-fms-extensions: Implement half of #pragma init_seg
Summary:
This pragma is very rare. We could *hypothetically* lower some uses of
it down to @llvm.global_ctors, but given that GlobalOpt isn't able to
optimize prioritized global ctors today, there's really no point.
If we wanted to do this in the future, I would check if the section used
in the pragma started with ".CRT$XC" and had up to two characters after
it. Those two characters could form the 16-bit initialization priority
that we support in @llvm.global_ctors. We would have to teach LLVM to
lower prioritized global ctors on COFF as well.
This should let us compile some silly uses of this pragma in WebKit /
Blink.
Reviewers: rsmith, majnemer
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D4549
llvm-svn: 213593
diff --git a/clang/lib/CodeGen/CGDeclCXX.cpp b/clang/lib/CodeGen/CGDeclCXX.cpp
index 6a03e9a..94cfe21 100644
--- a/clang/lib/CodeGen/CGDeclCXX.cpp
+++ b/clang/lib/CodeGen/CGDeclCXX.cpp
@@ -257,6 +257,32 @@
return Fn;
}
+/// Create a global pointer to a function that will initialize a global
+/// variable. The user has requested that this pointer be emitted in a specific
+/// section.
+void CodeGenModule::EmitPointerToInitFunc(const VarDecl *D,
+ llvm::GlobalVariable *GV,
+ llvm::Function *InitFunc,
+ InitSegAttr *ISA) {
+ llvm::GlobalVariable *PtrArray = new llvm::GlobalVariable(
+ TheModule, InitFunc->getType(), /*isConstant=*/true,
+ llvm::GlobalValue::PrivateLinkage, InitFunc, "__cxx_init_fn_ptr");
+ PtrArray->setSection(ISA->getSection());
+ addUsedGlobal(PtrArray);
+
+ // If the GV is already in a comdat group, then we have to join it.
+ llvm::Comdat *C = GV->getComdat();
+
+ // LinkOnce and Weak linkage are lowered down to a single-member comdat group.
+ // Make an explicit group so we can join it.
+ if (!C && (GV->hasWeakLinkage() || GV->hasLinkOnceLinkage())) {
+ C = TheModule.getOrInsertComdat(GV->getName());
+ GV->setComdat(C);
+ }
+ if (C)
+ PtrArray->setComdat(C);
+}
+
void
CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
llvm::GlobalVariable *Addr,
@@ -272,9 +298,9 @@
llvm::Function *Fn =
CreateGlobalInitOrDestructFunction(*this, FTy, FnName.str());
+ auto *ISA = D->getAttr<InitSegAttr>();
CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr,
PerformInit);
-
if (D->getTLSKind()) {
// FIXME: Should we support init_priority for thread_local?
// FIXME: Ideally, initialization of instantiated thread_local static data
@@ -283,7 +309,10 @@
// FIXME: We only need to register one __cxa_thread_atexit function for the
// entire TU.
CXXThreadLocalInits.push_back(Fn);
- } else if (const InitPriorityAttr *IPA = D->getAttr<InitPriorityAttr>()) {
+ } else if (PerformInit && ISA) {
+ EmitPointerToInitFunc(D, Addr, Fn, ISA);
+ DelayedCXXInitPosition.erase(D);
+ } else if (auto *IPA = D->getAttr<InitPriorityAttr>()) {
OrderGlobalInits Key(IPA->getPriority(), PrioritizedCXXGlobalInits.size());
PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
DelayedCXXInitPosition.erase(D);
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index c65598e..44597bf 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -1103,6 +1103,9 @@
llvm::GlobalVariable *Addr,
bool PerformInit);
+ void EmitPointerToInitFunc(const VarDecl *VD, llvm::GlobalVariable *Addr,
+ llvm::Function *InitFunc, InitSegAttr *ISA);
+
// FIXME: Hardcoding priority here is gross.
void AddGlobalCtor(llvm::Function *Ctor, int Priority = 65535,
llvm::Constant *AssociatedData = 0);
diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index a7b5f6e..b94c4bc 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -652,12 +652,61 @@
return true;
}
+// #pragma init_seg({ compiler | lib | user | "section-name" [, func-name]} )
bool Parser::HandlePragmaMSInitSeg(StringRef PragmaName,
SourceLocation PragmaLocation) {
- PP.Diag(PragmaLocation,
- PP.getDiagnostics().getCustomDiagID(
- DiagnosticsEngine::Error, "'#pragma init_seg' not implemented."));
- return false;
+ if (ExpectAndConsume(tok::l_paren, diag::warn_pragma_expected_lparen,
+ PragmaName))
+ return false;
+
+ // Parse either the known section names or the string section name.
