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llvm-project/clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist.cpp
Benjamin Kramer 3d8aa5c77d CodeGen: Emit constant temporaries into read-only globals. 
Instead of creating a copy on the stack just stash them in a private
constant global. This saves both the copying overhead and the stack
space, and gives the optimizer more room to constant fold.

This tries to make array temporaries more similar to regular arrays,
they can't use the same logic because a temporary has no VarDecl to be
bound to so we roll our own version here.

The original use case for this optimization was code like
  for (int i : {1, 2, 3, 4, 5, 6, 7, 8, 10})
    foo(i);
where without this patch (assuming that the loop is not unrolled) we
would alloca an array on the stack, copy the 10 values over and
iterate on that. With this patch we put the array in .text use it
directly. Apart from that case this helps on virtually any passing of
a constant std::initializer_list as a function argument.

Differential Revision: http://reviews.llvm.org/D8034

llvm-svn: 231508
2015-03-06 20:00:03 +00:00

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// RUN: %clang_cc1 -std=c++11 -triple x86_64-none-linux-gnu -emit-llvm -o - %s | FileCheck %s
namespace std {
typedef decltype(sizeof(int)) size_t;
// libc++'s implementation
template <class _E>
class initializer_list
{
const _E* __begin_;
size_t __size_;
initializer_list(const _E* __b, size_t __s)
: __begin_(__b),
__size_(__s)
{}
public:
typedef _E value_type;
typedef const _E& reference;
typedef const _E& const_reference;
typedef size_t size_type;
typedef const _E* iterator;
typedef const _E* const_iterator;
initializer_list() : __begin_(nullptr), __size_(0) {}
size_t size() const {return __size_;}
const _E* begin() const {return __begin_;}
const _E* end() const {return __begin_ + __size_;}
};
}
struct destroyme1 {
~destroyme1();
};
struct destroyme2 {
~destroyme2();
};
struct witharg1 {
witharg1(const destroyme1&);
~witharg1();
};
struct wantslist1 {
wantslist1(std::initializer_list<destroyme1>);
~wantslist1();
};
// CHECK: @_ZGR15globalInitList1_ = internal constant [3 x i32] [i32 1, i32 2, i32 3]
// CHECK: @globalInitList1 = global %{{[^ ]+}} { i32* getelementptr inbounds ([3 x i32]* @_ZGR15globalInitList1_, i32 0, i32 0), i{{32|64}} 3 }
std::initializer_list<int> globalInitList1 = {1, 2, 3};
namespace thread_local_global_array {
// FIXME: We should be able to constant-evaluate this even though the
// initializer is not a constant expression (pointers to thread_local
// objects aren't really a problem).
//
// CHECK: @_ZN25thread_local_global_array1xE = thread_local global
// CHECK: @_ZGRN25thread_local_global_array1xE_ = internal thread_local constant [4 x i32] [i32 1, i32 2, i32 3, i32 4]
std::initializer_list<int> thread_local x = { 1, 2, 3, 4 };
}
// CHECK: @globalInitList2 = global %{{[^ ]+}} zeroinitializer
// CHECK: @_ZGR15globalInitList2_ = internal global [2 x %[[WITHARG:[^ ]*]]] zeroinitializer
