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llvm-project/clang/test/CodeGenCXX/microsoft-abi-static-initializers.cpp
Richard Smith ae8d62c9c5 Add branch weights to branches for static initializers. 
The initializer for a static local variable cannot be hot, because it runs at
most once per program. That's not quite the same thing as having a low branch
probability, but under the assumption that the function is invoked many times,
modeling this as a branch probability seems reasonable.

For TLS variables, the situation is less clear, since the initialization side
of the branch can run multiple times in a program execution, but we still
expect initialization to be rare relative to non-initialization uses. It would
seem worthwhile to add a PGO counter along this path to make this estimation
more accurate in future.

For globals with guarded initialization, we don't yet apply any branch weights.
Due to our use of COMDATs, the guard will be reached exactly once per DSO, but
we have no idea how many DSOs will define the variable.

llvm-svn: 309195
2017-07-26 22:01:09 +00:00

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// RUN: %clang_cc1 -fms-extensions -fno-threadsafe-statics -emit-llvm %s -o - -mconstructor-aliases -triple=i386-pc-win32 | FileCheck %s
// CHECK: @llvm.global_ctors = appending global [5 x { i32, void ()*, i8* }] [
// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @"\01??__Eselectany1@@YAXXZ", i8* getelementptr inbounds (%struct.S, %struct.S* @"\01?selectany1@@3US@@A", i32 0, i32 0) },
// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @"\01??__Eselectany2@@YAXXZ", i8* getelementptr inbounds (%struct.S, %struct.S* @"\01?selectany2@@3US@@A", i32 0, i32 0) },
// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @"\01??__Es@?$ExportedTemplate@H@@2US@@A@YAXXZ", i8* getelementptr inbounds (%struct.S, %struct.S* @"\01?s@?$ExportedTemplate@H@@2US@@A", i32 0, i32 0) },
// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @"\01??__Efoo@?$B@H@@2VA@@A@YAXXZ", i8* bitcast (%class.A* @"\01?foo@?$B@H@@2VA@@A" to i8*) },
// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @_GLOBAL__sub_I_microsoft_abi_static_initializers.cpp, i8* null }
// CHECK: ]
struct S {
S();
~S();
};
S s;
// CHECK: define internal void @"\01??__Es@@YAXXZ"()
// CHECK: call x86_thiscallcc %struct.S* @"\01??0S@@QAE@XZ"
// CHECK: call i32 @atexit(void ()* @"\01??__Fs@@YAXXZ")
// CHECK: ret void
// CHECK: define internal void @"\01??__Fs@@YAXXZ"()
// CHECK: call x86_thiscallcc void @"\01??1S@@QAE@XZ"
// CHECK: ret void
// These globals should have initializers comdat associative with the global.
// See @llvm.global_ctors above.
__declspec(selectany) S selectany1;
__declspec(selectany) S selectany2;
// CHECK: define linkonce_odr void @"\01??__Eselectany1@@YAXXZ"() {{.*}} comdat
// CHECK-NOT: @"\01??_Bselectany1
// CHECK: call x86_thiscallcc %struct.S* @"\01??0S@@QAE@XZ"
// CHECK: ret void
// CHECK: define linkonce_odr void @"\01??__Eselectany2@@YAXXZ"() {{.*}} comdat
// CHECK-NOT: @"\01??_Bselectany2
// CHECK: call x86_thiscallcc %struct.S* @"\01??0S@@QAE@XZ"
// CHECK: ret void
// The implicitly instantiated static data member should have initializer
// comdat associative with the global.
template <typename T> struct __declspec(dllexport) ExportedTemplate {
static S s;
};
template <typename T> S ExportedTemplate<T>::s;
void useExportedTemplate(ExportedTemplate<int> x) {
(void)x.s;
}
void StaticLocal() {
static S TheS;
}
// CHECK-LABEL: define void @"\01?StaticLocal@@YAXXZ"()
// CHECK: load i32, i32* @"\01?$S1@?1??StaticLocal@@YAXXZ@4IA"
// CHECK: store i32 {{.*}}, i32* @"\01?$S1@?1??StaticLocal@@YAXXZ@4IA"
// CHECK: ret
void MultipleStatics() {
static S S1;
static S S2;
static S S3;
static S S4;
static S S5;
static S S6;
static S S7;
static S S8;
static S S9;
static S S10;
static S S11;
static S S12;
static S S13;
static S S14;
static S S15;
static S S16;
static S S17;
static S S18;
static S S19;
static S S20;
static S S21;
static S S22;
static S S23;
static S S24;
static S S25;
static S S26;
static S S27;
static S S28;
static S S29;
static S S30;
static S S31;
static S S32;
static S S33;
static S S34;
static S S35;
}
// CHECK-LABEL: define void @"\01?MultipleStatics@@YAXXZ"()
// CHECK: load i32, i32* @"\01?$S1@?1??MultipleStatics@@YAXXZ@4IA"
// CHECK: and i32 {{.*}}, 1
