[clang] 19e2174 - Revert "[Clang] Eagerly instantiate used constexpr function upon definition. (#73463)"
Corentin Jabot via cfe-commits
cfe-commits at lists.llvm.org
Sat Dec 2 04:36:29 PST 2023
Author: Corentin Jabot
Date: 2023-12-02T13:35:27+01:00
New Revision: 19e2174d54356e1654583a65ff9cd38eccf797ee
URL: https://github.com/llvm/llvm-project/commit/19e2174d54356e1654583a65ff9cd38eccf797ee
DIFF: https://github.com/llvm/llvm-project/commit/19e2174d54356e1654583a65ff9cd38eccf797ee.diff
LOG: Revert "[Clang] Eagerly instantiate used constexpr function upon definition. (#73463)"
This reverts commit 030047c432cac133738be68fa0974f70e69dd58d.
Breaks Qt and is inconsistent with GCC.
See the following issue for details:
Fixes #74069
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Sema/ExternalSemaSource.h
clang/include/clang/Sema/MultiplexExternalSemaSource.h
clang/include/clang/Sema/Sema.h
clang/include/clang/Serialization/ASTBitCodes.h
clang/include/clang/Serialization/ASTReader.h
clang/lib/Sema/MultiplexExternalSemaSource.cpp
clang/lib/Sema/SemaDecl.cpp
clang/lib/Sema/SemaExpr.cpp
clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
clang/lib/Serialization/ASTReader.cpp
clang/lib/Serialization/ASTWriter.cpp
Removed:
clang/test/PCH/instantiate-used-constexpr-function.cpp
clang/test/SemaTemplate/instantiate-used-constexpr-function.cpp
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 06796780f322..c7a948fd3fae 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -802,11 +802,6 @@ Bug Fixes to C++ Support
- Fix crash when parsing nested requirement. Fixes:
(`#73112 <https://github.com/llvm/llvm-project/issues/73112>`_)
-- Clang now immediately instantiates function template specializations
- at the end of the definition of the corresponding function template
- when the definition appears after the first point of instantiation.
- (`#73232 <https://github.com/llvm/llvm-project/issues/73232>`_)
-
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
- Fixed an import failure of recursive friend class template.
diff --git a/clang/include/clang/Sema/ExternalSemaSource.h b/clang/include/clang/Sema/ExternalSemaSource.h
index 8b41c5483458..22d1ee2df115 100644
--- a/clang/include/clang/Sema/ExternalSemaSource.h
+++ b/clang/include/clang/Sema/ExternalSemaSource.h
@@ -181,9 +181,6 @@ class ExternalSemaSource : public ExternalASTSource {
SmallVectorImpl<std::pair<ValueDecl *,
SourceLocation> > &Pending) {}
- virtual void ReadPendingInstantiationsOfConstexprEntity(
- const NamedDecl *D, llvm::SmallSetVector<NamedDecl *, 4> &Decls){};
-
/// Read the set of late parsed template functions for this source.
///
/// The external source should insert its own late parsed template functions
diff --git a/clang/include/clang/Sema/MultiplexExternalSemaSource.h b/clang/include/clang/Sema/MultiplexExternalSemaSource.h
index 6054ef39e54f..2bf91cb5212c 100644
--- a/clang/include/clang/Sema/MultiplexExternalSemaSource.h
+++ b/clang/include/clang/Sema/MultiplexExternalSemaSource.h
@@ -319,9 +319,6 @@ class MultiplexExternalSemaSource : public ExternalSemaSource {
void ReadPendingInstantiations(
SmallVectorImpl<std::pair<ValueDecl*, SourceLocation> >& Pending) override;
- virtual void ReadPendingInstantiationsOfConstexprEntity(
- const NamedDecl *D, llvm::SmallSetVector<NamedDecl *, 4> &Decls) override;
-
/// Read the set of late parsed template functions for this source.
///
/// The external source should insert its own late parsed template functions
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 8b2ed6f7cd8c..e745c01ae0ae 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -59,7 +59,6 @@
#include "clang/Sema/TypoCorrection.h"
#include "clang/Sema/Weak.h"
#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/SmallPtrSet.h"
@@ -10093,12 +10092,6 @@ class Sema final {
/// but have not yet been performed.
std::deque<PendingImplicitInstantiation> PendingInstantiations;
- /// Track constexpr functions referenced before they are (lexically) defined.
