17 files changed, 99 insertions, 24 deletions
diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index 468ce1d40e4..6a508dc8b64 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -163,7 +163,7 @@ void initializeInternalizeLegacyPassPass(PassRegistry&);
 void initializeIntervalPartitionPass(PassRegistry&);
 void initializeIRTranslatorPass(PassRegistry &);
 void initializeJumpThreadingPass(PassRegistry&);
-void initializeLCSSAPass(PassRegistry&);
+void initializeLCSSAWrapperPassPass(PassRegistry &);
 void initializeLICMPass(PassRegistry&);
 void initializeLazyValueInfoPass(PassRegistry&);
 void initializeLintPass(PassRegistry&);
diff --git a/llvm/include/llvm/Transforms/Utils/LCSSA.h b/llvm/include/llvm/Transforms/Utils/LCSSA.h
new file mode 100644
index 00000000000..f0277d02154
--- /dev/null
+++ b/llvm/include/llvm/Transforms/Utils/LCSSA.h
@@ -0,0 +1,44 @@
+//===- LCSSA.h - Loop-closed SSA transform Pass -----------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass transforms loops by placing phi nodes at the end of the loops for
+// all values that are live across the loop boundary.  For example, it turns
+// the left into the right code:
+//
+// for (...)                for (...)
+//   if (c)                   if (c)
+//     X1 = ...                 X1 = ...
+//   else                     else
+//     X2 = ...                 X2 = ...
+//   X3 = phi(X1, X2)         X3 = phi(X1, X2)
+// ... = X3 + 4             X4 = phi(X3)
+//                          ... = X4 + 4
+//
+// This is still valid LLVM; the extra phi nodes are purely redundant, and will
+// be trivially eliminated by InstCombine.  The major benefit of this
+// transformation is that it makes many other loop optimizations, such as
+// LoopUnswitching, simpler.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_LCSSA_H
+#define LLVM_TRANSFORMS_UTILS_LCSSA_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+/// Converts loops into loop-closed SSA form.
+class LCSSAPass : public PassInfoMixin<LCSSAPass> {
+public:
+  PreservedAnalyses run(Function &F, AnalysisManager<Function> &AM);
+};
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_LCSSA_H
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index ffffd3cdae9..7ad5bef610f 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -83,6 +83,7 @@
 #include "llvm/Transforms/Scalar/SROA.h"
 #include "llvm/Transforms/Scalar/SimplifyCFG.h"
 #include "llvm/Transforms/Scalar/Sink.h"
+#include "llvm/Transforms/Utils/LCSSA.h"
 #include "llvm/Transforms/Utils/MemorySSA.h"
 #include <type_traits>
 
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
index 9d4b848b75e..b72fcad5c54 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -127,6 +127,7 @@ FUNCTION_PASS("lower-expect", LowerExpectIntrinsicPass())
 FUNCTION_PASS("guard-widening", GuardWideningPass())
 FUNCTION_PASS("gvn", GVN())
 FUNCTION_PASS("partially-inline-libcalls", PartiallyInlineLibCallsPass())
+FUNCTION_PASS("lcssa", LCSSAPass())
 FUNCTION_PASS("print", PrintFunctionPass(dbgs()))
 FUNCTION_PASS("print<assumptions>", AssumptionPrinterPass(dbgs()))
 FUNCTION_PASS("print<block-freq>", BlockFrequencyPrinterPass(dbgs()))
diff --git a/llvm/lib/Transforms/Scalar/LoopInterchange.cpp b/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
index 05d187f7795..698b20a9a02 100644
--- a/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
@@ -1300,7 +1300,7 @@ INITIALIZE_PASS_DEPENDENCY(DependenceAnalysisWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
-INITIALIZE_PASS_DEPENDENCY(LCSSA)
+INITIALIZE_PASS_DEPENDENCY(LCSSAWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
 
 INITIALIZE_PASS_END(LoopInterchange, "loop-interchange",
diff --git a/llvm/lib/Transforms/Scalar/LoopVersioningLICM.cpp b/llvm/lib/Transforms/Scalar/LoopVersioningLICM.cpp
index 7ccf2271e62..106c660252e 100644
--- a/llvm/lib/Transforms/Scalar/LoopVersioningLICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopVersioningLICM.cpp
@@ -585,7 +585,7 @@ INITIALIZE_PASS_BEGIN(LoopVersioningLICM, "loop-versioning-licm",
 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(LCSSA)
+INITIALIZE_PASS_DEPENDENCY(LCSSAWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopAccessAnalysis)
 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
diff --git a/llvm/lib/Transforms/Utils/LCSSA.cpp b/llvm/lib/Transforms/Utils/LCSSA.cpp
index ba6345137d2..029164dbb46 100644
--- a/llvm/lib/Transforms/Utils/LCSSA.cpp
+++ b/llvm/lib/Transforms/Utils/LCSSA.cpp
@@ -27,7 +27,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/LCSSA.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/AliasAnalysis.h"
@@ -42,6 +42,7 @@
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/PredIteratorCache.h"
 #include "llvm/Pass.h"
+#include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/LoopUtils.h"
 #include "llvm/Transforms/Utils/SSAUpdater.h"
 using namespace llvm;
@@ -270,11 +271,20 @@ bool llvm::formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI,
   return Changed;
 }
 
