[Templight] Template Instantiation Observer

This patch adds a base-class called TemplateInstantiationObserver which gets
notified whenever a template instantiation is entered or exited during
semantic analysis. This is a base class used to implement the template
profiling and debugging tool called
Templight (https://github.com/mikael-s-persson/templight).

The patch also makes a few more changes:

* ActiveTemplateInstantiation class is moved out of the Sema class (so it can be used with inclusion of Sema.h).
* CreateFrontendAction function in front-end utilities is given external linkage (not longer a hidden static function).
* TemplateInstObserverChain data member added to Sema class to hold the list of template-inst observers.
* Notifications to the template-inst observer are added at the key places where templates are instantiated.

Patch by: Abel Sinkovics!

Differential Revision: https://reviews.llvm.org/D5767

llvm-svn: 324808
diff --git a/clang/test/Templight/templight-default-func-arg.cpp b/clang/test/Templight/templight-default-func-arg.cpp
new file mode 100644
index 0000000..19e6039
--- /dev/null
+++ b/clang/test/Templight/templight-default-func-arg.cpp
@@ -0,0 +1,73 @@
+// RUN: %clang_cc1 -std=c++14 -templight-dump %s 2>&1 | FileCheck %s
+template <class T>
+void foo(T b = 0) {};
+
+int main()
+{
+
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+foo$}}
+// CHECK: {{^kind:[ ]+ExplicitTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^orig:[ ]+'.*templight-default-func-arg.cpp:3:6'}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:72:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+foo$}}
+// CHECK: {{^kind:[ ]+ExplicitTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^orig:[ ]+'.*templight-default-func-arg.cpp:3:6'}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:72:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+foo$}}
+// CHECK: {{^kind:[ ]+DeducedTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^orig:[ ]+'.*templight-default-func-arg.cpp:3:6'}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:72:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+foo$}}
+// CHECK: {{^kind:[ ]+DeducedTemplateArgumentSubstitution$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^orig:[ ]+'.*templight-default-func-arg.cpp:3:6'}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:72:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^orig:[ ]+'.*templight-default-func-arg.cpp:3:6'}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:72:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^orig:[ ]+'.*templight-default-func-arg.cpp:3:6'}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:72:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+b$}}
+// CHECK: {{^kind:[ ]+DefaultFunctionArgumentInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^orig:[ ]+'.*templight-default-func-arg.cpp:3:12'}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:72:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+b$}}
+// CHECK: {{^kind:[ ]+DefaultFunctionArgumentInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^orig:[ ]+'.*templight-default-func-arg.cpp:3:12'}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:72:3'$}}
+//
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+Begin$}}
+// CHECK: {{^orig:[ ]+'.*templight-default-func-arg.cpp:3:6'}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:72:3'$}}
+// CHECK-LABEL: {{^---$}}
+// CHECK: {{^name:[ ]+'foo<int>'$}}
+// CHECK: {{^kind:[ ]+TemplateInstantiation$}}
+// CHECK: {{^event:[ ]+End$}}
+// CHECK: {{^orig:[ ]+'.*templight-default-func-arg.cpp:3:6'}}
+// CHECK: {{^poi:[ ]+'.*templight-default-func-arg.cpp:72:3'$}}
+  foo<int>();
+}