Default cascading style sheet for the HTML output of Docutils.
See http://docutils.sf.net/docs/howto/html-stylesheets.html for how to customize this style sheet. */
/* used to remove borders from tables and images */ .borderless, table.borderless td, table.borderless th { border: 0 }
table.borderless td, table.borderless th { /* Override padding for "table.docutils td" with "! important". The right padding separates the table cells. */ padding: 0 0.5em 0 0 ! important }
.first { /* Override more specific margin styles with "! important". */ margin-top: 0 ! important }
.last, .with-subtitle { margin-bottom: 0 ! important }
.hidden { display: none }
a.toc-backref { text-decoration: none ; color: black }
blockquote.epigraph { margin: 2em 5em ; }
dl.docutils dd { margin-bottom: 0.5em }
/* Uncomment (and remove this text!) to get bold-faced definition list terms dl.docutils dt { font-weight: bold } */
div.abstract { margin: 2em 5em }
div.abstract p.topic-title { font-weight: bold ; text-align: center }
div.admonition, div.attention, div.caution, div.danger, div.error, div.hint, div.important, div.note, div.tip, div.warning { margin: 2em ; border: medium outset ; padding: 1em }
div.admonition p.admonition-title, div.hint p.admonition-title, div.important p.admonition-title, div.note p.admonition-title, div.tip p.admonition-title { font-weight: bold ; font-family: sans-serif }
div.attention p.admonition-title, div.caution p.admonition-title, div.danger p.admonition-title, div.error p.admonition-title, div.warning p.admonition-title { color: red ; font-weight: bold ; font-family: sans-serif }
/* Uncomment (and remove this text!) to get reduced vertical space in compound paragraphs. div.compound .compound-first, div.compound .compound-middle { margin-bottom: 0.5em }
div.compound .compound-last, div.compound .compound-middle { margin-top: 0.5em } */
div.dedication { margin: 2em 5em ; text-align: center ; font-style: italic }
div.dedication p.topic-title { font-weight: bold ; font-style: normal }
div.figure { margin-left: 2em ; margin-right: 2em }
div.footer, div.header { clear: both; font-size: smaller }
div.line-block { display: block ; margin-top: 1em ; margin-bottom: 1em }
div.line-block div.line-block { margin-top: 0 ; margin-bottom: 0 ; margin-left: 1.5em }
div.sidebar { margin: 0 0 0.5em 1em ; border: medium outset ; padding: 1em ; background-color: #ffffee ; width: 40% ; float: right ; clear: right }
div.sidebar p.rubric { font-family: sans-serif ; font-size: medium }
div.system-messages { margin: 5em }
div.system-messages h1 { color: red }
div.system-message { border: medium outset ; padding: 1em }
div.system-message p.system-message-title { color: red ; font-weight: bold }
div.topic { margin: 2em }
h1.section-subtitle, h2.section-subtitle, h3.section-subtitle, h4.section-subtitle, h5.section-subtitle, h6.section-subtitle { margin-top: 0.4em }
h1.title { text-align: center }
h2.subtitle { text-align: center }
hr.docutils { width: 75% }
img.align-left, .figure.align-left{ clear: left ; float: left ; margin-right: 1em }
img.align-right, .figure.align-right { clear: right ; float: right ; margin-left: 1em }
.align-left { text-align: left }
.align-center { clear: both ; text-align: center }
.align-right { text-align: right }
/* reset inner alignment in figures */ div.align-right { text-align: left }
/* div.align-center * { / / text-align: left } */
ol.simple, ul.simple { margin-bottom: 1em }
ol.arabic { list-style: decimal }
ol.loweralpha { list-style: lower-alpha }
ol.upperalpha { list-style: upper-alpha }
ol.lowerroman { list-style: lower-roman }
ol.upperroman { list-style: upper-roman }
p.attribution { text-align: right ; margin-left: 50% }
p.caption { font-style: italic }
p.credits { font-style: italic ; font-size: smaller }
p.label { white-space: nowrap }
p.rubric { font-weight: bold ; font-size: larger ; color: maroon ; text-align: center }
p.sidebar-title { font-family: sans-serif ; font-weight: bold ; font-size: larger }
