[clang-ifs] Clang Interface Stubs, first version (second landing attempt).

This change reverts r363649; effectively re-landing r363626. At this point
clang::Index::CodegenNameGeneratorImpl has been refactored into
clang::AST::ASTNameGenerator. This makes it so that the previous circular link
dependency no longer exists, fixing the previous share lib
(-DBUILD_SHARED_LIBS=ON) build issue which was the reason for r363649.

Clang interface stubs (previously referred to as clang-ifsos) is a new frontend
action in clang that allows the generation of stub files that contain mangled
name info that can be used to produce a stub library. These stub libraries can
be useful for breaking up build dependencies and controlling access to a
library's internal symbols. Generation of these stubs can be invoked by:

clang -fvisibility=<visibility> -emit-interface-stubs \
                                -interface-stub-version=<interface format>

Notice that -fvisibility (along with use of visibility attributes) can be used
to control what symbols get generated. Currently the interface format is
experimental but there are a wide range of possibilities here.

Currently clang-ifs produces .ifs files that can be thought of as analogous to
object (.o) files, but just for the mangled symbol info. In a subsequent patch
I intend to add support for merging the .ifs files into one .ifs/.ifso file
that can be the input to something like llvm-elfabi to produce something like a
.so file or .dll (but without any of the code, just symbols).

Differential Revision: https://reviews.llvm.org/D60974

llvm-svn: 363948

1 files changed, 31 insertions, 0 deletions

diff --git a/clang/test/InterfaceStubs/template-namespace-function.cpp b/clang/test/InterfaceStubs/template-namespace-function.cpp
new file mode 100644
index 0000000..8793181
--- /dev/null
+++ b/clang/test/InterfaceStubs/template-namespace-function.cpp
@@ -0,0 +1,31 @@
+// RUN: %clang -target x86_64-unknown-linux-gnu -o - -emit-interface-stubs \
+// RUN: -interface-stub-version=experimental-tapi-elf-v1 %s | \
+// RUN: FileCheck %s
+
+// RUN: %clang -target x86_64-unknown-linux-gnu -o - -c %s | llvm-nm - 2>&1 | \
+// RUN: FileCheck -check-prefix=CHECK-SYMBOLS %s
+
+// CHECK: Symbols:
+// CHECK-DAG:  _ZN3qux3barEii: { Type: Func }
+// CHECK-DAG:  _ZN3baz3addIiEET_S1_S1_: { Type: Func }
+// CHECK-DAG:  _Z4fbarff: { Type: Func }
+// CHECK-DAG:  _ZN3baz3addIfEET_S1_S1_: { Type: Func }
+
+// Same symbols just different order.
+// CHECK-SYMBOLS-DAG:  _Z4fbarff
+// CHECK-SYMBOLS-DAG:  _ZN3baz3addIfEET_S1_S1_
+// CHECK-SYMBOLS-DAG:  _ZN3baz3addIiEET_S1_S1_
+// CHECK-SYMBOLS-DAG:  _ZN3qux3barEii
+
+namespace baz {
+template <typename T>
+T add(T a, T b) {
+  return a + b;
+}
+} // namespace baz
+
+namespace qux {
+int bar(int a, int b) { return baz::add<int>(a, b); }
+} // namespace qux
+
+float fbar(float a, float b) { return baz::add<float>(a, b); }