[clang-tidy] Enhance redundant-expression check

[etienneb]

Summary

This patch is adding support to recognize more complex redundant expressions.

[aaron.ballman]

clang-tidy/misc/RedundantExpressionCheck.cpp

124

s/bitween/between, however, I don't think this function adds much value; why not just call APSInt::compareValues() directly?

141

Why is off-by-one more useful than a stronger range analysis?

181

Same question here as above.

187

Can this be done before doing the more expensive value comparisons?

237

s/do/does

277

I can never remember myself, but how well does APSInt handle this situation if it causes overflow of the signed value? e.g., an 8-bit APSInt holding the value -128 being negated to 128 (which is outside the range of an 8-bit signed integer).

304

I'm not keen on this name because C11 has _Generic, for which we have a GenericSelectionExpr which is awfully close to this name.

clang-tidy/misc/RedundantExpressionCheck.h

31

& should bind to R.

Also, all of these functions can be marked const.

[etienneb]

address comments

[etienneb]

thx Aaron.

clang-tidy/misc/RedundantExpressionCheck.cpp

141

I don't get your point?

This function is comparing two ranges. Ranges are comparable only if they are compared to the same constant....
OR, if they are off-by one and the operator contains "equality".

As the comment state, x <= 4 is equivalent to x < 5.

To avoid problem with wrap around, the left value is incremented (the left value must be the smaller one: canonical form).

I don't get why we should use a range analysis? Is there some utility functions I'm not aware of?

187

it can be done before the previous if. But not the one at line 149 (which always returns).

277

In this case -128 (8-bits) will give -128.
The APSInt is behaving the same way than a real value of the same width and signedness.

I added an unittest to cover this case.

304

'Generic' is a too generic name :)

clang-tidy/misc/RedundantExpressionCheck.h

31

They can't be constant, they are calling 'diag' which is not const.

error: no matching function for call to ‘clang::tidy::misc::RedundantExpressionCheck::diag(clang::SourceLocation, const char [35]) const

[etienneb]

refactoring

[aaron.ballman]

clang-tidy/misc/RedundantExpressionCheck.cpp

31

I think this could be implemented using APInt overflow checks, no? APInt::sadd_ov()?

141

Ah, this may be confusion on my part. I was thinking "equivalent ranges" meaning "does one range cover another range", e.g., x < 12 is also covered by x < 4 in an expression like if (x < 4 && x < 12).

I think this code is fine as-is.

277

In this case -128 (8-bits) will give -128.

So negating -128 doesn't yield 128, it yields -128? That seems weird.

The APSInt is behaving the same way than a real value of the same width and signedness.

A real value of the same width and signedness has UB with that case, which is why I was asking. The range of an 8-bit signed int is -128 to 127, so negating -128 yields an out-of-range value. I want to make sure we aren't butchering that by canonicalizing the negate expression.

clang-tidy/misc/RedundantExpressionCheck.h

31

Hmmm, good point. Drat!

[alexfh]

A few nits.

clang-tidy/misc/RedundantExpressionCheck.cpp

138

How about replacing if (x) return true; return false; with return x;?

BTW, next function looks fine in this regard, since it has a chain of if (x) return true; if (y) return true; ....

185

Remove braces for consistency.

194

I'd slightly prefer it without "do": rangesFullyCoverDomain, rangeSubsumesRange, etc.

269

The last return seems to be dead code.

367

Not sure I understand this comment.

627

using llvm::APSInt; to remove some boilerplate?

650

Please add braces, when the body is more than one line.

654

ComparisonOperator->getOperatorLoc() and the message are repeated too many times. Pull them to local variables / constants?

[etienneb]

address comments

[etienneb]

clang-tidy/misc/RedundantExpressionCheck.cpp

31

It could be implemented using sadd_ov and uadd_ov.
The 'signedness' need to be take into account. The class 'APInt' doesn't not carry signedness.

Using the operator++ here let the instantiated type do the right increment and right comparison.

277

The value produced by 'canonicalNegateExpr' is the same value produced by executing the sub instruction on the CPU.
Even if the value make no sense in math.

Btw, there is a unittest to cover this case.

367

if ( implicit-int-to-bool(x) ) <<-- the implicit-int-to-bool(...) could be consider as x != 0

[alexfh]

A couple of nits. Otherwise looks good. Thanks!

clang-tidy/misc/RedundantExpressionCheck.cpp

232

nit: rangeSubsumesRange (note: subsume -> subsumes)

283

nit: I'd prefer "const" instead of "cst": saving two characters doesn't change much, I guess, but the loss of clarity is substantial.

[etienneb]

nits

clang-tidy/misc/RedundantExpressionCheck.h

 /// For the user-facing documentation see:
 /// http://clang.llvm.org/extra/clang-tidy/checks/misc-redundant-expression.html
 class RedundantExpressionCheck : public ClangTidyCheck {
 public:
   RedundantExpressionCheck(StringRef Name, ClangTidyContext *Context)
       : ClangTidyCheck(Name, Context) {}
   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+  void checkArithmeticExpr(const ast_matchers::MatchFinder::MatchResult &R);
+  void checkBitwiseExpr(const ast_matchers::MatchFinder::MatchResult &R);
+  void checkRelationalExpr(const ast_matchers::MatchFinder::MatchResult &R);
 };
 
