• Home
  • History
  • Annotate
  • only in /frameworks/compile/libbcc/
NameDateSize

..23-Aug-20164 KiB

Android.mk23-Aug-20163.8 KiB

bcinfo/23-Aug-20164 KiB

CleanSpec.mk23-Aug-20164.2 KiB

gdb_plugin/23-Aug-20164 KiB

include/23-Aug-20164 KiB

lib/23-Aug-20164 KiB

libbcc-device-build.mk23-Aug-20161.8 KiB

libbcc-host-build.mk23-Aug-20161.1 KiB

libbcc-targets.mk23-Aug-20161.6 KiB

libbcc.mk23-Aug-20161.5 KiB

libbcc.sha1.mk23-Aug-20161.8 KiB

llvm-loadable-libbcc.mk23-Aug-2016824

NOTICE23-Aug-201615.9 KiB

README.html23-Aug-201614.3 KiB

README.rst23-Aug-20166.9 KiB

tests/23-Aug-20164 KiB

tools/23-Aug-20164 KiB

README.html

1<?xml version="1.0" encoding="utf-8" ?>
2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
4<head>
5<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
6<meta name="generator" content="Docutils 0.6: http://docutils.sourceforge.net/" />
7<title>libbcc: A Versatile Bitcode Execution Engine for Mobile Devices</title>
8<style type="text/css">
9
10/*
11:Author: David Goodger (goodger@python.org)
12:Id: $Id: html4css1.css 5951 2009-05-18 18:03:10Z milde $
13:Copyright: This stylesheet has been placed in the public domain.
14
15Default cascading style sheet for the HTML output of Docutils.
16
17See http://docutils.sf.net/docs/howto/html-stylesheets.html for how to
18customize this style sheet.
19*/
20
21/* used to remove borders from tables and images */
22.borderless, table.borderless td, table.borderless th {
23  border: 0 }
24
25table.borderless td, table.borderless th {
26  /* Override padding for "table.docutils td" with "! important".
27     The right padding separates the table cells. */
28  padding: 0 0.5em 0 0 ! important }
29
30.first {
31  /* Override more specific margin styles with "! important". */
32  margin-top: 0 ! important }
33
34.last, .with-subtitle {
35  margin-bottom: 0 ! important }
36
37.hidden {
38  display: none }
39
40a.toc-backref {
41  text-decoration: none ;
42  color: black }
43
44blockquote.epigraph {
45  margin: 2em 5em ; }
46
47dl.docutils dd {
48  margin-bottom: 0.5em }
49
50/* Uncomment (and remove this text!) to get bold-faced definition list terms
51dl.docutils dt {
52  font-weight: bold }
53*/
54
55div.abstract {
56  margin: 2em 5em }
57
58div.abstract p.topic-title {
59  font-weight: bold ;
60  text-align: center }
61
62div.admonition, div.attention, div.caution, div.danger, div.error,
63div.hint, div.important, div.note, div.tip, div.warning {
64  margin: 2em ;
65  border: medium outset ;
66  padding: 1em }
67
68div.admonition p.admonition-title, div.hint p.admonition-title,
69div.important p.admonition-title, div.note p.admonition-title,
70div.tip p.admonition-title {
71  font-weight: bold ;
72  font-family: sans-serif }
73
74div.attention p.admonition-title, div.caution p.admonition-title,
75div.danger p.admonition-title, div.error p.admonition-title,
76div.warning p.admonition-title {
77  color: red ;
78  font-weight: bold ;
79  font-family: sans-serif }
80
81/* Uncomment (and remove this text!) to get reduced vertical space in
82   compound paragraphs.
83div.compound .compound-first, div.compound .compound-middle {
84  margin-bottom: 0.5em }
85
86div.compound .compound-last, div.compound .compound-middle {
87  margin-top: 0.5em }
88*/
89
90div.dedication {
91  margin: 2em 5em ;
92  text-align: center ;
93  font-style: italic }
94
95div.dedication p.topic-title {
96  font-weight: bold ;
97  font-style: normal }
98
99div.figure {
100  margin-left: 2em ;
101  margin-right: 2em }
102
103div.footer, div.header {
104  clear: both;
105  font-size: smaller }
106
107div.line-block {
108  display: block ;
109  margin-top: 1em ;
110  margin-bottom: 1em }
111
112div.line-block div.line-block {
113  margin-top: 0 ;
114  margin-bottom: 0 ;
115  margin-left: 1.5em }
116
117div.sidebar {
118  margin: 0 0 0.5em 1em ;
119  border: medium outset ;
120  padding: 1em ;
121  background-color: #ffffee ;
122  width: 40% ;
123  float: right ;
124  clear: right }
125
126div.sidebar p.rubric {
127  font-family: sans-serif ;
128  font-size: medium }
129
130div.system-messages {
131  margin: 5em }
