Codesbyusman updated this revision to Diff 452797.
Codesbyusman added a comment.
updating for the missing tautological compare warnings.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D130510/new/
https://reviews.llvm.org/D130510
Files:
clang/docs/ReleaseNotes.rst
clang/lib/Analysis/CFG.cpp
clang/test/Sema/warn-bitwise-compare.c
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
@@ -396,16 +396,18 @@
if (y == -1 && y != -1) // expected-note {{silence}}
calledFun(); // expected-warning {{will never be executed}}
- // 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(); // expected-warning {{will never be executed}}
+
+ // TODO: Extend warning to the following code:
+ if (x < -1)
calledFun();
+
if (-1 > x)
calledFun();
else
Index: clang/test/Sema/warn-bitwise-compare.c
===================================================================
--- clang/test/Sema/warn-bitwise-compare.c
+++ clang/test/Sema/warn-bitwise-compare.c
@@ -2,6 +2,7 @@
// RUN: %clang_cc1 -fsyntax-only -verify -Wall -Wno-unused %s
#define mydefine 2
+#define mydefine2 -2
enum {
ZERO,
@@ -11,29 +12,64 @@
void f(int x) {
if ((8 & x) == 3) {} // expected-warning {{bitwise comparison always evaluates to false}}
if ((x & 8) == 4) {} // expected-warning {{bitwise comparison always evaluates to false}}
+ if ((-8 & x) == 3) {} // expected-warning {{bitwise comparison always evaluates to false}}
+ if ((x & -8) == 4) {} // expected-warning {{bitwise comparison always evaluates to false}}
+
if ((x & 8) != 4) {} // expected-warning {{bitwise comparison always evaluates to true}}
if ((2 & x) != 4) {} // expected-warning {{bitwise comparison always evaluates to true}}
+ if ((x & -8) != 4) {} // expected-warning {{bitwise comparison always evaluates to true}}
+ if ((-2 & x) != 3) {} // expected-warning {{bitwise comparison always evaluates to true}}
+
if ((x | 4) == 3) {} // expected-warning {{bitwise comparison always evaluates to false}}
if ((x | 3) != 4) {} // expected-warning {{bitwise comparison always evaluates to true}}
if ((5 | x) != 3) {} // expected-warning {{bitwise comparison always evaluates to true}}
+
+ if ((x | -4) == 3) {} // expected-warning {{bitwise comparison always evaluates to false}}
+ if ((x | -3) != 4) {} // expected-warning {{bitwise comparison always evaluates to true}}
+ if ((-5 | x) != 3) {} // expected-warning {{bitwise comparison always evaluates to true}}
+
if ((x & 0x15) == 0x13) {} // expected-warning {{bitwise comparison always evaluates to false}}
+ if ((x & 0xFFEB) == 0x13) {} // expected-warning {{bitwise comparison always evaluates to false}}
+
if ((0x23 | x) == 0x155){} // expected-warning {{bitwise comparison always evaluates to false}}
+ if ((0xFFDD | x) == 0x155){} // expected-warning {{bitwise comparison always evaluates to false}}
if (!!((8 & x) == 3)) {} // expected-warning {{bitwise comparison always evaluates to false}}
+ if (!!((-8 & x) == 3)) {} // expected-warning {{bitwise comparison always evaluates to false}}
+
int y = ((8 & x) == 3) ? 1 : 2; // expected-warning {{bitwise comparison always evaluates to false}}
+ y = ((-8 & x) == 3) ? 1 : 2; // expected-warning {{bitwise comparison always evaluates to false}}
+ y = ((3 | x) != 5) ? 1 : 2; // expected-warning {{bitwise comparison always evaluates to true}}
+ y = ((-3 | x) != 5) ? 1 : 2; // expected-warning {{bitwise comparison always evaluates to true}}
if ((x & 8) == 8) {}
if ((x & 8) != 8) {}
if ((x | 4) == 4) {}
if ((x | 4) != 4) {}
+ if ((-2 & x) != 4) {}
+ if ((x & -8) == -8) {}
+ if ((x & -8) != -8) {}
+ if ((x | -4) == -4) {}
+ if ((x | -4) != -4) {}
+
if ((x & 9) == 8) {}
if ((x & 9) != 8) {}
if ((x | 4) == 5) {}
if ((x | 4) != 5) {}
+ if ((x & -9) == -10) {}
+ if ((x & -9) != -10) {}
+ if ((x | -4) == -3) {}
+ if ((x | -4) != -3) {}
+
+ if ((x^0) == 0) {}
+
if ((x & mydefine) == 8) {}
if ((x | mydefine) == 4) {}
+
+ if ((x & mydefine2) == 8) {}
+ if ((x | mydefine2) == 4) {}