 } // namespace misc
 } // namespace tidy
 } // namespace clang
 
 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_REDUNDANT_EXPRESSION_H

clang-tidy/misc/RedundantExpressionCheck.cpp

 #include "RedundantExpressionCheck.h"
 #include "../utils/Matchers.h"
 #include "../utils/OptionsUtils.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
 
 using namespace clang::ast_matchers;
+using namespace clang::tidy::matchers;
 
 namespace clang {
 namespace tidy {
 namespace misc {
 
+namespace {
+using llvm::APSInt;
+} // namespace
+
 static const char KnownBannedMacroNames[] =
     "EAGAIN;EWOULDBLOCK;SIGCLD;SIGCHLD;";
 
+static bool incrementWithoutOverflow(const APSInt &Value, APSInt &Result) {
+  Result = Value;
+  ++Result;
+  return Value < Result;
+}
+
 static bool areEquivalentNameSpecifier(const NestedNameSpecifier *Left,
                                        const NestedNameSpecifier *Right) {
   llvm::FoldingSetNodeID LeftID, RightID;
   Left->Profile(LeftID);
   Right->Profile(RightID);
   return LeftID == RightID;
 }
 
case Stmt::UnaryOperatorClass:
     return cast<UnaryOperator>(Left)->getOpcode() ==
            cast<UnaryOperator>(Right)->getOpcode();
   case Stmt::BinaryOperatorClass:
     return cast<BinaryOperator>(Left)->getOpcode() ==
            cast<BinaryOperator>(Right)->getOpcode();
   }
 }
 
