[modules] Don't emit initializers for VarDecls within a module eagerly whenever

we first touch any part of that module. Instead, defer them until the first
time that module is (transitively) imported. The initializer step for a module
then recursively initializes modules that its own headers imported.

For example, this avoids running the <iostream> global initializer in programs
that don't actually use iostreams, but do use other parts of the standard
library.

llvm-svn: 276159

8 files changed, 53 insertions, 8 deletions

diff --git a/clang/test/Modules/Inputs/unused-global-init/init.h b/clang/test/Modules/Inputs/unused-global-init/init.h
new file mode 100644
index 00000000000..29a932ae65b
--- /dev/null
+++ b/clang/test/Modules/Inputs/unused-global-init/init.h
@@ -0,0 +1 @@
+struct Init { Init(); ~Init(); } init;
diff --git a/clang/test/Modules/Inputs/unused-global-init/module.modulemap b/clang/test/Modules/Inputs/unused-global-init/module.modulemap
new file mode 100644
index 00000000000..c40f0efeb5e
--- /dev/null
+++ b/clang/test/Modules/Inputs/unused-global-init/module.modulemap
@@ -0,0 +1,3 @@
+module used { header "used.h" }
+module unused { header "unused.h" }
+module init { module a { header "init.h" } module b { header "other.h" } }
diff --git a/clang/test/Modules/Inputs/unused-global-init/other.h b/clang/test/Modules/Inputs/unused-global-init/other.h
new file mode 100644
index 00000000000..c6be1ad4c43
--- /dev/null
+++ b/clang/test/Modules/Inputs/unused-global-init/other.h
@@ -0,0 +1 @@
+// other.h
diff --git a/clang/test/Modules/Inputs/unused-global-init/unused.h b/clang/test/Modules/Inputs/unused-global-init/unused.h
new file mode 100644
index 00000000000..06c2a44ba21
--- /dev/null
+++ b/clang/test/Modules/Inputs/unused-global-init/unused.h
@@ -0,0 +1 @@
+// unused.h
diff --git a/clang/test/Modules/Inputs/unused-global-init/used.h b/clang/test/Modules/Inputs/unused-global-init/used.h
new file mode 100644
index 00000000000..689a13f4c8d
--- /dev/null
+++ b/clang/test/Modules/Inputs/unused-global-init/used.h
@@ -0,0 +1,2 @@
+// used.h
+#include "init.h"
diff --git a/clang/test/Modules/odr.cpp b/clang/test/Modules/odr.cpp
index 30143968ffb..9cdbb4f0806 100644
--- a/clang/test/Modules/odr.cpp
+++ b/clang/test/Modules/odr.cpp
@@ -15,9 +15,9 @@ bool b = F<int>{0} == F<int>{1};
 int x = f() + g();
 
 // expected-note@a.h:5 {{definition has no member 'e2'}}
-// expected-note@b.h:3 {{declaration of 'f' does not match}}
-// expected-note@b.h:1 {{definition has no member 'n'}}
+// expected-note@a.h:3 {{declaration of 'f' does not match}}
+// expected-note@a.h:1 {{definition has no member 'm'}}
 
 // expected-error@b.h:5 {{'E::e2' from module 'b' is not present in definition of 'E' in module 'a'}}
-// expected-error@a.h:3 {{'Y::f' from module 'a' is not present in definition of 'Y' in module 'b'}}
-// expected-error@a.h:2 {{'Y::n' from module 'a' is not present in definition of 'Y' in module 'b'}}
+// expected-error@b.h:3 {{'Y::f' from module 'b' is not present in definition of 'Y' in module 'a'}}
+// expected-error@b.h:2 {{'Y::m' from module 'b' is not present in definition of 'Y' in module 'a'}}
diff --git a/clang/test/Modules/templates.mm b/clang/test/Modules/templates.mm
index 190084ad2b7..cd80e2480bf 100644
--- a/clang/test/Modules/templates.mm
+++ b/clang/test/Modules/templates.mm
@@ -12,10 +12,10 @@ void testInlineRedeclEarly() {
 
 @import templates_right;
 
