now that all the decl reference and creation stuff is going through two
very simple places, reimplement the deferred decl emission logic to not be O(N^2),
fixing PR3810.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67447 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 109344b..93bf6dd 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -441,38 +441,26 @@
}
void CodeGenModule::EmitDeferred() {
- // Emit code for any deferred decl which was used. Since a
- // previously unused static decl may become used during the
- // generation of code for a static function, iterate until no
- // changes are made.
- bool Changed;
- do {
- Changed = false;
+ // Emit code for any potentially referenced deferred decls. Since a
+ // previously unused static decl may become used during the generation of code
+ // for a static function, iterate until no changes are made.
+ while (!DeferredDeclsToEmit.empty()) {
+ const ValueDecl *D = DeferredDeclsToEmit.back();
+ DeferredDeclsToEmit.pop_back();
+
+ // The mangled name for the decl must have been emitted in GlobalDeclMap.
+ // Look it up to see if it was defined with a stronger definition (e.g. an
+ // extern inline function with a strong function redefinition). If so,
+ // just ignore the deferred decl.
+ llvm::GlobalValue *CGRef = GlobalDeclMap[getMangledName(D)];
+ assert(CGRef && "Deferred decl wasn't referenced?");
- for (std::list<const ValueDecl*>::iterator i = DeferredDecls.begin(),
- e = DeferredDecls.end(); i != e; ) {
- const ValueDecl *D = *i;
-
- // Check if we have used a decl with the same name
- // FIXME: The AST should have some sort of aggregate decls or
- // global symbol map.
- // FIXME: This is missing some important cases. For example, we
- // need to check for uses in an alias.
- if (!GlobalDeclMap.count(getMangledName(D))) {
- ++i;
- continue;
- }
-
- // Emit the definition.
- EmitGlobalDefinition(D);
-
- // Erase the used decl from the list.
- i = DeferredDecls.erase(i);
-
- // Remember that we made a change.
- Changed = true;
- }
- } while (Changed);
+ if (!CGRef->isDeclaration())
+ continue;
+
+ // Otherwise, emit the definition and move on to the next one.
+ EmitGlobalDefinition(D);
+ }
}
/// EmitAnnotateAttr - Generate the llvm::ConstantStruct which contains the
@@ -552,6 +540,7 @@
return;
}
+ // Ignore declarations, they will be emitted on their first use.
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
// Forward declarations are emitted lazily on first use.
if (!FD->isThisDeclarationADefinition())
@@ -565,9 +554,20 @@
return;
}
- // Defer code generation when possible.
+ // Defer code generation when possible if this is a static definition, inline
+ // function etc. These we only want to emit if they are used.
if (MayDeferGeneration(Global)) {
- DeferredDecls.push_back(Global);
+ // If the value has already been used, add it directly to the
+ // DeferredDeclsToEmit list.
+ const char *MangledName = getMangledName(Global);
+ if (GlobalDeclMap.count(MangledName))
+ DeferredDeclsToEmit.push_back(Global);
+ else {
+ // Otherwise, remember that we saw a deferred decl with this name. The
+ // first use of the mangled name will cause it to move into
+ // DeferredDeclsToEmit.
+ DeferredDecls[MangledName] = Global;
+ }
return;
}
@@ -606,6 +606,19 @@
return llvm::ConstantExpr::getBitCast(Entry, PTy);
}
+ // This is the first use or definition of a mangled name. If there is a
+ // deferred decl with this name, remember that we need to emit it at the end
+ // of the file.
+ llvm::DenseMap<const char*, const ValueDecl*>::iterator DDI =
+ DeferredDecls.find(MangledName);
+ if (DDI != DeferredDecls.end()) {
+ // Move the potentially referenced deferred decl to the DeferredDeclsToEmit
+ // list, and remove it from DeferredDecls (since we don't need it anymore).
+ DeferredDeclsToEmit.push_back(DDI->second);
+ DeferredDecls.erase(DDI);
+ }
+
+
// This function doesn't have a complete type (for example, the return
// type is an incomplete struct). Use a fake type instead, and make
// sure not to try to set attributes.
@@ -648,7 +661,19 @@
const llvm::Type *PTy = llvm::PointerType::get(Ty, ASTTy.getAddressSpace());
return llvm::ConstantExpr::getBitCast(Entry, PTy);
}
-
+
+ // This is the first use or definition of a mangled name. If there is a
+ // deferred decl with this name, remember that we need to emit it at the end
+ // of the file.
+ llvm::DenseMap<const char*, const ValueDecl*>::iterator DDI =
+ DeferredDecls.find(MangledName);
+ if (DDI != DeferredDecls.end()) {
+ // Move the potentially referenced deferred decl to the DeferredDeclsToEmit
+ // list, and remove it from DeferredDecls (since we don't need it anymore).
+ DeferredDeclsToEmit.push_back(DDI->second);
+ DeferredDecls.erase(DDI);
+ }
+
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(Ty, false,
llvm::GlobalValue::ExternalLinkage,