llvm-6502/test/Feature/aliases.ll
Rafael Espindola f165cf7ce8 Prevent alias from pointing to weak aliases.
This adds back r204781.

Original message:

Aliases are just another name for a position in a file. As such, the
regular symbol resolutions are not applied. For example, given

define void @my_func() {
  ret void
}
@my_alias = alias weak void ()* @my_func
@my_alias2 = alias void ()* @my_alias

We produce without this patch:

        .weak   my_alias
my_alias = my_func
        .globl  my_alias2
my_alias2 = my_alias

That is, in the resulting ELF file my_alias, my_func and my_alias are
just 3 names pointing to offset 0 of .text. That is *not* the
semantics of IR linking. For example, linking in a

@my_alias = alias void ()* @other_func

would require the strong my_alias to override the weak one and
my_alias2 would end up pointing to other_func.

There is no way to represent that with aliases being just another
name, so the best solution seems to be to just disallow it, converting
a miscompile into an error.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204934 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-27 15:26:56 +00:00

37 lines
827 B
LLVM

; RUN: llvm-as < %s | llvm-dis > %t1.ll
; RUN: llvm-as %t1.ll -o - | llvm-dis > %t2.ll
; RUN: diff %t1.ll %t2.ll
@llvm.used = appending global [1 x i8*] [i8* bitcast (i32* @foo1 to i8*)], section "llvm.metadata"
@bar = global i32 0
@foo1 = alias i32* @bar
@foo2 = alias i32* @bar
@foo3 = alias i32* @foo2
%FunTy = type i32()
define i32 @foo_f() {
ret i32 0
}
@bar_f = alias weak_odr %FunTy* @foo_f
@bar_ff = alias i32()* @bar_f
@bar_i = alias internal i32* @bar
@A = alias bitcast (i32* @bar to i64*)
define i32 @test() {
entry:
%tmp = load i32* @foo1
%tmp1 = load i32* @foo2
%tmp0 = load i32* @bar_i
%tmp2 = call i32 @foo_f()
%tmp3 = add i32 %tmp, %tmp2
%tmp4 = call %FunTy* @bar_f()
%tmp5 = add i32 %tmp3, %tmp4
%tmp6 = add i32 %tmp1, %tmp5
%tmp7 = add i32 %tmp6, %tmp0
ret i32 %tmp7
}