+// For a given expression 'x', returns whether the ranges covered by the
+// relational operators are equivalent (i.e.  x <= 4 is equivalent to x < 5).
+static bool areEquivalentRanges(BinaryOperatorKind OpcodeLHS,
+                                const APSInt &ValueLHS,
+                                BinaryOperatorKind OpcodeRHS,
+                                const APSInt &ValueRHS) {
+  assert(APSInt::compareValues(ValueLHS, ValueRHS) <= 0 &&
+         "Values must be ordered");
+  // Handle the case where constants are the same: x <= 4  <==>  x <= 4.
+  if (APSInt::compareValues(ValueLHS, ValueRHS) == 0)
+    return OpcodeLHS == OpcodeRHS;
+
+  // Handle the case where constants are off by one: x <= 4  <==>  x < 5.
+  APSInt ValueLHS_plus1;
+  return ((OpcodeLHS == BO_LE && OpcodeRHS == BO_LT) ||
+          (OpcodeLHS == BO_GT && OpcodeRHS == BO_GE)) &&
+         incrementWithoutOverflow(ValueLHS, ValueLHS_plus1) &&
+         APSInt::compareValues(ValueLHS_plus1, ValueRHS) == 0;
+}
+
+// For a given expression 'x', returns whether the ranges covered by the
+// relational operators are fully disjoint (i.e. x < 4  and  x > 7).
+static bool areExclusiveRanges(BinaryOperatorKind OpcodeLHS,
+                               const APSInt &ValueLHS,
+                               BinaryOperatorKind OpcodeRHS,
+                               const APSInt &ValueRHS) {
+  assert(APSInt::compareValues(ValueLHS, ValueRHS) <= 0 &&
+         "Values must be ordered");
+
+  // Handle cases where the constants are the same.
+  if (APSInt::compareValues(ValueLHS, ValueRHS) == 0) {
+    switch (OpcodeLHS) {
+    case BO_EQ:
+      return OpcodeRHS == BO_NE || OpcodeRHS == BO_GT || OpcodeRHS == BO_LT;
+    case BO_NE:
+      return OpcodeRHS == BO_EQ;
+    case BO_LE:
+      return OpcodeRHS == BO_GT;
+    case BO_GE:
+      return OpcodeRHS == BO_LT;
+    case BO_LT:
+      return OpcodeRHS == BO_EQ || OpcodeRHS == BO_GT || OpcodeRHS == BO_GE;
+    case BO_GT:
+      return OpcodeRHS == BO_EQ || OpcodeRHS == BO_LT || OpcodeRHS == BO_LE;
+    default:
+      return false;
+    }
+  }
+
+  // Handle cases where the constants are different.
+  if ((OpcodeLHS == BO_EQ || OpcodeLHS == BO_LE || OpcodeLHS == BO_LE) &&
+      (OpcodeRHS == BO_EQ || OpcodeRHS == BO_GT || OpcodeRHS == BO_GE))
+    return true;
+
+  // Handle the case where constants are off by one: x > 5 && x < 6.
+  APSInt ValueLHS_plus1;
+  if (OpcodeLHS == BO_GT && OpcodeRHS == BO_LT &&
+      incrementWithoutOverflow(ValueLHS, ValueLHS_plus1) &&
+      APSInt::compareValues(ValueLHS_plus1, ValueRHS) == 0)
+    return true;
+
+  return false;
+}
+
+// Returns whether the ranges covered by the union of both relational
+// expressions covers the whole domain (i.e. x < 10  and  x > 0).
+static bool rangesFullyCoverDomain(BinaryOperatorKind OpcodeLHS,
+                                   const APSInt &ValueLHS,
+                                   BinaryOperatorKind OpcodeRHS,
+                                   const APSInt &ValueRHS) {
+  assert(APSInt::compareValues(ValueLHS, ValueRHS) <= 0 &&
+         "Values must be ordered");
+
+  // Handle cases where the constants are the same:  x < 5 || x >= 5.
+  if (APSInt::compareValues(ValueLHS, ValueRHS) == 0) {
+    switch (OpcodeLHS) {
+    case BO_EQ:
+      return OpcodeRHS == BO_NE;
+    case BO_NE:
+      return OpcodeRHS == BO_EQ;
+    case BO_LE:
+      return OpcodeRHS == BO_GT || OpcodeRHS == BO_GE;
+    case BO_LT:
+      return OpcodeRHS == BO_GE;
+    case BO_GE:
+      return OpcodeRHS == BO_LT || OpcodeRHS == BO_LE;
+    case BO_GT:
+      return OpcodeRHS == BO_LE;
+    default:
+      return false;
+    }
+  }
+
+  // Handle the case where constants are off by one: x <= 4 || x >= 5.
+  APSInt ValueLHS_plus1;
+  if (OpcodeLHS == BO_LE && OpcodeRHS == BO_GE &&
+      incrementWithoutOverflow(ValueLHS, ValueLHS_plus1) &&
+      APSInt::compareValues(ValueLHS_plus1, ValueRHS) == 0)
+    return true;
+
+  // Handle cases where the constants are different: x > 4 || x <= 7.
+  if ((OpcodeLHS == BO_GT || OpcodeLHS == BO_GE) &&
+      (OpcodeRHS == BO_LT || OpcodeRHS == BO_LE))
+    return true;
+
+  return false;
+}
+
+static bool rangeSubsumeRange(BinaryOperatorKind OpcodeLHS,
+                              const APSInt &ValueLHS,
+                              BinaryOperatorKind OpcodeRHS,
+                              const APSInt &ValueRHS) {
+  int Comparison = APSInt::compareValues(ValueLHS, ValueRHS);
+  switch (OpcodeLHS) {
+  case BO_EQ:
+    return OpcodeRHS == BO_EQ && Comparison == 0;
+  case BO_NE:
+    return (OpcodeRHS == BO_NE && Comparison == 0) ||
+           (OpcodeRHS == BO_EQ && Comparison != 0) ||
+           (OpcodeRHS == BO_LT && Comparison >= 0) ||
+           (OpcodeRHS == BO_LE && Comparison > 0) ||
+           (OpcodeRHS == BO_GT && Comparison <= 0) ||
+           (OpcodeRHS == BO_GE && Comparison < 0);
+
+  case BO_LT:
+    return ((OpcodeRHS == BO_LT && Comparison >= 0) ||
+            (OpcodeRHS == BO_LE && Comparison > 0) ||
+            (OpcodeRHS == BO_EQ && Comparison > 0));
+  case BO_GT:
+    return ((OpcodeRHS == BO_GT && Comparison <= 0) ||
+            (OpcodeRHS == BO_GE && Comparison < 0) ||
+            (OpcodeRHS == BO_EQ && Comparison < 0));
+  case BO_LE:
+    return (OpcodeRHS == BO_LT || OpcodeRHS == BO_LE || OpcodeRHS == BO_EQ) &&
+           Comparison >= 0;
+  case BO_GE:
+    return (OpcodeRHS == BO_GT || OpcodeRHS == BO_GE || OpcodeRHS == BO_EQ) &&
+           Comparison <= 0;
+  default:
+    return false;
+  }
+}
+
+static void canonicalNegateExpr(BinaryOperatorKind &Opcode, APSInt &Value) {
+  if (Opcode == BO_Sub) {
+    Opcode = BO_Add;
+    Value = -Value;
+  }
+}
+
+AST_MATCHER(Expr, isIntegerConstantExpr) {
+  if (Node.isInstantiationDependent())
+    return false;
+  return Node.isIntegerConstantExpr(Finder->getASTContext());
