Re-commit optimization bisect support (r267022) without new pass manager support.

The original commit was reverted because of a buildbot problem with LazyCallGraph::SCC handling (not related to the OptBisect handling).

Differential Revision: http://reviews.llvm.org/D19172



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267231 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Andrew Kaylor

include/llvm/Analysis/CallGraphSCCPass.h

@@ -77,15 +77,21 @@ class CallGraphSCCPass : public Pass {
   /// the call graph.  If the derived class implements this method, it should
   /// always explicitly call the implementation here.
   void getAnalysisUsage(AnalysisUsage &Info) const override;
+
+protected:
+  /// Optional passes call this function to check whether the pass should be
+  /// skipped. This is the case when optimization bisect is over the limit.
+  bool skipSCC(CallGraphSCC &SCC) const;
 };
 
 /// CallGraphSCC - This is a single SCC that a CallGraphSCCPass is run on.
 class CallGraphSCC {
+  const CallGraph &CG; // The call graph for this SCC.
   void *Context; // The CGPassManager object that is vending this.
   std::vector<CallGraphNode*> Nodes;
 
 public:
-  CallGraphSCC(void *context) : Context(context) {}
+  CallGraphSCC(CallGraph &cg, void *context) : CG(cg), Context(context) {}
 
   void initialize(CallGraphNode *const *I, CallGraphNode *const *E) {
     Nodes.assign(I, E);
@@ -101,6 +107,8 @@ class CallGraphSCC {
   typedef std::vector<CallGraphNode *>::const_iterator iterator;
   iterator begin() const { return Nodes.begin(); }
   iterator end() const { return Nodes.end(); }
+
+  const CallGraph &getCallGraph() { return CG; }
 };
 
 } // End llvm namespace

include/llvm/Analysis/LoopPass.h

@@ -88,9 +88,10 @@ class LoopPass : public Pass {
   virtual void deleteAnalysisLoop(Loop *L) {}
 
 protected:
-  /// skipOptnoneFunction - Containing function has Attribute::OptimizeNone
-  /// and most transformation passes should skip it.
-  bool skipOptnoneFunction(const Loop *L) const;
+  /// Optional passes call this function to check whether the pass should be
+  /// skipped. This is the case when Attribute::OptimizeNone is set or when
+  /// optimization bisect is over the limit.
+  bool skipLoop(const Loop *L) const;
 };
 
 class LPPassManager : public FunctionPass, public PMDataManager {

include/llvm/IR/LLVMContext.h

@@ -32,6 +32,7 @@ class DiagnosticInfo;
 template <typename T> class SmallVectorImpl;
 class Function;
 class DebugLoc;
+class OptBisect;
 
 /// This is an important class for using LLVM in a threaded context.  It
 /// (opaquely) owns and manages the core "global" data of LLVM's core
@@ -226,6 +227,9 @@ class LLVMContext {
     return OptionRegistry::instance().template get<ValT, Base, Mem>();
   }
 
+  /// \brief Access the object which manages optimization bisection for failure
+  /// analysis.
+  OptBisect &getOptBisect();
 private:
   LLVMContext(LLVMContext&) = delete;
   void operator=(LLVMContext&) = delete;

