supython-coder
diff --git a/‎clang/docs/analyzer/user-docs/CrossTranslationUnit.rst‎
Lines changed: 192 additions & 33 deletions b/‎clang/docs/analyzer/user-docs/CrossTranslationUnit.rst‎
Lines changed: 192 additions & 33 deletions
@@ -3,14 +3,33 @@ Cross Translation Unit (CTU) Analysis
 =====================================
 
 Normally, static analysis works in the boundary of one translation unit (TU).
-However, with additional steps and configuration we can enable the analysis to inline the definition of a function from another TU.
+However, with additional steps and configuration we can enable the analysis to inline the definition of a function from
+another TU.
 
 .. contents::
    :local:
 
-Manual CTU Analysis
--------------------
+Overview
+________
+CTU analysis can be used in a variety of ways. The importing of external TU definitions can work with pre-dumped PCH
+files or generating the necessary AST structure on-demand, during the analysis of the main TU. Driving the static
+analysis can also be implemented in multiple ways. The most direct way is to specify the necessary commandline options
+of the Clang frontend manually (and generate the prerequisite dependencies of the specific import method by hand). This
+process can be automated by other tools, like `CodeChecker <https://github.com/Ericsson/codechecker>`_ and scan-build-py
+(preference for the former).
+
+PCH-based analysis
+__________________
+The analysis needs the PCH dumps of all the translations units used in the project.
+These can be generated by the Clang Frontend itself, and must be arranged in a specific way in the filesystem.
+The index, which maps symbols' USR names to PCH dumps containing them must also be generated by the
+`clang-extdef-mapping`. This tool uses a :doc:`compilation database <../../JSONCompilationDatabase>` to
+determine the compilation flags used.
+The analysis invocation must be provided with the directory which contains the dumps and the mapping files.
+
 
+Manual CTU Analysis
+###################
 Let's consider these source files in our minimal example:
 
 .. code-block:: cpp
@@ -47,7 +66,8 @@ And a compilation database:
   ]
 
 We'd like to analyze `main.cpp` and discover the division by zero bug.
-In order to be able to inline the definition of `foo` from `foo.cpp` first we have to generate the `AST` (or `PCH`) file of `foo.cpp`:
+In order to be able to inline the definition of `foo` from `foo.cpp` first we have to generate the `AST` (or `PCH`) file
+of `foo.cpp`:
 
 .. code-block:: bash
 
@@ -58,7 +78,8 @@ In order to be able to inline the definition of `foo` from `foo.cpp` first we ha
   compile_commands.json  foo.cpp.ast  foo.cpp  main.cpp
   $
 
-The next step is to create a CTU index file which holds the `USR` name and location of external definitions in the source files:
+The next step is to create a CTU index file which holds the `USR` name and location of external definitions in the
+source files:
 
 .. code-block:: bash
 
@@ -85,47 +106,34 @@ We have to feed Clang with CTU specific extra arguments:
 
   $ pwd
   /path/to/your/project
-  $ clang++ --analyze -Xclang -analyzer-config -Xclang experimental-enable-naive-ctu-analysis=true -Xclang -analyzer-config -Xclang ctu-dir=. -Xclang -analyzer-output=plist-multi-file main.cpp
+  $ clang++ --analyze \
+      -Xclang -analyzer-config -Xclang experimental-enable-naive-ctu-analysis=true \
+      -Xclang -analyzer-config -Xclang ctu-dir=. \
+      -Xclang -analyzer-config -Xclang ctu-on-demand-parsing=false \
+      -Xclang -analyzer-output=plist-multi-file \
+      main.cpp
   main.cpp:5:12: warning: Division by zero
     return 3 / foo();
            ~~^~~~~~~
   1 warning generated.
   $ # The plist file with the result is generated.
-  $ ls
+  $ ls -F
   compile_commands.json  externalDefMap.txt  foo.ast  foo.cpp  foo.cpp.ast  main.cpp  main.plist
   $
 
-This manual procedure is error-prone and not scalable, therefore to analyze real projects it is recommended to use `CodeChecker` or `scan-build-py`.
+This manual procedure is error-prone and not scalable, therefore to analyze real projects it is recommended to use
+`CodeChecker` or `scan-build-py`.
 
