Handle pointer conversions for call instructions.

This also should complete the changes associated with removing pointer cast
instructions from the PNaCl bitcode file.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=3544
R=dschuff@chromium.org, jvoung@chromium.org

Review URL: https://codereview.chromium.org/23482002

3 files changed, 102 insertions, 79 deletions

diff --git a/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp b/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
index fbe1fc0165..028e750d92 100644
--- a/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
+++ b/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
@@ -1315,16 +1315,15 @@ Value *NaClBitcodeReader::ConvertOpToScalar(Value *Op, unsigned BBIndex,
 
 Value *NaClBitcodeReader::ConvertOpToType(Value *Op, Type *T,
                                           unsigned BBIndex) {
-  // Note: Currently only knows how to add inttoptr and bitcast type
-  // conversions for non-phi nodes, since these are the only elided
-  // instructions in the bitcode writer.
-  //
-  // TODO(kschimpf): Generalize this as we expand elided conversions.
   Type *OpTy = Op->getType();
   if (OpTy == T) return Op;
 
   if (OpTy->isPointerTy()) {
-    return CreateCast(BBIndex, Instruction::BitCast, T, Op);
+    if (T == IntPtrType) {
+      return ConvertOpToScalar(Op, BBIndex);
+    } else {
+      return CreateCast(BBIndex, Instruction::BitCast, T, Op);
+    }
   } else if (OpTy == IntPtrType) {
     return CreateCast(BBIndex, Instruction::IntToPtr, T, Op);
   }
@@ -1687,7 +1686,7 @@ bool NaClBitcodeReader::ParseFunctionBody(Function *F) {
         return Error("Invalid LOAD record");
       switch (GetPNaClVersion()) {
         case 1:
-	  I = new LoadInst(Op, "", Record[OpNum+1], (1 << Record[OpNum]) >> 1);
+          I = new LoadInst(Op, "", Record[OpNum+1], (1 << Record[OpNum]) >> 1);
           break;
         case 2: {
           // Add pointer cast to op.
@@ -1696,8 +1695,8 @@ bool NaClBitcodeReader::ParseFunctionBody(Function *F) {
             return Error("Invalid type for load instruction");
           Op = ConvertOpToType(Op, T->getPointerTo(), CurBBNo);
           if (Op == 0) return true;
-	  I = new LoadInst(Op, "", false, (1 << Record[OpNum]) >> 1);
-	  break;
+          I = new LoadInst(Op, "", false, (1 << Record[OpNum]) >> 1);
+          break;
         }
       }
       break;
@@ -1712,28 +1711,29 @@ bool NaClBitcodeReader::ParseFunctionBody(Function *F) {
         return Error("Invalid STORE record");
       switch (GetPNaClVersion()) {
       case 1:
-	if (OpNum+2 != Record.size())
-	  return Error("Invalid STORE record");
-	I = new StoreInst(Val, Ptr, Record[OpNum+1], (1 << Record[OpNum]) >> 1);
-	break;
+        if (OpNum+2 != Record.size())
+          return Error("Invalid STORE record");
+        I = new StoreInst(Val, Ptr, Record[OpNum+1], (1 << Record[OpNum]) >> 1);
+        break;
       case 2:
-	if (OpNum+1 != Record.size())
-	  return Error("Invalid STORE record");
+        if (OpNum+1 != Record.size())
+          return Error("Invalid STORE record");
         Val = ConvertOpToScalar(Val, CurBBNo);
         Ptr = ConvertOpToType(Ptr, Val->getType()->getPointerTo(), CurBBNo);
-	I = new StoreInst(Val, Ptr, false, (1 << Record[OpNum]) >> 1);
-	break;
+        I = new StoreInst(Val, Ptr, false, (1 << Record[OpNum]) >> 1);
+        break;
       }
       break;
     }
-    case naclbitc::FUNC_CODE_INST_CALL: {
+    case naclbitc::FUNC_CODE_INST_CALL:
+    case naclbitc::FUNC_CODE_INST_CALL_INDIRECT: {
       // CALL: [cc, fnid, arg0, arg1...]
-      if (Record.size() < 2)
+      // PNaCl version 2: CALL_INDIRECT: [cc, fnid, fnty, args...]
+      if ((Record.size() < 2) ||
+          (BitCode == naclbitc::FUNC_CODE_INST_CALL_INDIRECT &&
+           Record.size() < 3))
         return Error("Invalid CALL record");
 
