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direct_machine.cpp
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1 /* GRAPHITE2 LICENSING
2 
3  Copyright 2010, SIL International
4  All rights reserved.
5 
6  This library is free software; you can redistribute it and/or modify
7  it under the terms of the GNU Lesser General Public License as published
8  by the Free Software Foundation; either version 2.1 of License, or
9  (at your option) any later version.
10 
11  This program is distributed in the hope that it will be useful,
12  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  Lesser General Public License for more details.
15 
16  You should also have received a copy of the GNU Lesser General Public
17  License along with this library in the file named "LICENSE".
18  If not, write to the Free Software Foundation, 51 Franklin Street,
19  Suite 500, Boston, MA 02110-1335, USA or visit their web page on the
20  internet at http://www.fsf.org/licenses/lgpl.html.
21 
22 Alternatively, the contents of this file may be used under the terms of the
23 Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public
24 License, as published by the Free Software Foundation, either version 2
25 of the License or (at your option) any later version.
26 */
27 // This direct threaded interpreter implmentation for machine.h
28 // Author: Tim Eves
29 
30 // Build either this interpreter or the call_machine implementation.
31 // The direct threaded interpreter is relies upon a gcc feature called
32 // labels-as-values so is only portable to compilers that support the
33 // extension (gcc only as far as I know) however it should build on any
34 // architecture gcc supports.
35 // This is twice as fast as the call threaded model and is likely faster on
36 // inorder processors with short pipelines and little branch prediction such
37 // as the ARM and possibly Atom chips.
38 
39 
40 #include <cassert>
41 #include <cstring>
42 #include "inc/Machine.h"
43 #include "inc/Segment.h"
44 #include "inc/Slot.h"
45 #include "inc/Rule.h"
46 
47 #define STARTOP(name) name: {
48 #define ENDOP }; goto *((sp - sb)/Machine::STACK_MAX ? &&end : *++ip);
49 #define EXIT(status) { push(status); goto end; }
50 
51 #define do_(name) &&name
52 
53 
54 using namespace graphite2;
55 using namespace vm;
56 
57 namespace {
58 
59 // The GCC manual has this to say about labels as values:
60 // The &&foo expressions for the same label might have different values
61 // if the containing function is inlined or cloned. If a program relies
62 // on them being always the same, __attribute__((__noinline__,__noclone__))
63 // should be used to prevent inlining and cloning.
64 //
65 // is_return in Code.cpp relies on being able to do comparisons, so it needs
66 // them to be always the same.
67 //
68 // The GCC manual further adds:
69 // If &&foo is used in a static variable initializer, inlining and
70 // cloning is forbidden.
71 //
72 // In this file, &&foo *is* used in a static variable initializer, and it's not
73 // entirely clear whether this should prevent inlining of the function or not.
74 // In practice, though, clang 7 can end up inlining the function with ThinLTO,
75 // which breaks at least is_return. https://bugs.llvm.org/show_bug.cgi?id=39241
76 // So all in all, we need at least the __noinline__ attribute. __noclone__
77 // is not supported by clang.
78 __attribute__((__noinline__))
79 const void * direct_run(const bool get_table_mode,
80  const instr * program,
81  const byte * data,
82  Machine::stack_t * stack,
83  slotref * & __map,
84  uint8 _dir,
85  Machine::status_t & status,
86  SlotMap * __smap=0)
87 {
88  // We need to define and return to opcode table from within this function
89  // other inorder to take the addresses of the instruction bodies.
90  #include "inc/opcode_table.h"
91  if (get_table_mode)
92  return opcode_table;
93 
94  // Declare virtual machine registers
95  const instr * ip = program;
96  const byte * dp = data;
97  Machine::stack_t * sp = stack + Machine::STACK_GUARD,
98  * const sb = sp;
99  SlotMap & smap = *__smap;
100  Segment & seg = smap.segment;
101  slotref is = *__map,
102  * map = __map,
103  * const mapb = smap.begin()+smap.context();
104  uint8 dir = _dir;
105  int8 flags = 0;
106 
107  // start the program
108  goto **ip;
109 
110  // Pull in the opcode definitions
111  #include "inc/opcodes.h"
112 
113  end:
114  __map = map;
115  *__map = is;
116  return sp;
117 }
118 
119 }
120 
121 const opcode_t * Machine::getOpcodeTable() throw()
122 {
123  slotref * dummy;
125  return static_cast<const opcode_t *>(direct_run(true, 0, 0, 0, dummy, 0, dumstat));
126 }
127 
128 
130  const byte * data,
131  slotref * & is)
132 {
133  assert(program != 0);
134 
135  const stack_t *sp = static_cast<const stack_t *>(
136  direct_run(false, program, data, _stack, is, _map.dir(), _status, &_map));
137  const stack_t ret = sp == _stack+STACK_GUARD+1 ? *sp-- : 0;
139  return ret;
140 }
uint8 dir() const
Definition: Rule.h:123
static size_t const STACK_GUARD
Definition: Machine.h:142
stack_t _stack[STACK_MAX+2 *STACK_GUARD]
Definition: Machine.h:170
void check_final_stack(const stack_t *const sp)
Definition: Machine.h:195
stack_t run(const instr *program, const byte *data, slotref *&map)
#define dummy
Definition: devnag.c:313
int dummy
Definition: dummy.c:29
const char * program
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struct rect data
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assert(pcxLoadImage24((char *)((void *) 0), fp, pinfo, hdr))
static int ret
Definition: convert.c:72
#define __attribute__(A)
Definition: synctex.c:338
unsigned char uint8
Definition: tiff.h:60
char int8
Definition: tiff.h:58
void * instr
Definition: Machine.h:79
Definition: bits.h:30
#define dir
#define map
#define smap
#define status
#define flags
#define mapb
static const opcode_t opcode_table[]
Definition: opcode_table.h:44
RETTYPE mp_ptr mp_size_t mp_srcptr dp
Definition: sec_div.c:70
Definition: gd.c:2418
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#define is
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#define sp
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#define ip
Definition: stack.c:14
#define end(cp)
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