[clang] [clang] Emit bad shift warnings (PR #70307)
Budimir Aranđelović via cfe-commits
cfe-commits at lists.llvm.org
Tue Jan 23 06:44:39 PST 2024
https://github.com/budimirarandjelovicsyrmia updated https://github.com/llvm/llvm-project/pull/70307
>From c89be5f77740d0800339cca189312800f567ffb9 Mon Sep 17 00:00:00 2001
From: budimirarandjelovicsyrmia <budimir.arandjelovic at syrmia.com>
Date: Thu, 26 Oct 2023 10:39:52 +0200
Subject: [PATCH] [clang] Emit bad shift warnings
---
clang/lib/AST/ExprConstant.cpp | 11 +++++++----
clang/lib/Sema/SemaExpr.cpp | 21 +++++++++++++--------
clang/test/AST/Interp/shifts.cpp | 7 ++-----
clang/test/C/drs/dr0xx.c | 2 +-
clang/test/Sema/shift-count-negative.c | 8 ++++++++
clang/test/Sema/shift-count-overflow.c | 6 ++++++
clang/test/Sema/shift-negative-value.c | 8 ++++++++
clang/test/Sema/vla-2.c | 9 ++++++---
clang/test/SemaCXX/cxx2a-explicit-bool.cpp | 2 +-
clang/test/SemaCXX/shift.cpp | 1 -
10 files changed, 52 insertions(+), 23 deletions(-)
create mode 100644 clang/test/Sema/shift-count-negative.c
create mode 100644 clang/test/Sema/shift-count-overflow.c
create mode 100644 clang/test/Sema/shift-negative-value.c
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 78cfecbec9fd36..52ee2655c18f99 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -2803,9 +2803,10 @@ static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
// C++11 [expr.shift]p1: Shift width must be less than the bit width of
// the shifted type.
unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
- if (SA != RHS) {
+ if (SA != RHS && Info.getLangOpts().CPlusPlus11) {
Info.CCEDiag(E, diag::note_constexpr_large_shift)
- << RHS << E->getType() << LHS.getBitWidth();
+ << RHS << E->getType() << LHS.getBitWidth();
+ return false;
} else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) {
// C++11 [expr.shift]p2: A signed left shift must have a non-negative
// operand, and must not overflow the corresponding unsigned type.
@@ -2836,9 +2837,11 @@ static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
// C++11 [expr.shift]p1: Shift width must be less than the bit width of the
// shifted type.
unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
- if (SA != RHS)
+ if (SA != RHS && Info.getLangOpts().CPlusPlus11) {
Info.CCEDiag(E, diag::note_constexpr_large_shift)
- << RHS << E->getType() << LHS.getBitWidth();
+ << RHS << E->getType() << LHS.getBitWidth();
+ return false;
+ }
Result = LHS >> SA;
return true;
}
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 94f52004cf6c27..3efafd9bbb3613 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -11428,7 +11428,7 @@ static bool isScopedEnumerationType(QualType T) {
return false;
}
-static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
+static void DiagnoseBadShiftValues(Sema &S, ExprResult &LHS, ExprResult &RHS,
SourceLocation Loc, BinaryOperatorKind Opc,
QualType LHSType) {
// OpenCL 6.3j: shift values are effectively % word size of LHS (more defined),
@@ -11460,9 +11460,11 @@ static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
}
llvm::APInt LeftBits(Right.getBitWidth(), LeftSize);
if (Right.uge(LeftBits)) {
- S.DiagRuntimeBehavior(Loc, RHS.get(),
- S.PDiag(diag::warn_shift_gt_typewidth)
- << RHS.get()->getSourceRange());
+ if (!S.getLangOpts().CPlusPlus11) {
+ S.DiagRuntimeBehavior(Loc, RHS.get(),
+ S.PDiag(diag::warn_shift_gt_typewidth)
+ << RHS.get()->getSourceRange());
+ }
return;
}
@@ -11523,9 +11525,9 @@ static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
}
S.Diag(Loc, diag::warn_shift_result_gt_typewidth)
- << HexResult.str() << Result.getMinSignedBits() << LHSType
- << Left.getBitWidth() << LHS.get()->getSourceRange()
- << RHS.get()->getSourceRange();
+ << HexResult.str() << Result.getMinSignedBits() << LHSType
+ << Left.getBitWidth() << LHS.get()->getSourceRange()
+ << RHS.get()->getSourceRange();
}
/// Return the resulting type when a vector is shifted
@@ -19959,7 +19961,10 @@ bool Sema::DiagRuntimeBehavior(SourceLocation Loc, ArrayRef<const Stmt*> Stmts,
case ExpressionEvaluationContext::ConstantEvaluated:
case ExpressionEvaluationContext::ImmediateFunctionContext:
// Relevant diagnostics should be produced by constant evaluation.