- /// The key is the pattern, associated with a list of specialisations that
- /// need to be instantiated when the pattern is defined.
- llvm::DenseMap<NamedDecl *, SmallVector<NamedDecl *>>
- PendingInstantiationsOfConstexprEntities;
-
/// Queue of implicit template instantiations that cannot be performed
/// eagerly.
SmallVector<PendingImplicitInstantiation, 1> LateParsedInstantiations;
@@ -10417,9 +10410,6 @@ class Sema final {
bool Recursive = false,
bool DefinitionRequired = false,
bool AtEndOfTU = false);
-
- void PerformPendingInstantiationsOfConstexprFunctions(FunctionDecl *Template);
-
VarTemplateSpecializationDecl *BuildVarTemplateInstantiation(
VarTemplateDecl *VarTemplate, VarDecl *FromVar,
const TemplateArgumentList &TemplateArgList,
diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 08642889b0cf..fdd64f2abbe9 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -695,10 +695,6 @@ enum ASTRecordTypes {
/// Record code for an unterminated \#pragma clang assume_nonnull begin
/// recorded in a preamble.
PP_ASSUME_NONNULL_LOC = 67,
-
- /// Record code for constexpr templated entities that have been used but not
- /// yet instantiated.
- PENDING_INSTANTIATIONS_OF_CONSTEXPR_ENTITIES = 68,
};
/// Record types used within a source manager block.
diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
index 407fc614f483..7eefdca6815c 100644
--- a/clang/include/clang/Serialization/ASTReader.h
+++ b/clang/include/clang/Serialization/ASTReader.h
@@ -814,9 +814,6 @@ class ASTReader
/// is the instantiation location.
SmallVector<serialization::DeclID, 64> PendingInstantiations;
- llvm::DenseMap<serialization::DeclID, std::set<serialization::DeclID>>
- PendingInstantiationsOfConstexprEntities;
-
//@}
/// \name DiagnosticsEngine-relevant special data
@@ -2104,9 +2101,6 @@ class ASTReader
SmallVectorImpl<std::pair<ValueDecl *,
SourceLocation>> &Pending) override;
- virtual void ReadPendingInstantiationsOfConstexprEntity(
- const NamedDecl *D, llvm::SmallSetVector<NamedDecl *, 4> &Decls) override;
-
void ReadLateParsedTemplates(
llvm::MapVector<const FunctionDecl *, std::unique_ptr<LateParsedTemplate>>
&LPTMap) override;
diff --git a/clang/lib/Sema/MultiplexExternalSemaSource.cpp b/clang/lib/Sema/MultiplexExternalSemaSource.cpp
index 100794de60ee..058e22cb2b81 100644
--- a/clang/lib/Sema/MultiplexExternalSemaSource.cpp
+++ b/clang/lib/Sema/MultiplexExternalSemaSource.cpp
@@ -310,12 +310,6 @@ void MultiplexExternalSemaSource::ReadPendingInstantiations(
Sources[i]->ReadPendingInstantiations(Pending);
}
-void MultiplexExternalSemaSource::ReadPendingInstantiationsOfConstexprEntity(
- const NamedDecl *D, llvm::SmallSetVector<NamedDecl *, 4> &Decls) {
- for (size_t i = 0; i < Sources.size(); ++i)
- Sources[i]->ReadPendingInstantiationsOfConstexprEntity(D, Decls);
-}
-
void MultiplexExternalSemaSource::ReadLateParsedTemplates(
llvm::MapVector<const FunctionDecl *, std::unique_ptr<LateParsedTemplate>>
&LPTMap) {
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index c0d21ec330ac..f12424d33b7d 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -16286,9 +16286,6 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
if (FD && !FD->isDeleted())
checkTypeSupport(FD->getType(), FD->getLocation(), FD);
- if (FD && FD->isConstexpr() && FD->isTemplated())
- PerformPendingInstantiationsOfConstexprFunctions(FD);
-
return dcl;
}
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index b204cb01a0de..d1b2b8084b8f 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -19053,17 +19053,12 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func,
CodeSynthesisContexts.size())
PendingLocalImplicitInstantiations.push_back(
std::make_pair(Func, PointOfInstantiation));
- else if (Func->isConstexpr()) {
+ else if (Func->isConstexpr())
// Do not defer instantiations of constexpr functions, to avoid the
// expression evaluator needing to call back into Sema if it sees a
// call to such a function.
