[LTO] Fix linking with an alias defined using another alias.

When we're linking an alias which will be defined later, we neeed to
build a GlobalAlias, or else we'll crash later in
IRLinker::linkGlobalValueBody.

clang sometimes constructs aliases like this for C++ destructors.

Differential Revision: https://reviews.llvm.org/D49316

llvm-svn: 337053

2 files changed, 32 insertions, 0 deletions

diff --git a/llvm/test/LTO/Resolution/X86/Inputs/alias-alias-1.ll b/llvm/test/LTO/Resolution/X86/Inputs/alias-alias-1.ll
new file mode 100644
index 00000000000..956deabcfc8
--- /dev/null
+++ b/llvm/test/LTO/Resolution/X86/Inputs/alias-alias-1.ll
@@ -0,0 +1,5 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@a = external global i32
+@d = global i32* @a
diff --git a/llvm/test/LTO/Resolution/X86/alias-alias.ll b/llvm/test/LTO/Resolution/X86/alias-alias.ll
new file mode 100644
index 00000000000..eaf2615b0a0
--- /dev/null
+++ b/llvm/test/LTO/Resolution/X86/alias-alias.ll
@@ -0,0 +1,27 @@
+; RUN: llvm-as %s -o %t1.o
+; RUN: llvm-as %p/Inputs/alias-alias-1.ll -o %t2.o
+; RUN: llvm-lto2 run -o %t3.o %t1.o %t2.o -r %t2.o,a, -r %t2.o,d,px -r %t1.o,a,p -r %t1.o,c,p -r %t1.o,b -save-temps
+; RUN: llvm-dis < %t3.o.0.0.preopt.bc -o - | FileCheck %s
+; RUN: FileCheck --check-prefix=RES %s < %t3.o.resolution.txt
+
+; CHECK-NOT: alias
+; CHECK: @c = global i32 1
+; CHECK-NEXT: @d = global i32* @a
+; CHECK-EMPTY:
+; CHECK-NEXT: @a = weak alias i32, i32* @b
+; CHECK-NEXT: @b = internal alias i32, i32* @c
+
+; RES: 1.o{{$}}
+; RES-NEXT: {{^}}-r={{.*}}1.o,c,p{{$}}
+; RES-NEXT: {{^}}-r={{.*}}1.o,a,p{{$}}
+; RES-NEXT: {{^}}-r={{.*}}1.o,b,{{$}}
+; RES-NEXT: 2.o{{$}}
+; RES-NEXT: {{^}}-r={{.*}}2.o,a,{{$}}
+; RES-NEXT: {{^}}-r={{.*}}2.o,d,px{{$}}
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@a = weak alias i32, i32* @b
+@b = alias i32, i32* @c
+@c = global i32 1