132
133div.system-messages h1 {
134  color: red }
135
136div.system-message {
137  border: medium outset ;
138  padding: 1em }
139
140div.system-message p.system-message-title {
141  color: red ;
142  font-weight: bold }
143
144div.topic {
145  margin: 2em }
146
147h1.section-subtitle, h2.section-subtitle, h3.section-subtitle,
148h4.section-subtitle, h5.section-subtitle, h6.section-subtitle {
149  margin-top: 0.4em }
150
151h1.title {
152  text-align: center }
153
154h2.subtitle {
155  text-align: center }
156
157hr.docutils {
158  width: 75% }
159
160img.align-left, .figure.align-left{
161  clear: left ;
162  float: left ;
163  margin-right: 1em }
164
165img.align-right, .figure.align-right {
166  clear: right ;
167  float: right ;
168  margin-left: 1em }
169
170.align-left {
171  text-align: left }
172
173.align-center {
174  clear: both ;
175  text-align: center }
176
177.align-right {
178  text-align: right }
179
180/* reset inner alignment in figures */
181div.align-right {
182  text-align: left }
183
184/* div.align-center * { */
185/*   text-align: left } */
186
187ol.simple, ul.simple {
188  margin-bottom: 1em }
189
190ol.arabic {
191  list-style: decimal }
192
193ol.loweralpha {
194  list-style: lower-alpha }
195
196ol.upperalpha {
197  list-style: upper-alpha }
198
199ol.lowerroman {
200  list-style: lower-roman }
201
202ol.upperroman {
203  list-style: upper-roman }
204
205p.attribution {
206  text-align: right ;
207  margin-left: 50% }
208
209p.caption {
210  font-style: italic }
211
212p.credits {
213  font-style: italic ;
214  font-size: smaller }
215
216p.label {
217  white-space: nowrap }
218
219p.rubric {
220  font-weight: bold ;
221  font-size: larger ;
222  color: maroon ;
223  text-align: center }
224
225p.sidebar-title {
226  font-family: sans-serif ;
227  font-weight: bold ;
228  font-size: larger }
229
230p.sidebar-subtitle {
231  font-family: sans-serif ;
232  font-weight: bold }
233
234p.topic-title {
235  font-weight: bold }
236
237pre.address {
238  margin-bottom: 0 ;
239  margin-top: 0 ;
240  font: inherit }
241
242pre.literal-block, pre.doctest-block {
243  margin-left: 2em ;
244  margin-right: 2em }
245
246span.classifier {
247  font-family: sans-serif ;
248  font-style: oblique }
249
250span.classifier-delimiter {
251  font-family: sans-serif ;
252  font-weight: bold }
253
254span.interpreted {
255  font-family: sans-serif }
256
257span.option {
258  white-space: nowrap }
259
260span.pre {
261  white-space: pre }
262
263span.problematic {
264  color: red }
265
266span.section-subtitle {
267  /* font-size relative to parent (h1..h6 element) */
268  font-size: 80% }
269
270table.citation {
271  border-left: solid 1px gray;
272  margin-left: 1px }
273
274table.docinfo {
275  margin: 2em 4em }
276
277table.docutils {
278  margin-top: 0.5em ;
279  margin-bottom: 0.5em }
280
281table.footnote {
282  border-left: solid 1px black;
283  margin-left: 1px }
284
285table.docutils td, table.docutils th,
286table.docinfo td, table.docinfo th {
287  padding-left: 0.5em ;
288  padding-right: 0.5em ;
289  vertical-align: top }
290
291table.docutils th.field-name, table.docinfo th.docinfo-name {
292  font-weight: bold ;
293  text-align: left ;
294  white-space: nowrap ;
295  padding-left: 0 }
296
297h1 tt.docutils, h2 tt.docutils, h3 tt.docutils,
298h4 tt.docutils, h5 tt.docutils, h6 tt.docutils {
299  font-size: 100% }
300
301ul.auto-toc {
302  list-style-type: none }
303
304</style>
305</head>
306<body>
307<div class="document" id="libbcc-a-versatile-bitcode-execution-engine-for-mobile-devices">
308<h1 class="title">libbcc: A Versatile Bitcode Execution Engine for Mobile Devices</h1>
309
310<div class="section" id="introduction">
311<h1>Introduction</h1>
312<p>libbcc is an LLVM bitcode execution engine that compiles the bitcode
313to an in-memory executable. libbcc is versatile because:</p>
314<ul class="simple">
315<li>it implements both AOT (Ahead-of-Time) and JIT (Just-in-Time)
316compilation.</li>
317<li>Android devices demand fast start-up time, small size, and high
318performance <em>at the same time</em>. libbcc attempts to address these