InstantiateFunctionDefinition(PointOfInstantiation, Func);
- if (!Func->isDefined()) {
- PendingInstantiationsOfConstexprEntities
- [Func->getTemplateInstantiationPattern()->getCanonicalDecl()]
- .push_back(Func);
- }
- } else {
+ else {
Func->setInstantiationIsPending(true);
PendingInstantiations.push_back(
std::make_pair(Func, PointOfInstantiation));
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index aa367e0083e6..d768bb72e07c 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -6495,34 +6495,6 @@ void Sema::PerformPendingInstantiations(bool LocalOnly) {
PendingInstantiations.swap(delayedPCHInstantiations);
}
-// Instantiate all referenced specializations of the given function template
-// definition. This make sure that constexpr function templates that are defined
-// after the point of instantiation of their use can be evaluated after they
-// are defined. see CWG2497.
-void Sema::PerformPendingInstantiationsOfConstexprFunctions(FunctionDecl *Tpl) {
-
- auto InstantiateAll = [&](const auto &Range) {
- for (NamedDecl *D : Range) {
- FunctionDecl *Fun = cast<FunctionDecl>(D);
- InstantiateFunctionDefinition(Fun->getPointOfInstantiation(), Fun);
- }
- };
-
- auto It =
- PendingInstantiationsOfConstexprEntities.find(Tpl->getCanonicalDecl());
- if (It != PendingInstantiationsOfConstexprEntities.end()) {
- auto Decls = std::move(It->second);
- PendingInstantiationsOfConstexprEntities.erase(It);
- InstantiateAll(Decls);
- }
-
- llvm::SmallSetVector<NamedDecl *, 4> Decls;
- if (ExternalSource) {
- ExternalSource->ReadPendingInstantiationsOfConstexprEntity(Tpl, Decls);
- InstantiateAll(Decls);
- }
-}
-
void Sema::PerformDependentDiagnostics(const DeclContext *Pattern,
const MultiLevelTemplateArgumentList &TemplateArgs) {
for (auto *DD : Pattern->ddiags()) {
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index ef191c236507..f22da838424b 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3709,19 +3709,6 @@ llvm::Error ASTReader::ReadASTBlock(ModuleFile &F,
}
break;
- case PENDING_INSTANTIATIONS_OF_CONSTEXPR_ENTITIES:
- if (Record.size() % 2 != 0)
- return llvm::createStringError(
- std::errc::illegal_byte_sequence,
- "Invalid PENDING_INSTANTIATIONS_OF_CONSTEXPR_ENTITIES block");
-
- for (unsigned I = 0, N = Record.size(); I != N; /* in loop */) {
- DeclID Key = getGlobalDeclID(F, Record[I++]);
- DeclID Value = getGlobalDeclID(F, Record[I++]);
- PendingInstantiationsOfConstexprEntities[Key].insert(Value);
- }
- break;
-
case SEMA_DECL_REFS:
if (Record.size() != 3)
return llvm::createStringError(std::errc::illegal_byte_sequence,
@@ -8731,20 +8718,6 @@ void ASTReader::ReadPendingInstantiations(
PendingInstantiations.clear();
}
-void ASTReader::ReadPendingInstantiationsOfConstexprEntity(
- const NamedDecl *D, llvm::SmallSetVector<NamedDecl *, 4> &Decls) {
- for (auto *Redecl : D->redecls()) {
- if (!Redecl->isFromASTFile())
- continue;
- DeclID Id = Redecl->getGlobalID();
- auto It = PendingInstantiationsOfConstexprEntities.find(Id);
- if (It == PendingInstantiationsOfConstexprEntities.end())
- continue;
- for (DeclID InstantiationId : It->second)
- Decls.insert(cast<NamedDecl>(GetDecl(InstantiationId)));
- }
-}
-
void ASTReader::ReadLateParsedTemplates(
llvm::MapVector<const FunctionDecl *, std::unique_ptr<LateParsedTemplate>>
&LPTMap) {
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 8c8048fce026..6df815234e23 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -849,7 +849,6 @@ void ASTWriter::WriteBlockInfoBlock() {
RECORD(SEMA_DECL_REFS);
RECORD(WEAK_UNDECLARED_IDENTIFIERS);
RECORD(PENDING_IMPLICIT_INSTANTIATIONS);
- RECORD(PENDING_INSTANTIATIONS_OF_CONSTEXPR_ENTITIES);
RECORD(UPDATE_VISIBLE);
RECORD(DECL_UPDATE_OFFSETS);
RECORD(DECL_UPDATES);
@@ -4837,16 +4836,6 @@ ASTFileSignature ASTWriter::WriteASTCore(Sema &SemaRef, StringRef isysroot,
assert(SemaRef.PendingLocalImplicitInstantiations.empty() &&
"There are local ones at end of translation unit!");
- // Build a record containing all pending instantiations of constexpr
- // entities.
