glsl: move to compiler/

Signed-off-by: Emil Velikov <[email protected]>
Acked-by: Matt Turner <[email protected]>
Acked-by: Jose Fonseca <[email protected]>

2 files changed, 646 insertions, 0 deletions

diff --git a/src/compiler/glsl/tests/lower_jumps/.gitignore b/src/compiler/glsl/tests/lower_jumps/.gitignore
new file mode 100644
index 00000000000..e98df627fd8
--- /dev/null
+++ b/src/compiler/glsl/tests/lower_jumps/.gitignore
@@ -0,0 +1,3 @@
+*.opt_test
+*.expected
+*.out
diff --git a/src/compiler/glsl/tests/lower_jumps/create_test_cases.py b/src/compiler/glsl/tests/lower_jumps/create_test_cases.py
new file mode 100644
index 00000000000..3be1079bc14
--- /dev/null
+++ b/src/compiler/glsl/tests/lower_jumps/create_test_cases.py
@@ -0,0 +1,643 @@
+# coding=utf-8
+#
+# Copyright © 2011 Intel Corporation
+#
+# Permission is hereby granted, free of charge, to any person obtaining a
+# copy of this software and associated documentation files (the "Software"),
+# to deal in the Software without restriction, including without limitation
+# the rights to use, copy, modify, merge, publish, distribute, sublicense,
+# and/or sell copies of the Software, and to permit persons to whom the
+# Software is furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice (including the next
+# paragraph) shall be included in all copies or substantial portions of the
+# Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+# DEALINGS IN THE SOFTWARE.
+
+import os
+import os.path
+import re
+import subprocess
+import sys
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..')) # For access to sexps.py, which is in parent dir
+from sexps import *
+
+def make_test_case(f_name, ret_type, body):
+    """Create a simple optimization test case consisting of a single
+    function with the given name, return type, and body.
+
+    Global declarations are automatically created for any undeclared
+    variables that are referenced by the function.  All undeclared
+    variables are assumed to be floats.
+    """
+    check_sexp(body)
+    declarations = {}
+    def make_declarations(sexp, already_declared = ()):
+        if isinstance(sexp, list):
+            if len(sexp) == 2 and sexp[0] == 'var_ref':
+                if sexp[1] not in already_declared:
+                    declarations[sexp[1]] = [
+                        'declare', ['in'], 'float', sexp[1]]
+            elif len(sexp) == 4 and sexp[0] == 'assign':
+                assert sexp[2][0] == 'var_ref'
+                if sexp[2][1] not in already_declared:
+                    declarations[sexp[2][1]] = [
+                        'declare', ['out'], 'float', sexp[2][1]]
+                make_declarations(sexp[3], already_declared)
+            else:
+                already_declared = set(already_declared)
+                for s in sexp:
+                    if isinstance(s, list) and len(s) >= 4 and \
+                            s[0] == 'declare':
+                        already_declared.add(s[3])
+                    else:
+                        make_declarations(s, already_declared)
+    make_declarations(body)
+    return declarations.values() + \
+        [['function', f_name, ['signature', ret_type, ['parameters'], body]]]
+
+
+# The following functions can be used to build expressions.
+
+def const_float(value):
+    """Create an expression representing the given floating point value."""
+    return ['constant', 'float', ['{0:.6f}'.format(value)]]
+
+def const_bool(value):
+    """Create an expression representing the given boolean value.
+
+    If value is not a boolean, it is converted to a boolean.  So, for
+    instance, const_bool(1) is equivalent to const_bool(True).
+    """
+    return ['constant', 'bool', ['{0}'.format(1 if value else 0)]]
+
+def gt_zero(var_name):
+    """Create Construct the expression var_name > 0"""
+    return ['expression', 'bool', '>', ['var_ref', var_name], const_float(0)]
+
+
+# The following functions can be used to build complex control flow
+# statements.  All of these functions return statement lists (even
+# those which only create a single statement), so that statements can
+# be sequenced together using the '+' operator.
