[DeLICM] Add pass boilerplate code.

Add an empty DeLICM pass, without any functional parts.

Extracting the boilerplate from the the functional part reduces the size of the
code to review (https://reviews.llvm.org/D24716)

Suggested-by: Tobias Grosser <tobias@grosser.es>
llvm-svn: 288160

polly/include/polly/DeLICM.h

@@ -0,0 +1,35 @@
+//===------ DeLICM.h --------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Undo the effect of Loop Invariant Code Motion (LICM) and
+// GVN Partial Redundancy Elimination (PRE) on SCoP-level.
+//
+// Namely, remove register/scalar dependencies by mapping them back to array
+// elements.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef POLLY_DELICM_H
+#define POLLY_DELICM_H
+
+namespace llvm {
+class PassRegistry;
+class Pass;
+} // anonymous namespace
+
+namespace polly {
+/// Create a new DeLICM pass instance.
+llvm::Pass *createDeLICMPass();
+} // namespace polly
+
+namespace llvm {
+void initializeDeLICMPass(llvm::PassRegistry &);
+} // namespace llvm
+
+#endif /* POLLY_DELICM_H */

polly/include/polly/LinkAllPasses.h

@@ -48,6 +48,7 @@ llvm::Pass *createPPCGCodeGenerationPass();
 #endif
 llvm::Pass *createIslScheduleOptimizerPass();
 llvm::Pass *createFlattenSchedulePass();
+llvm::Pass *createDeLICMPass();
 
 extern char &CodePreparationID;
 } // namespace polly
@@ -82,6 +83,7 @@ struct PollyForcePassLinking {
 #endif
     polly::createIslScheduleOptimizerPass();
     polly::createFlattenSchedulePass();
+    polly::createDeLICMPass();
   }
 } PollyForcePassLinking; // Force link by creating a global definition.
 } // namespace
@@ -100,6 +102,7 @@ void initializePPCGCodeGenerationPass(llvm::PassRegistry &);
 void initializeIslScheduleOptimizerPass(llvm::PassRegistry &);
 void initializePollyCanonicalizePass(llvm::PassRegistry &);
 void initializeFlattenSchedulePass(llvm::PassRegistry &);
+void initializeDeLICMPass(llvm::PassRegistry &);
 } // namespace llvm
 
 #endif

polly/lib/CMakeLists.txt

@@ -57,6 +57,7 @@ add_polly_library(Polly
   Transform/ScheduleOptimizer.cpp
   Transform/FlattenSchedule.cpp
   Transform/FlattenAlgo.cpp
+  Transform/DeLICM.cpp
   ${POLLY_HEADER_FILES}
   )
 

polly/lib/Support/RegisterPasses.cpp

@@ -23,6 +23,7 @@
 #include "polly/Canonicalization.h"
 #include "polly/CodeGen/CodeGeneration.h"
 #include "polly/CodeGen/CodegenCleanup.h"
+#include "polly/DeLICM.h"
 #include "polly/DependenceInfo.h"
 #include "polly/FlattenSchedule.h"
 #include "polly/LinkAllPasses.h"
@@ -159,6 +160,11 @@ static cl::opt<bool>
                          cl::desc("Enable polyhedral interface of Polly"),
                          cl::Hidden, cl::init(false), cl::cat(PollyCategory));
 
+static cl::opt<bool>
+    EnableDeLICM("polly-enable-delicm",
+                 cl::desc("Eliminate scalar loop carried dependences"),
+                 cl::Hidden, cl::init(false), cl::cat(PollyCategory));
+
 namespace polly {
 void initializePollyPasses(PassRegistry &Registry) {
   initializeCodeGenerationPass(Registry);
@@ -181,6 +187,7 @@ void initializePollyPasses(PassRegistry &Registry) {
   initializeScopInfoWrapperPassPass(Registry);
   initializeCodegenCleanupPass(Registry);
   initializeFlattenSchedulePass(Registry);
+  initializeDeLICMPass(Registry);
 }
 
 /// Register Polly passes such that they form a polyhedral optimizer.
@@ -228,6 +235,9 @@ void registerPollyPasses(llvm::legacy::PassManagerBase &PM) {
   if (EnablePolyhedralInfo)
     PM.add(polly::createPolyhedralInfoPass());
 
+  if (EnableDeLICM)
+    PM.add(polly::createDeLICMPass());
+
   if (ImportJScop)
     PM.add(polly::createJSONImporterPass());
 

polly/lib/Transform/DeLICM.cpp

@@ -0,0 +1,70 @@
+//===------ DeLICM.cpp -----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Undo the effect of Loop Invariant Code Motion (LICM) and
+// GVN Partial Redundancy Elimination (PRE) on SCoP-level.
+//
+// Namely, remove register/scalar dependencies by mapping them back to array
+// elements.
+//
+//===----------------------------------------------------------------------===//
+
+#include "polly/DeLICM.h"
+#include "polly/ScopInfo.h"
+#include "polly/ScopPass.h"
+#define DEBUG_TYPE "polly-delicm"
+
+using namespace polly;
+using namespace llvm;
+
+namespace {
+
+class DeLICM : public ScopPass {
+private:
+  DeLICM(const DeLICM &) = delete;
+  const DeLICM &operator=(const DeLICM &) = delete;
+
+public:
+  static char ID;
+  explicit DeLICM() : ScopPass(ID) {}
+
+  virtual void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequiredTransitive<ScopInfoRegionPass>();
+    AU.setPreservesAll();
+  }
+
+  virtual bool runOnScop(Scop &S) override {
+    // Free resources for previous scop's computation, if not yet done.
+    releaseMemory();
+
+    // TODO: Run DeLICM algorithm
+
+    return false;
+  }
+
+  virtual void printScop(raw_ostream &OS, Scop &S) const override {
+    OS << "DeLICM result:\n";
+    // TODO: Print analysis results and performed transformation details
+  }
+
+  virtual void releaseMemory() override {
+    // TODO: Release resources (eg. shared_ptr to isl_ctx)
+  }
+};
+
+char DeLICM::ID;
+} // anonymous namespace
+
+Pass *polly::createDeLICMPass() { return new DeLICM(); }
+
+INITIALIZE_PASS_BEGIN(DeLICM, "polly-delicm", "Polly - DeLICM/DePRE", false,
+                      false)
+INITIALIZE_PASS_DEPENDENCY(ScopInfoWrapperPass)
+INITIALIZE_PASS_END(DeLICM, "polly-delicm", "Polly - DeLICM/DePRE", false,
+                    false)

polly/test/DeLICM/pass_existance.ll

@@ -0,0 +1,36 @@
+; RUN: opt %loadPolly -polly-delicm -analyze < %s | FileCheck %s
+;
+; Simple test for the existence of the DeLICM pass.
+;
+; // Simplest detected SCoP to run DeLICM on.
+; for (int j = 0; j < n; j += 1) {
+;   body: A[0] = 0.0;
+; }
+;
+define void @func(i32 %n, double* noalias nonnull %A) {
+entry:
+  br label %for
+
+for:
+  %j = phi i32 [0, %entry], [%j.inc, %inc]
+  %j.cmp = icmp slt i32 %j, %n
+  br i1 %j.cmp, label %body, label %exit
+
+    body:
+      store double 0.0, double* %A
+      br label %inc
+
+inc:
+  %j.inc = add nuw nsw i32 %j, 1
+  br label %for
+
+exit:
+  br label %return
+
+return:
+  ret void
+}
+
+
+; Verify that the DeLICM has a custom printScop() function.
+; CHECK: DeLICM result: