RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2024-10-19 19:12:56 +02:00
Code Issues Projects Releases Wiki Activity

Answer the FAQ: "can llvm convert C++ code to C?"

Browse Source 
llvm-svn: 29212
This commit is contained in:
Chris Lattner 2006-07-19 18:19:59 +00:00
parent d31b3778d8
commit 88be9e7472
1 changed files with 57 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
docs/FAQ.html
View File

@ -79,6 +79,8 @@
How can I disable all optimizations when compiling code using the LLVM GCC front end?
</li>
<li><a href="#translatec++">Can I use LLVM to convert C++ code to C code?</a></li>
</ol>
</li>
@ -501,6 +503,61 @@ code that you desire.
</p>
</div>
<div class="question">
<p>
<a name="translatec++">Can I use LLVM to convert C++ code to C code?</a>
</p>
</div>
<div class="answer">
<p>Yes, you can use LLVM to convert code from any language LLVM supports to C.
Note that the generated C code will be very low level (all loops are lowered
to gotos, etc) and not very pretty (comments are stripped, original source
formatting is totally lost, variables are renamed, expressions are regrouped),
so this may not be what you're looking for. However, this is a good way to add
C++ support for a processor that does not otherwise have a C++ compiler.
</p>
<p>Use commands like this:</p>
<ol>
<li><p>Compile your program as normal with llvm-g++:</p></li>
<div class="doc_code">$ llvm-g++ x.cpp -o program</div>
<p>or:</p>
<div class="doc_code">
llvm-g++ a.cpp -c
llvm-g++ b.cpp -c
llvm-g++ a.o b.o -o program
</div>
<p>With llvm-gcc3, this will generate program and program.bc. The .bc file is
the LLVM version of the program all linked together.</p>
<li><p>Convert the LLVM code to C code, using the LLC tool with the C
backend:</p></li>
<div class="doc_code">$ llc -march=c program.bc -o program.c</div>
<li><p>Finally, compile the c file:</p></li>
<div class="doc_code">$ cc x.c</div>
</ol>
<p>Note that, by default, the C backend does not support exception handling.
If you want/need it for a certain program, you can enable it by passing
"-enable-correct-eh-support" to the llc program. The resultant code will
use setjmp/longjmp to implement exception support that is correct but
relatively slow.
</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="cfe_code">Questions about code generated by the GCC front-end</a>