+/// Process all loops in the function, inner-most out.
+static bool formLCSSAOnAllLoops(LoopInfo *LI, DominatorTree &DT,
+                                ScalarEvolution *SE) {
+  bool Changed = false;
+  for (auto &L : *LI)
+    Changed |= formLCSSARecursively(*L, DT, LI, SE);
+  return Changed;
+}
+
 namespace {
-struct LCSSA : public FunctionPass {
+struct LCSSAWrapperPass : public FunctionPass {
   static char ID; // Pass identification, replacement for typeid
-  LCSSA() : FunctionPass(ID) {
-    initializeLCSSAPass(*PassRegistry::getPassRegistry());
+  LCSSAWrapperPass() : FunctionPass(ID) {
+    initializeLCSSAWrapperPassPass(*PassRegistry::getPassRegistry());
   }
 
   // Cached analysis information for the current function.
@@ -302,28 +312,40 @@ struct LCSSA : public FunctionPass {
 };
 }
 
-char LCSSA::ID = 0;
-INITIALIZE_PASS_BEGIN(LCSSA, "lcssa", "Loop-Closed SSA Form Pass", false, false)
+char LCSSAWrapperPass::ID = 0;
+INITIALIZE_PASS_BEGIN(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass",
+                      false, false)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
-INITIALIZE_PASS_END(LCSSA, "lcssa", "Loop-Closed SSA Form Pass", false, false)
-
-Pass *llvm::createLCSSAPass() { return new LCSSA(); }
-char &llvm::LCSSAID = LCSSA::ID;
+INITIALIZE_PASS_END(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass",
+                    false, false)
 
+Pass *llvm::createLCSSAPass() { return new LCSSAWrapperPass(); }
+char &llvm::LCSSAID = LCSSAWrapperPass::ID;
 
-/// Process all loops in the function, inner-most out.
-bool LCSSA::runOnFunction(Function &F) {
-  bool Changed = false;
+/// Transform \p F into loop-closed SSA form.
+bool LCSSAWrapperPass::runOnFunction(Function &F) {
   LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
   DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
   auto *SEWP = getAnalysisIfAvailable<ScalarEvolutionWrapperPass>();
   SE = SEWP ? &SEWP->getSE() : nullptr;
 
-  // Simplify each loop nest in the function.
-  for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
-    Changed |= formLCSSARecursively(**I, *DT, LI, SE);
-
-  return Changed;
+  return formLCSSAOnAllLoops(LI, *DT, SE);
 }
 
+PreservedAnalyses LCSSAPass::run(Function &F, AnalysisManager<Function> &AM) {
+  auto &LI = AM.getResult<LoopAnalysis>(F);
+  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
+  auto *SE = AM.getCachedResult<ScalarEvolutionAnalysis>(F);
+  if (!formLCSSAOnAllLoops(&LI, DT, SE))
+    return PreservedAnalyses::all();
+
+  // FIXME: There is no setPreservesCFG in the new PM. When that becomes
+  // available, it should be used here.
+  PreservedAnalyses PA;
+  PA.preserve<BasicAA>();
+  PA.preserve<GlobalsAA>();
+  PA.preserve<SCEVAA>();
+  PA.preserve<ScalarEvolutionAnalysis>();
+  return PA;
+}
diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index e77ab2aad62..4cc227df1f8 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -880,7 +880,7 @@ void llvm::initializeLoopPassPass(PassRegistry &Registry) {
   INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
   INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
   INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
-  INITIALIZE_PASS_DEPENDENCY(LCSSA)
+  INITIALIZE_PASS_DEPENDENCY(LCSSAWrapperPass)
   INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
   INITIALIZE_PASS_DEPENDENCY(BasicAAWrapperPass)
   INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
diff --git a/llvm/lib/Transforms/Utils/Utils.cpp b/llvm/lib/Transforms/Utils/Utils.cpp
index ee321d37138..cdff86b2553 100644
--- a/llvm/lib/Transforms/Utils/Utils.cpp
+++ b/llvm/lib/Transforms/Utils/Utils.cpp
@@ -24,7 +24,7 @@ void llvm::initializeTransformUtils(PassRegistry &Registry) {
   initializeAddDiscriminatorsPass(Registry);
   initializeBreakCriticalEdgesPass(Registry);
   initializeInstNamerPass(Registry);
-  initializeLCSSAPass(Registry);
+  initializeLCSSAWrapperPassPass(Registry);
   initializeLoopSimplifyPass(Registry);
   initializeLowerInvokePass(Registry);
   initializeLowerSwitchPass(Registry);
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 0203f6218e4..562ace39fe0 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -6193,7 +6193,7 @@ INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
 INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(LCSSA)
+INITIALIZE_PASS_DEPENDENCY(LCSSAWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
 INITIALIZE_PASS_DEPENDENCY(LoopAccessAnalysis)
diff --git a/llvm/test/Transforms/LCSSA/2006-06-12-MultipleExitsSameBlock.ll b/llvm/test/Transforms/LCSSA/2006-06-12-MultipleExitsSameBlock.ll
index 182ade79faa..5f9fd2633c8 100644
--- a/llvm/test/Transforms/LCSSA/2006-06-12-MultipleExitsSameBlock.ll
+++ b/llvm/test/Transforms/LCSSA/2006-06-12-MultipleExitsSameBlock.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -lcssa -S | FileCheck %s
+; RUN: opt < %s -passes=lcssa -S | FileCheck %s
 
