llc: Add -start-before/-stop-before options

[dschuff]

Hey, I just discovered this CL, and I'd love to have this for WebAssembly. LGTM, FWIW

[dschuff]

test/CodeGen/Generic/llc-start-stop.ll

5

Could add another line like
; RUN: not llc < %s -debug-pass=Structure -start-before=nonexistent -o /dev/null 2>&1 | FileCheck %s -check-prefix=NONEXISTENT-PASS
...
; NONEXISTENT-PASS: start-before pass is not registered

[MatzeB]

rebased, addressed comment. ping.

[hfinkel]

include/llvm/CodeGen/TargetPassConfig.h

151

These asserts should be report_fatal_error; the user might trigger them with bad command-line options (and I assume we still want them in release builds).

[qcolombet]

LGTM.

include/llvm/CodeGen/TargetPassConfig.h

151

Agreed. A follow-up commit is fine given we use to assert on that already.

[MatzeB]

include/llvm/CodeGen/TargetPassConfig.h

151

I'll leave this as an assert, but will add some error handling/catching for this case to llc.

Reasoning: I'd like to keep the llvm free of (unnecessary) commandline handling logic, that's the frontends job IMO (llc in this case). Ideally we would have all of this start/stop/before/after handling purely in llc, however when I tried to do that it turned out to be quite tricky so I left the code as is and went for the easy enhancement.

[rnk]

Sure, sounds reasonable. In this case we just happen to have fewer library consumers of the exported APIs. The only library consumers are the static thunk libraries.

[MatzeB]

In D23089#656538, @rnk wrote:

Sure, sounds reasonable. In this case we just happen to have fewer library consumers of the exported APIs. The only library consumers are the static thunk libraries.

Was this comment really meant for this review?

[rnk]

In D23089#656540, @MatzeB wrote:

Was this comment really meant for this review?

Hm, no, it was for https://reviews.llvm.org/D29052.

[luismarques]

This patch did not add the options to the documentation.

include/llvm/CodeGen/TargetPassConfig.h

public:
   static char EarlyTailDuplicateID;
 
   /// PostRAMachineLICM - A clone of the LICM pass that runs during late machine
   /// optimization after regalloc.
   static char PostRAMachineLICMID;
 
 private:
   PassManagerBase *PM;
-  AnalysisID StartBefore, StartAfter;
-  AnalysisID StopAfter;
+  AnalysisID StartBefore = nullptr;
+  AnalysisID StartAfter = nullptr;
+  AnalysisID StopBefore = nullptr;
+  AnalysisID StopAfter = nullptr;
   bool Started;
   bool Stopped;
   bool AddingMachinePasses;
 
 protected:
   TargetMachine *TM;
   PassConfigImpl *Impl; // Internal data structures
   bool Initialized;     // Flagged after all passes are configured.
public:
   /// If the StartAfter and StartBefore pass ID is zero, then compilation will
   /// begin at the normal point; otherwise, clear the Started flag to indicate
   /// that passes should not be added until the starting pass is seen.  If the
   /// Stop pass ID is zero, then compilation will continue to the end.
   ///
   /// This function expects that at least one of the StartAfter or the
   /// StartBefore pass IDs is null.
   void setStartStopPasses(AnalysisID StartBefore, AnalysisID StartAfter,
-                          AnalysisID StopAfter) {
-    if (StartAfter)
-      assert(!StartBefore && "Start after and start before passes are given");
+                          AnalysisID StopBefore, AnalysisID StopAfter) {
+    assert(!(StartBefore && StartAfter) &&
+           "Start after and start before passes are given");
+    assert(!(StopBefore && StopAfter) &&
+           "Stop after and stop before passed are given");
     this->StartBefore = StartBefore;
     this->StartAfter = StartAfter;
+    this->StopBefore = StopBefore;
     this->StopAfter = StopAfter;
     Started = (StartAfter == nullptr) && (StartBefore == nullptr);
   }
 
   void setDisableVerify(bool Disable) { setOpt(DisableVerify, Disable); }
 
   bool getEnableTailMerge() const { return EnableTailMerge; }
   void setEnableTailMerge(bool Enable) { setOpt(EnableTailMerge, Enable); }

include/llvm/Target/TargetMachine.h

public:
 
