Include translation unit filename in global ctor symbol names.

This makes it easier to see where a global ctor comes from, and it also makes
ASan's init order analyzer output easier to understand.  gcc does this too,
but only in -fPIC mode for some reason.  Don't do this for constructors with
explicit init priority.

Also prepend "sub_" before the 'I', that way regular constructors stay
lexicographically after symbols with init priority (because
ord('s') > ord('I')).  gold seems to ignore the name of constructor symbols,
and ld only looks at the symbol if it includes an init priority, which this
patch doesn't change.

Before: __GLOBAL_I_a
Now: __GLOBAL_sub_I_myfile.cc
llvm-svn: 208128
diff --git a/clang/test/CodeGenCXX/global-init.cpp b/clang/test/CodeGenCXX/global-init.cpp
index 69631c2..a425923 100644
--- a/clang/test/CodeGenCXX/global-init.cpp
+++ b/clang/test/CodeGenCXX/global-init.cpp
@@ -195,11 +195,11 @@
 // CHECK-NEXT:   sub
 // CHECK-NEXT:   store i32 {{.*}}, i32* @_ZN5test1L1yE
 
-// CHECK: define internal void @_GLOBAL__I_a() section "__TEXT,__StaticInit,regular,pure_instructions" {
+// CHECK: define internal void @_GLOBAL__sub_I_global_init.cpp() section "__TEXT,__StaticInit,regular,pure_instructions" {
 // CHECK:   call void [[TEST1_Y_INIT]]
 // CHECK:   call void [[TEST1_Z_INIT]]
 
 // rdar://problem/8090834: this should be nounwind
-// CHECK-NOEXC: define internal void @_GLOBAL__I_a() [[NUW:#[0-9]+]] section "__TEXT,__StaticInit,regular,pure_instructions" {
+// CHECK-NOEXC: define internal void @_GLOBAL__sub_I_global_init.cpp() [[NUW:#[0-9]+]] section "__TEXT,__StaticInit,regular,pure_instructions" {
 
 // CHECK-NOEXC: attributes [[NUW]] = { nounwind }