r259271 - Improve -Wconstant-conversion
Richard Trieu via cfe-commits
cfe-commits at lists.llvm.org
Fri Jan 29 15:51:16 PST 2016
Author: rtrieu
Date: Fri Jan 29 17:51:16 2016
New Revision: 259271
URL: http://llvm.org/viewvc/llvm-project?rev=259271&view=rev
Log:
Improve -Wconstant-conversion
Switch the evaluation from isIntegerConstantExpr to EvaluateAsInt.
EvaluateAsInt will evaluate more types of expressions than
isIntegerConstantExpr.
Move one case from -Wsign-conversion to -Wconstant-conversion. The case is:
1) Source and target types are signed
2) Source type is wider than the target type
3) The source constant value is positive
4) The conversion will store the value as negative in the target.
Modified:
cfe/trunk/lib/Sema/SemaChecking.cpp
cfe/trunk/test/CXX/expr/expr.const/p2-0x.cpp
cfe/trunk/test/Sema/constant-conversion.c
Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=259271&r1=259270&r2=259271&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
+++ cfe/trunk/lib/Sema/SemaChecking.cpp Fri Jan 29 17:51:16 2016
@@ -7578,7 +7578,7 @@ void CheckImplicitConversion(Sema &S, Ex
// 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 (E->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects)) {
if (S.SourceMgr.isInSystemMacro(CC))
return;
@@ -7603,6 +7603,42 @@ void CheckImplicitConversion(Sema &S, Ex
return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
}
+ if (TargetRange.Width == SourceRange.Width && !TargetRange.NonNegative &&
+ SourceRange.NonNegative && Source->isSignedIntegerType()) {
+ // Warn when doing a signed to signed conversion, warn if the positive
+ // source value is exactly the width of the target type, which will
+ // cause a negative value to be stored.
+
+ llvm::APSInt Value;
+ if (E->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects)) {
+ if (!S.SourceMgr.isInSystemMacro(CC)) {
+
+ IntegerLiteral *IntLit =
+ dyn_cast<IntegerLiteral>(E->IgnoreParenImpCasts());
+
+ // If initializing from a constant, and the constant starts with '0',
+ // then it is a binary, octal, or hexadecimal. Allow these constants
+ // to fill all the bits, even if there is a sign change.
+ if (!IntLit ||
+ *(S.getSourceManager().getCharacterData(IntLit->getLocStart())) !=
+ '0') {
+
+ 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 << E->getType() << T
+ << E->getSourceRange() << clang::SourceRange(CC));
+ return;
+ }
+ }
+ }
+ // Fall through for non-constants to give a sign conversion warning.
+ }
+
if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
(!TargetRange.NonNegative && SourceRange.NonNegative &&
SourceRange.Width == TargetRange.Width)) {
Modified: cfe/trunk/test/CXX/expr/expr.const/p2-0x.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/expr/expr.const/p2-0x.cpp?rev=259271&r1=259270&r2=259271&view=diff
==============================================================================
--- cfe/trunk/test/CXX/expr/expr.const/p2-0x.cpp (original)
+++ cfe/trunk/test/CXX/expr/expr.const/p2-0x.cpp Fri Jan 29 17:51:16 2016
@@ -242,8 +242,8 @@ namespace UndefinedBehavior {
constexpr int n13 = n5 + n5; // expected-error {{constant expression}} expected-note {{value -4294967296 is outside the range of }}
constexpr int n14 = n3 - n5; // expected-error {{constant expression}} expected-note {{value 4294967295 is outside the range of }}
constexpr int n15 = n5 * n5; // expected-error {{constant expression}} expected-note {{value 4611686018427387904 is outside the range of }}
- constexpr signed char c1 = 100 * 2; // ok
- constexpr signed char c2 = '\x64' * '\2'; // also ok
+ constexpr signed char c1 = 100 * 2; // ok expected-warning{{changes value}}
+ constexpr signed char c2 = '\x64' * '\2'; // also ok expected-warning{{changes value}}
constexpr long long ll1 = 0x7fffffffffffffff; // ok
constexpr long long ll2 = ll1 + 1; // expected-error {{constant}} expected-note {{ 9223372036854775808 }}
constexpr long long ll3 = -ll1 - 1; // ok
Modified: cfe/trunk/test/Sema/constant-conversion.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/constant-conversion.c?rev=259271&r1=259270&r2=259271&view=diff
==============================================================================
--- cfe/trunk/test/Sema/constant-conversion.c (original)
+++ cfe/trunk/test/Sema/constant-conversion.c Fri Jan 29 17:51:16 2016
@@ -80,3 +80,34 @@ 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}}
}
+
+void test9() {
+ const char max_char = 0x7F;
+ const short max_short = 0x7FFF;
+ const int max_int = 0x7FFFFFFF;
+
+ const short max_char_plus_one = (short)max_char + 1;
+ const int max_short_plus_one = (int)max_short + 1;
+ const long max_int_plus_one = (long)max_int + 1;
+
+ char new_char = max_char_plus_one; // expected-warning {{implicit conversion from 'const short' to 'char' changes value from 128 to -128}}
+ short new_short = max_short_plus_one; // expected-warning {{implicit conversion from 'const int' to 'short' changes value from 32768 to -32768}}
+ int new_int = max_int_plus_one; // expected-warning {{implicit conversion from 'const long' to 'int' changes value from 2147483648 to -2147483648}}
+
+ char hex_char = 0x80;
+ short hex_short = 0x8000;
+ int hex_int = 0x80000000;
+
+ char oct_char = 0200;
+ short oct_short = 0100000;
+ int oct_int = 020000000000;
+
+ char bin_char = 0b10000000;
+ short bin_short = 0b1000000000000000;
+ int bin_int = 0b10000000000000000000000000000000;
+
+#define CHAR_MACRO_HEX 0xff
+ char macro_char_hex = CHAR_MACRO_HEX;
+#define CHAR_MACRO_DEC 255
+ char macro_char_dec = CHAR_MACRO_DEC; // expected-warning {{implicit conversion from 'int' to 'char' changes value from 255 to -1}}
+}
More information about the cfe-commits
mailing list