r320124 - Fold together the in-range and out-of-range portions of -Wtautological-compare.
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Thu Dec 7 17:00:27 PST 2017
Author: rsmith
Date: Thu Dec 7 17:00:27 2017
New Revision: 320124
URL: http://llvm.org/viewvc/llvm-project?rev=320124&view=rev
Log:
Fold together the in-range and out-of-range portions of -Wtautological-compare.
Modified:
cfe/trunk/lib/Sema/SemaChecking.cpp
Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=320124&r1=320123&r2=320124&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
+++ cfe/trunk/lib/Sema/SemaChecking.cpp Thu Dec 7 17:00:27 2017
@@ -8801,12 +8801,7 @@ static bool CheckTautologicalComparison(
Expr *Constant, Expr *Other,
const llvm::APSInt &Value,
bool RhsConstant) {
- // Disable warning in template instantiations
- // and only analyze <, >, <= and >= operations.
- if (S.inTemplateInstantiation() || !E->isRelationalOp())
- return false;
-
- if (IsEnumConstOrFromMacro(S, Constant))
+ if (S.inTemplateInstantiation())
return false;
Expr *OriginalOther = Other;
@@ -8833,94 +8828,23 @@ static bool CheckTautologicalComparison(
OtherRange.Width =
std::min(Bitfield->getBitWidthValue(S.Context), OtherRange.Width);
- // Check whether the constant value can be represented in OtherRange. Bail
- // out if so; this isn't an out-of-range comparison.
+ // Determine the promoted range of the other type and see if a comparison of
+ // the constant against that range is tautological.
PromotedRange OtherPromotedRange(OtherRange, Value.getBitWidth(),
Value.isUnsigned());
-
auto Cmp = OtherPromotedRange.compare(Value);
- if (Cmp != PromotedRange::Min && Cmp != PromotedRange::Max &&
- Cmp != PromotedRange::OnlyValue)
- return false;
-
auto Result = PromotedRange::constantValue(E->getOpcode(), Cmp, RhsConstant);
if (!Result)
return false;
- // Should be enough for uint128 (39 decimal digits)
- SmallString<64> PrettySourceValue;
- llvm::raw_svector_ostream OS(PrettySourceValue);
- OS << Value;
-
- // FIXME: We use a somewhat different formatting for the cases involving
- // boolean values for historical reasons. We should pick a consistent way
- // of presenting these diagnostics.
- if (Other->isKnownToHaveBooleanValue()) {
- S.DiagRuntimeBehavior(
- E->getOperatorLoc(), E,
- S.PDiag(diag::warn_tautological_bool_compare)
- << OS.str() << classifyConstantValue(Constant)
- << OtherT << !OtherT->isBooleanType() << *Result
- << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
- return true;
- }
-
- unsigned Diag = (isKnownToHaveUnsignedValue(OriginalOther) && Value == 0)
- ? (HasEnumType(OriginalOther)
- ? diag::warn_unsigned_enum_always_true_comparison
- : diag::warn_unsigned_always_true_comparison)
- : diag::warn_tautological_constant_compare;
-
- S.Diag(E->getOperatorLoc(), Diag)
- << RhsConstant << OtherT << E->getOpcodeStr() << OS.str() << *Result
- << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
-
- return true;
-}
-
-static bool DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E,
- Expr *Constant, Expr *Other,
- const llvm::APSInt &Value,
- bool RhsConstant) {
- // Disable warning in template instantiations.
- if (S.inTemplateInstantiation())
- return false;
-
- Constant = Constant->IgnoreParenImpCasts();
- Other = Other->IgnoreParenImpCasts();
-
- // TODO: Investigate using GetExprRange() to get tighter bounds
- // on the bit ranges.
- QualType OtherT = Other->getType();
- if (const auto *AT = OtherT->getAs<AtomicType>())
- OtherT = AT->getValueType();
- IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
-
- // Whether we're treating Other as being a bool because of the form of
- // expression despite it having another type (typically 'int' in C).
