Exploit this-return of a callsite in a this-return function.
For constructors/desctructors that return 'this', if there exists a callsite
that returns 'this' and is immediately before the return instruction, make
sure we are using the return value from the callsite.
We don't need to keep 'this' alive through the callsite. It also enables
optimizations in the backend, such as tail call optimization.
rdar://12818789
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177211 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ItaniumCXXABI.cpp b/lib/CodeGen/ItaniumCXXABI.cpp
index 8c7a759..17e83a1 100644
--- a/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/lib/CodeGen/ItaniumCXXABI.cpp
@@ -112,7 +112,7 @@
void EmitInstanceFunctionProlog(CodeGenFunction &CGF);
- void EmitConstructorCall(CodeGenFunction &CGF,
+ llvm::Value *EmitConstructorCall(CodeGenFunction &CGF,
const CXXConstructorDecl *D,
CXXCtorType Type, bool ForVirtualBase,
bool Delegating,
@@ -177,11 +177,11 @@
llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, llvm::Value *allocPtr,
CharUnits cookieSize);
-private:
/// \brief Returns true if the given instance method is one of the
/// kinds that the ARM ABI says returns 'this'.
- static bool HasThisReturn(GlobalDecl GD) {
- const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
+ bool HasThisReturn(GlobalDecl GD) const {
+ const CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(GD.getDecl());
+ if (!MD) return false;
return ((isa<CXXDestructorDecl>(MD) && GD.getDtorType() != Dtor_Deleting) ||
(isa<CXXConstructorDecl>(MD)));
}
@@ -834,7 +834,7 @@
CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
}
-void ItaniumCXXABI::EmitConstructorCall(CodeGenFunction &CGF,
+llvm::Value *ItaniumCXXABI::EmitConstructorCall(CodeGenFunction &CGF,
const CXXConstructorDecl *D,
CXXCtorType Type, bool ForVirtualBase,
bool Delegating,
@@ -849,6 +849,7 @@
// FIXME: Provide a source location here.
CGF.EmitCXXMemberCall(D, SourceLocation(), Callee, ReturnValueSlot(), This,
VTT, VTTTy, ArgBeg, ArgEnd);
+ return Callee;
}
RValue ItaniumCXXABI::EmitVirtualDestructorCall(CodeGenFunction &CGF,