// CHECK: @_ZN15partly_constant1kE = global i32 0, align 4
// CHECK: @_ZN15partly_constant2ilE = global {{.*}} null, align 8
// CHECK: @[[PARTLY_CONSTANT_OUTER:_ZGRN15partly_constant2ilE.*]] = internal global {{.*}} zeroinitializer, align 8
// CHECK: @[[PARTLY_CONSTANT_INNER:_ZGRN15partly_constant2ilE.*]] = internal global [3 x {{.*}}] zeroinitializer, align 8
// CHECK: @[[PARTLY_CONSTANT_FIRST:_ZGRN15partly_constant2ilE.*]] = internal constant [3 x i32] [i32 1, i32 2, i32 3], align 4
// CHECK: @[[PARTLY_CONSTANT_SECOND:_ZGRN15partly_constant2ilE.*]] = internal global [2 x i32] zeroinitializer, align 4
// CHECK: @[[PARTLY_CONSTANT_THIRD:_ZGRN15partly_constant2ilE.*]] = internal constant [4 x i32] [i32 5, i32 6, i32 7, i32 8], align 4
// CHECK: @[[REFTMP1:.*]] = private constant [2 x i32] [i32 42, i32 43], comdat($_ZN7PR204451fILi0EEEvv), align 4
// CHECK: @[[REFTMP2:.*]] = private constant [3 x %{{.*}}] [%{{.*}} { i32 1 }, %{{.*}} { i32 2 }, %{{.*}} { i32 3 }], align 4
// CHECK: appending global
// thread_local initializer:
// CHECK-LABEL: define internal void
// CHECK: store i32* getelementptr inbounds ([4 x i32]* @_ZGRN25thread_local_global_array1xE_, i64 0, i64 0),
// CHECK: i32** getelementptr inbounds ({{.*}}* @_ZN25thread_local_global_array1xE, i32 0, i32 0), align 8
// CHECK: store i64 4, i64* getelementptr inbounds ({{.*}}* @_ZN25thread_local_global_array1xE, i32 0, i32 1), align 8
// CHECK-LABEL: define internal void
// CHECK: call void @_ZN8witharg1C1ERK10destroyme1(%[[WITHARG]]* getelementptr inbounds ([2 x %[[WITHARG]]]* @_ZGR15globalInitList2_, i{{32|64}} 0, i{{32|64}} 0
// CHECK: call void @_ZN8witharg1C1ERK10destroyme1(%[[WITHARG]]* getelementptr inbounds ([2 x %[[WITHARG]]]* @_ZGR15globalInitList2_, i{{32|64}} 0, i{{32|64}} 1
// CHECK: __cxa_atexit
// CHECK: store %[[WITHARG]]* getelementptr inbounds ([2 x %[[WITHARG]]]* @_ZGR15globalInitList2_, i64 0, i64 0),
// CHECK: %[[WITHARG]]** getelementptr inbounds (%{{.*}}* @globalInitList2, i32 0, i32 0), align 8
// CHECK: store i64 2, i64* getelementptr inbounds (%{{.*}}* @globalInitList2, i32 0, i32 1), align 8
// CHECK: call void @_ZN10destroyme1D1Ev
// CHECK: call void @_ZN10destroyme1D1Ev
std::initializer_list<witharg1> globalInitList2 = {
witharg1(destroyme1()), witharg1(destroyme1())
};
void fn1(int i) {
// CHECK-LABEL: define void @_Z3fn1i
// temporary array
// CHECK: [[array:%[^ ]+]] = alloca [3 x i32]
// CHECK: getelementptr inbounds [3 x i32], [3 x i32]* [[array]], i{{32|64}} 0
// CHECK-NEXT: store i32 1, i32*
// CHECK-NEXT: getelementptr
// CHECK-NEXT: store
// CHECK-NEXT: getelementptr
// CHECK-NEXT: load
// CHECK-NEXT: store
// init the list
// CHECK-NEXT: getelementptr
// CHECK-NEXT: getelementptr inbounds [3 x i32], [3 x i32]*
// CHECK-NEXT: store i32*
// CHECK-NEXT: getelementptr
// CHECK-NEXT: store i{{32|64}} 3
std::initializer_list<int> intlist{1, 2, i};
}
void fn2() {
// CHECK-LABEL: define void @_Z3fn2v
void target(std::initializer_list<destroyme1>);
// objects should be destroyed before dm2, after call returns
