Clean up static analyzer warnings.

Clang's static analyzer found several potential cases of undefined
behavior, use of un-initialized values, and potentially null pointer
dereferences in tablegen, Support, MC, and ADT. This cleans them up
with specific assertions on the assumptions of the code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224154 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/BitVector.h

@@ -450,6 +450,7 @@ class BitVector {
 
     // Grow the bitvector to have enough elements.
     Capacity = RHSWords;
+    assert(Capacity > 0 && "negative capacity?");
     BitWord *NewBits = (BitWord *)std::malloc(Capacity * sizeof(BitWord));
     std::memcpy(NewBits, RHS.Bits, Capacity * sizeof(BitWord));
 

include/llvm/ADT/SmallBitVector.h

@@ -292,8 +292,11 @@ class SmallBitVector {
   }
 
   SmallBitVector &set(unsigned Idx) {
-    if (isSmall())
+    if (isSmall()) {
+      assert(Idx <= std::numeric_limits<uintptr_t>::digits &&
+             "undefined behavior");
       setSmallBits(getSmallBits() | (uintptr_t(1) << Idx));
+    }
     else
       getPointer()->set(Idx);
     return *this;

lib/MC/MCAsmStreamer.cpp

@@ -682,7 +682,10 @@ void MCAsmStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
       // We truncate our partial emission to fit within the bounds of the
       // emission domain.  This produces nicer output and silences potential
       // truncation warnings when round tripping through another assembler.
-      ValueToEmit &= ~0ULL >> (64 - EmissionSize * 8);
+      uint64_t Shift = 64 - EmissionSize * 8;
+      assert(Shift < std::numeric_limits<unsigned long long>::digits &&
+             "undefined behavior");
+      ValueToEmit &= ~0ULL >> Shift;
       EmitIntValue(ValueToEmit, EmissionSize);
       Emitted += EmissionSize;
     }

lib/MC/MCObjectStreamer.cpp

@@ -405,7 +405,9 @@ void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue) {
 }
 
 void MCObjectStreamer::EmitZeros(uint64_t NumBytes) {
-  unsigned ItemSize = getCurrentSection().first->isVirtualSection() ? 0 : 1;
+  const MCSection *Sec = getCurrentSection().first;
+  assert(Sec && "need a section");
+  unsigned ItemSize = Sec->isVirtualSection() ? 0 : 1;
   insert(new MCFillFragment(0, ItemSize, NumBytes));
 }
 

lib/MC/MCParser/COFFAsmParser.cpp

@@ -582,7 +582,7 @@ bool COFFAsmParser::ParseSEHDirectiveHandlerData(StringRef, SMLoc) {
 }
 
 bool COFFAsmParser::ParseSEHDirectivePushReg(StringRef, SMLoc L) {
-  unsigned Reg;
+  unsigned Reg = 0;
   if (ParseSEHRegisterNumber(Reg))
     return true;
 
@@ -595,7 +595,7 @@ bool COFFAsmParser::ParseSEHDirectivePushReg(StringRef, SMLoc L) {
 }
 
 bool COFFAsmParser::ParseSEHDirectiveSetFrame(StringRef, SMLoc L) {
-  unsigned Reg;
+  unsigned Reg = 0;
   int64_t Off;
   if (ParseSEHRegisterNumber(Reg))
     return true;
@@ -636,7 +636,7 @@ bool COFFAsmParser::ParseSEHDirectiveAllocStack(StringRef, SMLoc) {
 }
 
 bool COFFAsmParser::ParseSEHDirectiveSaveReg(StringRef, SMLoc L) {
-  unsigned Reg;
+  unsigned Reg = 0;
   int64_t Off;
   if (ParseSEHRegisterNumber(Reg))
     return true;
@@ -663,7 +663,7 @@ bool COFFAsmParser::ParseSEHDirectiveSaveReg(StringRef, SMLoc L) {
 // FIXME: This method is inherently x86-specific. It should really be in the
 // x86 backend.
 bool COFFAsmParser::ParseSEHDirectiveSaveXMM(StringRef, SMLoc L) {
-  unsigned Reg;
+  unsigned Reg = 0;
   int64_t Off;
   if (ParseSEHRegisterNumber(Reg))
     return true;

lib/Support/ScaledNumber.cpp

@@ -169,8 +169,7 @@ static std::string toStringAPFloat(uint64_t D, int E, unsigned Precision) {
   int Shift = 63 - (NewE - E);
   assert(Shift <= LeadingZeros);
   assert(Shift == LeadingZeros || NewE == ScaledNumbers::MaxScale);
-  assert((Shift & (1u << std::numeric_limits<int>::digits)) == 0 &&
-         "undefined behavior");
+  assert(Shift >= 0 && Shift < 64 && "undefined behavior");
   D <<= Shift;
   E = NewE;
 

lib/Support/raw_ostream.cpp

@@ -312,6 +312,7 @@ raw_ostream &raw_ostream::write(const char *Ptr, size_t Size) {
     // than the buffer. Directly write the chunk that is a multiple of the
     // preferred buffer size and put the remainder in the buffer.
     if (LLVM_UNLIKELY(OutBufCur == OutBufStart)) {
+      assert(NumBytes != 0 && "undefined behavior");
       size_t BytesToWrite = Size - (Size % NumBytes);
       write_impl(Ptr, BytesToWrite);
       size_t BytesRemaining = Size - BytesToWrite;

lib/TableGen/Record.cpp

@@ -812,7 +812,7 @@ Init *UnOpInit::Fold(Record *CurRec, MultiClass *CurMultiClass) const {
             return VarInit::get(MCName, RV->getType());
           }
         }
-
+        assert(CurRec && "NULL pointer");
         if (Record *D = (CurRec->getRecords()).getDef(Name))
           return DefInit::get(D);
 

utils/TableGen/CodeGenDAGPatterns.cpp

@@ -2569,8 +2569,10 @@ FindPatternInputsAndOutputs(TreePattern *I, TreePatternNode *Pat,
       I->error("set destination should be a register!");
 
     DefInit *Val = dyn_cast<DefInit>(Dest->getLeafValue());
-    if (!Val)
+    if (!Val) {
       I->error("set destination should be a register!");
+      continue;
+    }
 
     if (Val->getDef()->isSubClassOf("RegisterClass") ||
         Val->getDef()->isSubClassOf("ValueType") ||

utils/TableGen/CodeGenInstruction.cpp

@@ -537,7 +537,7 @@ bool CodeGenInstAlias::tryAliasOpMatch(DagInit *Result, unsigned AliasOpNo,
   // If both are Operands with the same MVT, allow the conversion. It's
   // up to the user to make sure the values are appropriate, just like
   // for isel Pat's.
-  if (InstOpRec->isSubClassOf("Operand") &&
+  if (InstOpRec->isSubClassOf("Operand") && ADI &&
       ADI->getDef()->isSubClassOf("Operand")) {
     // FIXME: What other attributes should we check here? Identical
     // MIOperandInfo perhaps?

utils/TableGen/CodeGenRegisters.cpp

@@ -146,6 +146,7 @@ void CodeGenRegister::buildObjectGraph(CodeGenRegBank &RegBank) {
 }
 
 const std::string &CodeGenRegister::getName() const {
+  assert(TheDef && "no def");
   return TheDef->getName();
 }