+}
+
+// Returns a matcher for integer constant expression.
+static ast_matchers::internal::Matcher<Expr>
+matchIntegerConstantExpr(StringRef Id) {
+  std::string CstId = (Id + "-cst").str();
+  return expr(isIntegerConstantExpr()).bind(CstId);
+}
+
+// Retrieve the integer value matched by 'matchIntegerConstantExpr' with name
+// 'Id' and store it into 'Value'.
+static bool retrieveIntegerConstantExpr(const MatchFinder::MatchResult &Result,
+                                        StringRef Id, APSInt &Value) {
+  std::string CstId = (Id + "-cst").str();
+  const auto *CstExpr = Result.Nodes.getNodeAs<Expr>(CstId);
+  return CstExpr && CstExpr->isIntegerConstantExpr(Value, *Result.Context);
+}
+
+// Returns a matcher for a symbolic expression (any expression except ingeter
+// constant expression).
+static ast_matchers::internal::Matcher<Expr> matchSymbolicExpr(StringRef Id) {
+  std::string SymId = (Id + "-sym").str();
+  return ignoringParenImpCasts(
+      expr(unless(isIntegerConstantExpr())).bind(SymId));
+}
+
+// Retrieve the expression matched by 'matchSymbolicExpr' with name 'Id' and
+// store it into 'SymExpr'.
+static bool retrieveSymbolicExpr(const MatchFinder::MatchResult &Result,
+                                 StringRef Id, const Expr *&SymExpr) {
+  std::string SymId = (Id + "-sym").str();
+  if (const auto *Node = Result.Nodes.getNodeAs<Expr>(SymId)) {
+    SymExpr = Node;
+    return true;
+  }
+  return false;
+}
+
+// Match a binary operator between a symbolic expression and an integer constant
+// expression.
+static ast_matchers::internal::Matcher<Expr>
+matchBinOpIntegerConstantExpr(StringRef Id) {
+  const auto BinOpCstExpr =
+      expr(
+          anyOf(binaryOperator(anyOf(hasOperatorName("+"), hasOperatorName("|"),
+                                     hasOperatorName("&")),
+                               hasEitherOperand(matchSymbolicExpr(Id)),
+                               hasEitherOperand(matchIntegerConstantExpr(Id))),
+                binaryOperator(hasOperatorName("-"),
+                               hasLHS(matchSymbolicExpr(Id)),
+                               hasRHS(matchIntegerConstantExpr(Id)))))
+          .bind(Id);
+  return ignoringParenImpCasts(BinOpCstExpr);
+}
+
+// Retrieve sub-expressions matched by 'matchBinOpIntegerConstantExpr' with
+// name 'Id'.
+static bool
+retrieveBinOpIntegerConstantExpr(const MatchFinder::MatchResult &Result,
+                                 StringRef Id, BinaryOperatorKind &Opcode,
+                                 const Expr *&Symbol, APSInt &Value) {
+  if (const auto *BinExpr = Result.Nodes.getNodeAs<BinaryOperator>(Id)) {
+    Opcode = BinExpr->getOpcode();
+    return retrieveSymbolicExpr(Result, Id, Symbol) &&
+           retrieveIntegerConstantExpr(Result, Id, Value);
+  }
+  return false;
+}
+
+// Matches relational expression: 'Expr <op> k' (i.e. x < 2, x != 3, 12 <= x).
+static ast_matchers::internal::Matcher<Expr>
+matchRelationalIntegerConstantExpr(StringRef Id) {
+  std::string CastId = (Id + "-cast").str();
+  std::string SwapId = (Id + "-swap").str();
+  std::string NegateId = (Id + "-negate").str();
+
+  const auto RelationalExpr = ignoringParenImpCasts(binaryOperator(
+      isComparisonOperator(), expr().bind(Id),
+      anyOf(allOf(hasLHS(matchSymbolicExpr(Id)),
+                  hasRHS(matchIntegerConstantExpr(Id))),
+            allOf(hasLHS(matchIntegerConstantExpr(Id)),
+                  hasRHS(matchSymbolicExpr(Id)), expr().bind(SwapId)))));
+
+  // A cast can be matched as a comparator to zero. (i.e. if (x) is equivalent
+  // to if (x != 0)).
+  const auto CastExpr =
+      implicitCastExpr(hasCastKind(CK_IntegralToBoolean),
+                       hasSourceExpression(matchSymbolicExpr(Id)))
+          .bind(CastId);
+
+  const auto NegateRelationalExpr =
+      unaryOperator(hasOperatorName("!"),
+                    hasUnaryOperand(anyOf(CastExpr, RelationalExpr)))
+          .bind(NegateId);
+
+  const auto NegateNegateRelationalExpr =
+      unaryOperator(hasOperatorName("!"),
+                    hasUnaryOperand(unaryOperator(
+                        hasOperatorName("!"),
+                        hasUnaryOperand(anyOf(CastExpr, RelationalExpr)))));
+
+  return anyOf(RelationalExpr, CastExpr, NegateRelationalExpr,
+               NegateNegateRelationalExpr);
+}
+
+// Retrieve sub-expressions matched by 'matchRelationalIntegerConstantExpr' with
+// name 'Id'.
+static bool
+retrieveRelationalIntegerConstantExpr(const MatchFinder::MatchResult &Result,
+                                      StringRef Id, const Expr *&OperandExpr,
+                                      BinaryOperatorKind &Opcode,
+                                      const Expr *&Symbol, APSInt &Value) {
+  std::string CastId = (Id + "-cast").str();
+  std::string SwapId = (Id + "-swap").str();
+  std::string NegateId = (Id + "-negate").str();
+
+  if (const auto *Bin = Result.Nodes.getNodeAs<BinaryOperator>(Id)) {
+    // Operand received with explicit comparator.
+    Opcode = Bin->getOpcode();
+    OperandExpr = Bin;
+    if (!retrieveIntegerConstantExpr(Result, Id, Value))
+      return false;
+  } else if (const auto *Cast = Result.Nodes.getNodeAs<CastExpr>(CastId)) {
+    // Operand received with implicit comparator (cast).
+    Opcode = BO_NE;
+    OperandExpr = Cast;
+    Value = APSInt(32, 0);
+  } else {
+    return false;
+  }
+
+  if (!retrieveSymbolicExpr(Result, Id, Symbol))
+    return false;
+
+  if (Result.Nodes.getNodeAs<Expr>(SwapId))
+    Opcode = BinaryOperator::reverseComparisonOp(Opcode);
+  if (Result.Nodes.getNodeAs<Expr>(NegateId))
+    Opcode = BinaryOperator::negateComparisonOp(Opcode);
+
+  return true;
+}
+
 AST_MATCHER(BinaryOperator, operandsAreEquivalent) {
   return areEquivalentExpr(Node.getLHS(), Node.getRHS());
 }
 
