Perform two more constructor/destructor code-size optimizations:

1) emit base destructors as aliases to their unique base class destructors
under some careful conditions.  This is enabled for the same targets that can
support complete-to-base aliases, i.e. not darwin.

2) Emit non-variadic complete constructors for classes with no virtual bases
as calls to the base constructor.  This is enabled on all targets and in
theory can trigger in situations that the alias optimization can't (mostly
involving virtual bases, mostly not yet supported).

These are bundled together because I didn't think it worthwhile to split them,
not because they really need to be.

llvm-svn: 96842

5 files changed, 172 insertions, 10 deletions

diff --git a/clang/test/CodeGenCXX/constructors.cpp b/clang/test/CodeGenCXX/constructors.cpp
new file mode 100644
index 00000000000..2c95c91e111
--- /dev/null
+++ b/clang/test/CodeGenCXX/constructors.cpp
@@ -0,0 +1,94 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 %s -emit-llvm -o - | FileCheck %s
+
+struct Member { int x; Member(); Member(int); Member(const Member &); };
+struct VBase { int x; VBase(); VBase(int); VBase(const VBase &); };
+
+struct ValueClass {
+  ValueClass(int x, int y) : x(x), y(y) {}
+  int x;
+  int y;
+}; // subject to ABI trickery
+
+
+
+/* Test basic functionality. */
+class A {
+  A(struct Undeclared &);
+  A(ValueClass);
+  Member mem;
+};
+
+A::A(struct Undeclared &ref) : mem(0) {}
+
+// Check that delegation works.
+// CHECK: define void @_ZN1AC1ER10Undeclared(
+// CHECK: call void @_ZN1AC2ER10Undeclared(
+
+// CHECK: define void @_ZN1AC2ER10Undeclared(
+// CHECK: call void @_ZN6MemberC1Ei(
+
+A::A(ValueClass v) : mem(v.y - v.x) {}
+
+// CHECK: define void @_ZN1AC1E10ValueClass(
+// CHECK: call void @_ZN1AC2E10ValueClass(
+
+// CHECK: define void @_ZN1AC2E10ValueClass(
+// CHECK: call void @_ZN6MemberC1Ei(
+
+
+/* Test that things work for inheritance. */
+struct B : A {
+  B(struct Undeclared &);
+  Member mem;
+};
+
+B::B(struct Undeclared &ref) : A(ref), mem(1) {}
+
+// CHECK: define void @_ZN1BC1ER10Undeclared(
+// CHECK: call void @_ZN1BC2ER10Undeclared(
+
+// CHECK: define void @_ZN1BC2ER10Undeclared(
+// CHECK: call void @_ZN1AC2ER10Undeclared(
+// CHECK: call void @_ZN6MemberC1Ei(
+
+
+
+/* Test that the delegation optimization is disabled for classes with
+   virtual bases (for now).  This is necessary because a vbase
+   initializer could access one of the parameter variables by
+   reference.  That's a solvable problem, but let's not solve it right
+   now. */
+struct C : virtual A {
+  C(int);
+  Member mem;
+};
+C::C(int x) : A(ValueClass(x, x+1)), mem(x * x) {}
+
+// CHECK: define void @_ZN1CC1Ei(
+// CHECK: call void @_ZN10ValueClassC1Eii(
+// CHECK: call void @_ZN1AC2E10ValueClass(
+// CHECK: call void @_ZN6MemberC1Ei(
+
+// CHECK: define void @_ZN1CC2Ei(
+// CHECK: call void @_ZN6MemberC1Ei(
+
+
+
+/* Test that the delegation optimization is disabled for varargs
+   constructors. */
+struct D : A {
+  D(int, ...);
+  Member mem;
+};
+
+D::D(int x, ...) : A(ValueClass(x, x+1)), mem(x*x) {}
+
+// CHECK: define void @_ZN1DC1Eiz(
+// CHECK: call void @_ZN10ValueClassC1Eii(
+// CHECK: call void @_ZN1AC2E10ValueClass(
+// CHECK: call void @_ZN6MemberC1Ei(
+
+// CHECK: define void @_ZN1DC2Eiz(
+// CHECK: call void @_ZN10ValueClassC1Eii(
+// CHECK: call void @_ZN1AC2E10ValueClass(
+// CHECK: call void @_ZN6MemberC1Ei(
diff --git a/clang/test/CodeGenCXX/default-arguments.cpp b/clang/test/CodeGenCXX/default-arguments.cpp
index 282e5d0d504..2ed1567697c 100644
--- a/clang/test/CodeGenCXX/default-arguments.cpp
+++ b/clang/test/CodeGenCXX/default-arguments.cpp
@@ -43,11 +43,7 @@ struct C {
 };
 