include/llvm/IR/OptBisect.h

@@ -0,0 +1,81 @@
+//===----------- llvm/IR/OptBisect.h - LLVM Bisect support -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file declares the interface for bisecting optimizations.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_IR_OPTBISECT_H
+#define LLVM_IR_OPTBISECT_H
+
+namespace llvm {
+
+class Pass;
+class StringRef;
+class Twine;
+
+/// This class implements a mechanism to disable passes and individual
+/// optimizations at compile time based on a command line option
+/// (-opt-bisect-limit) in order to perform a bisecting search for
+/// optimization-related problems.
+class OptBisect {
+public:
+  /// \brief Default constructor, initializes the OptBisect state based on the
+  /// -opt-bisect-limit command line argument.
+  ///
+  /// By default, bisection is disabled.
+  ///
+  /// Clients should not instantiate this class directly.  All access should go
+  /// through LLVMContext.
+  OptBisect();
+
+  /// Checks the bisect limit to determine if the specified pass should run.
+  ///
+  /// This function will immediate return true if bisection is disabled. If the
+  /// bisect limit is set to -1, the function will print a message describing
+  /// the pass and the bisect number assigned to it and return true.  Otherwise,
+  /// the function will print a message with the bisect number assigned to the
+  /// pass and indicating whether or not the pass will be run and return true if
+  /// the bisect limit has not yet been exceded or false if it has.
+  ///
+  /// Most passes should not call this routine directly.  Instead, it is called
+  /// through a helper routine provided by the pass base class.  For instance,
+  /// function passes should call FunctionPass::skipFunction().
+  template <class UnitT>
+  bool shouldRunPass(const Pass *P, const UnitT &U);
+
+  /// Checks the bisect limit to determine if the optimization described by the
+  /// /p Desc argument should run.
+  ///
+  /// This function will immediate return true if bisection is disabled. If the
+  /// bisect limit is set to -1, the function will print a message with the
+  /// bisect number assigned to the optimization along with the /p Desc
+  /// description and return true.  Otherwise, the function will print a message
+  /// with the bisect number assigned to the optimization and indicating whether
+  /// or not the pass will be run and return true if the bisect limit has not
+  /// yet been exceded or false if it has.
+  ///
+  /// Passes may call this function to provide more fine grained control over
+  /// individual optimizations performed by the pass.  Passes which cannot be
+  /// skipped entirely (such as non-optional code generation passes) may still
+  /// call this function to control whether or not individual optional
+  /// transformations are performed.
+  bool shouldRunCase(const Twine &Desc);
+
+private:
+  bool checkPass(const StringRef PassName, const StringRef TargetDesc);
+
+  bool BisectEnabled = false;
+  unsigned LastBisectNum = 0;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_IR_OPTBISECT_H

include/llvm/Pass.h

@@ -251,6 +251,11 @@ class ModulePass : public Pass {
   explicit ModulePass(char &pid) : Pass(PT_Module, pid) {}
   // Force out-of-line virtual method.
   ~ModulePass() override;
+
+protected:
+  /// Optional passes call this function to check whether the pass should be
+  /// skipped. This is the case when optimization bisect is over the limit.
+  bool skipModule(Module &M) const;
 };
 
 
@@ -310,9 +315,10 @@ class FunctionPass : public Pass {
   PassManagerType getPotentialPassManagerType() const override;
 
 protected:
-  /// skipOptnoneFunction - This function has Attribute::OptimizeNone
-  /// and most transformation passes should skip it.
-  bool skipOptnoneFunction(const Function &F) const;
+  /// Optional passes call this function to check whether the pass should be
+  /// skipped. This is the case when Attribute::OptimizeNone is set or when
+  /// optimization bisect is over the limit.
+  bool skipFunction(const Function &F) const;
 };
 
 
@@ -359,9 +365,10 @@ class BasicBlockPass : public Pass {
   PassManagerType getPotentialPassManagerType() const override;
 
 protected:
-  /// skipOptnoneFunction - Containing function has Attribute::OptimizeNone
-  /// and most transformation passes should skip it.
-  bool skipOptnoneFunction(const BasicBlock &BB) const;
+  /// Optional passes call this function to check whether the pass should be
+  /// skipped. This is the case when Attribute::OptimizeNone is set or when
+  /// optimization bisect is over the limit.
+  bool skipBasicBlock(const BasicBlock &BB) const;
 };
 
 /// If the user specifies the -time-passes argument on an LLVM tool command line

lib/Analysis/CallGraphSCCPass.cpp

@@ -23,6 +23,7 @@
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/LegacyPassManagers.h"
+#include "llvm/IR/OptBisect.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Timer.h"
@@ -444,7 +445,7 @@ bool CGPassManager::runOnModule(Module &M) {
   // Walk the callgraph in bottom-up SCC order.
   scc_iterator<CallGraph*> CGI = scc_begin(&CG);
 
-  CallGraphSCC CurSCC(&CGI);
+  CallGraphSCC CurSCC(CG, &CGI);
   while (!CGI.isAtEnd()) {
     // Copy the current SCC and increment past it so that the pass can hack
     // on the SCC if it wants to without invalidating our iterator.
@@ -631,3 +632,9 @@ Pass *CallGraphSCCPass::createPrinterPass(raw_ostream &O,
   return new PrintCallGraphPass(Banner, O);
 }
 
