On Thu, Mar 28, 2013 at 4:53 PM, Timur Iskhodzhanov <[email protected]>wrote:
> Hi Sam, > > It looks like this change has uncovered some problems in Clang. > > I see a lot of compile-time errors on Linux like the following when > building Clang with Clang. > In file included from lib/Target/PowerPC/PPCJITInfo.cpp:17: > In file included from lib/Target/PowerPC/PPCTargetMachine.h:18: > In file included from /lib/Target/PowerPC/PPCISelLowering.h:22: > /include/llvm/Target/TargetLowering.h:1012:59: error: implicit > conversion from 'int' to 'uint8_t' (aka 'unsigned char') changes value > from -241 to 15 [-Werror,-Wconstant-conversion] > IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] &= ~0xf0; > Hm, we should probably allow bitwise &, |, and ^ if the constant operand's ignored bits are either all-0 or all-1. > which look related to your recent commits. > > Can you please take a look? > It makes some buildbots red... > > > 2013/3/28 Sam Panzer <[email protected]>: > > Author: panzer > > Date: Thu Mar 28 14:07:11 2013 > > New Revision: 178273 > > > > URL: http://llvm.org/viewvc/llvm-project?rev=178273&view=rev > > Log: > > Implemented a warning when an input several bitwise operations are > > likely be implicitly truncated: > > > > * All forms of Bitwise-and, bitwise-or, and integer multiplication. > > * The assignment form of integer addition, subtraction, and > exclusive-or > > * The RHS of the comma operator > > * The LHS of left shifts. > > > > Modified: > > cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td > > cfe/trunk/lib/Sema/SemaChecking.cpp > > cfe/trunk/test/Sema/constant-conversion.c > > > > Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td > > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=178273&r1=178272&r2=178273&view=diff > > > ============================================================================== > > --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original) > > +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Thu Mar 28 > 14:07:11 2013 > > @@ -2084,6 +2084,11 @@ def warn_impcast_integer_64_32 : Warning > > def warn_impcast_integer_precision_constant : Warning< > > "implicit conversion from %2 to %3 changes value from %0 to %1">, > > InGroup<ConstantConversion>; > > +def warn_impcast_integer_precision_binop_constant : Warning< > > + "implicit conversion of binary operation from %2 to %3 may change its > value; " > > + "value of operand would be changed from %0 to %1 if converted before " > > + "operation">, > > + InGroup<ConstantConversion>; > > def warn_impcast_bitfield_precision_constant : Warning< > > "implicit truncation from %2 to bitfield changes value from %0 to > %1">, > > InGroup<ConstantConversion>; > > > > Modified: cfe/trunk/lib/Sema/SemaChecking.cpp > > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=178273&r1=178272&r2=178273&view=diff > > > ============================================================================== > > --- cfe/trunk/lib/Sema/SemaChecking.cpp (original) > > +++ cfe/trunk/lib/Sema/SemaChecking.cpp Thu Mar 28 14:07:11 2013 > > @@ -4686,7 +4686,8 @@ static void AnalyzeAssignment(Sema &S, B > > // We want to recurse on the RHS as normal unless we're assigning to > > // a bitfield. > > if (FieldDecl *Bitfield = E->getLHS()->getBitField()) { > > - if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(), > > + if (E->getOpcode() != BO_AndAssign && > > + AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(), > > E->getOperatorLoc())) { > > // Recurse, ignoring any implicit conversions on the RHS. > > return AnalyzeImplicitConversions(S, > E->getRHS()->IgnoreParenImpCasts(), > > @@ -4795,8 +4796,82 @@ void CheckImplicitArgumentConversions(Se > > } > > } > > > > +// Try to evaluate E as an integer. If EvaluateAsInt succeeds, Value is > set to > > +// the resulting value, ResultExpr is set to E. > > +// Otherwise, the output parameters are not modified. > > +static bool EvalAsInt(ASTContext &Ctx, llvm::APSInt &Value, Expr *E, > > + Expr **ResultExpr) { > > + if (E->EvaluateAsInt(Value, Ctx, Expr::SE_AllowSideEffects)) { > > + *ResultExpr = E; > > + return true; > > + } > > + return false; > > +} > > + > > +// Returns true when Value's value would change when narrowed to > TargetRange. > > +static bool TruncationChangesValue(const llvm::APSInt &Value, > > + const IntRange &TargetRange, > > + bool IsBitwiseAnd) { > > + // Checks if there are any active non-sign bits past the width of > TargetRange. > > + if (IsBitwiseAnd) > > + return Value.getBitWidth() - Value.getNumSignBits() > > TargetRange.Width; > > + > > + llvm::APSInt UnsignedValue(Value); > > + unsigned BitWidth = TargetRange.NonNegative ? > > + UnsignedValue.getActiveBits() : Value.getMinSignedBits(); > > + return BitWidth > TargetRange.Width; > > +} > > + > > +// Determine if E is an expression containing or likely to contain an > implicit > > +// narrowing bug involving a constant. > > +// If so, Value is set to the value of that constant. NarrowedExpr is > set to the > > +// problematic sub-expression if it is a strict subset of E. > > +static bool OperandMightImplicitlyNarrow(ASTContext &Ctx, llvm::APSInt > &Value, > > + Expr *E, IntRange TargetRange, > > + Expr **NarrowedExpr) { > > + BinaryOperator *BO = dyn_cast<BinaryOperator>(E); > > + if (!BO) > > + return false; > > + > > + switch (BO->getOpcode()) { > > + case BO_And: > > + case BO_AndAssign: > > + return (EvalAsInt(Ctx, Value, BO->getLHS(), NarrowedExpr) > > + && TruncationChangesValue(Value, TargetRange, true)) || > > + (EvalAsInt(Ctx, Value, BO->getRHS(), NarrowedExpr) > > + && TruncationChangesValue(Value, TargetRange, true)); > > + > > + case BO_Or: > > + case BO_OrAssign: > > + // FIXME: Include BO_Add, BO_Sub, and BO_Xor when we avoid false > positives. > > + case BO_AddAssign: > > + case BO_SubAssign: > > + case BO_Mul: > > + case BO_MulAssign: > > + case BO_XorAssign: > > + return (EvalAsInt(Ctx, Value, BO->getLHS(), NarrowedExpr) > > + && TruncationChangesValue(Value, TargetRange, false)) || > > + (EvalAsInt(Ctx, Value, BO->getRHS(), NarrowedExpr) > > + && TruncationChangesValue(Value, TargetRange, false)); > > + > > + // We can ignore the left side of the comma operator, since the > value is > > + // explicitly ignored anyway. > > + case BO_Comma: > > + return EvalAsInt(Ctx, Value, BO->getRHS(), NarrowedExpr) && > > + TruncationChangesValue(Value, TargetRange, false); > > + > > + case BO_Shl: > > + return EvalAsInt(Ctx, Value, BO->getLHS(), NarrowedExpr) && > > + TruncationChangesValue(Value, TargetRange, false); > > + > > + default: > > + break; > > + } > > + return false; > > +} > > + > > void CheckImplicitConversion(Sema &S, Expr *E, QualType T, > > - SourceLocation CC, bool *ICContext = 0) { > > + SourceLocation CC, bool *ICContext = NULL) > { > > if (E->isTypeDependent() || E->isValueDependent()) return; > > > > const Type *Source = > S.Context.getCanonicalType(E->getType()).getTypePtr(); > > @@ -4977,17 +5052,30 @@ void CheckImplicitConversion(Sema &S, Ex > > IntRange SourceRange = GetExprRange(S.Context, E); > > IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, > Target); > > > > - if (SourceRange.Width > TargetRange.Width) { > > - // If the source is a constant, use a default-on diagnostic. > > - // TODO: this should happen for bitfield stores, too. > > - llvm::APSInt Value(32); > > - if (E->isIntegerConstantExpr(Value, S.Context)) { > > - if (S.SourceMgr.isInSystemMacro(CC)) > > - return; > > + llvm::APSInt Value(32); > > + Expr *NarrowedExpr = NULL; > > + // Use a default-on diagnostic if the source is involved in a > > + // narrowing-prone binary operation with a constant. > > + if (OperandMightImplicitlyNarrow(S.Context, Value, E, TargetRange, > > + &NarrowedExpr)) { > > + std::string PrettySourceValue = Value.toString(10); > > + std::string PrettyTargetValue = PrettyPrintInRange(Value, > TargetRange); > > + > > + S.DiagRuntimeBehavior(E->getExprLoc(), NarrowedExpr, > > + S.PDiag(diag::warn_impcast_integer_precision_binop_constant) > > + << PrettySourceValue << PrettyTargetValue > > + << E->getType() << T << NarrowedExpr->getSourceRange() > > + << clang::SourceRange(CC)); > > + return; > > + } else if (SourceRange.Width > TargetRange.Width) { > > + // People want to build with -Wshorten-64-to-32 and not > -Wconversion. > > + if (S.SourceMgr.isInSystemMacro(CC)) > > + return; > > > > + // If the source is a constant, use a default-on diagnostic. > > + if (E->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects)) { > > std::string PrettySourceValue = Value.toString(10); > > std::string PrettyTargetValue = PrettyPrintInRange(Value, > TargetRange); > > - > > S.DiagRuntimeBehavior(E->getExprLoc(), E, > > S.PDiag(diag::warn_impcast_integer_precision_constant) > > << PrettySourceValue << PrettyTargetValue > > @@ -4996,10 +5084,6 @@ void CheckImplicitConversion(Sema &S, Ex > > return; > > } > > > > - // People want to build with -Wshorten-64-to-32 and not > -Wconversion. > > - if (S.SourceMgr.isInSystemMacro(CC)) > > - return; > > - > > if (TargetRange.Width == 32 && S.Context.getIntWidth(E->getType()) > == 64) > > return DiagnoseImpCast(S, E, T, CC, > diag::warn_impcast_integer_64_32, > > /* pruneControlFlow */ true); > > @@ -5129,6 +5213,25 @@ void AnalyzeImplicitConversions(Sema &S, > > if (E->getType() != T) > > CheckImplicitConversion(S, E, T, CC); > > > > + // For CompoundAssignmentOperators, check the conversion from the > computed > > + // LHS type to the type of the assignee. > > + if (CompoundAssignOperator *CAO = > dyn_cast<CompoundAssignOperator>(E)) { > > + QualType LHST = CAO->getComputationLHSType(); > > + // This CheckImplicitConversion would trigger a warning in addition > to the > > + // more serious problem of using NULLs in arithmetic. > > + // Let the call to CheckImplicitConversion on the child expressions > at the > > + // bottom of this function handle them by filtering those out here. > > + // Similarly, disable the extra check for shift assignments, since > any > > + // narrowing would be less serious than a too-large shift count. > > + if (LHST != T && > > + T->isIntegralType(S.Context) && LHST->isIntegralType(S.Context) > && > > + !CAO->isShiftAssignOp() && > > + CAO->getRHS()->isNullPointerConstant(S.Context, > > + > Expr::NPC_ValueDependentIsNotNull) > > + != Expr::NPCK_GNUNull) > > + CheckImplicitConversion(S, CAO->getRHS(), T, CC); > > + } > > + > > // Now continue drilling into this expression. > > > > // Skip past explicit casts. > > @@ -5142,8 +5245,8 @@ void AnalyzeImplicitConversions(Sema &S, > > if (BO->isComparisonOp()) > > return AnalyzeComparison(S, BO); > > > > - // And with simple assignments. > > - if (BO->getOpcode() == BO_Assign) > > + // And with assignments. > > + if (BO->isAssignmentOp()) > > return AnalyzeAssignment(S, BO); > > } > > > > > > Modified: cfe/trunk/test/Sema/constant-conversion.c > > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/constant-conversion.c?rev=178273&r1=178272&r2=178273&view=diff > > > ============================================================================== > > --- cfe/trunk/test/Sema/constant-conversion.c (original) > > +++ cfe/trunk/test/Sema/constant-conversion.c Thu Mar 28 14:07:11 2013 > > @@ -66,13 +66,18 @@ void test7() { > > struct { > > unsigned int twoBits1:2; > > unsigned int twoBits2:2; > > - unsigned int reserved:28; > > + unsigned int twoBits3:2; > > + unsigned int reserved:26; > > } f; > > > > f.twoBits1 = ~1; // expected-warning {{implicit truncation from > 'int' to bitfield changes value from -2 to 2}} > > f.twoBits2 = ~2; // expected-warning {{implicit truncation from > 'int' to bitfield changes value from -3 to 1}} > > f.twoBits1 &= ~1; // no-warning > > f.twoBits2 &= ~2; // no-warning > > + f.twoBits3 |= 4; // expected-warning {{implicit truncation from > 'int' to bitfield changes value from 4 to 0}} > > + f.twoBits3 += 