   /// Add passes to the specified pass manager to get the specified file
   /// emitted.  Typically this will involve several steps of code generation.
   /// This method should return true if emission of this file type is not
   /// supported, or false on success.
   virtual bool addPassesToEmitFile(
       PassManagerBase &, raw_pwrite_stream &, CodeGenFileType,
       bool /*DisableVerify*/ = true, AnalysisID /*StartBefore*/ = nullptr,
-      AnalysisID /*StartAfter*/ = nullptr, AnalysisID /*StopAfter*/ = nullptr,
+      AnalysisID /*StartAfter*/ = nullptr, AnalysisID /*StopBefore*/ = nullptr,
+      AnalysisID /*StopAfter*/ = nullptr,
       MachineFunctionInitializer * /*MFInitializer*/ = nullptr) {
     return true;
   }
 
   /// Add passes to the specified pass manager to get machine code emitted with
   /// the MCJIT. This method returns true if machine code is not supported. It
   /// fills the MCContext Ctx pointer which can be used to build custom
   /// MCStreamer.
public:
   /// for generating a pipeline of CodeGen passes.
   virtual TargetPassConfig *createPassConfig(PassManagerBase &PM);
 
   /// Add passes to the specified pass manager to get the specified file
   /// emitted.  Typically this will involve several steps of code generation.
   bool addPassesToEmitFile(
       PassManagerBase &PM, raw_pwrite_stream &Out, CodeGenFileType FileType,
       bool DisableVerify = true, AnalysisID StartBefore = nullptr,
-      AnalysisID StartAfter = nullptr, AnalysisID StopAfter = nullptr,
+      AnalysisID StartAfter = nullptr, AnalysisID StopBefore = nullptr,
+      AnalysisID StopAfter = nullptr,
       MachineFunctionInitializer *MFInitializer = nullptr) override;
 
   /// Add passes to the specified pass manager to get machine code emitted with
   /// the MCJIT. This method returns true if machine code is not supported. It
   /// fills the MCContext Ctx pointer which can be used to build custom
   /// MCStreamer.
   bool addPassesToEmitMC(PassManagerBase &PM, MCContext *&Ctx,
                          raw_pwrite_stream &OS,

lib/CodeGen/LLVMTargetMachine.cpp

void LLVMTargetMachine::addMachineFunctionAnalysis(PassManagerBase &PM,
     MachineFunctionInitializer *MFInitializer) const {
   PM.add(new MachineFunctionAnalysis(*this, MFInitializer));
 }
 
 /// addPassesToX helper drives creation and initialization of TargetPassConfig.
 static MCContext *
 addPassesToGenerateCode(LLVMTargetMachine *TM, PassManagerBase &PM,
                         bool DisableVerify, AnalysisID StartBefore,
-                        AnalysisID StartAfter, AnalysisID StopAfter,
+                        AnalysisID StartAfter, AnalysisID StopBefore,
+                        AnalysisID StopAfter,
                         MachineFunctionInitializer *MFInitializer = nullptr) {
 
   // When in emulated TLS mode, add the LowerEmuTLS pass.
   if (TM->Options.EmulatedTLS)
     PM.add(createLowerEmuTLSPass(TM));
 
   PM.add(createPreISelIntrinsicLoweringPass());
 
   // Add internal analysis passes from the target machine.
   PM.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
 
   // Targets may override createPassConfig to provide a target-specific
   // subclass.
   TargetPassConfig *PassConfig = TM->createPassConfig(PM);
-  PassConfig->setStartStopPasses(StartBefore, StartAfter, StopAfter);
+  PassConfig->setStartStopPasses(StartBefore, StartAfter, StopBefore,
+                                 StopAfter);
 
