECK: sw.bb12:
+; CHECK-NEXT: switch i32 undef, label [[SW_DEFAULT:%.*]] [
+; CHECK-NEXT: i32 47, label [[SW_BB13:%.*]]
+; CHECK-NEXT: i32 8, label [[SW_BB13]]
+; CHECK-NEXT: ]
+; CHECK: sw.bb13:
+; CHECK-NEXT: unreachable
+; CHECK: sw.default:
+; CHECK-NEXT: unreachable
+; CHECK: sw.default23:
+; CHECK-NEXT: unreachable
+; CHECK: sw.epilog24:
+; CHECK-NEXT: [[PREVIOUS_3:%.*]] = phi i32 [ undef, [[SW_BB1]] ], [ 401, [[ENTRY:%.*]] ]
+; CHECK-NEXT: unreachable
+;
+entry:
+ br label %while.body
+
+while.body: ; preds = %entry
+ switch i32 undef, label %sw.default23 [
+ i32 129, label %sw.bb
+ i32 215, label %sw.bb1
+ i32 117, label %sw.bb1
+ i32 207, label %sw.bb1
+ i32 158, label %sw.bb1
+ i32 94, label %sw.bb1
+ i32 219, label %sw.bb1
+ i32 88, label %sw.bb1
+ i32 168, label %sw.bb1
+ i32 295, label %sw.bb1
+ i32 294, label %sw.bb1
+ i32 296, label %sw.bb1
+ i32 67, label %sw.bb1
+ i32 293, label %sw.bb1
+ i32 382, label %sw.bb1
+ i32 335, label %sw.bb1
+ i32 393, label %sw.bb1
+ i32 415, label %sw.bb1
+ i32 400, label %sw.bb1
+ i32 383, label %sw.bb1
+ i32 421, label %sw.bb1
+ i32 422, label %sw.bb1
+ i32 302, label %sw.bb1
+ i32 303, label %sw.bb1
+ i32 304, label %sw.bb1
+ i32 420, label %sw.bb1
+ i32 401, label %sw.epilog24
+ i32 53, label %sw.bb12
+ i32 44, label %sw.bb12
+ ]
+
+sw.bb: ; preds = %while.body
+ unreachable
+
+sw.bb1: ; preds = %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body, %while.body
+ br i1 false, label %land.lhs.true, label %sw.epilog24
+
+land.lhs.true: ; preds = %sw.bb1
+ br label %sw.epilog24
+
+sw.bb12: ; preds = %while.body, %while.body
+ switch i32 undef, label %sw.default [
+ i32 47, label %sw.bb13
+ i32 8, label %sw.bb13
+ ]
+
+sw.bb13: ; preds = %sw.bb12, %sw.bb12
+ unreachable
+
+sw.default: ; preds = %sw.bb12
+ unreachable
+
+sw.default23: ; preds = %while.body
+ unreachable
+
+sw.epilog24: ; preds = %land.lhs.true, %sw.bb1, %while.body
+ %Previous.3 = phi i32 [ undef, %land.lhs.true ], [ undef, %sw.bb1 ], [ 401, %while.body ]
+ unreachable
+}
diff --git a/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg6-dead-self-loop.ll b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg6-dead-self-loop.ll
new file mode 100644
index 000000000000..f9705a6948b2
--- /dev/null
+++ b/llvm/test/Examples/IRTransforms/SimplifyCFG/tut-simplify-cfg6-dead-self-loop.ll
@@ -0,0 +1,25 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v1 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v2 -S < %s | FileCheck %s
+; RUN: opt -tut-simplifycfg -tut-simplifycfg-version=v3 -S < %s | FileCheck %s
+
+define i32 @simp1() {
+; CHECK-LABEL: @simp1(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret i32 1
+; CHECK: bb.1:
+; CHECK-NEXT: br label [[BB_1:%.*]]
+; CHECK: bb.2:
+; CHECK-NEXT: [[P:%.*]] = phi i32 [ 0, [[BB_2:%.*]] ]
+; CHECK-NEXT: br label [[BB_2]]
+;
+entry:
+ ret i32 1
+
+bb.1:
+ br label %bb.1
+
+bb.2:
+ %p = phi i32 [ 0, %bb.2]
+ br label %bb.2
+}
diff --git a/llvm/tools/opt/CMakeLists.txt b/llvm/tools/opt/CMakeLists.txt
index 4ea9baf447a9..90730e324c7d 100644
--- a/llvm/tools/opt/CMakeLists.txt
+++ b/llvm/tools/opt/CMakeLists.txt
@@ -42,3 +42,7 @@ export_executable_symbols(opt)
if(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
target_link_libraries(opt PRIVATE Polly)
endif(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
+
+if(LLVM_BUILD_EXAMPLES)
+ target_link_libraries(opt PRIVATE ExampleIRTransforms)
+endif(LLVM_BUILD_EXAMPLES)
diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
index 1dc5dd448f30..1ad6079f67ba 100644
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -476,6 +476,10 @@ static TargetMachine* GetTargetMachine(Triple TheTriple, StringRef CPUStr,
getCodeModel(), GetCodeGenOptLevel());
}
+#ifdef BUILD_EXAMPLES
+void initializeExampleIRTransforms(llvm::PassRegistry &Registry);
+#endif
+
#ifdef LINK_POLLY_INTO_TOOLS
namespace polly {
void initializePollyPasses(llvm::PassRegistry &Registry);
@@ -557,6 +561,10 @@ int main(int argc, char **argv) {
initializeWriteBitcodePassPass(Registry);
initializeHardwareLoopsPass(Registry);
+#ifdef BUILD_EXAMPLES
+ initializeExampleIRTransforms(Registry);
+#endif
+
#ifdef LINK_POLLY_INTO_TOOLS
polly::initializePollyPasses(Registry);
#endif
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