fix grammaro's pointed out by daniel

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

diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp
index 0bff2b94e9d2d31f4a5c6b22e200878eb5a27eaf..298d5cf39162f788c5eb4b89649dc8d33f68ee42 100644 (file)
--- a/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -79,16 +79,47 @@ Pass *llvm::createFunctionAttrsPass() { return new FunctionAttrs(); }
 /// memory that is local to the function.  Global constants are considered
 /// local to all functions.
 bool FunctionAttrs::PointsToLocalMemory(Value *V) {
-  V = V->getUnderlyingObject();
-  // An alloca instruction defines local memory.
-  if (isa<AllocaInst>(V))
-    return true;
-  // A global constant counts as local memory for our purposes.
-  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
-    return GV->isConstant();
-  // Could look through phi nodes and selects here, but it doesn't seem
-  // to be useful in practice.
-  return false;
+  SmallVector<Value*, 16> Worklist;
+  unsigned MaxLookup = 8;
+
+  Worklist.push_back(V);
+
+  do {
+    V = Worklist.pop_back_val()->getUnderlyingObject();
+
+    // An alloca instruction defines local memory.
+    if (isa<AllocaInst>(V))
+      continue;
+
+    // A global constant counts as local memory for our purposes.
+    if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
+      if (!GV->isConstant())
+        return false;
+      continue;
+    }
+
+    // If both select values point to local memory, then so does the select.
+    if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
+      Worklist.push_back(SI->getTrueValue());
+      Worklist.push_back(SI->getFalseValue());
+      continue;
+    }
+
+    // If all values incoming to a phi node point to local memory, then so does
+    // the phi.
+    if (PHINode *PN = dyn_cast<PHINode>(V)) {
+      // Don't bother inspecting phi nodes with many operands.
+      if (PN->getNumIncomingValues() > MaxLookup)
+        return false;
+      for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
+        Worklist.push_back(PN->getIncomingValue(i));
+      continue;
+    }
+
+    return false;
+  } while (!Worklist.empty() && --MaxLookup);
+
+  return Worklist.empty();
 }
 
 /// AddReadAttrs - Deduce readonly/readnone attributes for the SCC.
@@ -144,7 +175,7 @@ bool FunctionAttrs::AddReadAttrs(const std::vector<CallGraphNode *> &SCC) {
             for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
                  CI != CE; ++CI) {
               Value *Arg = *CI;
-              if (isa<PointerType>(Arg->getType()) && !PointsToLocalMemory(Arg))
+              if (Arg->getType()->isPointerTy() && !PointsToLocalMemory(Arg))
                 // Writes memory.  Just give up.
                 return false;
             }
@@ -226,7 +257,7 @@ bool FunctionAttrs::AddNoCaptureAttrs(const std::vector<CallGraphNode *> &SCC) {
       continue;
 
     for (Function::arg_iterator A = F->arg_begin(), E = F->arg_end(); A!=E; ++A)
-      if (isa<PointerType>(A->getType()) && !A->hasNoCaptureAttr() &&
+      if (A->getType()->isPointerTy() && !A->hasNoCaptureAttr() &&
           !PointerMayBeCaptured(A, true, /*StoreCaptures=*/false)) {
         A->addAttr(Attribute::NoCapture);
         ++NumNoCapture;
@@ -331,7 +362,7 @@ bool FunctionAttrs::AddNoAliasAttrs(const std::vector<CallGraphNode *> &SCC) {
 
     // We annotate noalias return values, which are only applicable to 
     // pointer types.
-    if (!isa<PointerType>(F->getReturnType()))
+    if (!F->getReturnType()->isPointerTy())
       continue;
 
     if (!IsFunctionMallocLike(F, SCCNodes))
@@ -341,7 +372,7 @@ bool FunctionAttrs::AddNoAliasAttrs(const std::vector<CallGraphNode *> &SCC) {
   bool MadeChange = false;
   for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
     Function *F = SCC[i]->getFunction();
-    if (F->doesNotAlias(0) || !isa<PointerType>(F->getReturnType()))
+    if (F->doesNotAlias(0) || !F->getReturnType()->isPointerTy())
       continue;
 
     F->setDoesNotAlias(0);