 Automated CTU Analysis with CodeChecker
----------------------------------------
+#######################################
 The `CodeChecker <https://github.com/Ericsson/codechecker>`_ project fully supports automated CTU analysis with Clang.
 Once we have set up the `PATH` environment variable and we activated the python `venv` then it is all it takes:
 
 .. code-block:: bash
 
   $ CodeChecker analyze --ctu compile_commands.json -o reports
-  [INFO 2019-07-16 17:21] - Pre-analysis started.
-  [INFO 2019-07-16 17:21] - Collecting data for ctu analysis.
-  [INFO 2019-07-16 17:21] - [1/2] foo.cpp
-  [INFO 2019-07-16 17:21] - [2/2] main.cpp
-  [INFO 2019-07-16 17:21] - Pre-analysis finished.
-  [INFO 2019-07-16 17:21] - Starting static analysis ...
-  [INFO 2019-07-16 17:21] - [1/2] clangsa analyzed foo.cpp successfully.
-  [INFO 2019-07-16 17:21] - [2/2] clangsa analyzed main.cpp successfully.
-  [INFO 2019-07-16 17:21] - ----==== Summary ====----
-  [INFO 2019-07-16 17:21] - Successfully analyzed
-  [INFO 2019-07-16 17:21] -   clangsa: 2
-  [INFO 2019-07-16 17:21] - Total analyzed compilation commands: 2
-  [INFO 2019-07-16 17:21] - ----=================----
-  [INFO 2019-07-16 17:21] - Analysis finished.
-  [INFO 2019-07-16 17:21] - To view results in the terminal use the "CodeChecker parse" command.
-  [INFO 2019-07-16 17:21] - To store results use the "CodeChecker store" command.
-  [INFO 2019-07-16 17:21] - See --help and the user guide for further options about parsing and storing the reports.
-  [INFO 2019-07-16 17:21] - ----=================----
-  [INFO 2019-07-16 17:21] - Analysis length: 0.659618854523 sec.
-  $ ls
-  compile_commands.json  foo.cpp  foo.cpp.ast  main.cpp  reports
+  $ ls -F
+  compile_commands.json  foo.cpp  foo.cpp.ast  main.cpp  reports/
   $ tree reports
   reports
   ├── compile_cmd.json
@@ -174,9 +182,9 @@ Or we can use `CodeChecker parse -e html` to export the results into HTML format
   $ firefox html_out/index.html
 
 Automated CTU Analysis with scan-build-py (don't do it)
--------------------------------------------------------
-We actively develop CTU with CodeChecker as a "runner" script, `scan-build-py` is not actively developed for CTU.
-`scan-build-py` has various errors and issues, expect it to work with the very basic projects only.
+#############################################################
+We actively develop CTU with CodeChecker as the driver for this feature, `scan-build-py` is not actively developed for CTU.
+`scan-build-py` has various errors and issues, expect it to work only with the very basic projects only.
 
 Example usage of scan-build-py:
 