4; // expected-warning {{implicit truncation from > 'int' to bitfield changes value from 4 to 0}} > > + f.twoBits3 *= 4; // expected-warning {{implicit truncation from > 'int' to bitfield changes value from 4 to 0}} > > + f.twoBits3 |= 1; // no-warning > > } > > > > void test8() { > > @@ -80,3 +85,38 @@ void test8() { > > struct { enum E x : 1; } f; > > f.x = C; // expected-warning {{implicit truncation from 'int' to > bitfield changes value from 2 to 0}} > > } > > + > > +int func(int); > > + > > +void test9() { > > + unsigned char x = 0; > > + unsigned char y = 0; > > + x = y | 0x1ff; // expected-warning {{implicit conversion of binary > operation from 'int' to 'unsigned char' may change its value; value of > operand would be changed from 511 to 255 if converted before operation}} > > + x = y | 0xff; // no-warning > > + x = y & 0xdff; // expected-warning {{implicit conversion of binary > operation from 'int' to 'unsigned char' may change its value; value of > operand would be changed from 3583 to 255 if converted before operation}} > > + x = y & 0xff; // no-warning > > + x = y & ~1; // no-warning > > + x = 0x1ff | y; // expected-warning {{implicit conversion of binary > operation from 'int' to 'unsigned char' may change its value; value of > operand would be changed from 511 to 255 if converted before operation}} > > + x = 0xff | y; // no-warning > > + x = (y | 0x1ff); // expected-warning {{implicit conversion of binary > operation from 'int' to 'unsigned char' may change its value; value of > operand would be changed from 511 to 255 if converted before operation}} > > + x = (y | 0xff); // no-warning > > + x = 0xff + y; // no-warning > > + x += 0x1ff; // expected-warning {{implicit conversion from 'int' to > 'unsigned char' changes value from 511 to 255}} > > + x = 0xff - y; // no-warning > > + x -= 0x1ff; // expected-warning {{implicit conversion from 'int' to > 'unsigned char' changes value from 511 to 255}} > > + x = y * 0x1ff; // expected-warning {{implicit conversion of binary > operation from 'int' to 'unsigned char' may change its value; value of > operand would be changed from 511 to 255 if converted before operation}} > > + x = y * 0xff; // no-warning > > + x *= 0x1ff; // expected-warning {{implicit conversion from 'int' to > 'unsigned char' changes value from 511 to 255}} > > + x = y ^ 0xff; // no-warning > > + x ^= 0x1ff; // expected-warning {{implicit conversion from 'int' to > 'unsigned char' changes value from 511 to 255}} > > + x = (func(1), 0x1ff); // expected-warning {{implicit conversion of > binary operation from 'int' to 'unsigned char' may change its value; value > of operand would be changed from 511 to 255 if converted before operation}} > > + x = (func(1), 0xff); // no-warning > > + x = 0xff << y; // no-warning > > + x = 0x1ff << y; // expected-warning {{implicit conversion of binary > operation from 'int' to 'unsigned char' may change its value; value of > operand would be changed from 511 to 255 if converted before operation}} > > + > > + > > + // These next two tests make sure that both LHS and RHS are checked > for > > + // narrowing operations. > > + x = 0x1ff | 0xff; // expected-warning {{implicit conversion of binary > operation from 'int' to 'unsigned char' may change its value; value of > operand would be changed from 511 to 255 if converted before operation}} > > + x = 0xff | 0x1ff; // expected-warning {{implicit conversion of binary > operation from 'int' to 'unsigned char' may change its value; value of > operand would be changed from 511 to 255 if converted before operation}} > > +} > > > > > > _______________________________________________ > > cfe-commits mailing list > > [email protected] > > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits > _______________________________________________ > cfe-commits mailing list > [email protected] > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits >
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