   // Set PassConfig options provided by TargetMachine.
   PassConfig->setDisableVerify(DisableVerify);
 
   PM.add(PassConfig);
 
   PassConfig->addIRPasses();
 
addPassesToGenerateCode(LLVMTargetMachine *TM, PassManagerBase &PM,
   PassConfig->setInitialized();
 
   return &MMI.getContext();
 }
 
 bool LLVMTargetMachine::addPassesToEmitFile(
     PassManagerBase &PM, raw_pwrite_stream &Out, CodeGenFileType FileType,
     bool DisableVerify, AnalysisID StartBefore, AnalysisID StartAfter,
-    AnalysisID StopAfter, MachineFunctionInitializer *MFInitializer) {
+    AnalysisID StopBefore, AnalysisID StopAfter,
+    MachineFunctionInitializer *MFInitializer) {
   // Add common CodeGen passes.
   MCContext *Context =
       addPassesToGenerateCode(this, PM, DisableVerify, StartBefore, StartAfter,
-                              StopAfter, MFInitializer);
+                              StopBefore, StopAfter, MFInitializer);
   if (!Context)
     return true;
 
-  if (StopAfter) {
+  if (StopBefore || StopAfter) {
     PM.add(createPrintMIRPass(Out));
     return false;
   }
 
   if (Options.MCOptions.MCSaveTempLabels)
     Context->setAllowTemporaryLabels(false);
 
   const MCSubtargetInfo &STI = *getMCSubtargetInfo();

 /// code is not supported. It fills the MCContext Ctx pointer which can be
 /// used to build custom MCStreamer.
 ///
 bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM, MCContext *&Ctx,
                                           raw_pwrite_stream &Out,
                                           bool DisableVerify) {
   // Add common CodeGen passes.
   Ctx = addPassesToGenerateCode(this, PM, DisableVerify, nullptr, nullptr,
-                                nullptr);
+                                nullptr, nullptr);
   if (!Ctx)
     return true;
 
   if (Options.MCOptions.MCSaveTempLabels)
     Ctx->setAllowTemporaryLabels(false);
 
   // Create the code emitter for the target if it exists.  If not, .o file
   // emission fails.

lib/CodeGen/TargetPassConfig.cpp

 // Out of line virtual method.
 TargetPassConfig::~TargetPassConfig() {
   delete Impl;
 }
 
 // Out of line constructor provides default values for pass options and
 // registers all common codegen passes.
 TargetPassConfig::TargetPassConfig(TargetMachine *tm, PassManagerBase &pm)
-    : ImmutablePass(ID), PM(&pm), StartBefore(nullptr), StartAfter(nullptr),
-      StopAfter(nullptr), Started(true), Stopped(false),
+    : ImmutablePass(ID), PM(&pm), Started(true), Stopped(false),
       AddingMachinePasses(false), TM(tm), Impl(nullptr), Initialized(false),
       DisableVerify(false), EnableTailMerge(true) {
 
   Impl = new PassConfigImpl();
 
   // Register all target independent codegen passes to activate their PassIDs,
   // including this pass itself.
   initializeCodeGen(*PassRegistry::getPassRegistry());
void TargetPassConfig::addPass(Pass *P, bool verifyAfter, bool printAfter) {
   // Cache the Pass ID here in case the pass manager finds this pass is
   // redundant with ones already scheduled / available, and deletes it.
   // Fundamentally, once we add the pass to the manager, we no longer own it
   // and shouldn't reference it.
   AnalysisID PassID = P->getPassID();
 
   if (StartBefore == PassID)
     Started = true;
+  if (StopBefore == PassID)
+    Stopped = true;
   if (Started && !Stopped) {
     std::string Banner;
     // Construct banner message before PM->add() as that may delete the pass.
     if (AddingMachinePasses && (printAfter || verifyAfter))
       Banner = std::string("After ") + std::string(P->getPassName());
     PM->add(P);
     if (AddingMachinePasses) {
       if (printAfter)