-// CHECK-DAG: @list_left = global %class.List { %"struct.List<int>::node"* null, i32 8 }, align 8
-// CHECK-DAG: @list_right = global %class.List { %"struct.List<int>::node"* null, i32 12 }, align 8
-// CHECK-DAG: @_ZZ15testMixedStructvE1l = {{.*}} constant %class.List { %{{.*}}* null, i32 1 }, align 8
-// CHECK-DAG: @_ZZ15testMixedStructvE1r = {{.*}} constant %class.List { %{{.*}}* null, i32 2 }, align 8
+// CHECK-DAG: @list_left = global %[[LIST:.*]] { %[[LISTNODE:.*]]* null, i32 8 }, align 8
+// CHECK-DAG: @list_right = global %[[LIST]] { %[[LISTNODE]]* null, i32 12 }, align 8
+// CHECK-DAG: @_ZZ15testMixedStructvE1l = {{.*}} constant %[[LIST]] { %{{.*}}* null, i32 1 }, align 8
+// CHECK-DAG: @_ZZ15testMixedStructvE1r = {{.*}} constant %[[LIST]] { %{{.*}}* null, i32 2 }, align 8
 // CHECK-DAG: @_ZN29WithUndefinedStaticDataMemberIA_iE9undefinedE = external global
 
 void testTemplateClasses() {
diff --git a/clang/test/Modules/unused-global-init.cpp b/clang/test/Modules/unused-global-init.cpp
new file mode 100644
index 00000000000..3bd7a7f5a62
--- /dev/null
+++ b/clang/test/Modules/unused-global-init.cpp
@@ -0,0 +1,37 @@
+// RUN: rm -rf %t
+//
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x c++ -I %S/Inputs/unused-global-init -triple %itanium_abi_triple -emit-module %S/Inputs/unused-global-init/module.modulemap -fmodule-name=init -o %t/init.pcm
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x c++ -I %S/Inputs/unused-global-init -triple %itanium_abi_triple -emit-module %S/Inputs/unused-global-init/module.modulemap -fmodule-name=unused -o %t/unused.pcm -fmodule-file=%t/init.pcm
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x c++ -I %S/Inputs/unused-global-init -triple %itanium_abi_triple -emit-module %S/Inputs/unused-global-init/module.modulemap -fmodule-name=used -o %t/used.pcm -fmodule-file=%t/init.pcm
+//
+// No module file: init.h performs init.
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x c++ -I %S/Inputs/unused-global-init -triple %itanium_abi_triple -emit-llvm -o - %s -DINIT | FileCheck --check-prefix=CHECK-INIT %s
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x c++ -I %S/Inputs/unused-global-init -triple %itanium_abi_triple -emit-llvm -o - %s -DUSED | FileCheck --check-prefix=CHECK-INIT %s
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x c++ -I %S/Inputs/unused-global-init -triple %itanium_abi_triple -emit-llvm -o - %s -DOTHER -DUNUSED | FileCheck --check-prefix=CHECK-NO-INIT %s
+//
+// With module files: if there is a transitive import of any part of the
+// module, we run its global initializers (even if the imported piece is not
+// visible here).
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x c++ -I %S/Inputs/unused-global-init -triple %itanium_abi_triple -emit-llvm -o - %s -fmodule-file=%t/used.pcm -fmodule-file=%t/unused.pcm -DINIT | FileCheck --check-prefix=CHECK-INIT %s
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x c++ -I %S/Inputs/unused-global-init -triple %itanium_abi_triple -emit-llvm -o - %s -fmodule-file=%t/used.pcm -fmodule-file=%t/unused.pcm -DOTHER | FileCheck --check-prefix=CHECK-NO-INIT %s
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x c++ -I %S/Inputs/unused-global-init -triple %itanium_abi_triple -emit-llvm -o - %s -fmodule-file=%t/used.pcm -fmodule-file=%t/unused.pcm -DUSED | FileCheck --check-prefix=CHECK-INIT %s
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -x c++ -I %S/Inputs/unused-global-init -triple %itanium_abi_triple -emit-llvm -o - %s -fmodule-file=%t/used.pcm -fmodule-file=%t/unused.pcm -DUNUSED | FileCheck --check-prefix=CHECK-NO-INIT %s
+
+#ifdef INIT
+#include "init.h"
+#endif
+
+#ifdef OTHER
+#include "other.h"
+#endif
+
+#ifdef USED
+#include "used.h"
+#endif
+
+#ifdef UNUSED
+#include "unused.h"
+#endif
+
+// CHECK-INIT: call {{.*}}@_ZN4InitC
+// CHECK-NO-INIT-NOT: call {{.*}}@_ZN4InitC