p.sidebar-subtitle { font-family: sans-serif ; font-weight: bold }
p.topic-title { font-weight: bold }
pre.address { margin-bottom: 0 ; margin-top: 0 ; font: inherit }
pre.literal-block, pre.doctest-block { margin-left: 2em ; margin-right: 2em }
span.classifier { font-family: sans-serif ; font-style: oblique }
span.classifier-delimiter { font-family: sans-serif ; font-weight: bold }
span.interpreted { font-family: sans-serif }
span.option { white-space: nowrap }
span.pre { white-space: pre }
span.problematic { color: red }
span.section-subtitle { /* font-size relative to parent (h1..h6 element) */ font-size: 80% }
table.citation { border-left: solid 1px gray; margin-left: 1px }
table.docinfo { margin: 2em 4em }
table.docutils { margin-top: 0.5em ; margin-bottom: 0.5em }
table.footnote { border-left: solid 1px black; margin-left: 1px }
table.docutils td, table.docutils th, table.docinfo td, table.docinfo th { padding-left: 0.5em ; padding-right: 0.5em ; vertical-align: top }
table.docutils th.field-name, table.docinfo th.docinfo-name { font-weight: bold ; text-align: left ; white-space: nowrap ; padding-left: 0 }
h1 tt.docutils, h2 tt.docutils, h3 tt.docutils, h4 tt.docutils, h5 tt.docutils, h6 tt.docutils { font-size: 100% }
ul.auto-toc { list-style-type: none }
libbcc is an LLVM bitcode execution engine that compiles the bitcode to an in-memory executable. libbcc is versatile because:
libbcc provides:
Highlights of libbcc are:
libbcc supports bitcode from various language frontends, such as Renderscript, GLSL (pixelflinger2).
libbcc strives to balance between library size, launch time and steady-state performance:
The size of libbcc is aggressively reduced for mobile devices. We customize and improve upon the default Execution Engine from upstream. Otherwise, libbcc's execution engine can easily become at least 2 times bigger.
To reduce launch time, we support caching of binaries. Just-in-Time compilation are oftentimes Just-too-Late, if the given apps are performance-sensitive. Thus, we implemented AOT to get the best of both worlds: Fast launch time and high steady-state performance.
AOT is also important for projects such as NDK on LLVM with portability enhancement. Launch time reduction after we implemented AOT is signficant:
Apps libbcc without AOT libbcc with AOT launch time in libbcc launch time in libbcc App_1 1218ms 9ms App_2 842ms 4ms Wallpaper: MagicSmoke 182ms 3ms Halo 127ms 3ms Balls 149ms 3ms SceneGraph 146ms 90ms Model 104ms 4ms Fountain 57ms 3ms
AOT also masks the launching time overhead of on-device linking and helps it become reality.
For steady-state performance, we enable VFP3 and aggressive optimizations.
Currently we disable Lazy JITting.
Basic:
Reflection:
Debug:
A cache file (denoted as *.oBCC) for libbcc consists of several sections: header, string pool, dependencies table, relocation table, exported variable list, exported function list, pragma list, function information table, and bcc context. Every section should be aligned to a word size. Here is the brief description of each sections:
For furthur information, you may read bcc_cache.h, CacheReader.cpp, and CacheWriter.cpp for details.
Calls from Execution Environment or from/to within script:
On ARM, the first 4 arguments will go into r0, r1, r2, and r3, in that order. The remaining (if any) will go through stack.
For ext_vec_types such as float2, a set of registers will be used. In the case of float2, a register pair will be used. Specifically, if float2 is the first argument in the function prototype, float2.x will go into r0, and float2.y, r1.
Note: stack will be aligned to the coarsest-grained argument. In the case of float2 above as an argument, parameter stack will be aligned to an 8-byte boundary (if the sizes of other arguments are no greater than 8.)
Calls from/to a separate compilation unit: (E.g., calls to Execution Environment if those runtime library callees are not compiled using LLVM.)
On ARM, we use hardfp. Note that double will be placed in a register pair.