Svadev mailing list

[John Criswell <criswell AT illinois.edu>]

On 5/30/12 9:08 PM, Baozeng wrote:
> 2012/5/31 John 
> Criswell<criswell AT illinois.edu>:
> > On 5/30/12 9:03 AM, Baozeng wrote:
> > > Dear John,
> > > I added metadata information for global and stack variables(commit
> > > r157609 and commit r157670). Then I first test global variable with
> > > the following test:
> > >
> > > #include<stdlib.h>
> > >
> > > int p[33];
> > > int main() {
> > >    p[35] = 8;
> > >    return 0;
> > > }
> > > Then
> > > #clang -fmemsafety -bbc globaltest.c -o test
> > > -L/home/sploving/llvm/projects/safecode/Debug/lib
> > > It shows the following error:
> > > /tmp/globaltest-GkBpxH.o:globaltest.c:function sourcefile: error:
> > > undefined reference to 'baggy.metadata1'
> >
> > I don't see anything immediately wrong.  However, I'd like to point out that
> > in the command above, you're not using the -g option, and in the command
> > below, you are using the -g option.
> >
> > Do you get the problem both with and without the -g option?
> >
> >
> > > Its IR file is as the following(clang -g -fmemsafety -bbc globaltest.c
> > > -o test_me.bc -c -emit-llvm
> > > ):
> > >
> > > ; ModuleID = '<stdin>'
> > > target datalayout =
> > >
> > > "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32-S128"
> > > target triple = "i386-pc-linux-gnu"
> > >
> > > @llvm.global_ctors = appending global [1 x { i32, void ()* }] [{ i32,
> > > void ()* } { i32 0, void ()* @pool_ctor }]
> > > @baggy.metadata = common global { i32, i32* }
> > > @p = common global { [33 x i32], [116 x i8], { i32, i32* } } { [33 x
> > > i32] zeroinitializer, [116 x i8] zeroinitializer, { i32, i32* }*
> > > @baggy.metadata }, align 256
> > > @baggy.metadata1 = internal constant { i32, i32* }
> > > @sourcefile = internal constant { [28 x i8], [28 x i8], { i32, i32* }
> > > } { [28 x i8] c"/home/sploving/globaltest.c\00", [28 x i8]
> > > zeroinitializer, { i32, i32* }* @baggy.metadata1 }, align 64
> >
> > Try adding a zeroinitializer to the baggy.metadata global variables.  I get
> > an error about them not having any initializer when I try to use BBC with
> > libLTO.
> yes. I added a zeroinitializer to it and it works.

I also noticed that the metadata is given the same linkage as the global 
variable.  If possible, the metadata should be given internal linkage so 
that we don't get conflicts between compilation units.

-- John T.

> > > [snip]
> > >
> > >
> > > What is the matter with my commit?
> > >
> > > Another thing, are there any classic examples to test whether BBC
> > > support global and stack variables checking?
> > No.  To test it, you'll need to write your own sample programs.  Eventually,
> > we'll want to add lit tests for BBC.
> >
> > -- John T.