In general, llvm-link
works fine. Here's a simple demonstration (with LLVM built from trunk a few days ago):
$ cat lib.c
int libfoo(int x) {
return x * 2;
}
$ cat user.c
int libfoo(int);
int bar(int a, int b) {
return a + libfoo(b);
}
$ clang -emit-llvm -c user.c -o user.bc
$ clang -emit-llvm -c lib.c -o lib.bc
$ llvm-link lib.bc user.bc -o linked.bc
$ llvm-dis linked.bc
$ cat linked.ll
; ModuleID = 'linked.bc'
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define i32 @libfoo(i32 %x) nounwind uwtable {
entry:
%x.addr = alloca i32, align 4
store i32 %x, i32* %x.addr, align 4
%0 = load i32* %x.addr, align 4
%mul = mul nsw i32 %0, 2
ret i32 %mul
}
define i32 @bar(i32 %a, i32 %b) nounwind uwtable {
entry:
%a.addr = alloca i32, align 4
%b.addr = alloca i32, align 4
store i32 %a, i32* %a.addr, align 4
store i32 %b, i32* %b.addr, align 4
%0 = load i32* %a.addr, align 4
%1 = load i32* %b.addr, align 4
%call = call i32 @libfoo(i32 %1)
%add = add nsw i32 %0, %call
ret i32 %add
}
So you have to carefully examine your specific code for symbol duplication, missing, etc.