// CHECK: and i32 {{.*}}, 2
// CHECK: and i32 {{.*}}, 4
// CHECK: and i32 {{.*}}, 8
// CHECK: and i32 {{.*}}, 16
// ...
// CHECK: and i32 {{.*}}, -2147483648
// CHECK: load i32, i32* @"\01?$S1@?1??MultipleStatics@@YAXXZ@4IA.1"
// CHECK: and i32 {{.*}}, 1
// CHECK: and i32 {{.*}}, 2
// CHECK: and i32 {{.*}}, 4
// CHECK: ret
// Force WeakODRLinkage by using templates
class A {
public:
A() {}
~A() {}
int a;
};
template<typename T>
class B {
public:
static A foo;
};
template<typename T> A B<T>::foo;
inline S &UnreachableStatic() {
if (0) {
static S s; // bit 1
return s;
}
static S s; // bit 2
return s;
}
// CHECK-LABEL: define linkonce_odr dereferenceable({{[0-9]+}}) %struct.S* @"\01?UnreachableStatic@@YAAAUS@@XZ"() {{.*}} comdat
// CHECK: and i32 {{.*}}, 2
// CHECK: or i32 {{.*}}, 2
// CHECK: ret
inline S &getS() {
static S TheS;
return TheS;
}
// CHECK-LABEL: define linkonce_odr dereferenceable({{[0-9]+}}) %struct.S* @"\01?getS@@YAAAUS@@XZ"() {{.*}} comdat
// CHECK: load i32, i32* @"\01??_B?1??getS@@YAAAUS@@XZ@51"
// CHECK: and i32 {{.*}}, 1
// CHECK: icmp eq i32 {{.*}}, 0
// CHECK: br i1
// init:
// CHECK: or i32 {{.*}}, 1
// CHECK: store i32 {{.*}}, i32* @"\01??_B?1??getS@@YAAAUS@@XZ@51"
// CHECK: call x86_thiscallcc %struct.S* @"\01??0S@@QAE@XZ"(%struct.S* @"\01?TheS@?1??getS@@YAAAUS@@XZ@4U2@A")
// CHECK: call i32 @atexit(void ()* @"\01??__FTheS@?1??getS@@YAAAUS@@XZ@YAXXZ")
// CHECK: br label
// init.end:
// CHECK: ret %struct.S* @"\01?TheS@?1??getS@@YAAAUS@@XZ@4U2@A"
inline int enum_in_function() {
// CHECK-LABEL: define linkonce_odr i32 @"\01?enum_in_function@@YAHXZ"() {{.*}} comdat
static enum e { foo, bar, baz } x;
// CHECK: @"\01?x@?1??enum_in_function@@YAHXZ@4W4e@?1??1@YAHXZ@A"
static int y;
// CHECK: @"\01?y@?1??enum_in_function@@YAHXZ@4HA"
return x + y;
};
struct T {
enum e { foo, bar, baz };
int enum_in_struct() {
// CHECK-LABEL: define linkonce_odr x86_thiscallcc i32 @"\01?enum_in_struct@T@@QAEHXZ"({{.*}}) {{.*}} comdat
static int x;
// CHECK: @"\01?x@?1??enum_in_struct@T@@QAEHXZ@4HA"
return x++;
}
};
inline int switch_test(int x) {
// CHECK-LABEL: define linkonce_odr i32 @"\01?switch_test@@YAHH@Z"(i32 %x) {{.*}} comdat
switch (x) {
static int a;
// CHECK: @"\01?a@?3??switch_test@@YAHH@Z@4HA"
case 0:
a++;
return 1;
case 1:
static int b;
// CHECK: @"\01?b@?3??switch_test@@YAHH@Z@4HA"
return b++;
case 2: {
static int c;
// CHECK: @"\01?c@?4??switch_test@@YAHH@Z@4HA"
return b + c++;
}
};
}
int f();
inline void switch_test2() {
// CHECK-LABEL: define linkonce_odr void @"\01?switch_test2@@YAXXZ"() {{.*}} comdat
// CHECK: @"\01?x@?2??switch_test2@@YAXXZ@4HA"
switch (1) default: static int x = f();
}
namespace DynamicDLLImportInitVSMangling {
// Failing to pop the ExprEvalContexts when instantiating a dllimport var with
// dynamic initializer would cause subsequent static local numberings to be
// incorrect.
struct NonPOD { NonPOD(); };
template <typename T> struct A { static NonPOD x; };
template <typename T> NonPOD A<T>::x;
template struct __declspec(dllimport) A<int>;
inline int switch_test3() {
// CHECK-LABEL: define linkonce_odr i32 @"\01?switch_test3@DynamicDLLImportInitVSMangling@@YAHXZ"() {{.*}} comdat
static int local;
// CHECK: @"\01?local@?1??switch_test3@DynamicDLLImportInitVSMangling@@YAHXZ@4HA"
return local++;
}
}
void force_usage() {
UnreachableStatic();
getS();
(void)B<int>::foo; // (void) - force usage
enum_in_function();
(void)&T::enum_in_struct;
switch_test(1);
switch_test2();
DynamicDLLImportInitVSMangling::switch_test3();
}
// CHECK: define linkonce_odr void @"\01??__Efoo@?$B@H@@2VA@@A@YAXXZ"() {{.*}} comdat
// CHECK-NOT: and
// CHECK-NOT: ?_Bfoo@
// CHECK: call x86_thiscallcc %class.A* @"\01??0A@@QAE@XZ"
// CHECK: call i32 @atexit(void ()* @"\01??__Ffoo@?$B@H@@2VA@@A@YAXXZ")
// CHECK: ret void
// CHECK: define linkonce_odr x86_thiscallcc %class.A* @"\01??0A@@QAE@XZ"({{.*}}) {{.*}} comdat
// CHECK: define linkonce_odr x86_thiscallcc void @"\01??1A@@QAE@XZ"({{.*}}) {{.*}} comdat
// CHECK: define internal void @"\01??__Ffoo@?$B@H@@2VA@@A@YAXXZ"
// CHECK: call x86_thiscallcc void @"\01??1A@@QAE@XZ"{{.*}}foo
// CHECK: ret void
// CHECK: define internal void @_GLOBAL__sub_I_microsoft_abi_static_initializers.cpp()
// CHECK: call void @"\01??__Es@@YAXXZ"()
// CHECK: ret void
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