[PATCH] D128827: [WIP][SCCP] Don't track specialized functions unless they are recursive.

[Alexandros Lamprineas via Phabricator via llvm-commits]

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An attempt to fix a crash when compiling MultiSource from the llvm test suite with `FuncSpecializationMaxIters > 1`

  llvm/include/llvm/Analysis/ValueLattice.h:
  bool llvm::ValueLatticeElement::markConstant(llvm::Constant*, bool):
  Assertion `getConstant() == V && "Marking constant with different value"'
  
  llvm::ValueLatticeElement::markConstant(llvm::Constant*, bool)
  llvm::SCCPInstVisitor::markConstant(llvm::Value*, llvm::Constant*)
  llvm::SCCPInstVisitor::visitCastInst(llvm::CastInst&)
  llvm::SCCPInstVisitor::solve()
  llvm::FunctionSpecializer::specialize(llvm::SmallVectorImpl<llvm::Function*>&)


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D128827

Files:
  llvm/lib/Transforms/IPO/FunctionSpecialization.cpp


Index: llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
===================================================================
--- llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
+++ llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
@@ -438,6 +438,14 @@
   return true;
 }
 
+static bool isRecursive(Function *F) {
+  return any_of(F->users(), [F](User *U) {
+           if (auto *CS = dyn_cast<CallBase>(U))
+             return CS->getFunction() == F;
+           return false;
+         });
+}
+
 void FunctionSpecializer::specializeFunction(Function *F, SpecializationInfo &S,
                                              FuncList &WorkList) {
   ValueToValueMapTy Mappings;
@@ -451,6 +459,15 @@
   // with the given value.
   Solver.markArgInFuncSpecialization(Clone, S.Args);
 
+  if (isRecursive(F) && FuncSpecializationMaxIters > 1) {
+    // Initialize the state of the newly created functions, marking them
+    // argument-tracked and executable.
+    if (F->hasExactDefinition() && !F->hasFnAttribute(Attribute::Naked))
+      Solver.addTrackedFunction(Clone);
+    Solver.addArgumentTrackedFunction(Clone);
+    Solver.markBlockExecutable(&Clone->front());
+  }
+
   // Mark all the specialized functions
   WorkList.push_back(Clone);
   NbFunctionsSpecialized++;
@@ -736,15 +753,7 @@
                                                  FuncList &WorkList) {
   for (auto *F : WorkList) {
     SpecializedFuncs.insert(F);
-
-    // Initialize the state of the newly created functions, marking them
-    // argument-tracked and executable.
-    if (F->hasExactDefinition() && !F->hasFnAttribute(Attribute::Naked))
-      Solver.addTrackedFunction(F);
-
-    Solver.addArgumentTrackedFunction(F);
     Candidates.push_back(F);
-    Solver.markBlockExecutable(&F->front());
 
     // Replace the function arguments for the specialized functions.
     for (Argument &Arg : F->args())


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