-      // TODO(kschimpf): Fix handling of type conversion to arguments for PNaCl,
-      // to handle elided casts, once the bitcode writer knows how.
-
       unsigned CCInfo = Record[0];
 
       unsigned OpNum = 1;
@@ -1741,35 +1741,42 @@ bool NaClBitcodeReader::ParseFunctionBody(Function *F) {
       if (popValue(Record, &OpNum, NextValueNo, &Callee))
         return Error("Invalid CALL record");
 
-      PointerType *OpTy = dyn_cast<PointerType>(Callee->getType());
+      // Build function type for call.
       FunctionType *FTy = 0;
-      if (OpTy) FTy = dyn_cast<FunctionType>(OpTy->getElementType());
-      if (!FTy || Record.size() < FTy->getNumParams()+OpNum)
-        return Error("Invalid CALL record");
-
-      SmallVector<Value*, 16> Args;
-      // Read the fixed params.
-      for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i, ++OpNum) {
-        if (FTy->getParamType(i)->isLabelTy())
-          Args.push_back(getBasicBlock(Record[OpNum]));
-        else
-          Args.push_back(getValue(Record, OpNum, NextValueNo));
-        if (Args.back() == 0) return Error("Invalid CALL record");
-      }
-
-      // Read type/value pairs for varargs params.
-      if (!FTy->isVarArg()) {
-        if (OpNum != Record.size())
-          return Error("Invalid CALL record");
+      if (BitCode == naclbitc::FUNC_CODE_INST_CALL_INDIRECT) {
+        // Callee type has been elided, add back in.
+        Type *Type = getTypeByID(Record[2]);
+        ++OpNum;
+        if (FunctionType *FcnType = dyn_cast<FunctionType>(Type)) {
+          FTy = FcnType;
+          Callee = ConvertOpToType(Callee, FcnType->getPointerTo(), CurBBNo);
+        } else {
+          return Error("Invalid type for CALL_INDIRECT record");
+        }
       } else {
-        while (OpNum != Record.size()) {
-          Value *Op;
-          if (popValue(Record, &OpNum, NextValueNo, &Op))
-            return Error("Invalid CALL record");
-          Args.push_back(Op);
+        // Get type signature from callee.
+        if (PointerType *OpTy = dyn_cast<PointerType>(Callee->getType())) {
+          FTy = dyn_cast<FunctionType>(OpTy->getElementType());
         }
+        if (FTy == 0)
+          return Error("Invalid type for CALL record");
+      }
+
+      unsigned NumParams = Record.size() - OpNum;
+      if (NumParams != FTy->getNumParams())
+        return Error("Invalid CALL record");
+
+      // Process call arguments.
+      SmallVector<Value*, 6> Args;
+      for (unsigned Index = 0; Index < NumParams; ++Index) {
+        Value *Arg;
+        if (popValue(Record, &OpNum, NextValueNo, &Arg))
+          Error("Invalid argument in CALL record");
+        Arg = ConvertOpToType(Arg, FTy->getParamType(Index), CurBBNo);
+        Args.push_back(Arg);
       }
 
