gcc/doc/gccint/testsuites/support-for-testing-gimple-passes.rst

   1 ..
   2   Copyright 1988-2022 Free Software Foundation, Inc.
   3   This is part of the GCC manual.
   4   For copying conditions, see the copyright.rst file.
   5
   6 .. _gimple-tests:
   7
   8 Support for testing GIMPLE passes
   9 *********************************
  10
  11 As of gcc 7, C functions can be tagged with ``__GIMPLE`` to indicate
  12 that the function body will be GIMPLE, rather than C.  The compiler requires
  13 the option :option:`-fgimple` to enable this functionality.  For example:
  14
  15 .. code-block:: c++
  16
  17   /* { dg-do compile } */
  18   /* { dg-options "-O -fgimple" } */
  19
  20   void __GIMPLE (startwith ("dse2")) foo ()
  21   {
  22     int a;
  23
  24   bb_2:
  25     if (a > 4)
  26       goto bb_3;
  27     else
  28       goto bb_4;
  29
  30   bb_3:
  31     a_2 = 10;
  32     goto bb_5;
  33
  34   bb_4:
  35     a_3 = 20;
  36
  37   bb_5:
  38     a_1 = __PHI (bb_3: a_2, bb_4: a_3);
  39     a_4 = a_1 + 4;
  40
  41     return;
  42   }
  43
  44 The ``startwith`` argument indicates at which pass to begin.
  45
  46 Use the dump modifier ``-gimple`` (e.g. :option:`-fdump-tree-all-gimple`)
  47 to make tree dumps more closely follow the format accepted by the GIMPLE
  48 parser.
  49
  50 Example DejaGnu tests of GIMPLE can be seen in the source tree at
  51 :samp:`gcc/testsuite/gcc.dg/gimplefe-*.c`.
  52
  53 The ``__GIMPLE`` parser is integrated with the C tokenizer and
  54 preprocessor, so it should be possible to use macros to build out
  55 test coverage.