319design constraints.</li>
320<li>it supports on-device linking. Each device vendor can supply his or
321her own runtime bitcode library (lib*.bc) that differentiates his or
322her system. Specialization becomes ecosystem-friendly.</li>
323</ul>
324<p>libbcc provides:</p>
325<ul class="simple">
326<li>a <em>just-in-time bitcode compiler</em>, which translates the LLVM bitcode
327into machine code</li>
328<li>a <em>caching mechanism</em>, which can:<ul>
329<li>after each compilation, serialize the in-memory executable into a
330cache file.  Note that the compilation is triggered by a cache
331miss.</li>
332<li>load from the cache file upon cache-hit.</li>
333</ul>
334</li>
335</ul>
336<p>Highlights of libbcc are:</p>
337<ul>
338<li><p class="first">libbcc supports bitcode from various language frontends, such as
339Renderscript, GLSL (pixelflinger2).</p>
340</li>
341<li><p class="first">libbcc strives to balance between library size, launch time and
342steady-state performance:</p>
343<ul>
344<li><p class="first">The size of libbcc is aggressively reduced for mobile devices. We
345customize and improve upon the default Execution Engine from
346upstream. Otherwise, libbcc's execution engine can easily become
347at least 2 times bigger.</p>
348</li>
349<li><p class="first">To reduce launch time, we support caching of
350binaries. Just-in-Time compilation are oftentimes Just-too-Late,
351if the given apps are performance-sensitive. Thus, we implemented
352AOT to get the best of both worlds: Fast launch time and high
353steady-state performance.</p>
354<p>AOT is also important for projects such as NDK on LLVM with
355portability enhancement. Launch time reduction after we
356implemented AOT is signficant:</p>
357<pre class="literal-block">
358Apps          libbcc without AOT       libbcc with AOT
359              launch time in libbcc    launch time in libbcc
360App_1            1218ms                   9ms
361App_2            842ms                    4ms
362Wallpaper:
363  MagicSmoke     182ms                    3ms
364  Halo           127ms                    3ms
365Balls            149ms                    3ms
366SceneGraph       146ms                    90ms
367Model            104ms                    4ms
368Fountain         57ms                     3ms
369</pre>
370<p>AOT also masks the launching time overhead of on-device linking
371and helps it become reality.</p>
372</li>
373<li><p class="first">For steady-state performance, we enable VFP3 and aggressive
374optimizations.</p>
375</li>
376</ul>
377</li>
378<li><p class="first">Currently we disable Lazy JITting.</p>
379</li>
380</ul>
381</div>
382<div class="section" id="api">
383<h1>API</h1>
384<p><strong>Basic:</strong></p>
385<ul class="simple">
386<li><strong>bccCreateScript</strong> - Create new bcc script</li>
387<li><strong>bccRegisterSymbolCallback</strong> - Register the callback function for external
388symbol lookup</li>
389<li><strong>bccReadBC</strong> - Set the source bitcode for compilation</li>
390<li><strong>bccReadModule</strong> - Set the llvm::Module for compilation</li>
391<li><strong>bccLinkBC</strong> - Set the library bitcode for linking</li>
392<li><strong>bccPrepareExecutable</strong> - <em>deprecated</em> - Use bccPrepareExecutableEx instead</li>
393<li><strong>bccPrepareExecutableEx</strong> - Create the in-memory executable by either
394just-in-time compilation or cache loading</li>
395<li><strong>bccGetFuncAddr</strong> - Get the entry address of the function</li>
396<li><strong>bccDisposeScript</strong> - Destroy bcc script and release the resources</li>
397<li><strong>bccGetError</strong> - <em>deprecated</em> - Don't use this</li>
398</ul>
399<p><strong>Reflection:</strong></p>
400<ul class="simple">
401<li><strong>bccGetExportVarCount</strong> - Get the count of exported variables</li>
402<li><strong>bccGetExportVarList</strong> - Get the addresses of exported variables</li>
403<li><strong>bccGetExportFuncCount</strong> - Get the count of exported functions</li>
404<li><strong>bccGetExportFuncList</strong> - Get the addresses of exported functions</li>