 declare i1 @c1()
 
diff --git a/llvm/test/Transforms/LCSSA/2006-07-09-NoDominator.ll b/llvm/test/Transforms/LCSSA/2006-07-09-NoDominator.ll
index bc3d150fbdf..786744401d0 100644
--- a/llvm/test/Transforms/LCSSA/2006-07-09-NoDominator.ll
+++ b/llvm/test/Transforms/LCSSA/2006-07-09-NoDominator.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -lcssa
+; RUN: opt < %s -passes=lcssa
 
 	%struct.SetJmpMapEntry = type { i8*, i32, %struct.SetJmpMapEntry* }
 
diff --git a/llvm/test/Transforms/LCSSA/2006-10-31-UnreachableBlock.ll b/llvm/test/Transforms/LCSSA/2006-10-31-UnreachableBlock.ll
index ecb1be5c674..66760c565b8 100644
--- a/llvm/test/Transforms/LCSSA/2006-10-31-UnreachableBlock.ll
+++ b/llvm/test/Transforms/LCSSA/2006-10-31-UnreachableBlock.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -lcssa -disable-output
+; RUN: opt < %s -passes=lcssa -disable-output
 ; PR977
 ; END.
 
diff --git a/llvm/test/Transforms/LCSSA/basictest.ll b/llvm/test/Transforms/LCSSA/basictest.ll
index 602e21190f2..e13c244d9e0 100644
--- a/llvm/test/Transforms/LCSSA/basictest.ll
+++ b/llvm/test/Transforms/LCSSA/basictest.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -lcssa -S | FileCheck %s
+; RUN: opt < %s -passes=lcssa -S | FileCheck %s
 
 define void @lcssa(i1 %S2) {
 ; CHECK-LABEL: @lcssa
diff --git a/llvm/test/Transforms/LCSSA/invoke-dest.ll b/llvm/test/Transforms/LCSSA/invoke-dest.ll
index 1523d4ff1f6..05a0e2a5e95 100644
--- a/llvm/test/Transforms/LCSSA/invoke-dest.ll
+++ b/llvm/test/Transforms/LCSSA/invoke-dest.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -lcssa
+; RUN: opt < %s -passes=lcssa
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
 
diff --git a/llvm/test/Transforms/LCSSA/mixed-catch.ll b/llvm/test/Transforms/LCSSA/mixed-catch.ll
index 95d5b17bf08..1ae4cf8cdd0 100644
--- a/llvm/test/Transforms/LCSSA/mixed-catch.ll
+++ b/llvm/test/Transforms/LCSSA/mixed-catch.ll
@@ -1,4 +1,5 @@
 ; RUN: opt -lcssa -S < %s | FileCheck %s
+; RUN: opt -passes=lcssa -S < %s | FileCheck %s
 
 ; This test is based on the following C++ code:
 ;
diff --git a/llvm/test/Transforms/LCSSA/unused-phis.ll b/llvm/test/Transforms/LCSSA/unused-phis.ll
index 01b214b8e36..2c503f32713 100644
--- a/llvm/test/Transforms/LCSSA/unused-phis.ll
+++ b/llvm/test/Transforms/LCSSA/unused-phis.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -lcssa -S | FileCheck %s
+; RUN: opt < %s -passes=lcssa -S | FileCheck %s
 ; CHECK: exit1:
 ; CHECK: .lcssa =
 ; CHECK: exit2: