X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=docs%2FFAQ.html;h=95e425aac66990b875816ccc83b62839966481d3;hb=e562b1725ee068ff525082d1e9ba885c8928c72e;hp=96360d06a1ca42b60bbfe4ed0e8db00cc264904f;hpb=669ed45029765df223ba7e9cdc242f62c17497e4;p=oota-llvm.git diff --git a/docs/FAQ.html b/docs/FAQ.html index 96360d06a1c..95e425aac66 100644 --- a/docs/FAQ.html +++ b/docs/FAQ.html @@ -53,12 +53,15 @@
Some porting problems may exist in the following areas:
Adjust your PATH environment variable so that the correct - program appears first in the PATH. This may work, but may not be - convenient when you want them first in your path for other - work.
Run configure with an alternative PATH that is - correct. In a Borne compatible shell, the syntax would be:
- -PATH=[the path without the bad program] ./configure ...
+ correct. In a Borne compatible shell, the syntax would be: + ++% PATH=[the path without the bad program] ./configure ... ++
This is still somewhat inconvenient, but it allows configure - to do its work without having to adjust your PATH - permanently.
I've updated my source tree from Subversion, and now my build is trying to - use a file/directory that doesn't exist.
+I've updated my source tree from Subversion, and now my build is trying to +use a file/directory that doesn't exist.
If the Makefile already exists in your object tree, you can just run the following command in the top level directory of your object tree:
-./config.status <relative path to Makefile>
+
% ./config.status <relative path to Makefile>+
If the Makefile is new, you will have to modify the configure script to copy it over.
@@ -314,9 +316,7 @@ clean and then make in the directory that fails to build.For example, if you built LLVM with the command:
-% gmake ENABLE_PROFILING=1 -+
% gmake ENABLE_PROFILING=1
...then you must run the tests with the following commands:
@@ -354,12 +354,12 @@ build.This is a bug in GCC, and - affects projects other than LLVM. Try upgrading or downgrading your GCC.
+affects projects other than LLVM. Try upgrading or downgrading your GCC.After Subversion update, rebuilding gives the error - "No rule to make target".
+After Subversion update, rebuilding gives the error "No rule to make +target".
llvmc is experimental and isn't really supported. We suggest - using llvm-gcc instead.
+llvmc is experimental and isn't really supported. We suggest +using llvm-gcc instead.
The PyPy developers are working on integrating LLVM into the PyPy backend so that PyPy language can translate to LLVM.
What support is there for a higher level source language constructs for + +
+Your compiler front-end will communicate with LLVM by creating a module in + the LLVM intermediate representation (IR) format. Assuming you want to + write your language's compiler in the language itself (rather than C++), + there are 3 major ways to tackle generating LLVM IR from a front-end:
+If you go with the first option, the C bindings in include/llvm-c should + help a lot, since most languages have strong support for interfacing with + C. The most common hurdle with calling C from managed code is interfacing + with the garbage collector. The C interface was designed to require very + little memory management, and so is straightforward in this regard.
+I don't understand the GetElementPtr - instruction. Help!
+See The Often Misunderstood GEP - Instruction. + Instruction.
Use commands like this:
Compile your program as normal with llvm-g++:
Compile your program as normal with llvm-g++:
@@ -541,7 +591,7 @@ C++ support for a processor that does not otherwise have a C++ compiler.
or:
+or:
@@ -551,75 +601,49 @@ C++ support for a processor that does not otherwise have a C++ compiler.
With llvm-gcc3, this will generate program and program.bc. The .bc file is -the LLVM version of the program all linked together.
+With llvm-gcc3, this will generate program and program.bc. The .bc + file is the LLVM version of the program all linked together.
Convert the LLVM code to C code, using the LLC tool with the C -backend:
Convert the LLVM code to C code, using the LLC tool with the C + backend:
% llc -march=c program.bc -o program.c-
Finally, compile the c file:
Finally, compile the C file:
% cc x.c-
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. -
+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.
-Also note: this specific sequence of commands won't work if you use a -function defined in the C++ runtime library (or any other C++ library). To -access an external C++ library, you must manually -compile libstdc++ to LLVM bitcode, statically link it into your program, then -use the commands above to convert the whole result into C code. Alternatively, -you can compile the libraries and your application into two different chunks -of C code and link them.
+Also note: this specific sequence of commands won't work if you use a +function defined in the C++ runtime library (or any other C++ library). To +access an external C++ library, you must manually compile libstdc++ to LLVM +bitcode, statically link it into your program, then use the commands above to +convert the whole result into C code. Alternatively, you can compile the +libraries and your application into two different chunks of C code and link +them.
-The __main call is inserted by the C/C++ compiler in order to guarantee -that static constructors and destructors are called when the program starts up -and shuts down. In C, you can create static constructors and destructors by -using GCC extensions, and in C++ you can do so by creating a global variable -whose class has a ctor or dtor. -
- --The actual implementation of __main lives in the -llvm/runtime/GCCLibraries/crtend/ directory in the source-base, and is -linked in automatically when you link the program. -
-