405<li><strong>bccGetPragmaCount</strong> - Get the count of pragmas</li>
406<li><strong>bccGetPragmaList</strong> - Get the pragmas</li>
407</ul>
408<p><strong>Debug:</strong></p>
409<ul class="simple">
410<li><strong>bccGetFuncCount</strong> - Get the count of functions (including non-exported)</li>
411<li><strong>bccGetFuncInfoList</strong> - Get the function information (name, base, size)</li>
412</ul>
413</div>
414<div class="section" id="cache-file-format">
415<h1>Cache File Format</h1>
416<p>A cache file (denoted as *.oBCC) for libbcc consists of several sections:
417header, string pool, dependencies table, relocation table, exported
418variable list, exported function list, pragma list, function information
419table, and bcc context.  Every section should be aligned to a word size.
420Here is the brief description of each sections:</p>
421<ul class="simple">
422<li><strong>Header</strong> (MCO_Header) - The header of a cache file. It contains the
423magic word, version, machine integer type information (the endianness,
424the size of off_t, size_t, and ptr_t), and the size
425and offset of other sections.  The header section is guaranteed
426to be at the beginning of the cache file.</li>
427<li><strong>String Pool</strong> (MCO_StringPool) - A collection of serialized variable
428length strings.  The strp_index in the other part of the cache file
429represents the index of such string in this string pool.</li>
430<li><strong>Dependencies Table</strong> (MCO_DependencyTable) - The dependencies table.
431This table stores the resource name (or file path), the resource
432type (rather in APK or on the file system), and the SHA1 checksum.</li>
433<li><strong>Relocation Table</strong> (MCO_RelocationTable) - <em>not enabled</em></li>
434<li><strong>Exported Variable List</strong> (MCO_ExportVarList) -
435The list of the addresses of exported variables.</li>
436<li><strong>Exported Function List</strong> (MCO_ExportFuncList) -
437The list of the addresses of exported functions.</li>
438<li><strong>Pragma List</strong> (MCO_PragmaList) - The list of pragma key-value pair.</li>
439<li><strong>Function Information Table</strong> (MCO_FuncTable) - This is a table of
440function information, such as function name, function entry address,
441and function binary size.  Besides, the table should be ordered by
442function name.</li>
443<li><strong>Context</strong> - The context of the in-memory executable, including
444the code and the data.  The offset of context should aligned to
445a page size, so that we can mmap the context directly into memory.</li>
446</ul>
447<p>For furthur information, you may read <a class="reference external" href="include/bcc/bcc_cache.h">bcc_cache.h</a>,
448<a class="reference external" href="lib/bcc/CacheReader.cpp">CacheReader.cpp</a>, and
449<a class="reference external" href="lib/bcc/CacheWriter.cpp">CacheWriter.cpp</a> for details.</p>
450</div>
451<div class="section" id="jit-ed-code-calling-conventions">
452<h1>JIT'ed Code Calling Conventions</h1>
453<ol class="arabic">
454<li><p class="first">Calls from Execution Environment or from/to within script:</p>
455<p>On ARM, the first 4 arguments will go into r0, r1, r2, and r3, in that order.
456The remaining (if any) will go through stack.</p>
457<p>For ext_vec_types such as float2, a set of registers will be used. In the case
458of float2, a register pair will be used. Specifically, if float2 is the first
459argument in the function prototype, float2.x will go into r0, and float2.y,
460r1.</p>
461<p>Note: stack will be aligned to the coarsest-grained argument. In the case of
462float2 above as an argument, parameter stack will be aligned to an 8-byte
463boundary (if the sizes of other arguments are no greater than 8.)</p>
464</li>
465<li><p class="first">Calls from/to a separate compilation unit: (E.g., calls to Execution
466Environment if those runtime library callees are not compiled using LLVM.)</p>
467<p>On ARM, we use hardfp.  Note that double will be placed in a register pair.</p>
468</li>
469</ol>
470</div>
471</div>
472</body>
473</html>
474