 // CHECK: define void @_ZN1CC1Ev(
-// CHECK: call void @_ZN2A1C1Ev(
-// CHECK: call void @_ZN2A2C1Ev(
-// CHECK: call void @_ZN1BC1ERK2A1RK2A2(
-// CHECK: call void @_ZN2A2D1Ev
-// CHECK: call void @_ZN2A1D1Ev
+// CHECK: call void @_ZN1CC2Ev(
 
 // CHECK: define void @_ZN1CC2Ev(
 // CHECK: call void @_ZN2A1C1Ev(
diff --git a/clang/test/CodeGenCXX/destructors.cpp b/clang/test/CodeGenCXX/destructors.cpp
index f06661a7447..accd1b34986 100644
--- a/clang/test/CodeGenCXX/destructors.cpp
+++ b/clang/test/CodeGenCXX/destructors.cpp
@@ -1,4 +1,11 @@
 // RUN: %clang_cc1 %s -emit-llvm -o - -mconstructor-aliases | FileCheck %s
+
+// CHECK: @_ZN5test01AD1Ev = alias {{.*}} @_ZN5test01AD2Ev
+// CHECK: @_ZN5test11MD2Ev = alias {{.*}} @_ZN5test11AD2Ev
+// CHECK: @_ZN5test11ND2Ev = alias {{.*}} @_ZN5test11AD2Ev
+// CHECK: @_ZN5test11OD2Ev = alias {{.*}} @_ZN5test11AD2Ev
+// CHECK: @_ZN5test11SD2Ev = alias bitcast {{.*}} @_ZN5test11AD2Ev
+
 struct A {
   int a;
   
@@ -60,7 +67,7 @@ namespace test0 {
   // The function-try-block won't suppress -mconstructor-aliases here.
   A::~A() try { } catch (int i) {}
 
-// CHECK: @_ZN5test01AD1Ev = alias {{.*}} @_ZN5test01AD2Ev
+// complete destructor alias tested above
 
 // CHECK: define void @_ZN5test01AD2Ev
 // CHECK: invoke void @_ZN5test06MemberD1Ev
@@ -89,3 +96,40 @@ namespace test0 {
 // CHECK: invoke void @_ZN5test04BaseD2Ev
 // CHECK:   unwind label [[BASE_UNWIND:%[a-zA-Z0-9.]+]]
 }
+
+// Test base-class aliasing.
+namespace test1 {
+  struct A { ~A(); char ***m; }; // non-trivial destructor
+  struct B { ~B(); }; // non-trivial destructor
+  struct Empty { }; // trivial destructor, empty
+  struct NonEmpty { int x; }; // trivial destructor, non-empty
+
+  struct M : A { ~M(); };
+  M::~M() {} // alias tested above
+
+  struct N : A, Empty { ~N(); };
+  N::~N() {} // alias tested above
+
+  struct O : Empty, A { ~O(); };
+  O::~O() {} // alias tested above
+
+  struct P : NonEmpty, A { ~P(); };
+  P::~P() {} // CHECK: define void @_ZN5test11PD2Ev
+
+  struct Q : A, B { ~Q(); };
+  Q::~Q() {} // CHECK: define void @_ZN5test11QD2Ev
+
+  struct R : A { ~R(); };
+  R::~R() { A a; } // CHECK: define void @_ZN5test11RD2Ev
+
+  struct S : A { ~S(); int x; };
+  S::~S() {} // alias tested above
+
+  struct T : A { ~T(); B x; };
+  T::~T() {} // CHECK: define void @_ZN5test11TD2Ev
+
+  // The VTT parameter prevents this.  We could still make this work
+  // for calling conventions that are safe against extra parameters.
+  struct U : A, virtual B { ~U(); };
+  U::~U() {} // CHECK: define void @_ZN5test11UD2Ev
+}
diff --git a/clang/test/CodeGenCXX/virtual-destructor-calls.cpp b/clang/test/CodeGenCXX/virtual-destructor-calls.cpp
index 91fd598d4c9..c5b9262a067 100644
--- a/clang/test/CodeGenCXX/virtual-destructor-calls.cpp
+++ b/clang/test/CodeGenCXX/virtual-destructor-calls.cpp
@@ -1,16 +1,25 @@
 // RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-apple-darwin10 -mconstructor-aliases | FileCheck %s
 