@@ -191,3 +199,154 @@ Example usage of scan-build-py:
   Opening in existing browser session.
   ^C
   $
+
+On-demand analysis
+__________________
+The analysis produces the necessary AST structure of external TUs during analysis. This requires the
+compilation database in order to determine the exact compiler invocation used for each TU.
+The index, which maps function USR names to source files containing them must also be generated by the
+`clang-extdef-mapping`. The mapping of external definitions implicitly uses a
+:doc:`compilation database <../../JSONCompilationDatabase>` to determine the compilation flags used.
+Preferably the same compilation database should be used when generating the external definitions, and
+during analysis.  The analysis invocation must be provided with the directory which contains the mapping
+files, and the compilation database which is used to determine compiler flags.
+
+
+Manual CTU Analysis
+###################
+
+Let's consider these source files in our minimal example:
+
+.. code-block:: cpp
+
+  // main.cpp
+  int foo();
+
+  int main() {
+    return 3 / foo();
+  }
+
+.. code-block:: cpp
+
+  // foo.cpp
+  int foo() {
+    return 0;
+  }
+
+And a compilation database:
+
+.. code-block:: bash
+
+  [
+    {
+      "directory": "/path/to/your/project",
+      "command": "clang++ -c foo.cpp -o foo.o",
+      "file": "foo.cpp"
+    },
+    {
+      "directory": "/path/to/your/project",
+      "command": "clang++ -c main.cpp -o main.o",
+      "file": "main.cpp"
+    }
+  ]
+
+We'd like to analyze `main.cpp` and discover the division by zero bug.
+As we are using On-demand mode, we only need to create a CTU index file which holds the `USR` name and location of
+external definitions in the source files:
+
+.. code-block:: bash
+
+  $ clang-extdef-mapping -p . foo.cpp
+  c:@F@foo# /path/to/your/project/foo.cpp
+  $ clang-extdef-mapping -p . foo.cpp > externalDefMap.txt
+
+Now everything is available for the CTU analysis.
+We have to feed Clang with CTU specific extra arguments:
+
+.. code-block:: bash
+
+  $ pwd
+  /path/to/your/project
+  $ clang++ --analyze \
+      -Xclang -analyzer-config -Xclang experimental-enable-naive-ctu-analysis=true \
+      -Xclang -analyzer-config -Xclang ctu-dir=. \
+      -Xclang -analyzer-config -Xclang ctu-on-demand-parsing=true \
+      -Xclang -analyzer-config -Xclang ctu-on-demand-parsing-database=compile_commands.json \
+      -Xclang -analyzer-output=plist-multi-file \
+      main.cpp
+  main.cpp:5:12: warning: Division by zero
+    return 3 / foo();
+           ~~^~~~~~~
+  1 warning generated.
+  $ # The plist file with the result is generated.
+  $ ls -F
+  compile_commands.json  externalDefMap.txt  foo.cpp  main.cpp  main.plist
+  $
+
+This manual procedure is error-prone and not scalable, therefore to analyze real projects it is recommended to use
+`CodeChecker` or `scan-build-py`.
+
+Automated CTU Analysis with CodeChecker
+#######################################
+The `CodeChecker <https://github.com/Ericsson/codechecker>`_ project fully supports automated CTU analysis with Clang.
+Once we have set up the `PATH` environment variable and we activated the python `venv` then it is all it takes:
+
+.. code-block:: bash
+
+  $ CodeChecker analyze --ctu --ctu-on-demand compile_commands.json -o reports
+  $ ls -F
+  compile_commands.json  foo.cpp main.cpp  reports/
+  $ tree reports
+  reports
+  ├── compile_cmd.json
+  ├── compiler_info.json
+  ├── foo.cpp_53f6fbf7ab7ec9931301524b551959e2.plist
+  ├── main.cpp_23db3d8df52ff0812e6e5a03071c8337.plist
+  ├── metadata.json
+  └── unique_compile_commands.json
+
+  0 directories, 6 files
+  $
+
+The `plist` files contain the results of the analysis, which may be viewed with the regular analysis tools.
+E.g. one may use `CodeChecker parse` to view the results in command line:
+
+.. code-block:: bash
+
+  $ CodeChecker parse reports
+  [HIGH] /home/egbomrt/ctu_mini_raw_project/main.cpp:5:12: Division by zero [core.DivideZero]
+    return 3 / foo();
+             ^
+
+  Found 1 defect(s) in main.cpp
+
+
+  ----==== Summary ====----
+  -----------------------
+  Filename | Report count
+  -----------------------
+  main.cpp |            1
+  -----------------------
+  -----------------------
+  Severity | Report count
+  -----------------------
+  HIGH     |            1
+  -----------------------
+  ----=================----
+  Total number of reports: 1
+  ----=================----
+
+Or we can use `CodeChecker parse -e html` to export the results into HTML format:
+
+.. code-block:: bash
+
+  $ CodeChecker parse -e html -o html_out reports
+  $ firefox html_out/index.html
+
+Automated CTU Analysis with scan-build-py (don't do it)
+#######################################################
+We actively develop CTU with CodeChecker as the driver for feature, `scan-build-py` is not actively developed for CTU.
+`scan-build-py` has various errors and issues, expect it to work only with the very basic projects only.
+
+Currently On-demand analysis is not supported with `scan-build-py`.
+