// CHECK: call void @_Z6targetSt16initializer_listI10destroyme1E
target({ destroyme1(), destroyme1() });
// CHECK: call void @_ZN10destroyme1D1Ev
destroyme2 dm2;
// CHECK: call void @_ZN10destroyme2D1Ev
}
void fn3() {
// CHECK-LABEL: define void @_Z3fn3v
// objects should be destroyed after dm2
auto list = { destroyme1(), destroyme1() };
destroyme2 dm2;
// CHECK: call void @_ZN10destroyme2D1Ev
// CHECK: call void @_ZN10destroyme1D1Ev
}
void fn4() {
// CHECK-LABEL: define void @_Z3fn4v
void target(std::initializer_list<witharg1>);
// objects should be destroyed before dm2, after call returns
// CHECK: call void @_ZN8witharg1C1ERK10destroyme1
// CHECK: call void @_Z6targetSt16initializer_listI8witharg1E
target({ witharg1(destroyme1()), witharg1(destroyme1()) });
// CHECK: call void @_ZN8witharg1D1Ev
// CHECK: call void @_ZN10destroyme1D1Ev
destroyme2 dm2;
// CHECK: call void @_ZN10destroyme2D1Ev
}
void fn5() {
// CHECK-LABEL: define void @_Z3fn5v
// temps should be destroyed before dm2
// objects should be destroyed after dm2
// CHECK: call void @_ZN8witharg1C1ERK10destroyme1
auto list = { witharg1(destroyme1()), witharg1(destroyme1()) };
// CHECK: call void @_ZN10destroyme1D1Ev
destroyme2 dm2;
// CHECK: call void @_ZN10destroyme2D1Ev
// CHECK: call void @_ZN8witharg1D1Ev
}
void fn6() {
// CHECK-LABEL: define void @_Z3fn6v
void target(const wantslist1&);
// objects should be destroyed before dm2, after call returns
// CHECK: call void @_ZN10wantslist1C1ESt16initializer_listI10destroyme1E
// CHECK: call void @_Z6targetRK10wantslist1
target({ destroyme1(), destroyme1() });
// CHECK: call void @_ZN10wantslist1D1Ev
// CHECK: call void @_ZN10destroyme1D1Ev
destroyme2 dm2;
// CHECK: call void @_ZN10destroyme2D1Ev
}
void fn7() {
// CHECK-LABEL: define void @_Z3fn7v
// temps should be destroyed before dm2
// object should be destroyed after dm2
// CHECK: call void @_ZN10wantslist1C1ESt16initializer_listI10destroyme1E
wantslist1 wl = { destroyme1(), destroyme1() };
// CHECK: call void @_ZN10destroyme1D1Ev
destroyme2 dm2;
// CHECK: call void @_ZN10destroyme2D1Ev
// CHECK: call void @_ZN10wantslist1D1Ev
}
void fn8() {
// CHECK-LABEL: define void @_Z3fn8v
void target(std::initializer_list<std::initializer_list<destroyme1>>);
// objects should be destroyed before dm2, after call returns
// CHECK: call void @_Z6targetSt16initializer_listIS_I10destroyme1EE
std::initializer_list<destroyme1> inner;
target({ inner, { destroyme1() } });
// CHECK: call void @_ZN10destroyme1D1Ev
// Only one destroy loop, since only one inner init list is directly inited.
// CHECK-NOT: call void @_ZN10destroyme1D1Ev
destroyme2 dm2;
// CHECK: call void @_ZN10destroyme2D1Ev
}
void fn9() {
// CHECK-LABEL: define void @_Z3fn9v
// objects should be destroyed after dm2
std::initializer_list<destroyme1> inner;
std::initializer_list<std::initializer_list<destroyme1>> list =
{ inner, { destroyme1() } };
destroyme2 dm2;
// CHECK: call void @_ZN10destroyme2D1Ev
// CHECK: call void @_ZN10destroyme1D1Ev
// Only one destroy loop, since only one inner init list is directly inited.