 AST_MATCHER(ConditionalOperator, expressionsAreEquivalent) {
   return areEquivalentExpr(Node.getTrueExpr(), Node.getFalseExpr());
 }
 
Finder->addMatcher(
               hasOverloadedOperatorName(">"), hasOverloadedOperatorName(">="),
               hasOverloadedOperatorName("&&"), hasOverloadedOperatorName("||"),
               hasOverloadedOperatorName("=")),
           parametersAreEquivalent(),
           // Filter noisy false positives.
           unless(isMacro()), unless(isInTemplateInstantiation()))
           .bind("call"),
       this);
+
+  // Match common expressions and apply more checks to find redundant
+  // sub-expressions.
+  //   a) Expr <op> K1 == K2
+  //   b) Expr <op> K1 == Expr
+  //   c) Expr <op> K1 == Expr <op> K2
+  // see: 'checkArithmeticExpr' and 'checkBitwiseExpr'
+  const auto BinOpCstLeft = matchBinOpIntegerConstantExpr("lhs");
+  const auto BinOpCstRight = matchBinOpIntegerConstantExpr("rhs");
+  const auto CstRight = matchIntegerConstantExpr("rhs");
+  const auto SymRight = matchSymbolicExpr("rhs");
+
+  // Match expressions like: x <op> 0xFF == 0xF00.
+  Finder->addMatcher(binaryOperator(isComparisonOperator(),
+                                    hasEitherOperand(BinOpCstLeft),
+                                    hasEitherOperand(CstRight))
+                         .bind("binop-cst-compare-to-cst"),
+                     this);
+
+  // Match expressions like: x <op> 0xFF == x.
+  Finder->addMatcher(
+      binaryOperator(isComparisonOperator(),
+                     anyOf(allOf(hasLHS(BinOpCstLeft), hasRHS(SymRight)),
+                           allOf(hasLHS(SymRight), hasRHS(BinOpCstLeft))))
+          .bind("binop-cst-compare-to-sym"),
+      this);
+
+  // Match expressions like: x <op> 10 == x <op> 12.
+  Finder->addMatcher(binaryOperator(isComparisonOperator(),
+                                    hasLHS(BinOpCstLeft), hasRHS(BinOpCstRight),
+                                    // Already reported as redundant.
+                                    unless(operandsAreEquivalent()))
+                         .bind("binop-cst-compare-to-binop-cst"),
+                     this);
+
+  // Match relational expressions combined with logical operators and find
+  // redundant sub-expressions.
+  // see: 'checkRelationalExpr'
+
+  // Match expressions like: x < 2 && x > 2.
+  const auto ComparisonLeft = matchRelationalIntegerConstantExpr("lhs");
+  const auto ComparisonRight = matchRelationalIntegerConstantExpr("rhs");
+  Finder->addMatcher(
+      binaryOperator(anyOf(hasOperatorName("||"), hasOperatorName("&&")),
+                     hasLHS(ComparisonLeft), hasRHS(ComparisonRight),
+                     // Already reported as redundant.
+                     unless(operandsAreEquivalent()))
+          .bind("comparisons-of-symbol-and-cst"),
+      this);
+}
+
+void RedundantExpressionCheck::checkArithmeticExpr(
+    const MatchFinder::MatchResult &Result) {
+  APSInt LhsValue, RhsValue;
+  const Expr *LhsSymbol = nullptr, *RhsSymbol = nullptr;
+  BinaryOperatorKind LhsOpcode, RhsOpcode;
+
+  if (const auto *ComparisonOperator =
+          Result.Nodes.getNodeAs<BinaryOperator>("binop-cst-compare-to-sym")) {
+    BinaryOperatorKind Opcode = ComparisonOperator->getOpcode();
+    if (!retrieveBinOpIntegerConstantExpr(Result, "lhs", LhsOpcode, LhsSymbol,
+                                          LhsValue) ||
+        !retrieveSymbolicExpr(Result, "rhs", RhsSymbol) ||
+        !areEquivalentExpr(LhsSymbol, RhsSymbol))
+      return;
+
+    // Check expressions: x + k == x  or  x - k == x.
+    if (LhsOpcode == BO_Add || LhsOpcode == BO_Sub) {
+      if ((LhsValue != 0 && Opcode == BO_EQ) ||
+          (LhsValue == 0 && Opcode == BO_NE))
+        diag(ComparisonOperator->getOperatorLoc(),
+             "logical expression is always false");
+      else if ((LhsValue == 0 && Opcode == BO_EQ) ||
+               (LhsValue != 0 && Opcode == BO_NE))
+        diag(ComparisonOperator->getOperatorLoc(),
+             "logical expression is always true");
+    }
+  } else if (const auto *ComparisonOperator =
+                 Result.Nodes.getNodeAs<BinaryOperator>(
+                     "binop-cst-compare-to-binop-cst")) {
+
+    BinaryOperatorKind Opcode = ComparisonOperator->getOpcode();
+
+    if (!retrieveBinOpIntegerConstantExpr(Result, "lhs", LhsOpcode, LhsSymbol,
+                                          LhsValue) ||
+        !retrieveBinOpIntegerConstantExpr(Result, "rhs", RhsOpcode, RhsSymbol,
+                                          RhsValue) ||
+        !areEquivalentExpr(LhsSymbol, RhsSymbol))
+      return;
+
+    canonicalNegateExpr(LhsOpcode, LhsValue);