}
void g(int x) {
Index: clang/lib/Analysis/CFG.cpp
===================================================================
--- clang/lib/Analysis/CFG.cpp
+++ clang/lib/Analysis/CFG.cpp
@@ -964,43 +964,44 @@
const Expr *LHSExpr = B->getLHS()->IgnoreParens();
const Expr *RHSExpr = B->getRHS()->IgnoreParens();
- const IntegerLiteral *IntLiteral = dyn_cast<IntegerLiteral>(LHSExpr);
+ Optional<llvm::APInt> IntLiteral1 =
+ getIntegerLiteralSubexpressionValue(LHSExpr);
const Expr *BoolExpr = RHSExpr;
- if (!IntLiteral) {
- IntLiteral = dyn_cast<IntegerLiteral>(RHSExpr);
+ if (!IntLiteral1) {
+ IntLiteral1 = getIntegerLiteralSubexpressionValue(RHSExpr);
BoolExpr = LHSExpr;
}
- if (!IntLiteral)
+ if (!IntLiteral1)
return TryResult();
- const BinaryOperator *BitOp = dyn_cast<BinaryOperator>(BoolExpr);
+ const BinaryOperator *BitOp = dyn_cast<BinaryOperator>(BoolExpr->IgnoreParens());
if (BitOp && (BitOp->getOpcode() == BO_And ||
BitOp->getOpcode() == BO_Or)) {
const Expr *LHSExpr2 = BitOp->getLHS()->IgnoreParens();
const Expr *RHSExpr2 = BitOp->getRHS()->IgnoreParens();
- const IntegerLiteral *IntLiteral2 = dyn_cast<IntegerLiteral>(LHSExpr2);
+ Optional<llvm::APInt> IntLiteral2 =
+ getIntegerLiteralSubexpressionValue(LHSExpr2);
if (!IntLiteral2)
- IntLiteral2 = dyn_cast<IntegerLiteral>(RHSExpr2);
+ IntLiteral2 = getIntegerLiteralSubexpressionValue(RHSExpr2);
if (!IntLiteral2)
return TryResult();
- llvm::APInt L1 = IntLiteral->getValue();
- llvm::APInt L2 = IntLiteral2->getValue();
- if ((BitOp->getOpcode() == BO_And && (L2 & L1) != L1) ||
- (BitOp->getOpcode() == BO_Or && (L2 | L1) != L1)) {
+ if ((BitOp->getOpcode() == BO_And &&
+ (*IntLiteral2 & *IntLiteral1) != *IntLiteral1) ||
+ (BitOp->getOpcode() == BO_Or &&
+ (*IntLiteral2 | *IntLiteral1) != *IntLiteral1)) {
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();
- if ((IntValue == 1) || (IntValue == 0)) {
+ if ((*IntLiteral1 == 1) || (*IntLiteral1 == 0)) {
return TryResult();
}
return TryResult(B->getOpcode() != BO_EQ);
@@ -1009,6 +1010,51 @@
return TryResult();
}
+ Optional<llvm::APInt> getIntegerLiteralSubexpressionValue(const Expr *E) {
+ // The value to return;
+ Optional<llvm::APInt> Value = llvm::None;
+
+ const IntegerLiteral *IntLiteral = nullptr;
+ const UnaryOperator *UnOp = dyn_cast<UnaryOperator>(E->IgnoreParens());
+
+ // If unary.
+ if (UnOp) {
+ // Get the sub expression of the unary expression and get the Integer
+ // Literal.
+ const Expr *SubExpr = UnOp->getSubExpr();
+ IntLiteral = dyn_cast<IntegerLiteral>(SubExpr->IgnoreParens());
+
+ if (IntLiteral) {
+
+ Value = IntLiteral->getValue();
+ // Getting the Operator Code to perform them manually.
+ const UnaryOperatorKind OpCode = UnOp->getOpcode();
+
+ // Perform the operation manually.
+ switch (OpCode) {
+ case UO_Plus:
+ return Value;
+ case UO_Minus:
+ return -*Value;
+ case UO_Not:
+ return ~*Value;
+ case UO_LNot:
+ return *Value = !*Value;
+ default:
+ return Value;
+ }
+ }
+
+ } else {
+
+ IntLiteral = dyn_cast<IntegerLiteral>(E->IgnoreParens());
+ if (IntLiteral)
+ return Value = IntLiteral->getValue();
+ }
+
+ return Value;
+ }
+
TryResult analyzeLogicOperatorCondition(BinaryOperatorKind Relation,
const llvm::APSInt &Value1,
const llvm::APSInt &Value2) {
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -60,7 +60,10 @@
- No longer assert/miscompile when trying to make a vectorized ``_BitInt`` type
using the ``ext_vector_type`` attribute (the ``vector_size`` attribute was
already properly diagnosing this case).
-
+- ``-Wtautological-compare`` missed warnings for tautological comparisons
+ involving a negative integer literal. This fixes
+ `Issue 42918 <https://github.com/llvm/llvm-project/issues/42918>`_.
+
Improvements to Clang's diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
- Clang will now correctly diagnose as ill-formed a constant expression where an
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