Add Om1 lowering with no optimizations

README.rst

 Subzero - Fast code generator for PNaCl bitcode
 ===============================================
 
 Building
 --------
 
 You must have LLVM trunk source code available and built.  See
 http://llvm.org/docs/GettingStarted.html#getting-started-quickly-a-summary for
 guidance.
 
@@ skipping 16 matching lines @@
     ../llvm2ice ./ir_samples/<file>.ll
     ../llvm2ice ./tests_lit/llvm2ice_tests/<file>.ll
 
 At this time, ``llvm2ice`` accepts a few arguments:
 
     ``-help`` -- Show available arguments and possible values.
 
     ``-notranslate`` -- Suppress the ICE translation phase, which is useful if
     ICE is missing some support.
 
-    ``-target=<TARGET>`` -- Set the target architecture.  The default is x8632,
-    and x8632fast (generate x8632 code as fast as possible at the cost of code
-    quality) is also available.  Future targets include x8664, arm32, and arm64.
+    ``-target=<TARGET>`` -- Set the target architecture.  The default is x8632.
+    Future targets include x8664, arm32, and arm64.
+
+    ``-O<LEVEL>`` -- Set the optimization level.  Valid levels are ``2``, ``1``,
+    ``0``, ``-1``, and ``m1``.  Levels ``-1`` and ``m1`` are synonyms, and
+    represent the minimum optimization and worst code quality, but fastest code
+    generation.
 
     ``-verbose=<list>`` -- Set verbosity flags.  This argument allows a
     comma-separated list of values.  The default is ``none``, and the value
     ``inst,pred`` will roughly match the .ll bitcode file.  Of particular use
     are ``all`` and ``none``.
 
+    ``-o <FILE>`` -- Set the assembly output file name.  Default is stdout.
+
+    ``-log <FILE>`` -- Set the file name for diagnostic output (whose level is
+    controlled by ``-verbose``).  Default is stdout.
+
 See ir_samples/README.rst for more details.
 
 Running the test suite
 ----------------------
 
 Subzero uses the LLVM ``lit`` testing tool for its test suite, which lives in
 ``tests_lit``. To execute the test suite, first build Subzero, and then run::
 
     python <path_to_lit.py> -sv tests_lit
 
 ``path_to_lit`` is the direct path to the lit script in the LLVM source
 (``$LLVM_SRC_PATH/utils/lit/lit.py``).
 
 The above ``lit`` execution also needs the LLVM binary path in the
 ``LLVM_BIN_PATH`` env var.
 
 Assuming the LLVM paths are set up, ``make check`` is a convenient way to run
 the test suite.
 
 Assembling ``llvm2ice`` output
 ------------------------------
 
 Currently ``llvm2ice`` produces textual assembly code in a structure suitable
 for input to ``llvm-mc`` and currently using "intel" assembly syntax.  The first
 line of output is a convenient comment indicating how to pipe the output to
 ``llvm-mc`` to produce object code.