[clang] 67ee18c - [Clang] Add machinery to catch overflow in unary minus outside of a constant expression context
Shafik Yaghmour via cfe-commits
cfe-commits at lists.llvm.org
Tue Jan 31 09:35:21 PST 2023
Author: Shafik Yaghmour
Date: 2023-01-31T09:35:12-08:00
New Revision: 67ee18cc7a308ae8418689c4f03a1be73b8b874a
URL: https://github.com/llvm/llvm-project/commit/67ee18cc7a308ae8418689c4f03a1be73b8b874a
DIFF: https://github.com/llvm/llvm-project/commit/67ee18cc7a308ae8418689c4f03a1be73b8b874a.diff
LOG: [Clang] Add machinery to catch overflow in unary minus outside of a constant expression context
We provide several diagnostics for various undefined behaviors due to signed
integer overflow outside of a constant expression context. We were missing the
machinery to catch overflows due to unary minus.
Fixes: https://github.com/llvm/llvm-project/issues/31643
Differential Revision: https://reviews.llvm.org/D142867
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/lib/AST/ExprConstant.cpp
clang/lib/Sema/SemaChecking.cpp
clang/test/CXX/expr/expr.const/p2-0x.cpp
clang/test/SemaCXX/integer-overflow.cpp
clang/unittests/Support/TimeProfilerTest.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index efa9fe076b41f..0a1197044a71a 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -63,6 +63,9 @@ Bug Fixes
Improvements to Clang's diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+- We now generate a diagnostic for signed integer overflow due to unary minus
+ in a non-constant expression context. This fixes
+ `Issue 31643 <https://github.com/llvm/llvm-project/issues/31643>`_
Non-comprehensive list of changes in this release
-------------------------------------------------
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index e4c47b8b8b02f..3e2164c4eebc8 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -13502,10 +13502,16 @@ bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
return false;
if (!Result.isInt()) return Error(E);
const APSInt &Value = Result.getInt();
- if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow() &&
- !HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1),
- E->getType()))
- return false;
+ if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow()) {
+ if (Info.checkingForUndefinedBehavior())
+ Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
+ diag::warn_integer_constant_overflow)
+ << toString(Value, 10) << E->getType();
+
+ if (!HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1),
+ E->getType()))
+ return false;
+ }
return Success(-Value, E);
}
case UO_Not: {
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index da4ec30b65302..4602284309491 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -14876,7 +14876,7 @@ void Sema::CheckForIntOverflow (Expr *E) {
Expr *OriginalE = Exprs.pop_back_val();
Expr *E = OriginalE->IgnoreParenCasts();
- if (isa<BinaryOperator>(E)) {
+ if (isa<BinaryOperator, UnaryOperator>(E)) {
E->EvaluateForOverflow(Context);
continue;
}
diff --git a/clang/test/CXX/expr/expr.const/p2-0x.cpp b/clang/test/CXX/expr/expr.const/p2-0x.cpp
index a8dece1b90d5a..9044844607e05 100644
--- a/clang/test/CXX/expr/expr.const/p2-0x.cpp
+++ b/clang/test/CXX/expr/expr.const/p2-0x.cpp
@@ -146,6 +146,7 @@ namespace UndefinedBehavior {
constexpr int int_min = ~0x7fffffff;
constexpr int minus_int_min = -int_min; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
+ constexpr int minus_int_min_from_shift = -(1<<31); // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
constexpr int div0 = 3 / 0; // expected-error {{constant expression}} expected-note {{division by zero}}
constexpr int mod0 = 3 % 0; // expected-error {{constant expression}} expected-note {{division by zero}}
constexpr int int_min_div_minus_1 = int_min / -1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
diff --git a/clang/test/SemaCXX/integer-overflow.cpp b/clang/test/SemaCXX/integer-overflow.cpp
index 2d8b7455f95f5..870fbeb73cc1f 100644
--- a/clang/test/SemaCXX/integer-overflow.cpp
+++ b/clang/test/SemaCXX/integer-overflow.cpp
@@ -208,3 +208,9 @@ namespace EvaluationCrashes {
}
}
}
+
+namespace GH31643 {
+void f() {
+ int a = -(1<<31); // expected-warning {{overflow in expression; result is -2147483648 with type 'int'}}
+}
+}
diff --git a/clang/unittests/Support/TimeProfilerTest.cpp b/clang/unittests/Support/TimeProfilerTest.cpp
index 566cc6786461f..fdfbbfe4e3a9d 100644
--- a/clang/unittests/Support/TimeProfilerTest.cpp
+++ b/clang/unittests/Support/TimeProfilerTest.cpp
@@ -179,6 +179,7 @@ constexpr int slow_init_list[] = {1, 1, 2, 3, 5, 8, 13, 21}; // 25th line
Frontend
| EvaluateAsRValue (<test.cc:8:21>)
| EvaluateForOverflow (<test.cc:8:21, col:25>)
+| EvaluateForOverflow (<test.cc:8:30, col:32>)
| EvaluateAsRValue (<test.cc:9:14>)
| EvaluateForOverflow (<test.cc:9:9, col:14>)
| isPotentialConstantExpr (slow_namespace::slow_func)
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