// CHECK-NOT: call void @_ZN10destroyme1D1Ev
// CHECK: ret void
}
struct haslist1 {
std::initializer_list<int> il;
haslist1(int i);
};
// CHECK-LABEL: define void @_ZN8haslist1C2Ei
haslist1::haslist1(int i)
// CHECK: alloca [3 x i32]
// CHECK: store i32 %
// CHECK: store i32 2
// CHECK: store i32 3
: il{i, 2, 3}
{
destroyme2 dm2;
}
struct haslist2 {
std::initializer_list<destroyme1> il;
haslist2();
};
// CHECK-LABEL: define void @_ZN8haslist2C2Ev
haslist2::haslist2()
: il{destroyme1(), destroyme1()}
{
destroyme2 dm2;
// CHECK: call void @_ZN10destroyme2D1Ev
// CHECK: call void @_ZN10destroyme1D1Ev
}
void fn10(int i) {
// CHECK-LABEL: define void @_Z4fn10i
// CHECK: alloca [3 x i32]
// CHECK: call noalias i8* @_Znw{{[jm]}}
// CHECK: store i32 %
// CHECK: store i32 2
// CHECK: store i32 3
// CHECK: store i32*
(void) new std::initializer_list<int> {i, 2, 3};
}
void fn11() {
// CHECK-LABEL: define void @_Z4fn11v
(void) new std::initializer_list<destroyme1> {destroyme1(), destroyme1()};
// CHECK: call void @_ZN10destroyme1D1Ev
destroyme2 dm2;
// CHECK: call void @_ZN10destroyme2D1Ev
}
namespace PR12178 {
struct string {
string(int);
~string();
};
struct pair {
string a;
int b;
};
struct map {
map(std::initializer_list<pair>);
};
map m{ {1, 2}, {3, 4} };
}
namespace rdar13325066 {
struct X { ~X(); };
// CHECK-LABEL: define void @_ZN12rdar133250664loopERNS_1XES1_
void loop(X &x1, X &x2) {
// CHECK: br label
// CHECK: br i1
// CHECK: br label
// CHECK call void @_ZN12rdar133250661XD1Ev
// CHECK: br label
// CHECK: br label
// CHECK: call void @_ZN12rdar133250661XD1Ev
// CHECK: br i1
// CHECK: br label
// CHECK: ret void
for (X x : { x1, x2 }) { }
}
}
namespace dtors {
struct S {
S();
~S();
};
void z();
// CHECK-LABEL: define void @_ZN5dtors1fEv(
void f() {
// CHECK: call void @_ZN5dtors1SC1Ev(
// CHECK: call void @_ZN5dtors1SC1Ev(
std::initializer_list<S>{ S(), S() };
// Destruction loop for underlying array.
// CHECK: br label
// CHECK: call void @_ZN5dtors1SD1Ev(
// CHECK: br i1
// CHECK: call void @_ZN5dtors1zEv(
z();
// CHECK-NOT: call void @_ZN5dtors1SD1Ev(
}
// CHECK-LABEL: define void @_ZN5dtors1gEv(
void g() {
// CHECK: call void @_ZN5dtors1SC1Ev(
// CHECK: call void @_ZN5dtors1SC1Ev(
auto x = std::initializer_list<S>{ S(), S() };
// Destruction loop for underlying array.
// CHECK: br label
// CHECK: call void @_ZN5dtors1SD1Ev(
// CHECK: br i1
// CHECK: call void @_ZN5dtors1zEv(
z();
// CHECK-NOT: call void @_ZN5dtors1SD1Ev(
}
// CHECK-LABEL: define void @_ZN5dtors1hEv(
void h() {
// CHECK: call void @_ZN5dtors1SC1Ev(
// CHECK: call void @_ZN5dtors1SC1Ev(
std::initializer_list<S> x = { S(), S() };
// CHECK-NOT: call void @_ZN5dtors1SD1Ev(
// CHECK: call void @_ZN5dtors1zEv(
z();
// Destruction loop for underlying array.
// CHECK: br label
// CHECK: call void @_ZN5dtors1SD1Ev(
// CHECK: br i1
}
}
namespace partly_constant {
int k;
std::initializer_list<std::initializer_list<int>> &&il = { { 1, 2, 3 }, { 4, k }, { 5, 6, 7, 8 } };
// First init list.
// CHECK-NOT: @[[PARTLY_CONSTANT_FIRST]],
// CHECK: store i32* getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_FIRST]], i64 0, i64 0),
// CHECK: i32** getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_INNER]], i64 0, i64 0, i32 0)
// CHECK: store i64 3, i64* getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_INNER]], i64 0, i64 0, i32 1)
// CHECK-NOT: @[[PARTLY_CONSTANT_FIRST]],
//
// Second init list array (non-constant).
// CHECK: store i32 4, i32* getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_SECOND]], i64 0, i64 0)
// CHECK: load i32, i32* @_ZN15partly_constant1kE
// CHECK: store i32 {{.*}}, i32* getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_SECOND]], i64 0, i64 1)
//
// Second init list.