+
+def return_(value = None):
+    """Create a return statement."""
+    if value is not None:
+        return [['return', value]]
+    else:
+        return [['return']]
+
+def break_():
+    """Create a break statement."""
+    return ['break']
+
+def continue_():
+    """Create a continue statement."""
+    return ['continue']
+
+def simple_if(var_name, then_statements, else_statements = None):
+    """Create a statement of the form
+
+    if (var_name > 0.0) {
+       <then_statements>
+    } else {
+       <else_statements>
+    }
+
+    else_statements may be omitted.
+    """
+    if else_statements is None:
+        else_statements = []
+    check_sexp(then_statements)
+    check_sexp(else_statements)
+    return [['if', gt_zero(var_name), then_statements, else_statements]]
+
+def loop(statements):
+    """Create a loop containing the given statements as its loop
+    body.
+    """
+    check_sexp(statements)
+    return [['loop', statements]]
+
+def declare_temp(var_type, var_name):
+    """Create a declaration of the form
+
+    (declare (temporary) <var_type> <var_name)
+    """
+    return [['declare', ['temporary'], var_type, var_name]]
+
+def assign_x(var_name, value):
+    """Create a statement that assigns <value> to the variable
+    <var_name>.  The assignment uses the mask (x).
+    """
+    check_sexp(value)
+    return [['assign', ['x'], ['var_ref', var_name], value]]
+
+def complex_if(var_prefix, statements):
+    """Create a statement of the form
+
+    if (<var_prefix>a > 0.0) {
+       if (<var_prefix>b > 0.0) {
+          <statements>
+       }
+    }
+
+    This is useful in testing jump lowering, because if <statements>
+    ends in a jump, lower_jumps.cpp won't try to combine this
+    construct with the code that follows it, as it might do for a
+    simple if.
+
+    All variables used in the if statement are prefixed with
+    var_prefix.  This can be used to ensure uniqueness.
+    """
+    check_sexp(statements)
+    return simple_if(var_prefix + 'a', simple_if(var_prefix + 'b', statements))
+
+def declare_execute_flag():
+    """Create the statements that lower_jumps.cpp uses to declare and
+    initialize the temporary boolean execute_flag.
+    """
+    return declare_temp('bool', 'execute_flag') + \
+        assign_x('execute_flag', const_bool(True))
+
+def declare_return_flag():
+    """Create the statements that lower_jumps.cpp uses to declare and
+    initialize the temporary boolean return_flag.
+    """
+    return declare_temp('bool', 'return_flag') + \
+        assign_x('return_flag', const_bool(False))
+
+def declare_return_value():
+    """Create the statements that lower_jumps.cpp uses to declare and
+    initialize the temporary variable return_value.  Assume that
+    return_value is a float.
+    """
+    return declare_temp('float', 'return_value')
+
+def declare_break_flag():
+    """Create the statements that lower_jumps.cpp uses to declare and
+    initialize the temporary boolean break_flag.
+    """
+    return declare_temp('bool', 'break_flag') + \
+        assign_x('break_flag', const_bool(False))
+
+def lowered_return_simple(value = None):
+    """Create the statements that lower_jumps.cpp lowers a return
+    statement to, in situations where it does not need to clear the
+    execute flag.
+    """
+    if value:
+        result = assign_x('return_value', value)
+    else:
+        result = []
+    return result + assign_x('return_flag', const_bool(True))
+
+def lowered_return(value = None):
+    """Create the statements that lower_jumps.cpp lowers a return
+    statement to, in situations where it needs to clear the execute
+    flag.
+    """
+    return lowered_return_simple(value) + \
+        assign_x('execute_flag', const_bool(False))
+
+def lowered_continue():
+    """Create the statement that lower_jumps.cpp lowers a continue
+    statement to.
+    """
+    return assign_x('execute_flag', const_bool(False))
+
+def lowered_break_simple():
+    """Create the statement that lower_jumps.cpp lowers a break
+    statement to, in situations where it does not need to clear the
+    execute flag.
+    """
+    return assign_x('break_flag', const_bool(True))
+
+def lowered_break():
+    """Create the statement that lower_jumps.cpp lowers a break
+    statement to, in situations where it needs to clear the execute
+    flag.
+    """
+    return lowered_break_simple() + assign_x('execute_flag', const_bool(False))
+
+def if_execute_flag(statements):
+    """Wrap statements in an if test so that they will only execute if
+    execute_flag is True.
+    """
+    check_sexp(statements)
+    return [['if', ['var_ref', 'execute_flag'], statements, []]]
+
+def if_not_return_flag(statements):
+    """Wrap statements in an if test so that they will only execute if
+    return_flag is False.
+    """
+    check_sexp(statements)
+    return [['if', ['var_ref', 'return_flag'], [], statements]]
+
+def final_return():
+    """Create the return statement that lower_jumps.cpp places at the
+    end of a function when lowering returns.
+    """
+    return [['return', ['var_ref', 'return_value']]]
+
+def final_break():
+    """Create the conditional break statement that lower_jumps.cpp
+    places at the end of a function when lowering breaks.
+    """
+    return [['if', ['var_ref', 'break_flag'], break_(), []]]
+
+def bash_quote(*args):
+    """Quote the arguments appropriately so that bash will understand
+    each argument as a single word.
+    """
+    def quote_word(word):
+        for c in word:
+            if not (c.isalpha() or c.isdigit() or c in '@%_-+=:,./'):
+                break
+        else:
+            if not word:
+                return "''"
+            return word
+        return "'{0}'".format(word.replace("'", "'\"'\"'"))
+    return ' '.join(quote_word(word) for word in args)
+
+def create_test_case(doc_string, input_sexp, expected_sexp, test_name,
+                     pull_out_jumps=False, lower_sub_return=False,
+                     lower_main_return=False, lower_continue=False,
+                     lower_break=False):
+    """Create a test case that verifies that do_lower_jumps transforms
+    the given code in the expected way.
+    """
+    doc_lines = [line.strip() for line in doc_string.splitlines()]
+    doc_string = ''.join('# {0}\n'.format(line) for line in doc_lines if line != '')
+    check_sexp(input_sexp)
+    check_sexp(expected_sexp)
+    input_str = sexp_to_string(sort_decls(input_sexp))
+    expected_output = sexp_to_string(sort_decls(expected_sexp))
+
+    optimization = (
+        'do_lower_jumps({0:d}, {1:d}, {2:d}, {3:d}, {4:d})'.format(
+            pull_out_jumps, lower_sub_return, lower_main_return,
+            lower_continue, lower_break))
+    args = ['../../glsl_test', 'optpass', '--quiet', '--input-ir', optimization]
+    test_file = '{0}.opt_test'.format(test_name)
+    with open(test_file, 'w') as f:
+        f.write('#!/usr/bin/env bash\n#\n# This file was generated by create_test_cases.py.\n#\n')
+        f.write(doc_string)
+        f.write('{0} <<EOF\n'.format(bash_quote(*args)))
+        f.write('{0}\nEOF\n'.format(input_str))
+    os.chmod(test_file, 0774)
+    expected_file = '{0}.opt_test.expected'.format(test_name)
+    with open(expected_file, 'w') as f:
+        f.write('{0}\n'.format(expected_output))
+
+def test_lower_returns_main():
+    doc_string = """Test that do_lower_jumps respects the lower_main_return
+    flag in deciding whether to lower returns in the main
+    function.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            complex_if('', return_())
+            ))
+    expected_sexp = make_test_case('main', 'void', (
+            declare_execute_flag() +
+            declare_return_flag() +
+            complex_if('', lowered_return())
+            ))
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_returns_main_true',
+                     lower_main_return=True)
+    create_test_case(doc_string, input_sexp, input_sexp, 'lower_returns_main_false',
+                     lower_main_return=False)
+
+def test_lower_returns_sub():
+    doc_string = """Test that do_lower_jumps respects the lower_sub_return flag
+    in deciding whether to lower returns in subroutines.
+    """
+    input_sexp = make_test_case('sub', 'void', (
+            complex_if('', return_())
+            ))
+    expected_sexp = make_test_case('sub', 'void', (
+            declare_execute_flag() +
+            declare_return_flag() +
+            complex_if('', lowered_return())
+            ))
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_returns_sub_true',
+                     lower_sub_return=True)
+    create_test_case(doc_string, input_sexp, input_sexp, 'lower_returns_sub_false',
+                     lower_sub_return=False)
+
+def test_lower_returns_1():
+    doc_string = """Test that a void return at the end of a function is
+    eliminated.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            assign_x('a', const_float(1)) +
+            return_()
+            ))
+    expected_sexp = make_test_case('main', 'void', (
+            assign_x('a', const_float(1))
+            ))
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_returns_1',
+                     lower_main_return=True)
+
+def test_lower_returns_2():
+    doc_string = """Test that lowering is not performed on a non-void return at
+    the end of subroutine.
+    """
+    input_sexp = make_test_case('sub', 'float', (
+            assign_x('a', const_float(1)) +
+            return_(const_float(1))
+            ))
+    create_test_case(doc_string, input_sexp, input_sexp, 'lower_returns_2',
+                     lower_sub_return=True)
+
+def test_lower_returns_3():
+    doc_string = """Test lowering of returns when there is one nested inside a
+    complex structure of ifs, and one at the end of a function.
+
+    In this case, the latter return needs to be lowered because it
+    will not be at the end of the function once the final return
+    is inserted.
+    """
+    input_sexp = make_test_case('sub', 'float', (
+            complex_if('', return_(const_float(1))) +
+            return_(const_float(2))
+            ))
+    expected_sexp = make_test_case('sub', 'float', (
+            declare_execute_flag() +
+            declare_return_value() +
+            declare_return_flag() +
+            complex_if('', lowered_return(const_float(1))) +
+            if_execute_flag(lowered_return(const_float(2))) +
+            final_return()
+            ))
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_returns_3',
+                     lower_sub_return=True)
+
+def test_lower_returns_4():
+    doc_string = """Test that returns are properly lowered when they occur in
+    both branches of an if-statement.
+    """
+    input_sexp = make_test_case('sub', 'float', (
+            simple_if('a', return_(const_float(1)),
+                      return_(const_float(2)))
+            ))
+    expected_sexp = make_test_case('sub', 'float', (
+            declare_execute_flag() +
+            declare_return_value() +
+            declare_return_flag() +
+            simple_if('a', lowered_return(const_float(1)),
+                      lowered_return(const_float(2))) +
+            final_return()
+            ))
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_returns_4',
+                     lower_sub_return=True)
+
+def test_lower_unified_returns():
+    doc_string = """If both branches of an if statement end in a return, and
+    pull_out_jumps is True, then those returns should be lifted
+    outside the if and then properly lowered.
+
+    Verify that this lowering occurs during the same pass as the
+    lowering of other returns by checking that extra temporary
+    variables aren't generated.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            complex_if('a', return_()) +
+            simple_if('b', simple_if('c', return_(), return_()))
+            ))
+    expected_sexp = make_test_case('main', 'void', (
+            declare_execute_flag() +
+            declare_return_flag() +
+            complex_if('a', lowered_return()) +
+            if_execute_flag(simple_if('b', (simple_if('c', [], []) +
+                                            lowered_return())))
+            ))
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_unified_returns',
+                     lower_main_return=True, pull_out_jumps=True)
+
+def test_lower_pulled_out_jump():
+    doc_string = """If one branch of an if ends in a jump, and control cannot
+    fall out the bottom of the other branch, and pull_out_jumps is
+    True, then the jump is lifted outside the if.
+
+    Verify that this lowering occurs during the same pass as the
+    lowering of other jumps by checking that extra temporary
+    variables aren't generated.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            complex_if('a', return_()) +
+            loop(simple_if('b', simple_if('c', break_(), continue_()),
+                           return_())) +
+            assign_x('d', const_float(1))
+            ))
+    # Note: optimization produces two other effects: the break
+    # gets lifted out of the if statements, and the code after the
+    # loop gets guarded so that it only executes if the return
+    # flag is clear.
+    expected_sexp = make_test_case('main', 'void', (
+            declare_execute_flag() +
+            declare_return_flag() +
+            complex_if('a', lowered_return()) +
+            if_execute_flag(
+                loop(simple_if('b', simple_if('c', [], continue_()),
+                               lowered_return_simple()) +
+                     break_()) +
+                if_not_return_flag(assign_x('d', const_float(1))))
+            ))
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_pulled_out_jump',
+                     lower_main_return=True, pull_out_jumps=True)
+
+def test_lower_breaks_1():
+    doc_string = """If a loop contains an unconditional break at the bottom of
+    it, it should not be lowered."""
+    input_sexp = make_test_case('main', 'void', (
+            loop(assign_x('a', const_float(1)) +
+                 break_())
+            ))
+    expected_sexp = input_sexp
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_breaks_1', lower_break=True)
+
+def test_lower_breaks_2():
+    doc_string = """If a loop contains a conditional break at the bottom of it,
+    it should not be lowered if it is in the then-clause.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            loop(assign_x('a', const_float(1)) +
+                 simple_if('b', break_()))
+            ))
+    expected_sexp = input_sexp
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_breaks_2', lower_break=True)
+
+def test_lower_breaks_3():
+    doc_string = """If a loop contains a conditional break at the bottom of it,
+    it should not be lowered if it is in the then-clause, even if
+    there are statements preceding the break.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            loop(assign_x('a', const_float(1)) +
+                 simple_if('b', (assign_x('c', const_float(1)) +
+                                 break_())))
+            ))
+    expected_sexp = input_sexp
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_breaks_3', lower_break=True)
+
+def test_lower_breaks_4():
+    doc_string = """If a loop contains a conditional break at the bottom of it,
+    it should not be lowered if it is in the else-clause.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            loop(assign_x('a', const_float(1)) +
+                 simple_if('b', [], break_()))
+            ))
+    expected_sexp = input_sexp
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_breaks_4', lower_break=True)
+
+def test_lower_breaks_5():
+    doc_string = """If a loop contains a conditional break at the bottom of it,
+    it should not be lowered if it is in the else-clause, even if
+    there are statements preceding the break.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            loop(assign_x('a', const_float(1)) +
+                 simple_if('b', [], (assign_x('c', const_float(1)) +
+                                     break_())))
+            ))
+    expected_sexp = input_sexp
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_breaks_5', lower_break=True)
+
+def test_lower_breaks_6():
+    doc_string = """If a loop contains conditional breaks and continues, and
+    ends in an unconditional break, then the unconditional break
+    needs to be lowered, because it will no longer be at the end
+    of the loop after the final break is added.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            loop(simple_if('a', (complex_if('b', continue_()) +
+                                 complex_if('c', break_()))) +
+                 break_())
+            ))
+    expected_sexp = make_test_case('main', 'void', (
+            declare_break_flag() +
+            loop(declare_execute_flag() +
+                 simple_if(
+                    'a',
+                    (complex_if('b', lowered_continue()) +
+                     if_execute_flag(
+                            complex_if('c', lowered_break())))) +
+                 if_execute_flag(lowered_break_simple()) +
+                 final_break())
+            ))
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_breaks_6',
+                     lower_break=True, lower_continue=True)
+
+def test_lower_guarded_conditional_break():
+    doc_string = """Normally a conditional break at the end of a loop isn't
+    lowered, however if the conditional break gets placed inside
+    an if(execute_flag) because of earlier lowering of continues,
+    then the break needs to be lowered.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            loop(complex_if('a', continue_()) +
+                 simple_if('b', break_()))
+            ))
+    expected_sexp = make_test_case('main', 'void', (
+            declare_break_flag() +
+            loop(declare_execute_flag() +
+                 complex_if('a', lowered_continue()) +
+                 if_execute_flag(simple_if('b', lowered_break())) +
+                 final_break())
+            ))
+    create_test_case(doc_string, input_sexp, expected_sexp, 'lower_guarded_conditional_break',
+                     lower_break=True, lower_continue=True)
+
+def test_remove_continue_at_end_of_loop():
+    doc_string = """Test that a redundant continue-statement at the end of a
+    loop is removed.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            loop(assign_x('a', const_float(1)) +
+                 continue_())
+            ))
+    expected_sexp = make_test_case('main', 'void', (
+            loop(assign_x('a', const_float(1)))
+            ))
+    create_test_case(doc_string, input_sexp, expected_sexp, 'remove_continue_at_end_of_loop')
+
+def test_lower_return_void_at_end_of_loop():
+    doc_string = """Test that a return of void at the end of a loop is properly
+    lowered.
