Remove the "really gross hacks" that are there to deal with recursive functions.

Now we collect all of the call sites we are interested in inlining, then inline
them.  This entirely avoids issues with trying to inline a call site we got by
inlining another call site.  This also eliminates iterator invalidation issues.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12770 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 55 insertions, 84 deletions

diff --git a/lib/Transforms/IPO/InlineSimple.cpp b/lib/Transforms/IPO/InlineSimple.cpp
index 0c950c7ba3..c0d97c5515 100644
--- a/lib/Transforms/IPO/InlineSimple.cpp
+++ b/lib/Transforms/IPO/InlineSimple.cpp
@@ -217,13 +217,7 @@ int SimpleInliner::getInlineCost(CallSite CS) {
   // Don't inline into something too big, which would make it bigger.  Here, we
   // count each basic block as a single unit.
   //
-  // FIXME: THIS IS A TOTAL HACK.  The problem is that we don't keep track of
-  // which call sites are the result of an inlining operation.  Because of this,
-  // if we inline a recursive function into a callee, we will see a new call to
-  // the recursive function.  Every time we inline we get a new callsite for the
-  // function, which only stops when the caller reaches its inlining limit.
-  // Until the real problem is fixed, we apply this gnasty hack.
-  InlineCost += Caller->size();
+  InlineCost += Caller->size()/20;
 
 
   // Look at the size of the callee.  Each basic block counts as 20 units, and
diff --git a/lib/Transforms/IPO/Inliner.cpp b/lib/Transforms/IPO/Inliner.cpp
index c0861f1b67..325631a792 100644
--- a/lib/Transforms/IPO/Inliner.cpp
+++ b/lib/Transforms/IPO/Inliner.cpp
@@ -58,84 +58,67 @@ bool Inliner::runOnSCC(const std::vector<CallGraphNode*> &SCC) {
     if (F == 0 || F->isExternal()) continue;
     DEBUG(std::cerr << "  Inspecting function: " << F->getName() << "\n");
 
+    // Scan through and identify all call sites ahead of time so that we only
+    // inline call sites in the original functions, not call sites that result
+    // in inlining other functions.
+    std::vector<CallSite> CallSites;
     for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
-      for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
-        bool ShouldInc = true;
-        // Found a call or invoke instruction?
-        if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
-          CallSite CS = CallSite::get(I);
-          if (Function *Callee = CS.getCalledFunction())
-            if (!Callee->isExternal() && !IsRecursiveFunction.count(Callee)) {
-              // Determine whether this is a function IN the SCC...
-              bool inSCC = SCCFunctions.count(Callee);
+      for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) {
+        CallSite CS = CallSite::get(I);
+        if (CS.getInstruction() && CS.getCalledFunction() &&
+            !CS.getCalledFunction()->isExternal())
+          CallSites.push_back(CS);
+      }
 
-              // Keep track of whether this is a directly recursive function.
-              if (Callee == F) IsRecursiveFunction.insert(F);
+    // Now that we have all of the call sites, loop over them and inline them if
+    // it looks profitable to do so.
+    for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
+      CallSite CS = CallSites[i];
+      Function *Callee = CS.getCalledFunction();
+      // Determine whether this is a function IN the SCC...
+      bool inSCC = SCCFunctions.count(Callee);
+    
+      // If the policy determines that we should inline this function,
+      // try to do so...
+      int InlineCost = inSCC ? getRecursiveInlineCost(CS) : getInlineCost(CS);
+      if (InlineCost >= (int)InlineThreshold) {
+        DEBUG(std::cerr << "    NOT Inlining: cost=" << InlineCost
+              << ", Call: " << *CS.getInstruction());
+      } else {
+        DEBUG(std::cerr << "    Inlining: cost=" << InlineCost
+              << ", Call: " << *CS.getInstruction());
+      
+        Function *Caller = CS.getInstruction()->getParent()->getParent();
 
