llvm-6502/test/Transforms/GlobalOpt/alias-resolve.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

43 lines
783 B
LLVM

; RUN: opt < %s -globalopt -S | FileCheck %s
@foo1 = alias void ()* @foo2
; CHECK: @foo1 = alias void ()* @bar2
@foo2 = alias void()* @bar1
; CHECK: @foo2 = alias void ()* @bar2
@bar1 = alias void ()* @bar2
; CHECK: @bar1 = alias void ()* @bar2
@weak1 = alias weak void ()* @bar2
; CHECK: @weak1 = alias weak void ()* @bar2
define void @bar2() {
ret void
}
; CHECK: define void @bar2()
define void @baz() {
entry:
call void @foo1()
; CHECK: call void @bar2()
call void @foo2()
; CHECK: call void @bar2()
call void @bar1()
; CHECK: call void @bar2()
call void @weak1()
; CHECK: call void @weak1()
ret void
}
@foo3 = alias void ()* @bar3
; CHECK-NOT: bar3
define internal void @bar3() {
ret void
}
;CHECK: define void @foo3