README.rst

1===============================================================
2libbcc: A Versatile Bitcode Execution Engine for Mobile Devices
3===============================================================
4
5
6Introduction
7------------
8
9libbcc is an LLVM bitcode execution engine that compiles the bitcode
10to an in-memory executable. libbcc is versatile because:
11
12* it implements both AOT (Ahead-of-Time) and JIT (Just-in-Time)
13  compilation.
14
15* Android devices demand fast start-up time, small size, and high
16  performance *at the same time*. libbcc attempts to address these
17  design constraints.
18
19* it supports on-device linking. Each device vendor can supply his or
20  her own runtime bitcode library (lib*.bc) that differentiates his or
21  her system. Specialization becomes ecosystem-friendly.
22
23libbcc provides:
24
25* a *just-in-time bitcode compiler*, which translates the LLVM bitcode
26  into machine code
27
28* a *caching mechanism*, which can:
29
30  * after each compilation, serialize the in-memory executable into a
31    cache file.  Note that the compilation is triggered by a cache
32    miss.
33  * load from the cache file upon cache-hit.
34
35Highlights of libbcc are:
36
37* libbcc supports bitcode from various language frontends, such as
38  Renderscript, GLSL (pixelflinger2).
39
40* libbcc strives to balance between library size, launch time and
41  steady-state performance:
42
43  * The size of libbcc is aggressively reduced for mobile devices. We
44    customize and improve upon the default Execution Engine from
45    upstream. Otherwise, libbcc's execution engine can easily become
46    at least 2 times bigger.
47
48  * To reduce launch time, we support caching of
49    binaries. Just-in-Time compilation are oftentimes Just-too-Late,
50    if the given apps are performance-sensitive. Thus, we implemented
51    AOT to get the best of both worlds: Fast launch time and high
52    steady-state performance.
53
54    AOT is also important for projects such as NDK on LLVM with
55    portability enhancement. Launch time reduction after we
56    implemented AOT is signficant::
57
58
59     Apps          libbcc without AOT       libbcc with AOT
60                   launch time in libbcc    launch time in libbcc
61     App_1            1218ms                   9ms
62     App_2            842ms                    4ms
63     Wallpaper:
64       MagicSmoke     182ms                    3ms
65       Halo           127ms                    3ms
66     Balls            149ms                    3ms
67     SceneGraph       146ms                    90ms
68     Model            104ms                    4ms
69     Fountain         57ms                     3ms
70
71    AOT also masks the launching time overhead of on-device linking
72    and helps it become reality.
73
74  * For steady-state performance, we enable VFP3 and aggressive
75    optimizations.
76
77* Currently we disable Lazy JITting.
78
79
80
81API
82---
83
84**Basic:**
85
86* **bccCreateScript** - Create new bcc script
87
88* **bccRegisterSymbolCallback** - Register the callback function for external
89  symbol lookup
90
91* **bccReadBC** - Set the source bitcode for compilation
92
93* **bccReadModule** - Set the llvm::Module for compilation
94
95* **bccLinkBC** - Set the library bitcode for linking
96
97* **bccPrepareExecutable** - *deprecated* - Use bccPrepareExecutableEx instead
98
99* **bccPrepareExecutableEx** - Create the in-memory executable by either
100  just-in-time compilation or cache loading
101
102* **bccGetFuncAddr** - Get the entry address of the function
103
104* **bccDisposeScript** - Destroy bcc script and release the resources
105
106* **bccGetError** - *deprecated* - Don't use this
107
108
109**Reflection:**
110
