Hi Richard,
this breaks Wunreachable-code which now ignore "weak" on redeclarations:
thakis@thakis:~/src/llvm-project$ cat foo.cc
extern "C" void foo(void);
extern "C" __attribute__((weak)) decltype(foo) foo;
void g(), h();
void f() {
if (foo)
return g();
h();
}
thakis@thakis:~/src/llvm-project$ out/gn/bin/clang -Wunreachable-code -c
foo.cc
foo.cc:8:5: warning: code will never be executed [-Wunreachable-code]
h();
^
This seems to be a somewhat common pattern for calling new functions.
(Chromium bug: https://crbug.com/1125102)
On Thu, Sep 3, 2020 at 6:35 PM Richard Smith via cfe-commits <
cfe-commits@lists.llvm.org> wrote:
>
> Author: Richard Smith
> Date: 2020-09-03T15:35:12-07:00
> New Revision: e6393ee813178e9d3306b8e3c6949a4f32f8a2cb
>
> URL:
> https://github.com/llvm/llvm-project/commit/e6393ee813178e9d3306b8e3c6949a4f32f8a2cb
> DIFF:
> https://github.com/llvm/llvm-project/commit/e6393ee813178e9d3306b8e3c6949a4f32f8a2cb.diff
>
> LOG: Canonicalize declaration pointers when forming APValues.
>
> References to different declarations of the same entity aren't different
> values, so shouldn't have different representations.
>
> Added:
>
>
> Modified:
> clang/include/clang/AST/APValue.h
> clang/lib/AST/APValue.cpp
> clang/lib/AST/ExprConstant.cpp
> clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p9.cpp
> clang/test/OpenMP/ordered_messages.cpp
>
> Removed:
>
>
>
>
> ################################################################################
> diff --git a/clang/include/clang/AST/APValue.h
> b/clang/include/clang/AST/APValue.h
> index 87e4bd7f84c1..485e6c2602cf 100644
> --- a/clang/include/clang/AST/APValue.h
> +++ b/clang/include/clang/AST/APValue.h
> @@ -174,6 +174,7 @@ class APValue {
> return !(LHS == RHS);
> }
> friend llvm::hash_code hash_value(const LValueBase &Base);
> + friend struct llvm::DenseMapInfo<LValueBase>;
>
> private:
> PtrTy Ptr;
> @@ -201,8 +202,7 @@ class APValue {
>
> public:
> LValuePathEntry() : Value() {}
> - LValuePathEntry(BaseOrMemberType BaseOrMember)
> - :
> Value{reinterpret_cast<uintptr_t>(BaseOrMember.getOpaqueValue())} {}
> + LValuePathEntry(BaseOrMemberType BaseOrMember);
> static LValuePathEntry ArrayIndex(uint64_t Index) {
> LValuePathEntry Result;
> Result.Value = Index;
>
> diff --git a/clang/lib/AST/APValue.cpp b/clang/lib/AST/APValue.cpp
> index 2a8834b4db0c..7531229654cf 100644
> --- a/clang/lib/AST/APValue.cpp
> +++ b/clang/lib/AST/APValue.cpp
> @@ -38,7 +38,7 @@ static_assert(
> "Type is insufficiently aligned");
>
> APValue::LValueBase::LValueBase(const ValueDecl *P, unsigned I, unsigned
> V)
> - : Ptr(P), Local{I, V} {}
> + : Ptr(P ? cast<ValueDecl>(P->getCanonicalDecl()) : nullptr), Local{I,
> V} {}
> APValue::LValueBase::LValueBase(const Expr *P, unsigned I, unsigned V)
> : Ptr(P), Local{I, V} {}
>
> @@ -82,13 +82,19 @@ bool operator==(const APValue::LValueBase &LHS,
> const APValue::LValueBase &RHS) {
> if (LHS.Ptr != RHS.Ptr)
> return false;
> - if (LHS.is<TypeInfoLValue>())
> + if (LHS.is<TypeInfoLValue>() || LHS.is<DynamicAllocLValue>())
> return true;
> return LHS.Local.CallIndex == RHS.Local.CallIndex &&
> LHS.Local.Version == RHS.Local.Version;
> }
> }
>
> +APValue::LValuePathEntry::LValuePathEntry(BaseOrMemberType BaseOrMember) {
> + if (const Decl *D = BaseOrMember.getPointer())
> + BaseOrMember.setPointer(D->getCanonicalDecl());
> + Value = reinterpret_cast<uintptr_t>(BaseOrMember.getOpaqueValue());
> +}
> +
> namespace {
> struct LVBase {
> APValue::LValueBase Base;
> @@ -113,14 +119,16 @@ APValue::LValueBase::operator bool () const {
>
> clang::APValue::LValueBase
> llvm::DenseMapInfo<clang::APValue::LValueBase>::getEmptyKey() {
> - return clang::APValue::LValueBase(
> - DenseMapInfo<const ValueDecl*>::getEmptyKey());
> + clang::APValue::LValueBase B;
> + B.Ptr = DenseMapInfo<const ValueDecl*>::getEmptyKey();
> + return B;
> }
>
> clang::APValue::LValueBase
> llvm::DenseMapInfo<clang::APValue::LValueBase>::getTombstoneKey() {
> - return clang::APValue::LValueBase(
> - DenseMapInfo<const ValueDecl*>::getTombstoneKey());
> + clang::APValue::LValueBase B;
> + B.Ptr = DenseMapInfo<const ValueDecl*>::getTombstoneKey();
> + return B;
> }
>
> namespace clang {
> @@ -757,8 +765,10 @@ void APValue::MakeMemberPointer(const ValueDecl
> *Member, bool IsDerivedMember,
> assert(isAbsent() && "Bad state change");