+    canonicalNegateExpr(RhsOpcode, RhsValue);
+
+    // Check expressions: x + 1 == x + 2  or  x + 1 != x + 2.
+    if (LhsOpcode == BO_Add && RhsOpcode == BO_Add) {
+      if ((Opcode == BO_EQ && APSInt::compareValues(LhsValue, RhsValue) == 0) ||
+          (Opcode == BO_NE && APSInt::compareValues(LhsValue, RhsValue) != 0)) {
+        diag(ComparisonOperator->getOperatorLoc(),
+             "logical expression is always true");
+      } else if ((Opcode == BO_EQ &&
+                  APSInt::compareValues(LhsValue, RhsValue) != 0) ||
+                 (Opcode == BO_NE &&
+                  APSInt::compareValues(LhsValue, RhsValue) == 0)) {
+        diag(ComparisonOperator->getOperatorLoc(),
+             "logical expression is always false");
+      }
+    }
+  }
+}
+
+void RedundantExpressionCheck::checkBitwiseExpr(
+    const MatchFinder::MatchResult &Result) {
+  if (const auto *ComparisonOperator =
+          Result.Nodes.getNodeAs<BinaryOperator>("binop-cst-compare-to-cst")) {
+    BinaryOperatorKind Opcode = ComparisonOperator->getOpcode();
+
+    APSInt LhsValue, RhsValue;
+    const Expr *LhsSymbol = nullptr;
+    BinaryOperatorKind LhsOpcode;
+    if (!retrieveBinOpIntegerConstantExpr(Result, "lhs", LhsOpcode, LhsSymbol,
+                                          LhsValue) ||
+        !retrieveIntegerConstantExpr(Result, "rhs", RhsValue))
+      return;
+
+    uint64_t LhsConstant = LhsValue.getZExtValue();
+    uint64_t RhsConstant = RhsValue.getZExtValue();
+    SourceLocation Loc = ComparisonOperator->getOperatorLoc();
+
+    // Check expression: x & k1 == k2  (i.e. x & 0xFF == 0xF00)
+    if (LhsOpcode == BO_And && (LhsConstant & RhsConstant) != RhsConstant) {
+      if (Opcode == BO_EQ)
+        diag(Loc, "logical expression is always false");
+      else if (Opcode == BO_NE)
+        diag(Loc, "logical expression is always true");
+    }
+
+    // Check expression: x | k1 == k2  (i.e. x | 0xFF == 0xF00)
+    if (LhsOpcode == BO_Or && (LhsConstant | RhsConstant) != RhsConstant) {
+      if (Opcode == BO_EQ)
+        diag(Loc, "logical expression is always false");
+      else if (Opcode == BO_NE)
+        diag(Loc, "logical expression is always true");
+    }
+  }
+}
+
+void RedundantExpressionCheck::checkRelationalExpr(
+    const MatchFinder::MatchResult &Result) {
+  if (const auto *ComparisonOperator = Result.Nodes.getNodeAs<BinaryOperator>(
+          "comparisons-of-symbol-and-cst")) {
+    // Matched expressions are: (x <op> k1) <REL> (x <op> k2).
+    BinaryOperatorKind Opcode = ComparisonOperator->getOpcode();
+
+    const Expr *LhsExpr = nullptr, *RhsExpr = nullptr;
+    APSInt LhsValue, RhsValue;
+    const Expr *LhsSymbol = nullptr, *RhsSymbol = nullptr;
+    BinaryOperatorKind LhsOpcode, RhsOpcode;
+    if (!retrieveRelationalIntegerConstantExpr(
+            Result, "lhs", LhsExpr, LhsOpcode, LhsSymbol, LhsValue) ||
+        !retrieveRelationalIntegerConstantExpr(
+            Result, "rhs", RhsExpr, RhsOpcode, RhsSymbol, RhsValue) ||
+        !areEquivalentExpr(LhsSymbol, RhsSymbol))
+      return;
+
+    // Bring to a canonical form: smallest constant must be on the left side.
+    if (APSInt::compareValues(LhsValue, RhsValue) > 0) {
+      std::swap(LhsExpr, RhsExpr);
+      std::swap(LhsValue, RhsValue);
+      std::swap(LhsSymbol, RhsSymbol);
+      std::swap(LhsOpcode, RhsOpcode);
+    }
+
+    if ((Opcode == BO_LAnd || Opcode == BO_LOr) &&
+        areEquivalentRanges(LhsOpcode, LhsValue, RhsOpcode, RhsValue)) {
+      diag(ComparisonOperator->getOperatorLoc(),
+           "equivalent expression on both side of logical operator");
+      return;
+    }
+
+    if (Opcode == BO_LAnd) {
+      if (areExclusiveRanges(LhsOpcode, LhsValue, RhsOpcode, RhsValue)) {
+        diag(ComparisonOperator->getOperatorLoc(),
+             "logical expression is always false");
+      } else if (rangeSubsumeRange(LhsOpcode, LhsValue, RhsOpcode, RhsValue)) {
+        diag(LhsExpr->getExprLoc(), "expression is redundant");
+      } else if (rangeSubsumeRange(RhsOpcode, RhsValue, LhsOpcode, LhsValue)) {
+        diag(RhsExpr->getExprLoc(), "expression is redundant");
+      }
+    }
+
+    if (Opcode == BO_LOr) {
+      if (rangesFullyCoverDomain(LhsOpcode, LhsValue, RhsOpcode, RhsValue)) {
+        diag(ComparisonOperator->getOperatorLoc(),
+             "logical expression is always true");
+      } else if (rangeSubsumeRange(LhsOpcode, LhsValue, RhsOpcode, RhsValue)) {
+        diag(RhsExpr->getExprLoc(), "expression is redundant");
+      } else if (rangeSubsumeRange(RhsOpcode, RhsValue, LhsOpcode, LhsValue)) {
+        diag(LhsExpr->getExprLoc(), "expression is redundant");
+      }
+    }
+  }
 }
 
