WIP: Try adding method to stop after specific runs of passes

[arsenm]

Summary

Currently if you use -{start,stop}-{before,after}, it picks
the first instance with the matching pass name. If you run
the same pass multiple times, there's no way to distinguish them.

Allow specifying a run index with ,N to specify which you mean (e.g. -stop-before=si-shrink-instructions,1")

Just handle -stop-after before committing to how this should work

[MatzeB]

Seems useful. Please implement consistently for all stop/start args and document it somewhere.

[arsenm]

Make more complete

[arsenm]

Forgot to add file

[thegameg]

LGTM, thanks!

[arsenm]

r348285

include/llvm/CodeGen/TargetPassConfig.h

 /// to the internals of other CodeGen passes.
 class TargetPassConfig : public ImmutablePass {
 private:
   PassManagerBase *PM = nullptr;
   AnalysisID StartBefore = nullptr;
   AnalysisID StartAfter = nullptr;
   AnalysisID StopBefore = nullptr;
   AnalysisID StopAfter = nullptr;
+
+  unsigned StopAfterInstanceNum = 0;
+  unsigned StopAfterCount = 0;
+
   bool Started = true;
   bool Stopped = false;
   bool AddingMachinePasses = false;
 
   /// Set the StartAfter, StartBefore and StopAfter passes to allow running only
   /// a portion of the normal code-gen pass sequence.
   ///
   /// If the StartAfter and StartBefore pass ID is zero, then compilation will

lib/CodeGen/TargetPassConfig.cpp

static const PassInfo *getPassInfo(StringRef PassName) {
   return PI;
 }
 
 static AnalysisID getPassIDFromName(StringRef PassName) {
   const PassInfo *PI = getPassInfo(PassName);
   return PI ? PI->getTypeInfo() : nullptr;
 }
 
+static std::pair<StringRef, unsigned> getPassNameAndInstanceNum(StringRef PassName) {
+  StringRef Name, InstanceNumStr;
+  std::tie(Name, InstanceNumStr) = PassName.split(',');
+
+  unsigned InstanceNum;
+  if (InstanceNumStr.getAsInteger(10, InstanceNum))
+    return std::make_pair(Name, 0);
+
+  return std::make_pair(Name, InstanceNum);
+}
+
 void TargetPassConfig::setStartStopPasses() {
+  StringRef StopAfterName;
+  std::tie(StopAfterName, StopAfterInstanceNum) = getPassNameAndInstanceNum(StopAfterOpt);
+
+
   StartBefore = getPassIDFromName(StartBeforeOpt);
   StartAfter = getPassIDFromName(StartAfterOpt);
   StopBefore = getPassIDFromName(StopBeforeOpt);
-  StopAfter = getPassIDFromName(StopAfterOpt);
+  StopAfter = getPassIDFromName(StopAfterName);
   if (StartBefore && StartAfter)
     report_fatal_error(Twine(StartBeforeOptName) + Twine(" and ") +
                        Twine(StartAfterOptName) + Twine(" specified!"));
   if (StopBefore && StopAfter)
     report_fatal_error(Twine(StopBeforeOptName) + Twine(" and ") +
                        Twine(StopAfterOptName) + Twine(" specified!"));
   Started = (StartAfter == nullptr) && (StartBefore == nullptr);
 }
if (Started && !Stopped) {
     // Add the passes after the pass P if there is any.
     for (auto IP : Impl->InsertedPasses) {
       if (IP.TargetPassID == PassID)
         addPass(IP.getInsertedPass(), IP.VerifyAfter, IP.PrintAfter);
     }
   } else {
     delete P;
   }
-  if (StopAfter == PassID)
+
+  if (StopAfter == PassID && StopAfterCount++ == StopAfterInstanceNum4)
     Stopped = true;
+
   if (StartAfter == PassID)
     Started = true;
   if (Stopped && !Started)
     report_fatal_error("Cannot stop compilation after pass that is not run");
 }
 
 /// Add a CodeGen pass at this point in the pipeline after checking for target
 /// and command line overrides.