+      // Construct call.
       I = CallInst::Create(Callee, Args);
       cast<CallInst>(I)->setCallingConv(GetDecodedCallingConv(CCInfo>>1));
       cast<CallInst>(I)->setTailCall(CCInfo & 1);
diff --git a/lib/Bitcode/NaCl/Writer/NaClBitcodeWriter.cpp b/lib/Bitcode/NaCl/Writer/NaClBitcodeWriter.cpp
index 6624ad1d7c..2ac88c92a4 100644
--- a/lib/Bitcode/NaCl/Writer/NaClBitcodeWriter.cpp
+++ b/lib/Bitcode/NaCl/Writer/NaClBitcodeWriter.cpp
@@ -975,32 +975,47 @@ static bool WriteInstruction(const Instruction &I, unsigned InstID,
     }
     break;
   case Instruction::Call: {
-    const CallInst &CI = cast<CallInst>(I);
-    PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());
-    FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
-
-    Code = naclbitc::FUNC_CODE_INST_CALL;
-
-    Vals.push_back((GetEncodedCallingConv(CI.getCallingConv()) << 1)
-                   | unsigned(CI.isTailCall()));
-    pushValue(CI.getCalledValue(), InstID, Vals, VE, Stream);  // Callee
-
-    // Emit value #'s for the fixed parameters.
-    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
-      // Check for labels (can happen with asm labels).
-      if (FTy->getParamType(i)->isLabelTy())
-        Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
-      else
-        // fixed param.
-        pushValue(CI.getArgOperand(i), InstID, Vals, VE, Stream);
+    // CALL: [cc, fnid, args...]
+    // PNaCl version 2: CALL_INDIRECT: [cc, fnid, fnty, args...]
+
+    const CallInst &Call = cast<CallInst>(I);
+    const Value* Callee = Call.getCalledValue();
+    Vals.push_back((GetEncodedCallingConv(Call.getCallingConv()) << 1)
+                   | unsigned(Call.isTailCall()));
+
+    pushValue(Callee, InstID, Vals, VE, Stream);
+
+    switch (PNaClVersion) {
+    case 1:
+      Code = naclbitc::FUNC_CODE_INST_CALL;
+      break;
+    case 2:
+      if (Callee == VE.ElideCasts(Callee)) {
+        // Since the call pointer has not been elided, we know that
+        // the call pointer has the type signature of the called
+        // function.  This implies that the reader can use the type
+        // signature of the callee to figure out how to add casts to
+        // the arguments.
+        Code = naclbitc::FUNC_CODE_INST_CALL;
+      } else {
+        // If the cast was elided, a pointer conversion to a pointer
+        // was applied, meaning that this is an indirect call. For the
+        // reader, this implies that we can't use the type signature
+        // of the callee to resolve elided call arguments, since it is
+        // not known. Hence, we must send the type signature to the
+        // reader.
+        Code = naclbitc::FUNC_CODE_INST_CALL_INDIRECT;
+        PointerType *FcnPtrType =
+          cast<PointerType>(Callee->getType());
+        FunctionType *FcnType =
+          cast<FunctionType>(FcnPtrType->getElementType());
+        Vals.push_back(VE.getTypeID(FcnType));
+      }
+      break;
     }
 
-    // Emit type/value pairs for varargs params.
-    if (FTy->isVarArg()) {
-      for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
-           i != e; ++i)
-        // varargs
-        pushValue(CI.getArgOperand(i), InstID, Vals, VE, Stream);
+    for (unsigned I = 0, E = Call.getNumArgOperands(); I < E; ++I) {
+      pushValue(Call.getArgOperand(I), InstID, Vals, VE, Stream);
     }
     break;
   }
diff --git a/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp b/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp
index 060a6d63f4..8cfdf13240 100644
--- a/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp
+++ b/lib/Bitcode/NaCl/Writer/NaClValueEnumerator.cpp
@@ -438,9 +438,6 @@ static bool ExpectsNormalizedPtr(const Value *V, const Instruction *Arg) {
   const Instruction *I = dyn_cast<Instruction>(V);
   if (I == 0) return false;
 
-  // TODO(kschimpf) Expand this list to any operation that can handle
-  // normalized pointers. That is loads and stores, function calls, and
-  // instrinsic calls.
   switch (I->getOpcode()) {
   default:
     return false;
@@ -448,6 +445,10 @@ static bool ExpectsNormalizedPtr(const Value *V, const Instruction *Arg) {
     return I->getOperand(0) == Arg;
   case Instruction::Store:
     return I->getOperand(1) == Arg;
+  case Instruction::Call:
+    // For function calls, the function operand is normalized, and for
+    // intrinsic calls, all pointer arguments are normalized.
+    return true;
   }
 }
 
@@ -493,12 +494,13 @@ static bool ExpectsScalarValue(const Value *V, const Instruction *Arg) {
       const SelectInst *Op = dyn_cast<SelectInst>(I);
       return Arg == Op->getTrueValue() || Arg == Op->getFalseValue();
     }
+    case Instruction::Call: {
+      // All operands (except the first, which must be a function pointer),
+      // can be scalar values.
+      const CallInst *Call = cast<CallInst>(I);
+      return Call->getCalledValue() != Arg;
+    }
     }
-    // TODO(kschimpf): Need to think more about how to handle following
-    // instructions:
-    // case Instruction::IntToPtr:
-    // case Instruction::BitCast:
-    // case Instruction::Call:
   }
 }
 
@@ -526,7 +528,6 @@ static inline bool IsInherentPtr(const Value *V) {
 // llvm/lib/Transforms/NaCl/ReplacePtrsWithInts.cpp.
 const Value *NaClValueEnumerator::ElideCasts(const Value *V) {
   if (PNaClVersion == 1) return V;
-  // TODO(kschimpf): Expand this out to cover all cases.
   if (const Instruction *I = dyn_cast<Instruction>(V)) {
     switch (I->getOpcode()) {
     default: