[function-attrs] Refactor code to handle shorter code with early exits.

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

diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp
index 7d2b351ae5c569b04dc24bef0d60dd65121cd8df..6c357ed03a805be0b5a8d6c5928417dce7da2a01 100644 (file)
--- a/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -130,39 +130,45 @@ checkFunctionMemoryAccess(Function &F, AAResults &AAR,
       if (CS.getCalledFunction() && SCCNodes.count(CS.getCalledFunction()))
         continue;
       FunctionModRefBehavior MRB = AAR.getModRefBehavior(CS);
-      // If the call doesn't access arbitrary memory, we may be able to
-      // figure out something.
-      if (AliasAnalysis::onlyAccessesArgPointees(MRB)) {
-        // If the call does access argument pointees, check each argument.
-        if (AliasAnalysis::doesAccessArgPointees(MRB))
-          // Check whether all pointer arguments point to local memory, and
-          // ignore calls that only access local memory.
-          for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
-               CI != CE; ++CI) {
-            Value *Arg = *CI;
-            if (Arg->getType()->isPointerTy()) {
-              AAMDNodes AAInfo;
-              I->getAAMetadata(AAInfo);
-
-              MemoryLocation Loc(Arg, MemoryLocation::UnknownSize, AAInfo);
-              if (!AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true)) {
-                if (MRB & MRI_Mod)
-                  // Writes non-local memory.  Give up.
-                  return MAK_MayWrite;
-                if (MRB & MRI_Ref)
-                  // Ok, it reads non-local memory.
-                  ReadsMemory = true;
-              }
-            }
-          }
+
+      // If the call doesn't access memory, we're done.
+      if (!(MRB & MRI_ModRef))
         continue;
+
+      if (!AliasAnalysis::onlyAccessesArgPointees(MRB)) {
+        // The call could access any memory. If that includes writes, give up.
+        if (MRB & MRI_Mod)
+          return MAK_MayWrite;
+        // If it reads, note it.
+        if (MRB & MRI_Ref)
+          ReadsMemory = true;
+        continue;
+      }
+
+      // Check whether all pointer arguments point to local memory, and
+      // ignore calls that only access local memory.
+      for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
+           CI != CE; ++CI) {
+        Value *Arg = *CI;
+        if (!Arg->getType()->isPointerTy())
+          continue;
+
+        AAMDNodes AAInfo;
+        I->getAAMetadata(AAInfo);
+        MemoryLocation Loc(Arg, MemoryLocation::UnknownSize, AAInfo);
+
+        // Skip accesses to local or constant memory as they don't impact the
+        // externally visible mod/ref behavior.
+        if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
+          continue;
+
+        if (MRB & MRI_Mod)
+          // Writes non-local memory.  Give up.
+          return MAK_MayWrite;
+        if (MRB & MRI_Ref)
+          // Ok, it reads non-local memory.
+          ReadsMemory = true;
       }
-      // The call could access any memory. If that includes writes, give up.
-      if (MRB & MRI_Mod)
-        return MAK_MayWrite;
-      // If it reads, note it.
-      if (MRB & MRI_Ref)
-        ReadsMemory = true;
       continue;
     } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
       // Ignore non-volatile loads from local memory. (Atomic is okay here.)
@@ -347,7 +353,7 @@ struct ArgumentUsesTracker : public CaptureTracker {
         return true;
       }
       if (PI == U) {
-        Uses.push_back(AI);
+        Uses.push_back(&*AI);
         Found = true;
         break;
       }
@@ -466,7 +472,7 @@ determinePointerReadAttrs(Argument *A,
             return Attribute::None;
           }
           Captures &= !CS.doesNotCapture(A - B);
-          if (SCCNodes.count(AI))
+          if (SCCNodes.count(&*AI))
             continue;
           if (!CS.onlyReadsMemory() && !CS.onlyReadsMemory(A - B))
             return Attribute::None;
@@ -551,7 +557,7 @@ bool FunctionAttrs::AddArgumentAttrs(const CallGraphSCC &SCC) {
       bool HasNonLocalUses = false;
       if (!A->hasNoCaptureAttr()) {
         ArgumentUsesTracker Tracker(SCCNodes);
-        PointerMayBeCaptured(A, &Tracker);
+        PointerMayBeCaptured(&*A, &Tracker);
         if (!Tracker.Captured) {
           if (Tracker.Uses.empty()) {
             // If it's trivially not captured, mark it nocapture now.
@@ -563,7 +569,7 @@ bool FunctionAttrs::AddArgumentAttrs(const CallGraphSCC &SCC) {
             // If it's not trivially captured and not trivially not captured,
             // then it must be calling into another function in our SCC. Save
             // its particulars for Argument-SCC analysis later.
-            ArgumentGraphNode *Node = AG[A];
+            ArgumentGraphNode *Node = AG[&*A];
             for (SmallVectorImpl<Argument *>::iterator
                      UI = Tracker.Uses.begin(),
                      UE = Tracker.Uses.end();
@@ -582,8 +588,8 @@ bool FunctionAttrs::AddArgumentAttrs(const CallGraphSCC &SCC) {
         // will be dependent on the iteration order through the functions in the
         // SCC.
         SmallPtrSet<Argument *, 8> Self;
-        Self.insert(A);
-        Attribute::AttrKind R = determinePointerReadAttrs(A, Self);
+        Self.insert(&*A);
+        Attribute::AttrKind R = determinePointerReadAttrs(&*A, Self);
         if (R != Attribute::None) {
           AttrBuilder B;
           B.addAttribute(R);