Revert "[FunctionAttrs] Identify norecurse functions"

[oota-llvm.git] / lib / Transforms / IPO / FunctionAttrs.cpp

diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp
index edebc26d475e53262b58aa71b7f3e304aa1c5908..351809ddedec6475dc961dc0a630c5218df8f46c 100644 (file)
--- a/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -50,7 +50,6 @@ STATISTIC(NumReadOnlyArg, "Number of arguments marked readonly");
 STATISTIC(NumNoAlias, "Number of function returns marked noalias");
 STATISTIC(NumNonNullReturn, "Number of function returns marked nonnull");
 STATISTIC(NumAnnotated, "Number of attributes added to library functions");
-STATISTIC(NumNoRecurse, "Number of functions marked as norecurse");
 
 namespace {
 typedef SmallSetVector<Function *, 8> SCCNodeSet;
@@ -64,12 +63,7 @@ struct FunctionAttrs : public CallGraphSCCPass {
   }
 
   bool runOnSCC(CallGraphSCC &SCC) override;
-  bool doInitialization(CallGraph &CG) override {
-    Revisit.clear();
-    return false;
-  }
-  bool doFinalization(CallGraph &CG) override;
-  
+
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.setPreservesCFG();
     AU.addRequired<AssumptionCacheTracker>();
@@ -79,7 +73,6 @@ struct FunctionAttrs : public CallGraphSCCPass {
 
 private:
   TargetLibraryInfo *TLI;
-  SmallVector<WeakVH,16> Revisit;
 };
 }
 
@@ -983,14 +976,6 @@ static void setDoesNotAlias(Function &F, unsigned n) {
   }
 }
 
-static bool setDoesNotRecurse(Function &F) {
-  if (F.doesNotRecurse())
-    return false;
-  F.setDoesNotRecurse();
-  ++NumNoRecurse;
-  return true;
-}
-
 /// Analyze the name and prototype of the given function and set any applicable
 /// attributes.
 ///
@@ -1794,55 +1779,6 @@ static bool inferPrototypeAttributes(Function &F, const TargetLibraryInfo &TLI)
   return true;
 }
 
-static bool addNoRecurseAttrs(const CallGraphSCC &SCC,
-                              SmallVectorImpl<WeakVH> &Revisit) {
-  // Try and identify functions that do not recurse.
-
-  // If the SCC contains multiple nodes we know for sure there is recursion.
-  if (!SCC.isSingular())
-    return false;
-
-  const CallGraphNode *CGN = *SCC.begin();
-  Function *F = CGN->getFunction();
-  if (!F || F->isDeclaration() || F->doesNotRecurse())
-    return false;
-
-  // If all of the calls in F are identifiable and are to norecurse functions, F
-  // is norecurse. This check also detects self-recursion as F is not currently
-  // marked norecurse, so any called from F to F will not be marked norecurse.
-  if (std::all_of(CGN->begin(), CGN->end(),
-                  [](const CallGraphNode::CallRecord &CR) {
-                    Function *F = CR.second->getFunction();
-                    return F && F->doesNotRecurse();
-                  }))
-    // Function calls a potentially recursive function.
-    return setDoesNotRecurse(*F);
-
-  // We know that F is not obviously recursive, but we haven't been able to
-  // prove that it doesn't actually recurse. Add it to the Revisit list to try
-  // again top-down later.
-  Revisit.push_back(F);
-  return false;
-}
-
-static bool addNoRecurseAttrsTopDownOnly(Function *F) {
-  // If F is internal and all uses are in norecurse functions, then F is also
-  // norecurse.
-  if (F->doesNotRecurse())
-    return false;
-  if (F->hasInternalLinkage()) {
-    for (auto *U : F->users())
-      if (auto *I = dyn_cast<Instruction>(U)) {
-        if (!I->getParent()->getParent()->doesNotRecurse())
-          return false;
-      } else {
-        return false;
-      }
-    return setDoesNotRecurse(*F);
-  }
-  return false;
-}
-
 bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
   TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
   bool Changed = false;
@@ -1890,19 +1826,6 @@ bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
     Changed |= addNoAliasAttrs(SCCNodes);
     Changed |= addNonNullAttrs(SCCNodes, *TLI);
   }
-  
-  Changed |= addNoRecurseAttrs(SCC, Revisit);
-  return Changed;
-}
 
-bool FunctionAttrs::doFinalization(CallGraph &CG) {
-  bool Changed = false;
-  // When iterating over SCCs we visit functions in a bottom-up fashion. Some of
-  // the rules we have for identifying norecurse functions work best with a
-  // top-down walk, so look again at all the functions we previously marked as
-  // worth revisiting, in top-down order.
-  for (auto &F : reverse(Revisit))
-    if (F)
-      Changed |= addNoRecurseAttrsTopDownOnly(cast<Function>((Value*)F));
   return Changed;
 }