 void RedundantExpressionCheck::check(const MatchFinder::MatchResult &Result) {
   if (const auto *BinOp = Result.Nodes.getNodeAs<BinaryOperator>("binary"))
     diag(BinOp->getOperatorLoc(), "both side of operator are equivalent");
   if (const auto *CondOp = Result.Nodes.getNodeAs<ConditionalOperator>("cond"))
     diag(CondOp->getColonLoc(), "'true' and 'false' expression are equivalent");
   if (const auto *Call = Result.Nodes.getNodeAs<CXXOperatorCallExpr>("call"))
     diag(Call->getOperatorLoc(),
          "both side of overloaded operator are equivalent");
+
+  checkArithmeticExpr(Result);
+  checkBitwiseExpr(Result);
+  checkRelationalExpr(Result);
 }
 
 } // namespace misc
 } // namespace tidy
 } // namespace clang

test/clang-tidy/misc-redundant-expression.cpp

-// RUN: %check_clang_tidy %s misc-redundant-expression %t
+// RUN: %check_clang_tidy %s misc-redundant-expression %t -- -- -std=c++11
+
+typedef __INT64_TYPE__ I64;
 
 struct Point {
   int x;
   int y;
   int a[5];
 } P;
 
 extern Point P1;
int Test(int X, int Y) {
   if (P.a[X - P.x] != P.a[X - P.x]) return 1;
   // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: both side of operator are equivalent
 
   if ((int)X < (int)X) return 1;
   // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: both side of operator are equivalent
 
   if ( + "dummy" == + "dummy") return 1;
   // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: both side of operator are equivalent
-  if (L"abc" == L"abc") return 1;     
+  if (L"abc" == L"abc") return 1;
   // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: both side of operator are equivalent
 
   if (foo(0) - 2 < foo(0) - 2) return 1;
   // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: both side of operator are equivalent
   if (foo(bar(0)) < (foo(bar((0))))) return 1;
   // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: both side of operator are equivalent
 
   if (P1.x < P2.x && P1.x < P2.x) return 1;
   // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: both side of operator are equivalent
   if (P2.a[P1.x + 2] < P2.x && P2.a[(P1.x) + (2)] < (P2.x)) return 1;
   // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: both side of operator are equivalent
 
   return 0;
 }
 
 int Valid(int X, int Y) {
   if (X != Y) return 1;
-  if (X == X + 0) return 1;
+  if (X == Y + 0) return 1;
   if (P.x == P.y) return 1;
   if (P.a[P.x] < P.a[P.y]) return 1;
   if (P.a[0] < P.a[1]) return 1;
 
   if (P.a[0] < P.a[0ULL]) return 1;
   if (0 < 0ULL) return 1;
   if ((int)0 < (int)0ULL) return 1;
 