+bool CallGraphSCCPass::skipSCC(CallGraphSCC &SCC) const {
+  return !SCC.getCallGraph().getModule()
+              .getContext()
+              .getOptBisect()
+              .shouldRunPass(this, SCC);
+}

lib/Analysis/LoopPass.cpp

@@ -16,6 +16,7 @@
 #include "llvm/Analysis/LoopPass.h"
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/OptBisect.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Timer.h"
@@ -335,11 +336,16 @@ void LoopPass::assignPassManager(PMStack &PMS,
   LPPM->add(this);
 }
 
-// Containing function has Attribute::OptimizeNone and transformation
-// passes should skip it.
-bool LoopPass::skipOptnoneFunction(const Loop *L) const {
+bool LoopPass::skipLoop(const Loop *L) const {
   const Function *F = L->getHeader()->getParent();
-  if (F && F->hasFnAttribute(Attribute::OptimizeNone)) {
+  if (!F)
+    return false;
+  // Check the opt bisect limit.
+  LLVMContext &Context = F->getContext();
+  if (!Context.getOptBisect().shouldRunPass(this, *L))
+    return true;
+  // Check for the OptimizeNone attribute.
+  if (F->hasFnAttribute(Attribute::OptimizeNone)) {
     // FIXME: Report this to dbgs() only once per function.
     DEBUG(dbgs() << "Skipping pass '" << getPassName()
           << "' in function " << F->getName() << "\n");

lib/CodeGen/BranchFolding.cpp

@@ -90,7 +90,7 @@ INITIALIZE_PASS(BranchFolderPass, "branch-folder",
                 "Control Flow Optimizer", false, false)
 
 bool BranchFolderPass::runOnMachineFunction(MachineFunction &MF) {
-  if (skipOptnoneFunction(*MF.getFunction()))
+  if (skipFunction(*MF.getFunction()))
     return false;
 
   TargetPassConfig *PassConfig = &getAnalysis<TargetPassConfig>();

lib/CodeGen/CodeGenPrepare.cpp

@@ -211,7 +211,7 @@ FunctionPass *llvm::createCodeGenPreparePass(const TargetMachine *TM) {
 }
 
 bool CodeGenPrepare::runOnFunction(Function &F) {
-  if (skipOptnoneFunction(F))
+  if (skipFunction(F))
     return false;
 
   DL = &F.getParent()->getDataLayout();

lib/CodeGen/DeadMachineInstructionElim.cpp

@@ -90,7 +90,7 @@ bool DeadMachineInstructionElim::isDead(const MachineInstr *MI) const {
 }
 
 bool DeadMachineInstructionElim::runOnMachineFunction(MachineFunction &MF) {
-  if (skipOptnoneFunction(*MF.getFunction()))
+  if (skipFunction(*MF.getFunction()))
     return false;
 
   bool AnyChanges = false;

lib/CodeGen/LowerEmuTLS.cpp

@@ -63,6 +63,9 @@ ModulePass *llvm::createLowerEmuTLSPass(const TargetMachine *TM) {
 }
 
 bool LowerEmuTLS::runOnModule(Module &M) {
+  if (skipModule(M))
+    return false;
+
   if (!TM || !TM->Options.EmulatedTLS)
     return false;
 

lib/CodeGen/MachineBlockPlacement.cpp

@@ -1430,7 +1430,7 @@ bool MachineBlockPlacement::runOnMachineFunction(MachineFunction &F) {
   if (std::next(F.begin()) == F.end())
     return false;
 
-  if (skipOptnoneFunction(*F.getFunction()))
+  if (skipFunction(*F.getFunction()))
     return false;
 
   MBPI = &getAnalysis<MachineBranchProbabilityInfo>();

lib/CodeGen/MachineCSE.cpp

@@ -704,7 +704,7 @@ bool MachineCSE::PerformCSE(MachineDomTreeNode *Node) {
 }
 
 bool MachineCSE::runOnMachineFunction(MachineFunction &MF) {
-  if (skipOptnoneFunction(*MF.getFunction()))
+  if (skipFunction(*MF.getFunction()))
     return false;
 
   TII = MF.getSubtarget().getInstrInfo();

lib/CodeGen/MachineCopyPropagation.cpp

@@ -349,7 +349,7 @@ void MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
 }
 
 bool MachineCopyPropagation::runOnMachineFunction(MachineFunction &MF) {
-  if (skipOptnoneFunction(*MF.getFunction()))
+  if (skipFunction(*MF.getFunction()))
     return false;
 
