From 6ea30b0af2cc1d955e08bf96ecd09e37c61b601d Mon Sep 17 00:00:00 2001 From: John Criswell Date: Tue, 18 Nov 2003 16:05:23 +0000 Subject: Added information on the GCC front end. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10067 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/FAQ.html | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) (limited to 'docs') diff --git a/docs/FAQ.html b/docs/FAQ.html index a40b215..e44defb 100644 --- a/docs/FAQ.html +++ b/docs/FAQ.html @@ -306,6 +306,69 @@ build.

+
+ GCC Front End +
+ +
+

+When I compile software that uses a configure script, the configure script +thinks my system has all of the header files and libraries it is testing for. +How do I get configure to work correctly? +

+
+ +
+

+The configure script is getting things wrong because the LLVM linker allows +symbols to be undefined at link time (so that they can be resolved during JIT +or translation to the C back end). That is why configure thinks your system +"has everything." +

+

+To work around this, perform the following steps: +

+ +
    +
  1. + Make sure the CC and CXX environment variables contains the full path to the + LLVM GCC front end. +
  2. + +
  3. + Make sure that the regular C compiler is first in your PATH. +
  4. + +
  5. + Add the string "-Wl,-native" to your CFLAGS environment variable. +
  6. +
+ +

+This will allow the gccld linker to create a native code executable instead of +a shell script that runs the JIT. Creating native code requires standard +linkage, which in turn will allow the configure script to find out if code is +not linking on your system because the feature isn't available on your system. +

+
+ +
+When I compile code using the LLVM GCC front end, it complains that it cannot +find crtend.o. +

+
+ +
+In order to find crtend.o, you must have the directory in which it lives in +your LLVM_LIB_SEARCH_PATH environment variable. For the binary distribution of +the LLVM GCC front end, this will be the full path of the bytecode-libs +directory inside of the LLVM GCC distribution. +

+
+ +