-              // If the policy determines that we should inline this function,
-              // try to do so...
-              int InlineCost = inSCC ? getRecursiveInlineCost(CS) :
-                                       getInlineCost(CS);
-              if (InlineCost >= (int)InlineThreshold) {
-                DEBUG(std::cerr << "    NOT Inlining: cost=" << InlineCost
-                                << ", Call: " << *CS.getInstruction());
-              } else {
-                DEBUG(std::cerr << "    Inlining: cost=" << InlineCost
-                                << ", Call: " << *CS.getInstruction());
+        // Attempt to inline the function...
+        if (InlineFunction(CS)) {
+          ++NumInlined;
+  
+          if (Callee->hasOneUse())
+            if (ConstantPointerRef *CPR =
+                dyn_cast<ConstantPointerRef>(Callee->use_back()))
+              if (CPR->use_empty())
+                CPR->destroyConstant();
+        
+          // If we inlined the last possible call site to the function,
+          // delete the function body now.
+          if (Callee->use_empty() && Callee != Caller &&
+              (Callee->hasInternalLinkage() || Callee->hasLinkOnceLinkage())) {
+            DEBUG(std::cerr << "    -> Deleting dead function: "
+                  << (void*)Callee << Callee->getName() << "\n");
+            std::set<Function*>::iterator I = SCCFunctions.find(Callee);
+            if (I != SCCFunctions.end())    // Remove function from this SCC.
+              SCCFunctions.erase(I);
 
-                // Save an iterator to the instruction before the call if it
-                // exists, otherwise get an iterator at the end of the
-                // block... because the call will be destroyed.
-                //
-                BasicBlock::iterator SI;
-                if (I != BB->begin()) {
-                  SI = I; --SI;           // Instruction before the call...
-                } else {
-                  SI = BB->end();
-                }
-                
-                if (performInlining(CS, SCCFunctions)) {
-                  // Move to instruction before the call...
-                  I = (SI == BB->end()) ? BB->begin() : SI;
-                  ShouldInc = false; // Don't increment iterator until next time
-                  Changed = true;
-                }
-              }
-            }
+            Callee->getParent()->getFunctionList().erase(Callee);
+            ++NumDeleted;
+          }
+          Changed = true;
         }
-        if (ShouldInc) ++I;
       }
+    }
   }
-  return Changed;
-}
-
-bool Inliner::performInlining(CallSite CS, std::set<Function*> &SCC) {
-  Function *Callee = CS.getCalledFunction();
-  Function *Caller = CS.getInstruction()->getParent()->getParent();
 
-  // Attempt to inline the function...
-  if (!InlineFunction(CS)) return false;
-  ++NumInlined;
-  
-  if (Callee->hasOneUse())
-    if (ConstantPointerRef *CPR =
-        dyn_cast<ConstantPointerRef>(Callee->use_back()))
-      if (CPR->use_empty())
-        CPR->destroyConstant();
-  
-  // If we inlined the last possible call site to the function,
-  // delete the function body now.
-  if (Callee->use_empty() && Callee != Caller &&
-      (Callee->hasInternalLinkage() || Callee->hasLinkOnceLinkage())) {
-    DEBUG(std::cerr << "    -> Deleting dead function: " << (void*)Callee
-                    << Callee->getName() << "\n");
-    std::set<Function*>::iterator I = SCC.find(Callee);
-    if (I != SCC.end())       // Remove function from this SCC...
-      SCC.erase(I);
-
-    Callee->getParent()->getFunctionList().erase(Callee);
-    ++NumDeleted;
-  }
-  return true; 
+  return Changed;
 }
 
diff --git a/lib/Transforms/IPO/Inliner.h b/lib/Transforms/IPO/Inliner.h
index 805876c54d..b63fe2ac05 100644
--- a/lib/Transforms/IPO/Inliner.h
+++ b/lib/Transforms/IPO/Inliner.h
@@ -56,12 +56,6 @@ struct Inliner : public CallGraphSCCPass {
 private:
   // InlineThreshold - Cache the value here for easy access.
   unsigned InlineThreshold;
-
-  // IsRecursiveFunction - This contains all functions which are directly
-  // recursive, which we do NOT want to inline into other functions.
-  std::set<Function*> IsRecursiveFunction;
-
-  bool performInlining(CallSite CS, std::set<Function*> &SCC);
 };
 
 } // End llvm namespace