   Changed = false;

lib/CodeGen/MachineLICM.cpp

@@ -260,7 +260,7 @@ static bool LoopIsOuterMostWithPredecessor(MachineLoop *CurLoop) {
 }
 
 bool MachineLICM::runOnMachineFunction(MachineFunction &MF) {
-  if (skipOptnoneFunction(*MF.getFunction()))
+  if (skipFunction(*MF.getFunction()))
     return false;
 
   Changed = FirstInLoop = false;

lib/CodeGen/MachineScheduler.cpp

@@ -324,7 +324,7 @@ ScheduleDAGInstrs *PostMachineScheduler::createPostMachineScheduler() {
 /// design would be to split blocks at scheduling boundaries, but LLVM has a
 /// general bias against block splitting purely for implementation simplicity.
 bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) {
-  if (skipOptnoneFunction(*mf.getFunction()))
+  if (skipFunction(*mf.getFunction()))
     return false;
 
   if (EnableMachineSched.getNumOccurrences()) {
@@ -362,7 +362,7 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) {
 }
 
 bool PostMachineScheduler::runOnMachineFunction(MachineFunction &mf) {
-  if (skipOptnoneFunction(*mf.getFunction()))
+  if (skipFunction(*mf.getFunction()))
     return false;
 
   if (EnablePostRAMachineSched.getNumOccurrences()) {

lib/CodeGen/MachineSink.cpp

@@ -257,7 +257,7 @@ MachineSinking::AllUsesDominatedByBlock(unsigned Reg,
 }
 
 bool MachineSinking::runOnMachineFunction(MachineFunction &MF) {
-  if (skipOptnoneFunction(*MF.getFunction()))
+  if (skipFunction(*MF.getFunction()))
     return false;
 
   DEBUG(dbgs() << "******** Machine Sinking ********\n");

lib/CodeGen/OptimizePHIs.cpp

@@ -63,7 +63,7 @@ INITIALIZE_PASS(OptimizePHIs, "opt-phis",
                 "Optimize machine instruction PHIs", false, false)
 
 bool OptimizePHIs::runOnMachineFunction(MachineFunction &Fn) {
-  if (skipOptnoneFunction(*Fn.getFunction()))
+  if (skipFunction(*Fn.getFunction()))
     return false;
 
   MRI = &Fn.getRegInfo();

lib/CodeGen/PeepholeOptimizer.cpp

@@ -1471,7 +1471,7 @@ bool PeepholeOptimizer::foldRedundantNAPhysCopy(
 }
 
 bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
-  if (skipOptnoneFunction(*MF.getFunction()))
+  if (skipFunction(*MF.getFunction()))
     return false;
 
   DEBUG(dbgs() << "********** PEEPHOLE OPTIMIZER **********\n");

lib/CodeGen/PostRASchedulerList.cpp

@@ -273,7 +273,7 @@ bool PostRAScheduler::enablePostRAScheduler(
 }
 
 bool PostRAScheduler::runOnMachineFunction(MachineFunction &Fn) {
-  if (skipOptnoneFunction(*Fn.getFunction()))
+  if (skipFunction(*Fn.getFunction()))
     return false;
 
   TII = Fn.getSubtarget().getInstrInfo();

lib/CodeGen/StackColoring.cpp

@@ -657,7 +657,7 @@ void StackColoring::expungeSlotMap(DenseMap<int, int> &SlotRemap,
 }
 
 bool StackColoring::runOnMachineFunction(MachineFunction &Func) {
-  if (skipOptnoneFunction(*Func.getFunction()))
+  if (skipFunction(*Func.getFunction()))
     return false;
 
   DEBUG(dbgs() << "********** Stack Coloring **********\n"

lib/CodeGen/TailDuplication.cpp

@@ -44,7 +44,7 @@ INITIALIZE_PASS(TailDuplicatePass, "tailduplication", "Tail Duplication", false,
                 false)
 
 bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
-  if (skipOptnoneFunction(*MF.getFunction()))
+  if (skipFunction(*MF.getFunction()))
     return false;
 
   auto MMI = getAnalysisIfAvailable<MachineModuleInfo>();

lib/IR/CMakeLists.txt

@@ -39,6 +39,7 @@ add_llvm_library(LLVMCore
   Module.cpp
   ModuleSummaryIndex.cpp
   Operator.cpp
+  OptBisect.cpp
   Pass.cpp
   PassManager.cpp
   PassRegistry.cpp