Add back code for supporting old mingw versions. Should bring the bots back.

[oota-llvm.git] / docs / TestingGuide.rst

diff --git a/docs/TestingGuide.rst b/docs/TestingGuide.rst
index 143c323154d96e583253b85bdd086b31b6462856..3cfbb219e6509c8d488b789fd0f2cbddc5827a1f 100644 (file)
--- a/docs/TestingGuide.rst
+++ b/docs/TestingGuide.rst
@@ -224,40 +224,19 @@ Below is an example of legal RUN lines in a ``.ll`` file:
     ; RUN: diff %t1 %t2
 
 As with a Unix shell, the RUN lines permit pipelines and I/O
     ; RUN: diff %t1 %t2
 
 As with a Unix shell, the RUN lines permit pipelines and I/O

-redirection to be used. However, the usage is slightly different than
-for Bash. In general, it's useful to read the code of other tests to figure out
-what you can use in yours. The major differences are:
-
--  You can't do ``2>&1``. That will cause :program:`lit` to write to a file
-   named ``&1``. Usually this is done to get stderr to go through a pipe. You
-   can do that with ``|&`` so replace this idiom:
-   ``... 2>&1 | grep`` with ``... |& grep``
--  You can only redirect to a file, not to another descriptor and not
-   from a here document.
+redirection to be used.

 
 There are some quoting rules that you must pay attention to when writing
 your RUN lines. In general nothing needs to be quoted. :program:`lit` won't
 strip off any quote characters so they will get passed to the invoked program.
 
 There are some quoting rules that you must pay attention to when writing
 your RUN lines. In general nothing needs to be quoted. :program:`lit` won't
 strip off any quote characters so they will get passed to the invoked program.

-For example:
-
-.. code-block:: bash
-
-    ... | grep 'find this string'
-
-This will fail because the ``'`` characters are passed to ``grep``. This would
-make ``grep`` to look for ``'find`` in the files ``this`` and
-``string'``. To avoid this use curly braces to tell :program:`lit` that it
-should treat everything enclosed as one value. So our example would become:
-
-.. code-block:: bash
-
-    ... | grep {find this string}
+To avoid this use curly braces to tell :program:`lit` that it should treat
+everything enclosed as one value.

 
 In general, you should strive to keep your RUN lines as simple as possible,
 
 In general, you should strive to keep your RUN lines as simple as possible,

-using them only to run tools that generate the output you can then examine. The
-recommended way to examine output to figure out if the test passes it using the
-:doc:`FileCheck tool <CommandGuide/FileCheck>`. The usage of ``grep`` in RUN
-lines is discouraged.
+using them only to run tools that generate textual output you can then examine.
+The recommended way to examine output to figure out if the test passes is using
+the :doc:`FileCheck tool <CommandGuide/FileCheck>`. *[The usage of grep in RUN
+lines is deprecated - please do not send or commit patches that use it.]*

 
 Fragile tests
 -------------
 
 Fragile tests
 -------------


@@ -296,23 +275,65 @@ This test will fail if placed into a ``download`` directory.
 To make your tests robust, always use ``opt ... < %s`` in the RUN line.
 :program:`opt` does not output a ``ModuleID`` when input comes from stdin.
 
 To make your tests robust, always use ``opt ... < %s`` in the RUN line.
 :program:`opt` does not output a ``ModuleID`` when input comes from stdin.
 

-The FileCheck utility
----------------------
-
-A powerful feature of the RUN lines is that it allows any arbitrary
-commands to be executed as part of the test harness. While standard
-(portable) unix tools like ``grep`` work fine on run lines, as you see
-above, there are a lot of caveats due to interaction with shell syntax,
-and we want to make sure the run lines are portable to a wide range of
-systems. Another major problem is that ``grep`` is not very good at checking
-to verify that the output of a tools contains a series of different
-output in a specific order. The :program:`FileCheck` tool was designed to
-help with these problems.
-
-:program:`FileCheck` is designed to read a file to check from standard input,
-and the set of things to verify from a file specified as a command line
-argument. :program:`FileCheck` is described in :doc:`the FileCheck man page
-<CommandGuide/FileCheck>`.
+Platform-Specific Tests
+-----------------------
+
+Whenever adding tests that require the knowledge of a specific platform,
+either related to code generated, specific output or back-end features,
+you must make sure to isolate the features, so that buildbots that
+run on different architectures (and don't even compile all back-ends),
+don't fail.
+
+The first problem is to check for target-specific output, for example sizes
+of structures, paths and architecture names, for example:
+
+* Tests containing Windows paths will fail on Linux and vice-versa.
+* Tests that check for ``x86_64`` somewhere in the text will fail anywhere else.
+* Tests where the debug information calculates the size of types and structures.
+
+Also, if the test rely on any behaviour that is coded in any back-end, it must
+go in its own directory. So, for instance, code generator tests for ARM go
+into ``test/CodeGen/ARM`` and so on. Those directories contain a special
+``lit`` configuration file that ensure all tests in that directory will
+only run if a specific back-end is compiled and available.
+
+For instance, on ``test/CodeGen/ARM``, the ``lit.local.cfg`` is:
+
+.. code-block:: python
+
+  config.suffixes = ['.ll', '.c', '.cpp', '.test']
+  targets = set(config.root.targets_to_build.split())
+  if not 'ARM' in targets:
+    config.unsupported = True
+
+Other platform-specific tests are those that depend on a specific feature
+of a specific sub-architecture, for example only to Intel chips that support ``AVX2``.
+
+For instance, ``test/CodeGen/X86/psubus.ll`` tests three sub-architecture
+variants:
+
+.. code-block:: llvm
+
+  ; RUN: llc -mcpu=core2 < %s | FileCheck %s -check-prefix=SSE2
+  ; RUN: llc -mcpu=corei7-avx < %s | FileCheck %s -check-prefix=AVX1
+  ; RUN: llc -mcpu=core-avx2 < %s | FileCheck %s -check-prefix=AVX2
+
+And the checks are different:
+
+.. code-block:: llvm
+
+  ; SSE2: @test1
+  ; SSE2: psubusw LCPI0_0(%rip), %xmm0
+  ; AVX1: @test1
+  ; AVX1: vpsubusw LCPI0_0(%rip), %xmm0, %xmm0
+  ; AVX2: @test1
+  ; AVX2: vpsubusw LCPI0_0(%rip), %xmm0, %xmm0
+
+So, if you're testing for a behaviour that you know is platform-specific or
+depends on special features of sub-architectures, you must add the specific
+triple, test with the specific FileCheck and put it into the specific
+directory that will filter out all other architectures.
+

 
 Variables and substitutions
 ---------------------------
 
 Variables and substitutions
 ---------------------------