- bool OtherIsBooleanDespiteType =
- !OtherT->isBooleanType() && Other->isKnownToHaveBooleanValue();
- if (OtherIsBooleanDespiteType)
- OtherRange = IntRange::forBoolType();
-
- if (FieldDecl *Bitfield = Other->getSourceBitField())
- if (!Bitfield->getBitWidth()->isValueDependent())
- OtherRange.Width =
- std::min(Bitfield->getBitWidthValue(S.Context), OtherRange.Width);
-
- // Check whether the constant value can be represented in OtherRange. Bail
- // out if so; this isn't an out-of-range comparison.
- PromotedRange OtherPromotedRange(OtherRange, Value.getBitWidth(),
- Value.isUnsigned());
- auto Cmp = OtherPromotedRange.compare(Value);
-
- // If Value is in the range of possible Other values, this comparison is not
- // tautological.
- if (Cmp & PromotedRange::InRangeFlag)
- return false;
-
- auto IsTrue = PromotedRange::constantValue(E->getOpcode(), Cmp, RhsConstant);
- if (!IsTrue)
+ // Suppress the diagnostic for an in-range comparison if the constant comes
+ // from a macro or enumerator. We don't want to diagnose
+ //
+ // some_long_value <= INT_MAX
+ //
+ // when sizeof(int) == sizeof(long).
+ bool InRange = Cmp & PromotedRange::InRangeFlag;
+ if (InRange && IsEnumConstOrFromMacro(S, Constant))
return false;
// If this is a comparison to an enum constant, include that
@@ -8929,6 +8853,7 @@ static bool DiagnoseOutOfRangeComparison
if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Constant))
ED = dyn_cast<EnumConstantDecl>(DR->getDecl());
+ // Should be enough for uint128 (39 decimal digits)
SmallString<64> PrettySourceValue;
llvm::raw_svector_ostream OS(PrettySourceValue);
if (ED)
@@ -8936,14 +8861,30 @@ static bool DiagnoseOutOfRangeComparison
else
OS << Value;
- S.DiagRuntimeBehavior(
- E->getOperatorLoc(), E,
- S.PDiag(diag::warn_out_of_range_compare)
- << OS.str() << classifyConstantValue(Constant)
- << OtherT << OtherIsBooleanDespiteType << *IsTrue
- << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
+ // FIXME: We use a somewhat different formatting for the in-range cases and
+ // cases involving boolean values for historical reasons. We should pick a
+ // consistent way of presenting these diagnostics.
+ if (!InRange || Other->isKnownToHaveBooleanValue()) {
+ S.DiagRuntimeBehavior(
+ E->getOperatorLoc(), E,
+ S.PDiag(!InRange ? diag::warn_out_of_range_compare
+ : diag::warn_tautological_bool_compare)
+ << OS.str() << classifyConstantValue(Constant)
+ << OtherT << OtherIsBooleanDespiteType << *Result
+ << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
+ } else {
+ unsigned Diag = (isKnownToHaveUnsignedValue(OriginalOther) && Value == 0)
+ ? (HasEnumType(OriginalOther)
+ ? diag::warn_unsigned_enum_always_true_comparison
+ : diag::warn_unsigned_always_true_comparison)
+ : diag::warn_tautological_constant_compare;
+
+ S.Diag(E->getOperatorLoc(), Diag)
+ << RhsConstant << OtherT << E->getOpcodeStr() << OS.str() << *Result
+ << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
+ }
- return true;
+ return true;
}
/// Analyze the operands of the given comparison. Implements the
@@ -8993,12 +8934,8 @@ static void AnalyzeComparison(Sema &S, B
// Check whether an integer constant comparison results in a value
// of 'true' or 'false'.
-
if (CheckTautologicalComparison(S, E, Const, Other, Value, RhsConstant))
return AnalyzeImpConvsInComparison(S, E);
-
- if (DiagnoseOutOfRangeComparison(S, E, Const, Other, Value, RhsConstant))
- return AnalyzeImpConvsInComparison(S, E);
}
}
More information about the cfe-commits
mailing list