Modular Codegen: Include testing for inline asm as well as some commentary on...

Modular Codegen: Include testing for inline asm as well as some commentary on the implementaiton choice.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@300106 91177308-0d34-0410-b5e6-96231b3b80d8

test/Modules/Inputs/codegen/foo.h

@@ -28,3 +28,5 @@ inline void inst_decl() {
   (void)sizeof(&inst<int>);
   inst<float>();
 }
+
+asm("narf");

test/Modules/codegen.test

@@ -6,6 +6,20 @@ RUN: %clang_cc1 -triple=x86_64-linux-gnu -fmodules-codegen -fmodules-debuginfo -
 RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -debug-info-kind=limited -o - %t/foo.pcm | FileCheck --check-prefix=FOO --check-prefix=BOTH %s
 RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -debug-info-kind=limited -o - -fmodules -fmodule-file=%t/foo.pcm %S/Inputs/codegen/use.cpp | FileCheck --check-prefix=BOTH --check-prefix=USE %s
 
+For want of any better definition, inline asm goes "everywhere" the same as it
+if it were in a header (with the disadvantage that the inline asm will be
+included in the program if the module is used, even if the header containing
+the inline asm is never included - unlike a non-modular build).
+
+This is inconsistent with how namespace scope static variables are handled -
+where they only appear in the code that includes a header. This functionality
+was implemented to workaround/support the initialization of iostreams
+(implemented as a namespace scope static in the header - only to be provided
+when that specific header is included in the program).
+
+FOO: module asm "narf"
+USE: module asm "narf"
+
 FOO: $_Z2f1PKcz = comdat any
 FOO: $_ZN13implicit_dtorD1Ev = comdat any
 USE: $_Z4instIiEvv = comdat any