+struct Member {
+  ~Member();
+};
+
 struct A {
   virtual ~A();
 };
 
 struct B : A {
+  Member m;
   virtual ~B();
 };
 
 // Complete dtor: just an alias because there are no virtual bases.
 // CHECK: @_ZN1BD1Ev = alias {{.*}} @_ZN1BD2Ev
 
+// (aliases from C)
+// CHECK: @_ZN1CD1Ev = alias {{.*}} @_ZN1CD2Ev
+// CHECK: @_ZN1CD2Ev = alias bitcast {{.*}} @_ZN1BD2Ev
+
 // Deleting dtor: defers to the complete dtor.
 // CHECK: define void @_ZN1BD0Ev
 // CHECK: call void @_ZN1BD1Ev
@@ -18,6 +27,22 @@ struct B : A {
 
 // Base dtor: actually calls A's base dtor.
 // CHECK: define void @_ZN1BD2Ev
+// CHECK: call void @_ZN6MemberD1Ev
 // CHECK: call void @_ZN1AD2Ev
 
 B::~B() { }
+
+struct C : B {
+  ~C();
+};
+
+C::~C() { }
+
+// Complete dtor: just an alias (checked above).
+
+// Deleting dtor: defers to the complete dtor.
+// CHECK: define void @_ZN1CD0Ev
+// CHECK: call void @_ZN1CD1Ev
+// CHECK: call void @_ZdlPv
+
+// Base dtor: just an alias to B's base dtor.
diff --git a/clang/test/CodeGenCXX/vtable-pointer-initialization.cpp b/clang/test/CodeGenCXX/vtable-pointer-initialization.cpp
index ebe531529b8..75620ab8e62 100644
--- a/clang/test/CodeGenCXX/vtable-pointer-initialization.cpp
+++ b/clang/test/CodeGenCXX/vtable-pointer-initialization.cpp
@@ -42,13 +42,16 @@ struct B : Base {
 void f() { B b; }
 
 // CHECK: define linkonce_odr void @_ZN1BC1Ev(
-// CHECK: call void @_ZN4BaseC2Ev(
-// CHECK: store i8** getelementptr inbounds ([3 x i8*]* @_ZTV1B, i64 0, i64 2)
-// CHECK: call void @_ZN5FieldC1Ev
-// CHECK: ret void
+// CHECK: call void @_ZN1BC2Ev(
 
 // CHECK: define linkonce_odr void @_ZN1BD1Ev(
 // CHECK: store i8** getelementptr inbounds ([3 x i8*]* @_ZTV1B, i64 0, i64 2)
 // CHECK: call void @_ZN5FieldD1Ev(
 // CHECK: call void @_ZN4BaseD2Ev(
 // CHECK: ret void
+
+// CHECK: define linkonce_odr void @_ZN1BC2Ev(
+// CHECK: call void @_ZN4BaseC2Ev(
+// CHECK: store i8** getelementptr inbounds ([3 x i8*]* @_ZTV1B, i64 0, i64 2)
+// CHECK: call void @_ZN5FieldC1Ev
+// CHECK: ret void