llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: None (serge-sans-paille) <details> <summary>Changes</summary> This implements a warning that's similar to what GCC does in that context: both memcpy and memset require their first and second operand to be trivially copyable, let's warn if that's not the case. --- Full diff: https://github.com/llvm/llvm-project/pull/111434.diff 3 Files Affected: - (modified) clang/include/clang/Basic/DiagnosticSemaKinds.td (+4) - (modified) clang/lib/Sema/SemaChecking.cpp (+24) - (modified) clang/test/SemaCXX/constexpr-string.cpp (+4) ``````````diff diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index 583475327c5227..d9bff4a559b3b7 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -790,6 +790,10 @@ def warn_cstruct_memaccess : Warning< "%1 call is a pointer to record %2 that is not trivial to " "%select{primitive-default-initialize|primitive-copy}3">, InGroup<NonTrivialMemaccess>; +def warn_cxxstruct_memaccess : Warning< + "%select{destination for|source of|first operand of|second operand of}0 this " + "%1 call is a pointer to record %2 that is not trivially-copyable">, + InGroup<NonTrivialMemaccess>; def note_nontrivial_field : Note< "field is non-trivial to %select{copy|default-initialize}0">; def err_non_trivial_c_union_in_invalid_context : Error< diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index 2bcb930acdcb57..46dda34d0ac8f3 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -8899,18 +8899,42 @@ void Sema::CheckMemaccessArguments(const CallExpr *Call, << ArgIdx << FnName << PointeeTy << Call->getCallee()->getSourceRange()); else if (const auto *RT = PointeeTy->getAs<RecordType>()) { + + auto IsTriviallyCopyableCXXRecord = [](auto const *RT) { + auto const *D = RT->getDecl(); + if (!D) + return true; + auto const *RD = dyn_cast<CXXRecordDecl>(D); + if (!RD) + return true; + RD = RD->getDefinition(); + if (!RD) + return true; + return RD->isTriviallyCopyable(); + }; + if ((BId == Builtin::BImemset || BId == Builtin::BIbzero) && RT->getDecl()->isNonTrivialToPrimitiveDefaultInitialize()) { DiagRuntimeBehavior(Dest->getExprLoc(), Dest, PDiag(diag::warn_cstruct_memaccess) << ArgIdx << FnName << PointeeTy << 0); SearchNonTrivialToInitializeField::diag(PointeeTy, Dest, *this); + } else if ((BId == Builtin::BImemset || BId == Builtin::BIbzero) && + !IsTriviallyCopyableCXXRecord(RT)) { + DiagRuntimeBehavior(Dest->getExprLoc(), Dest, + PDiag(diag::warn_cxxstruct_memaccess) + << ArgIdx << FnName << PointeeTy); } else if ((BId == Builtin::BImemcpy || BId == Builtin::BImemmove) && RT->getDecl()->isNonTrivialToPrimitiveCopy()) { DiagRuntimeBehavior(Dest->getExprLoc(), Dest, PDiag(diag::warn_cstruct_memaccess) << ArgIdx << FnName << PointeeTy << 1); SearchNonTrivialToCopyField::diag(PointeeTy, Dest, *this); + } else if ((BId == Builtin::BImemcpy || BId == Builtin::BImemmove) && + !IsTriviallyCopyableCXXRecord(RT)) { + DiagRuntimeBehavior(Dest->getExprLoc(), Dest, + PDiag(diag::warn_cxxstruct_memaccess) + << ArgIdx << FnName << PointeeTy); } else { continue; } diff --git a/clang/test/SemaCXX/constexpr-string.cpp b/clang/test/SemaCXX/constexpr-string.cpp index c456740ef7551f..26e2e138ef34e0 100644 --- a/clang/test/SemaCXX/constexpr-string.cpp +++ b/clang/test/SemaCXX/constexpr-string.cpp @@ -603,12 +603,16 @@ namespace MemcpyEtc { }; constexpr bool test_nontrivial_memcpy() { // expected-error {{never produces a constant}} NonTrivial arr[3] = {}; + // expected-warning@+2 {{source of this '__builtin_memcpy' call is a pointer to record 'NonTrivial' that is not trivially-copyable}} + // expected-note@+1 {{explicitly cast the pointer to silence this warning}} __builtin_memcpy(arr, arr + 1, sizeof(NonTrivial)); // expected-note 2{{non-trivially-copyable}} return true; } static_assert(test_nontrivial_memcpy()); // expected-error {{constant}} expected-note {{in call}} constexpr bool test_nontrivial_memmove() { // expected-error {{never produces a constant}} NonTrivial arr[3] = {}; + // expected-warning@+2 {{source of this '__builtin_memcpy' call is a pointer to record 'NonTrivial' that is not trivially-copyable}} + // expected-note@+1 {{explicitly cast the pointer to silence this warning}} __builtin_memcpy(arr, arr + 1, sizeof(NonTrivial)); // expected-note 2{{non-trivially-copyable}} return true; } `````````` </details> https://github.com/llvm/llvm-project/pull/111434 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
