Partial specialization was not checking the callsite to make sure it was using the same constants as the specialization, leading to calls to the wrong specialization. Patch by Takumi Nakamura\!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105528 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/PartialSpecialization.cpp

@@ -32,6 +32,10 @@
 using namespace llvm;
 
 STATISTIC(numSpecialized, "Number of specialized functions created");
+STATISTIC(numReplaced, "Number of callers replaced by specialization");
+
+// Maximum number of arguments markable interested
+static const int MaxInterests = 6;
 
 // Call must be used at least occasionally
 static const int CallsMin = 5;
@@ -40,8 +44,9 @@ static const int CallsMin = 5;
 static const double ConstValPercent = .1;
 
 namespace {
+  typedef SmallVector<int, MaxInterests> InterestingArgVector;
   class PartSpec : public ModulePass {
-    void scanForInterest(Function&, SmallVector<int, 6>&);
+    void scanForInterest(Function&, InterestingArgVector&);
     int scanDistribution(Function&, int, std::map<Constant*, int>&);
   public :
     static char ID; // Pass identification, replacement for typeid
@@ -61,11 +66,13 @@ static Function*
 SpecializeFunction(Function* F, 
                    DenseMap<const Value*, Value*>& replacements) {
   // arg numbers of deleted arguments
-  DenseSet<unsigned> deleted;
+  DenseMap<unsigned, const Argument*> deleted;
   for (DenseMap<const Value*, Value*>::iterator 
          repb = replacements.begin(), repe = replacements.end();
-       repb != repe; ++repb)
-    deleted.insert(cast<Argument>(repb->first)->getArgNo());
+       repb != repe; ++repb) {
+    Argument const *arg = cast<const Argument>(repb->first);
+    deleted[arg->getArgNo()] = arg;
+  }
 
   Function* NF = CloneFunction(F, replacements);
   NF->setLinkage(GlobalValue::InternalLinkage);
@@ -80,9 +87,23 @@ SpecializeFunction(Function* F,
       if (CS.getCalledFunction() == F) {
         
         SmallVector<Value*, 6> args;
-        for (unsigned x = 0; x < CS.arg_size(); ++x)
-          if (!deleted.count(x))
-            args.push_back(CS.getArgument(x));
+        // Assemble the non-specialized arguments for the updated callsite.
+        // In the process, make sure that the specialized arguments are
+        // constant and match the specialization.  If that's not the case,
+        // this callsite needs to call the original or some other
+        // specialization; don't change it here.
+        CallSite::arg_iterator as = CS.arg_begin(), ae = CS.arg_end();
+        for (CallSite::arg_iterator ai = as; ai != ae; ++ai) {
+          DenseMap<unsigned, const Argument*>::iterator delit = deleted.find(
+            std::distance(as, ai));
+          if (delit == deleted.end())
+            args.push_back(cast<Value>(ai));
+          else {
+            Constant *ci = dyn_cast<Constant>(ai);
+            if (!(ci && ci == replacements[delit->second]))
+              goto next_use;
+          }
+        }
         Value* NCall;
         if (CallInst *CI = dyn_cast<CallInst>(i)) {
           NCall = CallInst::Create(NF, args.begin(), args.end(), 
@@ -99,8 +120,11 @@ SpecializeFunction(Function* F,
         }
         CS.getInstruction()->replaceAllUsesWith(NCall);
         CS.getInstruction()->eraseFromParent();
+        ++numReplaced;
       }
     }
+  next_use:
+    ;
   }
   return NF;
 }
@@ -111,7 +135,7 @@ bool PartSpec::runOnModule(Module &M) {
   for (Module::iterator I = M.begin(); I != M.end(); ++I) {
     Function &F = *I;
     if (F.isDeclaration() || F.mayBeOverridden()) continue;
-    SmallVector<int, 6> interestingArgs;
+    InterestingArgVector interestingArgs;
     scanForInterest(F, interestingArgs);
 
     // Find the first interesting Argument that we can specialize on
@@ -143,7 +167,7 @@ bool PartSpec::runOnModule(Module &M) {
 
 /// scanForInterest - This function decides which arguments would be worth
 /// specializing on.
-void PartSpec::scanForInterest(Function& F, SmallVector<int, 6>& args) {
+void PartSpec::scanForInterest(Function& F, InterestingArgVector& args) {
   for(Function::arg_iterator ii = F.arg_begin(), ee = F.arg_end();
       ii != ee; ++ii) {
     for(Value::use_iterator ui = ii->use_begin(), ue = ii->use_end();

test/Transforms/PartialSpecialize/dg.exp

@@ -0,0 +1,3 @@
+load_lib llvm.exp
+
+RunLLVMTests [lsort [glob -nocomplain $srcdir/$subdir/*.{ll,c,cpp}]]

test/Transforms/PartialSpecialize/two-specializations.ll

@@ -0,0 +1,32 @@
+; If there are two specializations of a function, make sure each callsite
+; calls the right one.
+;
+; RUN: opt -S -partialspecialization %s | FileCheck %s
+declare void @callback1()
+declare void @callback2()
+
+define internal void @UseCallback(void()* %pCallback) {
+  call void %pCallback()
+  ret void
+}
+
+define void @foo(void()* %pNonConstCallback)
+{
+Entry:
+; CHECK: Entry
+; CHECK-NEXT: call void @UseCallback1()
+; CHECK-NEXT: call void @UseCallback1()
+; CHECK-NEXT: call void @UseCallback2()
+; CHECK-NEXT: call void @UseCallback(void ()* %pNonConstCallback)
+; CHECK-NEXT: call void @UseCallback1()
+; CHECK-NEXT: call void @UseCallback2()
+; CHECK-NEXT: call void @UseCallback2()
+  call void @UseCallback(void()* @callback1)
+  call void @UseCallback(void()* @callback1)
+  call void @UseCallback(void()* @callback2)
+  call void @UseCallback(void()* %pNonConstCallback)
+  call void @UseCallback(void()* @callback1)
+  call void @UseCallback(void()* @callback2)
+  call void @UseCallback(void()* @callback2)
+  ret void
+}