[C++11] Make this interface accept const Use pointers and use override

to ensure we don't mess up any of the overrides. Necessary for cleaning
up the Value use iterators and enabling range-based traversing of use
lists.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202958 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/CaptureTracking.h

@@ -45,12 +45,12 @@ namespace llvm {
     /// capture) return false. To search it, return true.
     ///
     /// U->getUser() is always an Instruction.
-    virtual bool shouldExplore(Use *U);
+    virtual bool shouldExplore(const Use *U);
 
     /// captured - Information about the pointer was captured by the user of
     /// use U. Return true to stop the traversal or false to continue looking
     /// for more capturing instructions.
-    virtual bool captured(Use *U) = 0;
+    virtual bool captured(const Use *U) = 0;
   };
 
   /// PointerMayBeCaptured - Visit the value and the values derived from it and

lib/Analysis/AliasAnalysis.cpp

@@ -372,7 +372,7 @@ namespace {
 
     void tooManyUses() override { Captured = true; }
 
-    bool shouldExplore(Use *U) override {
+    bool shouldExplore(const Use *U) override {
       Instruction *I = cast<Instruction>(U->getUser());
       BasicBlock *BB = I->getParent();
       // We explore this usage only if the usage can reach "BeforeHere".
@@ -388,7 +388,7 @@ namespace {
       return true;
     }
 
-    bool captured(Use *U) override {
+    bool captured(const Use *U) override {
       Instruction *I = cast<Instruction>(U->getUser());
       BasicBlock *BB = I->getParent();
       // Same logic as in shouldExplore.

lib/Analysis/CaptureTracking.cpp

@@ -28,7 +28,7 @@ using namespace llvm;
 
 CaptureTracker::~CaptureTracker() {}
 
-bool CaptureTracker::shouldExplore(Use *U) { return true; }
+bool CaptureTracker::shouldExplore(const Use *U) { return true; }
 
 namespace {
   struct SimpleCaptureTracker : public CaptureTracker {
@@ -37,7 +37,7 @@ namespace {
 
     void tooManyUses() override { Captured = true; }
 
-    bool captured(Use *U) override {
+    bool captured(const Use *U) override {
       if (isa<ReturnInst>(U->getUser()) && !ReturnCaptures)
         return false;
 
@@ -81,8 +81,8 @@ static int const Threshold = 20;
 
 void llvm::PointerMayBeCaptured(const Value *V, CaptureTracker *Tracker) {
   assert(V->getType()->isPointerTy() && "Capture is for pointers only!");
-  SmallVector<Use*, Threshold> Worklist;
-  SmallSet<Use*, Threshold> Visited;
+  SmallVector<const Use *, Threshold> Worklist;
+  SmallSet<const Use *, Threshold> Visited;
   int Count = 0;
 
   for (Value::const_use_iterator UI = V->use_begin(), UE = V->use_end();
@@ -99,7 +99,7 @@ void llvm::PointerMayBeCaptured(const Value *V, CaptureTracker *Tracker) {
   }
 
   while (!Worklist.empty()) {
-    Use *U = Worklist.pop_back_val();
+    const Use *U = Worklist.pop_back_val();
     Instruction *I = cast<Instruction>(U->getUser());
     V = U->get();
 

lib/Transforms/IPO/FunctionAttrs.cpp

@@ -344,7 +344,7 @@ namespace {
 
     void tooManyUses() override { Captured = true; }
 
-    bool captured(Use *U) override {
+    bool captured(const Use *U) override {
       CallSite CS(U->getUser());
       if (!CS.getInstruction()) { Captured = true; return true; }
 

lib/Transforms/Scalar/TailRecursionElimination.cpp

@@ -151,14 +151,14 @@ struct AllocaCaptureTracker : public CaptureTracker {
 
   void tooManyUses() override { Captured = true; }
 
-  bool shouldExplore(Use *U) override {
+  bool shouldExplore(const Use *U) override {
     Value *V = U->getUser();
     if (isa<CallInst>(V) || isa<InvokeInst>(V))
       UsesAlloca.insert(V);
     return true;
   }
 
-  bool captured(Use *U) override {
+  bool captured(const Use *U) override {
     if (isa<ReturnInst>(U->getUser()))
       return false;
     Captured = true;