> MemberPointerData *MPD = new ((void*)(char*)Data.buffer)
> MemberPointerData;
> Kind = MemberPointer;
> - MPD->MemberAndIsDerivedMember.setPointer(Member);
> + MPD->MemberAndIsDerivedMember.setPointer(
> + Member ? cast<ValueDecl>(Member->getCanonicalDecl()) : nullptr);
> MPD->MemberAndIsDerivedMember.setInt(IsDerivedMember);
> MPD->resizePath(Path.size());
> - memcpy(MPD->getPath(), Path.data(), Path.size()*sizeof(const
> CXXRecordDecl*));
> + for (unsigned I = 0; I != Path.size(); ++I)
> + MPD->getPath()[I] = Path[I]->getCanonicalDecl();
> }
>
> diff --git a/clang/lib/AST/ExprConstant.cpp
> b/clang/lib/AST/ExprConstant.cpp
> index e8f132dd4803..8e43b62662ee 100644
> --- a/clang/lib/AST/ExprConstant.cpp
> +++ b/clang/lib/AST/ExprConstant.cpp
> @@ -1978,18 +1978,11 @@ static bool HasSameBase(const LValue &A, const
> LValue &B) {
> return false;
>
> if (A.getLValueBase().getOpaqueValue() !=
> - B.getLValueBase().getOpaqueValue()) {
> - const Decl *ADecl = GetLValueBaseDecl(A);
> - if (!ADecl)
> - return false;
> - const Decl *BDecl = GetLValueBaseDecl(B);
> - if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl())
> - return false;
> - }
> + B.getLValueBase().getOpaqueValue())
> + return false;
>
> - return IsGlobalLValue(A.getLValueBase()) ||
> - (A.getLValueCallIndex() == B.getLValueCallIndex() &&
> - A.getLValueVersion() == B.getLValueVersion());
> + return A.getLValueCallIndex() == B.getLValueCallIndex() &&
> + A.getLValueVersion() == B.getLValueVersion();
> }
>
> static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
> @@ -3108,7 +3101,8 @@ static bool evaluateVarDeclInit(EvalInfo &Info,
> const Expr *E,
>
> // If we're currently evaluating the initializer of this declaration,
> use that
> // in-flight value.
> - if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) {
> + if (declaresSameEntity(Info.EvaluatingDecl.dyn_cast<const ValueDecl
> *>(),
> + VD)) {
> Result = Info.EvaluatingDeclValue;
> return true;
> }
>
> diff --git a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p9.cpp
> b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p9.cpp
> index 8d51dbde7177..3720b277af7a 100644
> --- a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p9.cpp
> +++ b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p9.cpp
> @@ -24,11 +24,10 @@ constexpr double &ni3; // expected-error {{declaration
> of reference variable 'ni
>
> constexpr int nc1 = i; // expected-error {{constexpr variable 'nc1' must
> be initialized by a constant expression}} expected-note {{read of non-const
> variable 'i' is not allowed in a constant expression}}
> constexpr C nc2 = C(); // expected-error {{cannot have non-literal type
> 'const C'}}
> -int &f(); // expected-note {{declared here}}
> +int &f(); // expected-note 2{{declared here}}
> constexpr int &nc3 = f(); // expected-error {{constexpr variable 'nc3'
> must be initialized by a constant expression}} expected-note
> {{non-constexpr function 'f' cannot be used in a constant expression}}
> constexpr int nc4(i); // expected-error {{constexpr variable 'nc4' must
> be initialized by a constant expression}} expected-note {{read of non-const
> variable 'i' is not allowed in a constant expression}}
> constexpr C nc5((C())); // expected-error {{cannot have non-literal type
> 'const C'}}
> -int &f(); // expected-note {{here}}
> constexpr int &nc6(f()); // expected-error {{constexpr variable 'nc6'
> must be initialized by a constant expression}} expected-note
> {{non-constexpr function 'f'}}
>
> struct pixel {
>
> diff --git a/clang/test/OpenMP/ordered_messages.cpp
> b/clang/test/OpenMP/ordered_messages.cpp
> index f6b9dbd6d27f..8a3a86443eb8 100644
> --- a/clang/test/OpenMP/ordered_messages.cpp
> +++ b/clang/test/OpenMP/ordered_messages.cpp
> @@ -16,6 +16,9 @@ void xxx(int argc) {
> }
>
> int foo();
> +#if __cplusplus >= 201103L
> +// expected-note@-2 {{declared here}}
> +#endif
>
> template <class T>
> T foo() {
> @@ -176,7 +179,7 @@ T foo() {
>
> int foo() {
> #if __cplusplus >= 201103L
> -// expected-note@-2 2 {{declared here}}
> +// expected-note@-2 {{declared here}}
> #endif
> int k;
> #pragma omp for ordered
>
>
>
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> cfe-commits@lists.llvm.org
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>
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