From 7a27439393add94048b73f6f6040c64c657e92cc Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sat, 6 Oct 2007 05:23:00 +0000 Subject: [PATCH] various minor edits, e.g. & -> & git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@42681 91177308-0d34-0410-b5e6-96231b3b80d8 --- www/features.html | 223 ++++++++++++++++++++++++---------------------- 1 file changed, 116 insertions(+), 107 deletions(-) diff --git a/www/features.html b/www/features.html index d6e4d1ee50..540a9e9097 100644 --- a/www/features.html +++ b/www/features.html @@ -1,108 +1,117 @@ - - - - - - - Clang - Features - - - - - - -
-

Features of Clang

-This page outlines the main goals of Clang, as well as some compelling reasons why you should consider using Clang. In the "Goals" section below, you will find a brief, bulletted overview of the goals and features that we are striving for in the development of Clang. However, in the "Key Features" section you will find a more detailed presentation on what we believe are some key drawing points for the LLVM front-end. If you are new to Clang and the LLVM front-end, and you want a reason for considering working on or using the new front-end, then make sure you check out the "Key Features" section. -

Goals

- -

Key Features

-There are several key features which we believe will make Clang a compelling alternative. These features are designed to make things easier for both the compiler developer (people working on Clang and derivative products) and the application developer (those who use Clang/LLVM). -

Library based architecture

-A major design concept for the LLVM front-end involves using a library based architecture. In this library based architecture, various parts of the front-end can be cleanly divided into separate libraries which can then be mixed up for different needs and uses. In addition, the library based approach makes it much easier for new developers to get involved and extend LLVM to do new and unique things. In the words of Chris, -
"The world needs better compiler tools, tools which are built as libraries. This design point allows reuse of the tools in new and novel ways. However, building the tools as libraries isn't enough: they must have clean APIs, be as decoupled from each other as possible, and be easy to modify/extend. This requires clean layering, decent design, and avoiding tying the libraries to a specific use."
-Currently, the LLVM front-end is divided into the following libraries: - -As an example of the power of this library based design.... If you wanted to build a preprocessor, you would take the Basic and Lexer libraries. If you want an indexer, you would take the previous two and add the Parser library and some actions for indexing. If you want a refactoring, static analysis, or source-to-source compiler tool, you would then add the AST building and semantic analyzer libraries. -In the end, LLVM's library based design will provide developers with many more possibilities. - -

Speed & Memory

-Another major focus of LLVM's frontend is speed (for all libraries). Even at this early stage, the LLVM front-end is quicker than gcc and uses less memory.
-
-
Memory:
- -
This test was run using Mac OS X's Carbon.h header, which is 12.3MB spread across 558 files! - Although this is one of the worst case scenarios for GCC, it shows how clang's implemenation is significantly more memory efficient. -
-
Notes: - Most of the additional memory used by GCC is due to extra data that is added in, which is not needed by the Clang front-end. -
-
-
-
Performance:
- -
Even at this early stage, the C parser for Clang is able to achieve significantly better performance. -
-
-
-
Performance:
- -
By moving to distributed compiling using distcc, the performance improvement also becomes noticeable.
-
Notes: - These are SPEC2006 benchmarks using Distcc.
-
- -

Expressive Diagnostics

-The design of the Clang driver (one of the LLVM front_end libraries) provies more detailed diagnostic information.
-
-
Clang vs GCC:
- -
There are several things to take note of in this example: -
    -
  • The error messages from Clang are more detailed. -
  • Clang shows you exactly where the error is, plus the range it has a problem with. -
-
-
Notes:The first results are from clang; the second results are from gcc.
-
-

Better Integration with IDEs

-Another benefit of Clang is that it was designed to integrate better with IDEs. In IDEs, the more information the IDE can get to, the better. The clang driver already provides more detailed (and useful) information than gcc. However, because of the library based design of LLVM, you can access additional information by mixing and matching parts of the library to create specialized development and debug tools. In this sense, LLVM is friendlier towards IDEs. -
- + + + + + + + Clang - Features + + + + + + +
+

Features of Clang

+

+This page outlines the main goals of Clang, as well as some compelling reasons why you should consider using Clang. In the Goals section below, you will find a brief, bulleted overview of the goals and features that we are striving for in the development of Clang. However, in the Key Features section you will find a more detailed presentation on what we believe are some key drawing points for the Clang front-end.

+ +

If you are new to Clang and the LLVM front-end, and you want a reason for considering working on or using the new front-end, then make sure you check out the Key Features section.

+ +

Goals

+ +

Key Features

+ +There are several key features which we believe make Clang an exciting front-end. These features are designed to make things easier for both the compiler developer (people working on Clang and derivative products) and the application developer (those who use Clang/LLVM). + +

Library based architecture

+A major design concept for the LLVM front-end involves using a library based architecture. In this library based architecture, various parts of the front-end can be cleanly divided into separate libraries which can then be mixed up for different needs and uses. In addition, the library based approach makes it much easier for new developers to get involved and extend LLVM to do new and unique things. In the words of Chris, +
"The world needs better compiler tools, tools which are built as libraries. This design point allows reuse of the tools in new and novel ways. However, building the tools as libraries isn't enough: they must have clean APIs, be as decoupled from each other as possible, and be easy to modify/extend. This requires clean layering, decent design, and avoiding tying the libraries to a specific use."
+Currently, the LLVM front-end is divided into the following libraries: + +As an example of the power of this library based design.... If you wanted to build a preprocessor, you would take the Basic and Lexer libraries. If you want an indexer, you would take the previous two and add the Parser library and some actions for indexing. If you want a refactoring, static analysis, or source-to-source compiler tool, you would then add the AST building and semantic analyzer libraries. +In the end, LLVM's library based design will provide developers with many more possibilities. + +

Speed and Memory

+Another major focus of LLVM's frontend is speed (for all libraries). Even at this early stage, the LLVM front-end is quicker than gcc and uses less memory.
+
+
Memory:
+ +
This test was run using Mac OS X's Carbon.h header, which is 12.3MB spread across 558 files! + Although this is one of the worst case scenarios for GCC, it shows how clang's implemenation is significantly more memory efficient. +
+
Notes: + Most of the additional memory used by GCC is due to extra data that is added in, which is not needed by the Clang front-end. +
+
+
+
Performance:
+ +
Even at this early stage, the C parser for Clang is able to achieve significantly better performance. +
+
+
+
Performance:
+ +
By moving to distributed compiling using distcc, the performance improvement also becomes noticeable.
+
Notes: + These are SPEC2006 benchmarks using Distcc.
+
+ +

Expressive Diagnostics

+The design of the Clang driver (one of the LLVM front_end libraries) provies more detailed diagnostic information.
+
+
Clang vs GCC:
+ +
There are several things to take note of in this example: +
    +
  • The error messages from Clang are more detailed. +
  • Clang shows you exactly where the error is, plus the range it has a problem with. +
+
+
Notes:The first results are from clang; the second results are from gcc.
+
+

Better Integration with IDEs

+Another benefit of Clang is that it was designed to integrate better with IDEs. In IDEs, the more information the IDE can get to, the better. The clang driver already provides more detailed (and useful) information than gcc. However, because of the library based design of LLVM, you can access additional information by mixing and matching parts of the library to create specialized development and debug tools. In this sense, LLVM is friendlier towards IDEs. +
+ \ No newline at end of file -- 2.40.0