test/CodeGen/Generic/llc-start-stop.ll

+; RUN: llc < %s -debug-pass=Structure -stop-after=loop-reduce -o /dev/null 2>&1 | FileCheck %s -check-prefix=STOP-AFTER
+; RUN: llc < %s -debug-pass=Structure -stop-before=loop-reduce -o /dev/null 2>&1 | FileCheck %s -check-prefix=STOP-BEFORE
+; RUN: llc < %s -debug-pass=Structure -start-after=loop-reduce -o /dev/null 2>&1 | FileCheck %s -check-prefix=START-AFTER
+; RUN: llc < %s -debug-pass=Structure -start-before=loop-reduce -o /dev/null 2>&1 | FileCheck %s -check-prefix=START-BEFORE
+
+; STOP-AFTER: -loop-reduce
+; STOP-AFTER: Dominator Tree Construction
+; STOP-AFTER: Loop Strength Reduction
+; STOP-AFTER-NEXT: Machine Function Analysis
+; STOP-AFTER-NEXT: MIR Printing Pass
+
+; STOP-BEFORE-NOT: -loop-reduce
+; STOP-BEFORE: Dominator Tree Construction
+; STOP-BEFORE-NOT: Loop Strength Reduction
+
+; START-AFTER: -machine-branch-prob -pre-isel-intrinsic-lowering
+; START-AFTER: FunctionPass Manager
+; START-AFTER-NEXT: Lower Garbage Collection Instructions
+
+; START-BEFORE: -machine-branch-prob -pre-isel-intrinsic-lowering
+; START-BEFORE: FunctionPass Manager
+; START-BEFORE: Loop Strength Reduction
+; START-BEFORE-NEXT: Lower Garbage Collection Instructions

test/CodeGen/Generic/stop-after.ll

-; RUN: llc < %s -debug-pass=Structure -stop-after=loop-reduce -o /dev/null 2>&1 | FileCheck %s -check-prefix=STOP
-; RUN: llc < %s -debug-pass=Structure -start-after=loop-reduce -o /dev/null 2>&1 | FileCheck %s -check-prefix=START
-
-; STOP: -loop-reduce
-; STOP: Loop Strength Reduction
-; STOP-NEXT: Machine Function Analysis
-; STOP-NEXT: MIR Printing Pass
-
-; START: -machine-branch-prob -pre-isel-intrinsic-lowering
-; START: FunctionPass Manager
-; START-NEXT: Lower Garbage Collection Instructions

tools/llc/llc.cpp

CompileTwice("compile-twice", cl::Hidden,
                           "manager and verify the result is the same."),
                  cl::init(false));
 
 static cl::opt<bool> DiscardValueNames(
     "discard-value-names",
     cl::desc("Discard names from Value (other than GlobalValue)."),
     cl::init(false), cl::Hidden);
 
+static cl::opt<std::string> StopBefore("stop-before",
+    cl::desc("Stop compilation before a specific pass"),
+    cl::value_desc("pass-name"), cl::init(""));
+
 static cl::opt<std::string> StopAfter("stop-after",
     cl::desc("Stop compilation after a specific pass"),
     cl::value_desc("pass-name"), cl::init(""));
 
+static cl::opt<std::string> StartBefore("start-before",
+    cl::desc("Resume compilation before a specific pass"),
+    cl::value_desc("pass-name"), cl::init(""));
+
 static cl::opt<std::string> StartAfter("start-after",
     cl::desc("Resume compilation after a specific pass"),
     cl::value_desc("pass-name"), cl::init(""));
 
 namespace {
 static ManagedStatic<std::vector<std::string>> RunPassNames;
 
 struct RunPassOption {
static bool addPass(PassManagerBase &PM, const char *argv0,
   }
   std::string Banner = std::string("After ") + std::string(P->getPassName());
   PM.add(P);
   TPC.printAndVerify(Banner);
 
