[llvm-commits] [llvm] r72377 - /llvm/trunk/tools/bugpoint/CrashDebugger.cpp

[Nick Lewycky]

Author: nicholas
Date: Mon May 25 00:30:00 2009
New Revision: 72377

URL: http://llvm.org/viewvc/llvm-project?rev=72377&view=rev
Log:
Add a bisection step on the list of instructions before doing the linear
simplification. It's not clear to me whether this can replace the first of the
linear instruction simplification stages or not, so I left it in.

Modified:
    llvm/trunk/tools/bugpoint/CrashDebugger.cpp

Modified: llvm/trunk/tools/bugpoint/CrashDebugger.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/bugpoint/CrashDebugger.cpp?rev=72377&r1=72376&r2=72377&view=diff

==============================================================================
--- llvm/trunk/tools/bugpoint/CrashDebugger.cpp (original)
+++ llvm/trunk/tools/bugpoint/CrashDebugger.cpp Mon May 25 00:30:00 2009
@@ -342,6 +342,82 @@
   return false;
 }
 
+namespace {
+  /// ReduceCrashingInstructions reducer - This works by removing the specified
+  /// non-terminator instructions and replacing them with undef.
+  ///
+  class ReduceCrashingInstructions : public ListReducer<const Instruction*> {
+    BugDriver &BD;
+    bool (*TestFn)(BugDriver &, Module *);
+  public:
+    ReduceCrashingInstructions(BugDriver &bd, bool (*testFn)(BugDriver &,
+                                                             Module *))
+      : BD(bd), TestFn(testFn) {}
+
+    virtual TestResult doTest(std::vector<const Instruction*> &Prefix,
+                              std::vector<const Instruction*> &Kept) {
+      if (!Kept.empty() && TestInsts(Kept))
+        return KeepSuffix;
+      if (!Prefix.empty() && TestInsts(Prefix))
+        return KeepPrefix;
+      return NoFailure;
+    }
+
+    bool TestInsts(std::vector<const Instruction*> &Prefix);
+  };
+}
+
+bool ReduceCrashingInstructions::TestInsts(std::vector<const Instruction*>
+                                           &Insts) {
+  // Clone the program to try hacking it apart...
+  DenseMap<const Value*, Value*> ValueMap;
+  Module *M = CloneModule(BD.getProgram(), ValueMap);
+
+  // Convert list to set for fast lookup...
+  SmallPtrSet<Instruction*, 64> Instructions;
+  for (unsigned i = 0, e = Insts.size(); i != e; ++i) {
+    assert(!isa<TerminatorInst>(Insts[i]));
+    Instructions.insert(cast<Instruction>(ValueMap[Insts[i]]));
+  }
+
+  std::cout << "Checking for crash with only " << Instructions.size();
+  if (Instructions.size() == 1)
+    std::cout << " instruction: ";
+  else
+    std::cout << " instructions: ";
+
+  for (Module::iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI)
+    for (Function::iterator FI = MI->begin(), FE = MI->end(); FI != FE; ++FI)
+      for (BasicBlock::iterator I = FI->begin(), E = FI->end(); I != E;) {
+        Instruction *Inst = I++;
+        if (!Instructions.count(Inst) && !isa<TerminatorInst>(Inst)) {
+          if (Inst->getType() != Type::VoidTy)
+            Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
+          Inst->eraseFromParent();
+        }
+      }
+
+  // Verify that this is still valid.
+  PassManager Passes;
+  Passes.add(createVerifierPass());
+  Passes.run(*M);
+
+  // Try running on the hacked up program...
+  if (TestFn(BD, M)) {
+    BD.setNewProgram(M);      // It crashed, keep the trimmed version...
+
+    // Make sure to use instruction pointers that point into the now-current
+    // module, and that they don't include any deleted blocks.
+    Insts.clear();
+    for (SmallPtrSet<Instruction*, 64>::const_iterator I = Instructions.begin(),
+             E = Instructions.end(); I != E; ++I)
+      Insts.push_back(*I);
+    return true;
+  }
+  delete M;  // It didn't crash, try something else.
+  return false;
+}
+
 /// DebugACrash - Given a predicate that determines whether a component crashes
 /// on a program, try to destructively reduce the program while still keeping
 /// the predicate true.
@@ -432,6 +508,22 @@
       BD.EmitProgressBitcode("reduced-blocks");
   }
 
+  // Attempt to delete instructions using bisection. This should help out nasty
+  // cases with large basic blocks where the problem is at one end.
+  if (!BugpointIsInterrupted) {
+    std::vector<const Instruction*> Insts;
+    for (Module::const_iterator MI = BD.getProgram()->begin(),
+           ME = BD.getProgram()->end(); MI != ME; ++MI)
+      for (Function::const_iterator FI = MI->begin(), FE = MI->end(); FI != FE;
+           ++FI)
+        for (BasicBlock::const_iterator I = FI->begin(), E = FI->end();
+             I != E; ++I)
+          if (!isa<TerminatorInst>(I))
+            Insts.push_back(I);
+
+    ReduceCrashingInstructions(BD, TestFn).reduceList(Insts);
+  }
+
   // FIXME: This should use the list reducer to converge faster by deleting
   // larger chunks of instructions at a time!
   unsigned Simplification = 2;