[NFC] Address compiler warnings: C4146 - Cases where we can swap to using ~ operator (microsoft#7551)

Addresses microsoft#7550.

Author: alsepkow

include/llvm/ADT/StringExtras.h

@@ -36,12 +36,12 @@ static inline StringRef toStringRef(bool B) {
 /// Interpret the given character \p C as a hexadecimal digit and return its
 /// value.
 ///
-/// If \p C is not a valid hex digit, -1U is returned.
+/// If \p C is not a valid hex digit, ~0U is returned.
 static inline unsigned hexDigitValue(char C) {
   if (C >= '0' && C <= '9') return C-'0';
   if (C >= 'a' && C <= 'f') return C-'a'+10U;
   if (C >= 'A' && C <= 'F') return C-'A'+10U;
-  return -1U;
+  return ~0U;
 }
 
 /// utohex_buffer - Emit the specified number into the buffer specified by

include/llvm/CodeGen/SelectionDAGNodes.h

@@ -191,12 +191,12 @@ class SDValue {
 template<> struct DenseMapInfo<SDValue> {
   static inline SDValue getEmptyKey() {
     SDValue V;
-    V.ResNo = -1U;
+    V.ResNo = ~0U;
     return V;
   }
   static inline SDValue getTombstoneKey() {
     SDValue V;
-    V.ResNo = -2U;
+    V.ResNo = ~1U;
     return V;
   }
   static unsigned getHashValue(const SDValue &Val) {
@@ -879,7 +879,7 @@ inline SDValue::SDValue(SDNode *node, unsigned resno)
     : Node(node), ResNo(resno) {
   assert((!Node || ResNo < Node->getNumValues()) &&
          "Invalid result number for the given node!");
-  assert(ResNo < -2U && "Cannot use result numbers reserved for DenseMaps.");
+  assert(ResNo < ~1U && "Cannot use result numbers reserved for DenseMaps.");
 }
 
 inline unsigned SDValue::getOpcode() const {

include/llvm/DebugInfo/DWARF/DWARFDebugRangeList.h

@@ -49,9 +49,9 @@ class DWARFDebugRangeList {
     bool isBaseAddressSelectionEntry(uint8_t AddressSize) const {
       assert(AddressSize == 4 || AddressSize == 8);
       if (AddressSize == 4)
-        return StartAddress == -1U;
+        return StartAddress == ~0U;
       else
-        return StartAddress == -1ULL;
+        return StartAddress == ~0ULL;
     }
   };
 

include/llvm/Support/LEB128.h

@@ -103,7 +103,7 @@ inline int64_t decodeSLEB128(const uint8_t *p, unsigned *n = nullptr) {
   } while (Byte >= 128);
   // Sign extend negative numbers.
   if (Byte & 0x40)
-    Value |= (-1ULL) << Shift;
+    Value |= (~0ULL) << Shift;
   if (n)
     *n = (unsigned)(p - orig_p);
   return Value;

lib/Bitcode/Reader/BitcodeReader.cpp

@@ -2401,7 +2401,7 @@ uint64_t BitcodeReader::decodeSignRotatedValue(uint64_t V) {
   if ((V & 1) == 0)
     return V >> 1;
   if (V != 1)
-    return -(V >> 1);
+    return ~(V >> 1) + 1;
   // There is no such thing as -0 with integers.  "-0" really means MININT.
   return 1ULL << 63;
 }

lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -1360,7 +1360,7 @@ static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
   if ((int64_t)V >= 0)
     Vals.push_back(V << 1);
   else
-    Vals.push_back((-V << 1) | 1);
+    Vals.push_back(((~V + 1) << 1) | 1);
 }
 
 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
@@ -1437,7 +1437,7 @@ static void WriteConstants(unsigned FirstVal, unsigned LastVal,
       continue;
     }
     const Constant *C = cast<Constant>(V);
-    unsigned Code = -1U;
+    unsigned Code = ~0U;
     unsigned AbbrevToUse = 0;
     if (C->isNullValue()) {
       Code = bitc::CST_CODE_NULL;

lib/DXIL/DxilUtil.cpp

@@ -181,11 +181,11 @@ void PrintUnescapedString(StringRef Name, raw_ostream &Out) {
     if (C == '\\') {
       C = Name[++i];
       unsigned value = hexDigitValue(C);
-      if (value != -1U) {
+      if (value != ~0U) {
         C = (unsigned char)value;
         unsigned value2 = hexDigitValue(Name[i + 1]);
-        assert(value2 != -1U && "otherwise, not a two digit hex escape");
-        if (value2 != -1U) {
+        assert(value2 != ~0U && "otherwise, not a two digit hex escape");
+        if (value2 != ~0U) {
           C = (C << 4) + (unsigned char)value2;
           ++i;
         }

lib/Support/APFloat.cpp

@@ -331,7 +331,7 @@ trailingHexadecimalFraction(StringRef::iterator p, StringRef::iterator end,
 
   /* If we ran off the end it is exactly zero or one-half, otherwise
      a little more.  */
-  if (hexDigit == -1U)
+  if (hexDigit == ~0U)
     return digitValue == 0 ? lfExactlyZero: lfExactlyHalf;
   else
     return digitValue == 0 ? lfLessThanHalf: lfMoreThanHalf;
@@ -2368,7 +2368,7 @@ APFloat::convertFromHexadecimalString(StringRef s, roundingMode rounding_mode)
     }
 
     hex_value = hexDigitValue(*p);
-    if (hex_value == -1U)
+    if (hex_value == ~0U)
       break;
 
     p++;

lib/Support/DataExtractor.cpp

@@ -168,7 +168,7 @@ int64_t DataExtractor::getSLEB128(uint32_t *offset_ptr) const {
 
   // Sign bit of byte is 2nd high order bit (0x40)
   if (shift < 64 && (byte & 0x40))
-    result |= -(1ULL << shift);
+    result |= (~(1ULL << shift) + 1);
 
   *offset_ptr = offset;
   return result;

lib/Transforms/IPO/DeadArgumentElimination.cpp

@@ -146,7 +146,7 @@ namespace {
   private:
     Liveness MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses);
     Liveness SurveyUse(const Use *U, UseVector &MaybeLiveUses,
-                       unsigned RetValNum = -1U);
+                       unsigned RetValNum = ~0U);
     Liveness SurveyUses(const Value *V, UseVector &MaybeLiveUses);
 
     void SurveyFunction(const Function &F);
@@ -442,7 +442,7 @@ DAE::Liveness DAE::SurveyUse(const Use *U,
       // that U is really a use of an insertvalue instruction that uses the
       // original Use.
       const Function *F = RI->getParent()->getParent();
-      if (RetValNum != -1U) {
+      if (RetValNum != ~0U) {
         RetOrArg Use = CreateRet(F, RetValNum);
         // We might be live, depending on the liveness of Use.
         return MarkIfNotLive(Use, MaybeLiveUses);