111* **bccGetExportVarCount** - Get the count of exported variables
112
113* **bccGetExportVarList** - Get the addresses of exported variables
114
115* **bccGetExportFuncCount** - Get the count of exported functions
116
117* **bccGetExportFuncList** - Get the addresses of exported functions
118
119* **bccGetPragmaCount** - Get the count of pragmas
120
121* **bccGetPragmaList** - Get the pragmas
122
123
124**Debug:**
125
126* **bccGetFuncCount** - Get the count of functions (including non-exported)
127
128* **bccGetFuncInfoList** - Get the function information (name, base, size)
129
130
131
132Cache File Format
133-----------------
134
135A cache file (denoted as \*.oBCC) for libbcc consists of several sections:
136header, string pool, dependencies table, relocation table, exported
137variable list, exported function list, pragma list, function information
138table, and bcc context.  Every section should be aligned to a word size.
139Here is the brief description of each sections:
140
141* **Header** (MCO_Header) - The header of a cache file. It contains the
142  magic word, version, machine integer type information (the endianness,
143  the size of off_t, size_t, and ptr_t), and the size
144  and offset of other sections.  The header section is guaranteed
145  to be at the beginning of the cache file.
146
147* **String Pool** (MCO_StringPool) - A collection of serialized variable
148  length strings.  The strp_index in the other part of the cache file
149  represents the index of such string in this string pool.
150
151* **Dependencies Table** (MCO_DependencyTable) - The dependencies table.
152  This table stores the resource name (or file path), the resource
153  type (rather in APK or on the file system), and the SHA1 checksum.
154
155* **Relocation Table** (MCO_RelocationTable) - *not enabled*
156
157* **Exported Variable List** (MCO_ExportVarList) -
158  The list of the addresses of exported variables.
159
160* **Exported Function List** (MCO_ExportFuncList) -
161  The list of the addresses of exported functions.
162
163* **Pragma List** (MCO_PragmaList) - The list of pragma key-value pair.
164
165* **Function Information Table** (MCO_FuncTable) - This is a table of
166  function information, such as function name, function entry address,
167  and function binary size.  Besides, the table should be ordered by
168  function name.
169
170* **Context** - The context of the in-memory executable, including
171  the code and the data.  The offset of context should aligned to
172  a page size, so that we can mmap the context directly into memory.
173
174For furthur information, you may read `bcc_cache.h <include/bcc/bcc_cache.h>`_,
175`CacheReader.cpp <lib/bcc/CacheReader.cpp>`_, and
176`CacheWriter.cpp <lib/bcc/CacheWriter.cpp>`_ for details.
177
178
179
180JIT'ed Code Calling Conventions
181-------------------------------
182
1831. Calls from Execution Environment or from/to within script:
184
185   On ARM, the first 4 arguments will go into r0, r1, r2, and r3, in that order.
186   The remaining (if any) will go through stack.
187
188   For ext_vec_types such as float2, a set of registers will be used. In the case
189   of float2, a register pair will be used. Specifically, if float2 is the first
190   argument in the function prototype, float2.x will go into r0, and float2.y,
191   r1.
192
193   Note: stack will be aligned to the coarsest-grained argument. In the case of
194   float2 above as an argument, parameter stack will be aligned to an 8-byte
195   boundary (if the sizes of other arguments are no greater than 8.)
196
1972. Calls from/to a separate compilation unit: (E.g., calls to Execution
198   Environment if those runtime library callees are not compiled using LLVM.)
199
200   On ARM, we use hardfp.  Note that double will be placed in a register pair.
201