[PATCH] D130510: Missing tautological compare warnings due to unary operators

[Muhammad Usman Shahid via Phabricator via cfe-commits]

Codesbyusman updated this revision to Diff 447453.
Codesbyusman added a comment.

also updating for the Xor bitwise operator


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D130510/new/

https://reviews.llvm.org/D130510

Files:
  clang/lib/Analysis/CFG.cpp
  clang/test/SemaCXX/warn-unreachable.cpp


Index: clang/test/SemaCXX/warn-unreachable.cpp
===================================================================
--- clang/test/SemaCXX/warn-unreachable.cpp
+++ clang/test/SemaCXX/warn-unreachable.cpp
@@ -399,13 +399,13 @@
   // TODO: Extend warning to the following code:
   if (x < -1)
     calledFun();
-  if (x == -1)
-    calledFun();
+  if (x == -1)   // expected-note {{silence}}
+    calledFun(); // expected-warning {{will never be executed}}
 
-  if (x != -1)
+  if (x != -1)   // expected-note {{silence}}
     calledFun();
   else
-    calledFun();
+    calledFun(); // expected-warning {{will never be executed}}
   if (-1 > x)
     calledFun();
   else
Index: clang/lib/Analysis/CFG.cpp
===================================================================
--- clang/lib/Analysis/CFG.cpp
+++ clang/lib/Analysis/CFG.cpp
@@ -964,42 +964,51 @@
     const Expr *LHSExpr = B->getLHS()->IgnoreParens();
     const Expr *RHSExpr = B->getRHS()->IgnoreParens();
 
-    const IntegerLiteral *IntLiteral = dyn_cast<IntegerLiteral>(LHSExpr);
-    const Expr *BoolExpr = RHSExpr;
+    const Expr *BoolExpr = nullptr; // To store the expression.
+    Expr::EvalResult IntExprResult; // If integer literal then will save value.
 
-    if (!IntLiteral) {
-      IntLiteral = dyn_cast<IntegerLiteral>(RHSExpr);
+    if (LHSExpr->EvaluateAsInt(IntExprResult, *Context)) {
+       // Evaluating value.
+      BoolExpr = RHSExpr;
+    }
+    else if (RHSExpr->EvaluateAsInt(IntExprResult, *Context)) {
       BoolExpr = LHSExpr;
     }
-
-    if (!IntLiteral)
+    else
+    {
       return TryResult();
+    }
 
     const BinaryOperator *BitOp = dyn_cast<BinaryOperator>(BoolExpr);
     if (BitOp && (BitOp->getOpcode() == BO_And ||
-                  BitOp->getOpcode() == BO_Or)) {
+                  BitOp->getOpcode() == BO_Or  || 
+                  BitOp->getOpcode() == BO_Xor)) {
       const Expr *LHSExpr2 = BitOp->getLHS()->IgnoreParens();
       const Expr *RHSExpr2 = BitOp->getRHS()->IgnoreParens();
+      
+      // If integer literal in expression identified then will save value.
+      Expr::EvalResult IntExprResult2; 
 
-      const IntegerLiteral *IntLiteral2 = dyn_cast<IntegerLiteral>(LHSExpr2);
-
-      if (!IntLiteral2)
-        IntLiteral2 = dyn_cast<IntegerLiteral>(RHSExpr2);
-
-      if (!IntLiteral2)
+      
+      if (LHSExpr2->EvaluateAsInt(IntExprResult2, *Context));
+      else if ( RHSExpr2->EvaluateAsInt(IntExprResult2, *Context));
+      else
         return TryResult();
 
-      llvm::APInt L1 = IntLiteral->getValue();
-      llvm::APInt L2 = IntLiteral2->getValue();
+      // Getting the values as integer from the evaluation expression to use for comparision.
+      llvm::APInt L1 = IntExprResult.Val.getInt(); 
+      llvm::APInt L2 = IntExprResult2.Val.getInt();
+
       if ((BitOp->getOpcode() == BO_And && (L2 & L1) != L1) ||
-          (BitOp->getOpcode() == BO_Or  && (L2 | L1) != L1)) {
+          (BitOp->getOpcode() == BO_Or  && (L2 | L1) != L1) || 
+          (BitOp->getOpcode() == BO_Xor && (L2 ^ L1) != L1) ) {
         if (BuildOpts.Observer)
           BuildOpts.Observer->compareBitwiseEquality(B,
                                                      B->getOpcode() != BO_EQ);
         TryResult(B->getOpcode() != BO_EQ);
       }
     } else if (BoolExpr->isKnownToHaveBooleanValue()) {
-      llvm::APInt IntValue = IntLiteral->getValue();
+      llvm::APInt IntValue = IntExprResult.Val.getInt(); // Getting the value.
       if ((IntValue == 1) || (IntValue == 0)) {
         return TryResult();
       }


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