- break;
+
+ // Solution below works for warnings detected in
+ // Sema::DiagnoseBadShiftValues()
+ return DiagIfReachable(Loc, Stmts, PD);
case ExpressionEvaluationContext::PotentiallyEvaluated:
case ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
diff --git a/clang/test/AST/Interp/shifts.cpp b/clang/test/AST/Interp/shifts.cpp
index b1df7b85cc9f2b..c11ba0f6f3a19e 100644
--- a/clang/test/AST/Interp/shifts.cpp
+++ b/clang/test/AST/Interp/shifts.cpp
@@ -33,13 +33,10 @@ namespace shifts {
// FIXME: 'implicit conversion' warning missing in the new interpreter. \
// cxx17-warning {{shift count >= width of type}} \
// ref-warning {{shift count >= width of type}} \
- // ref-warning {{implicit conversion}} \
- // ref-cxx17-warning {{shift count >= width of type}} \
- // ref-cxx17-warning {{implicit conversion}}
+ // ref-cxx17-warning {{shift count >= width of type}}
c = 1 >> (unsigned)-1; // expected-warning {{shift count >= width of type}} \
// cxx17-warning {{shift count >= width of type}} \
- // ref-warning {{shift count >= width of type}} \
- // ref-cxx17-warning {{shift count >= width of type}}
+ // ref-warning {{shift count >= width of type}}
c = 1 << c;
c <<= 0;
c >>= 0;
diff --git a/clang/test/C/drs/dr0xx.c b/clang/test/C/drs/dr0xx.c
index 6a3717f0729b60..6ec224868fea5f 100644
--- a/clang/test/C/drs/dr0xx.c
+++ b/clang/test/C/drs/dr0xx.c
@@ -426,7 +426,7 @@ void dr081(void) {
/* Demonstrate that we don't crash when left shifting a signed value; that's
* implementation defined behavior.
*/
- _Static_assert(-1 << 1 == -2, "fail"); /* Didn't shift a zero into the "sign bit". */
+ _Static_assert(-1 << 1 == -2, "fail"); /* Undefined behvaior since C99 */
_Static_assert(1 << 3 == 1u << 3u, "fail"); /* Shift of a positive signed value does sensible things. */
}
diff --git a/clang/test/Sema/shift-count-negative.c b/clang/test/Sema/shift-count-negative.c
new file mode 100644
index 00000000000000..af16332e0b0ee7
--- /dev/null
+++ b/clang/test/Sema/shift-count-negative.c
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wshift-count-negative %s
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wall %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wshift-count-negative %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wall %s
+
+enum shiftof {
+ X = (1<<-29) // expected-warning {{shift count is negative}}
+};
diff --git a/clang/test/Sema/shift-count-overflow.c b/clang/test/Sema/shift-count-overflow.c
new file mode 100644
index 00000000000000..99803cdd8e5252
--- /dev/null
+++ b/clang/test/Sema/shift-count-overflow.c
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wshift-count-overflow %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wall %s
+
+enum shiftof {
+ X = (1<<32) // expected-warning {{shift count >= width of type}}
+};
diff --git a/clang/test/Sema/shift-negative-value.c b/clang/test/Sema/shift-negative-value.c
new file mode 100644
index 00000000000000..ce6c5f2c5c419e
--- /dev/null
+++ b/clang/test/Sema/shift-negative-value.c
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wshift-negative-value %s
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wall %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wshift-negative-value %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wall %s
+
+enum shiftof {
+ X = (-1<<29) // expected-warning {{shifting a negative signed value is undefined}}
+};
diff --git a/clang/test/Sema/vla-2.c b/clang/test/Sema/vla-2.c
index 316931f2706077..140dd4facb7464 100644
--- a/clang/test/Sema/vla-2.c
+++ b/clang/test/Sema/vla-2.c
@@ -4,14 +4,17 @@
// a different codepath when we have already emitted an error.)
int PotentiallyEvaluatedSizeofWarn(int n) {
- return (int)sizeof *(0 << 32,(int(*)[n])0); // expected-warning {{left operand of comma operator has no effect}} expected-warning {{shift count >= width of type}}
+ return (int)sizeof *(0 << 32,(int(*)[n])0); /* expected-warning {{shift count >= width of type}}
+ expected-warning {{left operand of comma operator has no effect}} */
}
void PotentiallyEvaluatedTypeofWarn(int n) {
- __typeof(*(0 << 32,(int(*)[n])0)) x; // expected-warning {{left operand of comma operator has no effect}} expected-warning {{shift count >= width of type}}
+ __typeof(*(0 << 32,(int(*)[n])0)) x; /* expected-warning {{shift count >= width of type}}
+ expected-warning {{left operand of comma operator has no effect}} */
(void)x;
}
void PotentiallyEvaluatedArrayBoundWarn(int n) {
- (void)*(int(*)[(0 << 32,n)])0; // expected-warning {{left operand of comma operator has no effect}}
+ (void)*(int(*)[(0 << 32,n)])0; /* expected-warning {{shift count >= width of type}}
+ expected-warning {{left operand of comma operator has no effect}} */
}
diff --git a/clang/test/SemaCXX/cxx2a-explicit-bool.cpp b/clang/test/SemaCXX/cxx2a-explicit-bool.cpp
index ad2a3a1ea75e9f..16b23348197e37 100644
--- a/clang/test/SemaCXX/cxx2a-explicit-bool.cpp
+++ b/clang/test/SemaCXX/cxx2a-explicit-bool.cpp
@@ -21,7 +21,7 @@ namespace special_cases
template<int a>
struct A {
// expected-note at -1+ {{candidate constructor}}
- explicit(1 << a)
+ explicit(1 << a) // expected-warning {{shift count is negative}}
// expected-note at -1 {{negative shift count -1}}
// expected-error at -2 {{explicit specifier argument is not a constant expression}}
A(int);
diff --git a/clang/test/SemaCXX/shift.cpp b/clang/test/SemaCXX/shift.cpp
index 89a98791d3eba7..c3249b124e926a 100644
--- a/clang/test/SemaCXX/shift.cpp
+++ b/clang/test/SemaCXX/shift.cpp
@@ -22,7 +22,6 @@ void test() {
c = 1 << -1; // expected-warning {{shift count is negative}}
c = 1 >> -1; // expected-warning {{shift count is negative}}
c = 1 << (unsigned)-1; // expected-warning {{shift count >= width of type}}
- // expected-warning at -1 {{implicit conversion}}
c = 1 >> (unsigned)-1; // expected-warning {{shift count >= width of type}}
c = 1 << c;
c <<= 0;
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