// CHECK: store i32* getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_SECOND]], i64 0, i64 0),
// CHECK: i32** getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_INNER]], i64 0, i64 1, i32 0)
// CHECK: store i64 2, i64* getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_INNER]], i64 0, i64 1, i32 1)
//
// Third init list.
// CHECK-NOT: @[[PARTLY_CONSTANT_THIRD]],
// CHECK: store i32* getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_THIRD]], i64 0, i64 0),
// CHECK: i32** getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_INNER]], i64 0, i64 2, i32 0)
// CHECK: store i64 4, i64* getelementptr inbounds ({{.*}}* @_ZGRN15partly_constant2ilE4_, i64 0, i64 2, i32 1)
// CHECK-NOT: @[[PARTLY_CONSTANT_THIRD]],
//
// Outer init list.
// CHECK: store {{.*}}* getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_INNER]], i64 0, i64 0),
// CHECK: {{.*}}** getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_OUTER]], i32 0, i32 0)
// CHECK: store i64 3, i64* getelementptr inbounds ({{.*}}* @[[PARTLY_CONSTANT_OUTER]], i32 0, i32 1)
//
// 'il' reference.
// CHECK: store {{.*}}* @[[PARTLY_CONSTANT_OUTER]], {{.*}}** @_ZN15partly_constant2ilE, align 8
}
namespace nested {
struct A { A(); ~A(); };
struct B { const A &a; ~B(); };
struct C { std::initializer_list<B> b; ~C(); };
void f();
// CHECK-LABEL: define void @_ZN6nested1gEv(
void g() {
// CHECK: call void @_ZN6nested1AC1Ev(
// CHECK-NOT: call
// CHECK: call void @_ZN6nested1AC1Ev(
// CHECK-NOT: call
const C &c { { { A() }, { A() } } };
// CHECK: call void @_ZN6nested1fEv(
// CHECK-NOT: call
f();
// CHECK: call void @_ZN6nested1CD1Ev(
// CHECK-NOT: call
// Destroy B[2] array.
// FIXME: This isn't technically correct: reverse construction order would
// destroy the second B then the second A then the first B then the first A.
// CHECK: call void @_ZN6nested1BD1Ev(
// CHECK-NOT: call
// CHECK: br
// CHECK-NOT: call
// CHECK: call void @_ZN6nested1AD1Ev(
// CHECK-NOT: call
// CHECK: call void @_ZN6nested1AD1Ev(
// CHECK-NOT: call
// CHECK: }
}
}
namespace DR1070 {
struct A {
A(std::initializer_list<int>);
};
struct B {
int i;
A a;
};
B b = {1};
struct C {
std::initializer_list<int> a;
B b;
std::initializer_list<double> c;
};
C c = {};
}
namespace ArrayOfInitList {
struct S {
S(std::initializer_list<int>);
};
S x[1] = {};
}
namespace PR20445 {
struct vector { vector(std::initializer_list<int>); };
struct MyClass { explicit MyClass(const vector &v); };
template<int x> void f() { new MyClass({42, 43}); }
template void f<0>();
// CHECK-LABEL: define {{.*}} @_ZN7PR204451fILi0EEEvv(
// CHECK: store i32* getelementptr inbounds ([2 x i32]* @[[REFTMP1]], i64 0, i64 0)
// CHECK: call void @_ZN7PR204456vectorC1ESt16initializer_listIiE(
// CHECK: call void @_ZN7PR204457MyClassC1ERKNS_6vectorE(
}
namespace ConstExpr {
class C {
int x;
public:
constexpr C(int x) : x(x) {}
};
void f(std::initializer_list<C>);
void g() {
// CHECK-LABEL: _ZN9ConstExpr1gEv
// CHECK: store %"class.ConstExpr::C"* getelementptr inbounds ([3 x %"class.ConstExpr::C"]* @[[REFTMP2]], i64 0, i64 0)
// CHECK: call void @_ZN9ConstExpr1fESt16initializer_listINS_1CEE
f({C(1), C(2), C(3)});
}
}
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