Introduction
-Building with link time optimization requires cooperation from the system linker. LTO support on Linux systems requires that you use the gold linker which supports @@ -33,14 +33,14 @@ project.
The LLVM gold plugin implements the gold plugin interface on top of -libLTO. +libLTO. The same plugin can also be used by other tools such as ar and nm.
How to build it
-You need to have gold with plugin support and build the LLVMgold plugin. Check whether you have gold running /usr/bin/ld -v. It will report “GNU gold” or else “GNU ld” if not. If you have @@ -72,9 +72,9 @@ placed.
Usage
-The linker takes a -plugin option that points to the path of the plugin .so file. To find out what link command gcc would run in a given situation, run gcc -v [...] and look @@ -95,14 +95,13 @@ placed. own gold, be sure to install the ar and nm-new you built to /usr/bin.
-
The following example shows a worked example of the gold plugin mixing LLVM bitcode and native code.
@@ -145,14 +144,20 @@ $ llvm-gcc -use-gold-plugin a.a b.o -o main # <-- link with LLVMgold plugin
Gold informs the plugin that foo3 is never referenced outside the IR, leading LLVM to delete that function. However, unlike in the - libLTO + libLTO example gold does not currently eliminate foo4.
+ + Quickstart for using LTO with autotooled projects + +
-Once your system ld, ar and nm all support LLVM bitcode, everything is in place for an easy to use LTO build of autotooled projects:
@@ -189,9 +194,9 @@ export CFLAGS="-O4"Licensing
-Gold is licensed under the GPLv3. LLVMgold uses the interface file plugin-api.h from gold which means that the resulting LLVMgold.so binary is also GPLv3. This can still be used to link non-GPLv3 programs just @@ -206,7 +211,7 @@ as much as gold could without the plugin.
- The LLVM Compiler Infrastructure
+ The LLVM Compiler Infrastructure
Last modified: $Date: 2010-04-16 23:58:21 -0800 (Fri, 16 Apr 2010) $