- RecordData PendingInstantiationsOfConstexprEntities;
- for (const auto &I : SemaRef.PendingInstantiationsOfConstexprEntities) {
- for (const auto &Elem : I.second) {
- AddDeclRef(I.first, PendingInstantiationsOfConstexprEntities);
- AddDeclRef(Elem, PendingInstantiationsOfConstexprEntities);
- }
- }
-
// Build a record containing some declaration references.
RecordData SemaDeclRefs;
if (SemaRef.StdNamespace || SemaRef.StdBadAlloc || SemaRef.StdAlignValT) {
@@ -5164,11 +5153,6 @@ ASTFileSignature ASTWriter::WriteASTCore(Sema &SemaRef, StringRef isysroot,
if (!PendingInstantiations.empty())
Stream.EmitRecord(PENDING_IMPLICIT_INSTANTIATIONS, PendingInstantiations);
- // Write the record containing pending instantiations of constexpr entities.
- if (!PendingInstantiationsOfConstexprEntities.empty())
- Stream.EmitRecord(PENDING_INSTANTIATIONS_OF_CONSTEXPR_ENTITIES,
- PendingInstantiationsOfConstexprEntities);
-
// Write the record containing declaration references of Sema.
if (!SemaDeclRefs.empty())
Stream.EmitRecord(SEMA_DECL_REFS, SemaDeclRefs);
diff --git a/clang/test/PCH/instantiate-used-constexpr-function.cpp b/clang/test/PCH/instantiate-used-constexpr-function.cpp
deleted file mode 100644
index 3930d0467d86..000000000000
--- a/clang/test/PCH/instantiate-used-constexpr-function.cpp
+++ /dev/null
@@ -1,17 +0,0 @@
-// RUN: %clang_cc1 -std=c++2a -emit-pch %s -o %t
-// RUN: %clang_cc1 -std=c++2a -include-pch %t -verify %s
-
-// expected-no-diagnostics
-
-#ifndef HEADER
-#define HEADER
-
-template<typename T> constexpr T f();
-constexpr int g() { return f<int>(); } // #1
-
-#else /*included pch*/
-
-template<typename T> constexpr T f() { return 123; }
-int k[g()];
-
-#endif // HEADER
diff --git a/clang/test/SemaTemplate/instantiate-used-constexpr-function.cpp b/clang/test/SemaTemplate/instantiate-used-constexpr-function.cpp
deleted file mode 100644
index 61a7fb013768..000000000000
--- a/clang/test/SemaTemplate/instantiate-used-constexpr-function.cpp
+++ /dev/null
@@ -1,30 +0,0 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
-// expected-no-diagnostics
-
-namespace GH73232 {
-
-template <typename _CharT>
-struct basic_string {
- constexpr void _M_construct();
- constexpr basic_string() {
- _M_construct();
- }
-};
-
-basic_string<char> a;
-
-template <typename _CharT>
-constexpr void basic_string<_CharT>::_M_construct(){}
-constexpr basic_string<char> str{};
-
-template <typename T>
-constexpr void g(T);
-
-constexpr int f() { g(0); return 0; }
-
-template <typename T>
-constexpr void g(T) {}
-
-constexpr int z = f();
-
-}
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