+    """
+    input_sexp = make_test_case('main', 'void', (
+            loop(assign_x('a', const_float(1)) +
+                 return_()) +
+            assign_x('b', const_float(2))
+            ))
+    expected_sexp = make_test_case('main', 'void', (
+            declare_return_flag() +
+            loop(assign_x('a', const_float(1)) +
+                 lowered_return_simple() +
+                 break_()) +
+            if_not_return_flag(assign_x('b', const_float(2)))
+            ))
+    create_test_case(doc_string, input_sexp, input_sexp, 'return_void_at_end_of_loop_lower_nothing')
+    create_test_case(doc_string, input_sexp, expected_sexp, 'return_void_at_end_of_loop_lower_return',
+                     lower_main_return=True)
+    create_test_case(doc_string, input_sexp, expected_sexp, 'return_void_at_end_of_loop_lower_return_and_break',
+                     lower_main_return=True, lower_break=True)
+
+def test_lower_return_non_void_at_end_of_loop():
+    doc_string = """Test that a non-void return at the end of a loop is
+    properly lowered.
+    """
+    input_sexp = make_test_case('sub', 'float', (
+            loop(assign_x('a', const_float(1)) +
+                 return_(const_float(2))) +
+            assign_x('b', const_float(3)) +
+            return_(const_float(4))
+            ))
+    expected_sexp = make_test_case('sub', 'float', (
+            declare_execute_flag() +
+            declare_return_value() +
+            declare_return_flag() +
+            loop(assign_x('a', const_float(1)) +
+                 lowered_return_simple(const_float(2)) +
+                 break_()) +
+            if_not_return_flag(assign_x('b', const_float(3)) +
+                               lowered_return(const_float(4))) +
+            final_return()
+            ))
+    create_test_case(doc_string, input_sexp, input_sexp, 'return_non_void_at_end_of_loop_lower_nothing')
+    create_test_case(doc_string, input_sexp, expected_sexp, 'return_non_void_at_end_of_loop_lower_return',
+                     lower_sub_return=True)
+    create_test_case(doc_string, input_sexp, expected_sexp, 'return_non_void_at_end_of_loop_lower_return_and_break',
+                     lower_sub_return=True, lower_break=True)
+
+if __name__ == '__main__':
+    test_lower_returns_main()
+    test_lower_returns_sub()
+    test_lower_returns_1()
+    test_lower_returns_2()
+    test_lower_returns_3()
+    test_lower_returns_4()
+    test_lower_unified_returns()
+    test_lower_pulled_out_jump()
+    test_lower_breaks_1()
+    test_lower_breaks_2()
+    test_lower_breaks_3()
+    test_lower_breaks_4()
+    test_lower_breaks_5()
+    test_lower_breaks_6()
+    test_lower_guarded_conditional_break()
+    test_remove_continue_at_end_of_loop()
+    test_lower_return_void_at_end_of_loop()
+    test_lower_return_non_void_at_end_of_loop()