microsoft · alsepkow · Jun 19, 2025
diff --git a/include/llvm/ADT/StringExtras.h b/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

diff --git a/include/llvm/CodeGen/SelectionDAGNodes.h b/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 {

diff --git a/include/llvm/DebugInfo/DWARF/DWARFDebugRangeList.h b/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;
     }
   };
 

diff --git a/include/llvm/Support/LEB128.h b/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;

diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/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;
 }

diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/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;

diff --git a/lib/DXIL/DxilUtil.cpp b/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;
         }

diff --git a/lib/Support/APFloat.cpp b/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++;

diff --git a/lib/Support/DataExtractor.cpp b/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;

diff --git a/lib/Transforms/IPO/DeadArgumentElimination.cpp b/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);

diff --git a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -998,7 +998,7 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
     for (unsigned i = 0; i < VWidth; i++) {
       if (DemandedElts[i]) {
         unsigned MaskVal = Shuffle->getMaskValue(i);
-        if (MaskVal != -1u) {
+        if (MaskVal != ~0u) {
           assert(MaskVal < LHSVWidth * 2 &&
                  "shufflevector mask index out of range!");
           if (MaskVal < LHSVWidth)
@@ -1022,7 +1022,7 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
     bool NewUndefElts = false;
     for (unsigned i = 0; i < VWidth; i++) {
       unsigned MaskVal = Shuffle->getMaskValue(i);
-      if (MaskVal == -1u) {
+      if (MaskVal == ~0u) {
         UndefElts.setBit(i);
       } else if (!DemandedElts[i]) {
         NewUndefElts = true;

diff --git a/tools/clang/lib/Lex/LiteralSupport.cpp b/tools/clang/lib/Lex/LiteralSupport.cpp
@@ -141,8 +141,12 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
     // Hex escapes are a maximal series of hex digits.
     bool Overflow = false;
     for (; ThisTokBuf != ThisTokEnd; ++ThisTokBuf) {
-      int CharVal = llvm::hexDigitValue(ThisTokBuf[0]);
-      if (CharVal == -1) break;
+      // originally returned -1 for invalid hex digits, now returns ~0u
+      // signature: static inline unsigned int llvm::hexDigitValue(char C)
+      unsigned int CharVal = llvm::hexDigitValue(ThisTokBuf[0]);
+      if (CharVal == ~0U)
+        break;
+
       // About to shift out a digit?
       if (ResultChar & 0xF0000000)
         Overflow = true;
@@ -245,7 +249,7 @@ void clang::expandUCNs(SmallVectorImpl<char> &Buf, StringRef Input) {
     uint32_t CodePoint = 0;
     for (++I; NumHexDigits != 0; ++I, --NumHexDigits) {
       unsigned Value = llvm::hexDigitValue(*I);
-      assert(Value != -1U);
+      assert(Value != ~0U);
 
       CodePoint <<= 4;
       CodePoint += Value;
@@ -278,8 +282,9 @@ static bool ProcessUCNEscape(const char *ThisTokBegin, const char *&ThisTokBuf,
   UcnLen = (ThisTokBuf[-1] == 'u' ? 4 : 8);
   unsigned short UcnLenSave = UcnLen;
   for (; ThisTokBuf != ThisTokEnd && UcnLenSave; ++ThisTokBuf, UcnLenSave--) {
-    int CharVal = llvm::hexDigitValue(ThisTokBuf[0]);
-    if (CharVal == -1) break;
+    unsigned int CharVal = llvm::hexDigitValue(ThisTokBuf[0]);
+    if (CharVal == ~0U)
+      break;
     UcnVal <<= 4;
     UcnVal |= CharVal;
   }

diff --git a/tools/clang/lib/Sema/SemaDecl.cpp b/tools/clang/lib/Sema/SemaDecl.cpp
@@ -5331,7 +5331,7 @@ bool Sema::inferObjCARCLifetime(ValueDecl *decl) {
   Qualifiers::ObjCLifetime lifetime = type.getObjCLifetime();
   if (lifetime == Qualifiers::OCL_Autoreleasing) {
     // Various kinds of declaration aren't allowed to be __autoreleasing.
-    unsigned kind = -1U;
+    unsigned kind = ~0U;
     if (VarDecl *var = dyn_cast<VarDecl>(decl)) {
       if (var->hasAttr<BlocksAttr>())
         kind = 0; // __block
@@ -5343,7 +5343,7 @@ bool Sema::inferObjCARCLifetime(ValueDecl *decl) {
       kind = 2; // field
     }
 
-    if (kind != -1U) {
+    if (kind != ~0U) {
       Diag(decl->getLocation(), diag::err_arc_autoreleasing_var)
         << kind;
     }