Hi,
I'm trying to start using gc with llvm, and was trying to get
started with the shadow-stack plugin. I'm having trouble putting
everything together, even in this simple case. My compiler generates
the necessary gcroot instructions and for now I would be glad just
being able to walk through the roots and print out some numbers.
For example, I have the following my.ll file:
my.ll:
declare {} @__printi(i64)
define i32 @mymain() gc "shadow-stack" {
entry:
%0 = alloca [0 x i64]*
%1 = call [0 x i64]* @malloc(i64 80)
store [0 x i64]* %1, [0 x i64]** %0
%2 = bitcast [0 x i64]** %0 to i8**
call void @llvm.gcroot(i8** %2, i8* null)
%3 = getelementptr [0 x i64]* %1, i32 0, i32 2
%4 = load i64* %3
%printi = call {} @__printi(i64 %4)
ret i32 0
}
declare noalias [0 x i64]* @malloc(i64) nounwind
declare void @llvm.gcroot(i8**, i8*) nounwind
I'm allocating a 10 element i64 array and then printing
its third element using a library function printi.
On the other hand, I have copied on the file gc.cpp the
code given in the LLVM GC documentation defining a visitor
function visitGCRoots for the shadow-stack plugin and finally
I have on mylib.c the following:
mylib.c
#include <stdio.h>
void __printi (long x)
{
printf ("%ld\n", x);
}
extern int mymain (void);
int main (void)
{
return mymain ();
}
Now I'm trying to compile everything with
> llc my.ll
> g++ my.s mylib.c gc.cpp
But get the following error
ld: in /var/folders/Ea/EakEx6b+GBSo6cUn2AnFZk+++TI/-Tmp-//ccTjTjtW.o, section
not found for address 0x6D200E00000004DD
collect2: ld returned 1 exit status
How do I have to do to compile?
Thanks!
N