   return false;
 }
 
+static AnalysisID getPassID(const char *argv0, const char *OptionName,
+                            StringRef PassName) {
+  if (PassName.empty())
+    return nullptr;
+
+  const PassRegistry &PR = *PassRegistry::getPassRegistry();
+  const PassInfo *PI = PR.getPassInfo(PassName);
+  if (!PI) {
+    errs() << argv0 << ": " << OptionName << " pass is not registered.\n";
+    exit(1);
+  }
+  return PI->getTypeInfo();
+}
+
 static int compileModule(char **argv, LLVMContext &Context) {
   // Load the module to be compiled...
   SMDiagnostic Err;
   std::unique_ptr<Module> M;
   std::unique_ptr<MIRParser> MIR;
   Triple TheTriple;
 
   bool SkipModule = MCPU == "help" ||
if (RelaxAll.getNumOccurrences() > 0 &&
     std::unique_ptr<raw_svector_ostream> BOS;
     if ((FileType != TargetMachine::CGFT_AssemblyFile &&
          !Out->os().supportsSeeking()) ||
         CompileTwice) {
       BOS = make_unique<raw_svector_ostream>(Buffer);
       OS = BOS.get();
     }
 
-    AnalysisID StartBeforeID = nullptr;
-    AnalysisID StartAfterID = nullptr;
-    AnalysisID StopAfterID = nullptr;
-    const PassRegistry *PR = PassRegistry::getPassRegistry();
     if (!RunPassNames->empty()) {
-      if (!StartAfter.empty() || !StopAfter.empty()) {
+      if (!StartAfter.empty() || !StopAfter.empty() || !StartBefore.empty() ||
+          !StopBefore.empty()) {
         errs() << argv[0] << ": start-after and/or stop-after passes are "
                              "redundant when run-pass is specified.\n";
         return 1;
       }
       if (!MIR) {
         errs() << argv[0] << ": run-pass needs a .mir input.\n";
         return 1;
       }
       LLVMTargetMachine &LLVMTM = static_cast<LLVMTargetMachine&>(*Target);
       TargetPassConfig &TPC = *LLVMTM.createPassConfig(PM);
       PM.add(&TPC);
       LLVMTM.addMachineModuleInfo(PM);
       LLVMTM.addMachineFunctionAnalysis(PM, MIR.get());
       TPC.printAndVerify("");
 
       for (const std::string &RunPassName : *RunPassNames) {
         if (addPass(PM, argv[0], RunPassName, TPC))
           return 1;
       }
       PM.add(createPrintMIRPass(*OS));
     } else {
-      if (!StartAfter.empty()) {
-        const PassInfo *PI = PR->getPassInfo(StartAfter);
-        if (!PI) {
-          errs() << argv[0] << ": start-after pass is not registered.\n";
-          return 1;
-        }
-        StartAfterID = PI->getTypeInfo();
-      }
-      if (!StopAfter.empty()) {
-        const PassInfo *PI = PR->getPassInfo(StopAfter);
-        if (!PI) {
-          errs() << argv[0] << ": stop-after pass is not registered.\n";
-          return 1;
-        }
-        StopAfterID = PI->getTypeInfo();
-      }
+      const char *argv0 = argv[0];
+      AnalysisID StartBeforeID = getPassID(argv0, "start-before", StartBefore);
+      AnalysisID StartAfterID = getPassID(argv0, "start-after", StartAfter);
+      AnalysisID StopAfterID = getPassID(argv0, "stop-after", StopAfter);
+      AnalysisID StopBeforeID = getPassID(argv0, "stop-before", StopBefore);
 
       // Ask the target to add backend passes as necessary.
       if (Target->addPassesToEmitFile(PM, *OS, FileType, NoVerify,
-                                      StartBeforeID, StartAfterID, StopAfterID,
-                                      MIR.get())) {
+                                      StartBeforeID, StartAfterID, StopBeforeID,
+                                      StopAfterID, MIR.get())) {
         errs() << argv[0] << ": target does not support generation of this"
                << " file type!\n";
         return 1;
       }
     }
 
     // Before executing passes, print the final values of the LLVM options.
     cl::PrintOptionValues();