Changes in directory llvm/docs:
FAQ.html updated: 1.36 -> 1.37
---
Log message:
Answer the FAQ: "can llvm convert C++ code to C?"
---
Diffs of the changes: (+58 -1)
FAQ.html | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 58 insertions(+), 1 deletion(-)
Index: llvm/docs/FAQ.html
diff -u llvm/docs/FAQ.html:1.36 llvm/docs/FAQ.html:1.37
--- llvm/docs/FAQ.html:1.36 Wed Apr 26 16:03:17 2006
+++ llvm/docs/FAQ.html Wed Jul 19 13:19:59 2006
@@ -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 @@
</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>
@@ -614,7 +671,7 @@
src="http://www.w3.org/Icons/valid-html401"; alt="Valid HTML 4.01!"></a>
<a href="http://llvm.org";>LLVM Compiler Infrastructure</a><br>
- Last modified: $Date: 2006/04/26 21:03:17 $
+ Last modified: $Date: 2006/07/19 18:19:59 $
</address>
</body>
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