 };
 template <typename T, typename U>
 void TemplateCheck() {
   static_assert(T::Value == U::Value, "should be identical");
   static_assert(T::Value == T::Value, "should be identical");
   // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: both side of overloaded operator are equivalent
 }
 void TestTemplate() { TemplateCheck<MyClass, MyClass>(); }
+
+int TestArithmetic(int X, int Y) {
+  if (X + 1 == X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always false
+  if (X + 1 != X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+  if (X - 1 == X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always false
+  if (X - 1 != X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+
+  if (X + 1LL == X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: logical expression is always false
+  if (X + 1ULL == X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: logical expression is always false
+
+  if (X == X + 1) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: logical expression is always false
+  if (X != X + 1) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: logical expression is always true
+  if (X == X - 1) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: logical expression is always false
+  if (X != X - 1) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: logical expression is always true
+
+  if (X != X - 1U) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: logical expression is always true
+  if (X != X - 1LL) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: logical expression is always true
+
+  if ((X+X) != (X+X) - 1) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+
+  if (X + 1 == X + 2) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always false
+  if (X + 1 != X + 2) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+
+  if (X - 1 == X - 2) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always false
+  if (X - 1 != X - 2) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+
+  if (X + 1 == X - -1) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+  if (X + 1 != X - -1) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always false
+  if (X + 1 == X - -2) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always false
+  if (X + 1 != X - -2) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+
+  if (X + 1 == X - (~0)) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+  if (X + 1 == X - (~0U)) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+  if (X + 1 == X - (~0ULL)) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+
+  // Should not match.
+  if (X + 0.5 == X) return 1;
+  if (X + 1 == Y) return 1;
+  if (X + 1 == Y + 1) return 1;
+  if (X + 1 == Y + 2) return 1;
+
+  return 0;
+}
+
+int TestBitwise(int X) {
+  if ((X & 0xFF) == 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always false
+  if ((X & 0xFF) != 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always true
+  if ((X | 0xFF) == 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always false
+  if ((X | 0xFF) != 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always true
+
+  if ((X | 0xFFULL) != 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: logical expression is always true
+  if ((X | 0xFF) != 0xF00ULL) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always true
+
+  if ((0xFF & X) == 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always false
+  if ((0xFF & X) != 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always true
+  if ((0xFF & X) == 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always false
+  if ((0xFF & X) != 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always true
+
+  if ((0xFFLL & X) == 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: logical expression is always false
+  if ((0xFF & X) == 0xF00ULL) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always false
+
+  return 0;
+}
+
+int TestRelational(int X, int Y) {
+  if (X == 10 && X != 10) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: logical expression is always false
+  if (X == 10 && (X != 10)) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: logical expression is always false
+  if (X == 10 && !(X == 10)) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: logical expression is always false
+  if (!(X != 10) && !(X == 10)) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always false
+
+  if (X == 10ULL && X != 10ULL) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always false
+  if (!(X != 10U) && !(X == 10)) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: logical expression is always false
+  if (!(X != 10LL) && !(X == 10)) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: logical expression is always false
+  if (!(X != 10ULL) && !(X == 10)) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: logical expression is always false
+
+  if (X == 0 && X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: logical expression is always false
+  if (X != 0 && !X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: logical expression is always false
+  if (X && !X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: logical expression is always false
+
+  if (X && !!X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: equivalent expression on both side of logical operator
+  if (X != 0 && X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: equivalent expression on both side of logical operator
+  if (X != 0 && !!X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: equivalent expression on both side of logical operator
+  if (X == 0 && !X) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: equivalent expression on both side of logical operator
+
+  if (X == 10 && X > 10) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: logical expression is always false
+  if (X == 10 && X < 10) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: logical expression is always false
+  if (X < 10 && X > 10) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: logical expression is always false
+  if (X <= 10 && X > 10) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: logical expression is always false
+  if (X < 10 && X >= 10) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: logical expression is always false
+  if (X < 10 && X == 10) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: logical expression is always false
+
+  if (X > 5 && X <= 5) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always false
+  if (X > -5 && X <= -5) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: logical expression is always false
+
+  if (X < 10 || X >= 10) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: logical expression is always true
+  if (X <= 10 || X > 10) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: logical expression is always true
+  if (X <= 10 || X >= 11) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: logical expression is always true
+
+  if (X < 7 && X < 6) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant
+  if (X < 7 && X < 7) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: both side of operator are equivalent
+  if (X < 7 && X < 8) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: expression is redundant
+
+  if (X < 7 && X <= 5) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant 
+  if (X < 7 && X <= 6) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: equivalent expression on both side of logical operator
+  if (X < 7 && X <= 7) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: expression is redundant
+  if (X < 7 && X <= 8) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: expression is redundant
+
+  if (X <= 7 && X < 6) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant
+  if (X <= 7 && X < 7) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant
+  if (X <= 7 && X < 8) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: equivalent expression on both side of logical operator
+
+  if (X <= 7 && X <= 5) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant
+  if (X <= 7 && X <= 6) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant
+  if (X <= 7 && X <= 7) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: both side of operator are equivalent
+  if (X <= 7 && X <= 8) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: expression is redundant 
+
+  if (X == 11 && X > 10) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: expression is redundant 
+  if (X == 11 && X < 12) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: expression is redundant 
+  if (X > 10 && X == 11) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant 
+  if (X < 12 && X == 11) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant 
+ 
+  if (X != 11 && X == 42) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant 
+  if (X != 11 && X > 11) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant 
+  if (X != 11 && X < 11) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant 
+  if (X != 11 && X < 8) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant 
+  if (X != 11 && X > 14) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant 
+
+  if (X < 7 || X < 6) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: expression is redundant
+  if (X < 7 || X < 7) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: both side of operator are equivalent
+  if (X < 7 || X < 8) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: expression is redundant
+
+  // Should not match.
+  if (X == 10 && Y == 10) return 1;
+  if (X != 10 && X != 12) return 1;
+  if (X == 10 || X == 12) return 1;
+  if (X < 10 || X > 12) return 1;
+  if (X > 10 && X < 12) return 1;
+  if (X < 10 || X >= 12) return 1;
+  if (X > 10 && X <= 12) return 1;
+  if (X <= 10 || X > 12) return 1;
+  if (X >= 10 && X < 12) return 1;
+  if (X <= 10 || X >= 12) return 1;
+  if (X >= 10 && X <= 12) return 1;
+  if (X >= 10 && X <= 11) return 1;
+  if (X >= 10 && X < 11) return 1;
+  if (X > 10 && X <= 11) return 1;
+  if (X > 10 && X != 11) return 1;
+  if (X >= 10 && X <= 10) return 1;
+  if (X <= 10 && X >= 10) return 1;
+  if (!X && !Y) return 1;
+  if (!X && Y) return 1;
+  if (!X && Y == 0) return 1;
+  if (X == 10 && Y != 10) return 1;
+  if (X < 0 || X > 0) return 1;
+
+  return 0;
+}
+
+int TestValidExpression(int X) {
+  if (X - 1 == 1 - X) return 1;
+  if (2 * X == X) return 1;
+  if ((X << 1) == X) return 1;
+
+  return 0;
+}
+
+enum Color { Red, Yellow, Green };
+int TestRelatiopnalWithEnum(enum Color C) {
+  if (C == Red && C == Yellow) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: logical expression is always false
+  if (C == Red && C != Red) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: logical expression is always false
+
+  // Should not match.
+  if (C == Red || C == Yellow) return 1;
+  if (C != Red && C != Yellow) return 1;
+
+  return 0;
+}
+
+template<class T>
+int TestRelationalTemplated(int X) {
+  // This test causes a corner case with |isIntegerConstantExpr| where the type
+  // is dependant. There is an assert failing when evaluating
+  // sizeof(<incomplet-type>).
+  if (sizeof(T) == 4 || sizeof(T) == 8) return 1;
+
+  if (X + 0 == -X) return 1;
+  if (X + 0 < X) return 1;
+
+  return 0;
+}
+
+int TestWithSignedUnsigned(int X) {
+  if (X + 1 == X + 1ULL) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: logical expression is always true
+  if ((X & 0xFFU) == 0xF00) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: logical expression is always false
+  if ((X & 0xFF) == 0xF00U) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: logical expression is always false
+  if ((X & 0xFFU) == 0xF00U) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: logical expression is always false
+
+  return 0;
+}
+
+int TestWithLong(int X, I64 Y) {
+  if (X + 0ULL == -X) return 1;
+  if (Y + 0 == -Y) return 1;
+  if (Y <= 10 && X >= 10LL) return 1;
+  if (Y <= 10 && X >= 10ULL) return 1;
+  if (X <= 10 || X > 12LL) return 1;
+  if (X <= 10 || X > 12ULL) return 1;
+  if (Y <= 10 || Y > 12) return 1;
+
+  return 0;
+}
+
+int TestWithMinMaxInt(int X) {
+  if (X <= X + 0xFFFFFFFFU) return 1;
+  if (X <= X + 0x7FFFFFFF) return 1;
+  if (X <= X + 0x80000000) return 1;
+  if (X <= 0xFFFFFFFFU && X > 0) return 1;
+  if (X <= 0xFFFFFFFFU && X > 0U) return 1;
+
+  if (X + 0x80000000 == X - 0x80000000) return 1;
+  // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: logical expression is always true
+
+  if (X > 0x7FFFFFFF || X < ((-0x7FFFFFFF)-1)) return 1;
+  if (X <= 0x7FFFFFFF && X >= ((-0x7FFFFFFF)-1)) return 1;
+  
+  return 0;
+}