Honor objc_precise_lifetime in GC mode by feeding the value
in the variable to an inline asm which gets run when the variable
goes out of scope.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133840 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index b6ad130..7e126d9 100644
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -364,6 +364,20 @@
}
};
+ struct ExtendGCLifetime : EHScopeStack::Cleanup {
+ const VarDecl &Var;
+ ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
+
+ void Emit(CodeGenFunction &CGF, bool forEH) {
+ // Compute the address of the local variable, in case it's a
+ // byref or something.
+ DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
+ SourceLocation());
+ llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE));
+ CGF.EmitExtendGCLifetime(value);
+ }
+ };
+
struct CallCleanupFunction : EHScopeStack::Cleanup {
llvm::Constant *CleanupFn;
const CGFunctionInfo &FnInfo;
@@ -1029,6 +1043,12 @@
}
}
+ // In GC mode, honor objc_precise_lifetime.
+ if (getLangOptions().getGCMode() != LangOptions::NonGC &&
+ D.hasAttr<ObjCPreciseLifetimeAttr>()) {
+ EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
+ }
+
// Handle the cleanup attribute.
if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
const FunctionDecl *FD = CA->getFunctionDecl();
diff --git a/lib/CodeGen/CGObjC.cpp b/lib/CodeGen/CGObjC.cpp
index 9107e98..62ee03c 100644
--- a/lib/CodeGen/CGObjC.cpp
+++ b/lib/CodeGen/CGObjC.cpp
@@ -2484,4 +2484,22 @@
DI->EmitRegionEnd(Builder);
}
}
+
+/// EmitExtendGCLifetime - Given a pointer to an Objective-C object,
+/// make sure it survives garbage collection until this point.
+void CodeGenFunction::EmitExtendGCLifetime(llvm::Value *object) {
+ // We just use an inline assembly.
+ const llvm::Type *paramTypes[] = { VoidPtrTy };
+ llvm::FunctionType *extenderType
+ = llvm::FunctionType::get(VoidTy, paramTypes, /*variadic*/ false);
+ llvm::Value *extender
+ = llvm::InlineAsm::get(extenderType,
+ /* assembly */ "",
+ /* constraints */ "r",
+ /* side effects */ true);
+
+ object = Builder.CreateBitCast(object, VoidPtrTy);
+ Builder.CreateCall(extender, object)->setDoesNotThrow();
+}
+
CGObjCRuntime::~CGObjCRuntime() {}
diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index fea2e61..717f319 100644
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/lib/CodeGen/CodeGenFunction.h
@@ -2146,6 +2146,10 @@
void EmitGCMemmoveCollectable(llvm::Value *DestPtr, llvm::Value *SrcPtr,
QualType Ty);
+ /// EmitExtendGCLifetime - Given a pointer to an Objective-C object,
+ /// make sure it survives garbage collection until this point.
+ void EmitExtendGCLifetime(llvm::Value *object);
+
/// EmitComplexExpr - Emit the computation of the specified expression of
/// complex type, returning the result.
ComplexPairTy EmitComplexExpr(const Expr *E,