+ StringLiteral *SegmentName = nullptr;
+ if (Tok.isAnyIdentifier()) {
+ auto *II = Tok.getIdentifierInfo();
+ StringRef Section = llvm::StringSwitch<StringRef>(II->getName())
+ .Case("compiler", "\".CRT$XCC\"")
+ .Case("lib", "\".CRT$XCL\"")
+ .Case("user", "\".CRT$XCU\"")
+ .Default("");
+
+ if (!Section.empty()) {
+ // Pretend the user wrote the appropriate string literal here.
+ Token Toks[1];
+ Toks[0].startToken();
+ Toks[0].setKind(tok::string_literal);
+ Toks[0].setLocation(Tok.getLocation());
+ Toks[0].setLiteralData(Section.data());
+ Toks[0].setLength(Section.size());
+ SegmentName =
+ cast<StringLiteral>(Actions.ActOnStringLiteral(Toks, nullptr).get());
+ PP.Lex(Tok);
+ }
+ } else if (Tok.is(tok::string_literal)) {
+ ExprResult StringResult = ParseStringLiteralExpression();
+ if (StringResult.isInvalid())
+ return false;
+ SegmentName = cast<StringLiteral>(StringResult.get());
+ if (SegmentName->getCharByteWidth() != 1) {
+ PP.Diag(PragmaLocation, diag::warn_pragma_expected_non_wide_string)
+ << PragmaName;
+ return false;
+ }
+ // FIXME: Add support for the '[, func-name]' part of the pragma.
+ }
+
+ if (!SegmentName) {
+ PP.Diag(PragmaLocation, diag::warn_pragma_expected_init_seg) << PragmaName;
+ return false;
+ }
+
+ if (ExpectAndConsume(tok::r_paren, diag::warn_pragma_expected_rparen,
+ PragmaName) ||
+ ExpectAndConsume(tok::eof, diag::warn_pragma_extra_tokens_at_eol,
+ PragmaName))
+ return false;
+
+ Actions.ActOnPragmaMSInitSeg(PragmaLocation, SegmentName);
+ return true;
}
struct PragmaLoopHintInfo {
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index d28e046..37ce157 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -109,7 +109,7 @@
}
bool Parser::ExpectAndConsume(tok::TokenKind ExpectedTok, unsigned DiagID,
- const char *Msg) {
+ StringRef Msg) {
if (Tok.is(ExpectedTok) || Tok.is(tok::code_completion)) {
ConsumeAnyToken();
return false;
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 478c34f..2c65332 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -87,7 +87,7 @@
LangOpts.getMSPointerToMemberRepresentationMethod()),
VtorDispModeStack(1, MSVtorDispAttr::Mode(LangOpts.VtorDispMode)),
DataSegStack(nullptr), BSSSegStack(nullptr), ConstSegStack(nullptr),
- CodeSegStack(nullptr), VisContext(nullptr),
+ CodeSegStack(nullptr), CurInitSeg(nullptr), VisContext(nullptr),
IsBuildingRecoveryCallExpr(false),
ExprNeedsCleanups(false), LateTemplateParser(nullptr),
OpaqueParser(nullptr), IdResolver(pp), StdInitializerList(nullptr),
diff --git a/clang/lib/Sema/SemaAttr.cpp b/clang/lib/Sema/SemaAttr.cpp
index 7c182a1..a7d606d 100644
--- a/clang/lib/Sema/SemaAttr.cpp
+++ b/clang/lib/Sema/SemaAttr.cpp
@@ -431,6 +431,15 @@
UnifySection(SegmentName->getString(), SectionFlags, PragmaLocation);
}
+void Sema::ActOnPragmaMSInitSeg(SourceLocation PragmaLocation,
+ StringLiteral *SegmentName) {
+ // There's no stack to maintain, so we just have a current section. When we
+ // see the default section, reset our current section back to null so we stop
+ // tacking on unnecessary attributes.
+ CurInitSeg = SegmentName->getString() == ".CRT$XCU" ? nullptr : SegmentName;
+ CurInitSegLoc = PragmaLocation;
+}
+
void Sema::ActOnPragmaUnused(const Token &IdTok, Scope *curScope,
SourceLocation PragmaLoc) {
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 3e930f4..bbe6930 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9125,6 +9125,13 @@
if (const SectionAttr *SA = var->getAttr<SectionAttr>())
if (UnifySection(SA->getName(), SectionFlags, var))
var->dropAttr<SectionAttr>();
+
+ // Apply the init_seg attribute if this has an initializer. If the
+ // initializer turns out to not be dynamic, we'll end up ignoring this
+ // attribute.
+ if (CurInitSeg && var->getInit())
+ var->addAttr(InitSegAttr::CreateImplicit(Context, CurInitSeg->getString(),
+ CurInitSegLoc));
}
// All the following checks are C++ only.