Error if we see an alias to a declaration.

In ELF and COFF an alias is just another offset in a section. There is no way
to represent an alias to something in another file.

In MachO, the spec has the N_INDR type which should allow for exactly that, but
is not currently implemented. Given that it is specified but not implemented,
we error in codegen to avoid miscompiling but don't reject aliases to
declarations in the verifier to leave the option open of implementing it.

In the past we have used alias to declarations as a way of implementing
weakref, which is why it exists in some old tests which this patch updates.

llvm-svn: 194705

5 files changed, 18 insertions, 5 deletions

diff --git a/llvm/test/CodeGen/X86/2007-09-06-ExtWeakAliasee.ll b/llvm/test/CodeGen/X86/2007-09-06-ExtWeakAliasee.ll
index c5d2a46f92c..7e37ef5c40d 100644
--- a/llvm/test/CodeGen/X86/2007-09-06-ExtWeakAliasee.ll
+++ b/llvm/test/CodeGen/X86/2007-09-06-ExtWeakAliasee.ll
@@ -1,4 +1,6 @@
 ; RUN: llc < %s -march=x86 | grep weak | count 2
 @__gthrw_pthread_once = alias weak i32 (i32*, void ()*)* @pthread_once		; <i32 (i32*, void ()*)*> [#uses=0]
 
-declare extern_weak i32 @pthread_once(i32*, void ()*)
+define weak i32 @pthread_once(i32*, void ()*) {
+  ret i32 0
+}
diff --git a/llvm/test/CodeGen/X86/2008-03-14-SpillerCrash.ll b/llvm/test/CodeGen/X86/2008-03-14-SpillerCrash.ll
index 8946415108f..18b3714f851 100644
--- a/llvm/test/CodeGen/X86/2008-03-14-SpillerCrash.ll
+++ b/llvm/test/CodeGen/X86/2008-03-14-SpillerCrash.ll
@@ -45,4 +45,6 @@ bb383:		; preds = %bb374.us, %bb311.split
 	ret i64 0
 }
 
-declare i64 @__wcstoll_l(i32*, i32**, i32, %struct.__locale_struct*) nounwind 
+define i64 @__wcstoll_l(i32*, i32**, i32, %struct.__locale_struct*) nounwind {
+  ret i64 0
+}
diff --git a/llvm/test/CodeGen/X86/alias-error.ll b/llvm/test/CodeGen/X86/alias-error.ll
new file mode 100644
index 00000000000..89b0876a837
--- /dev/null
+++ b/llvm/test/CodeGen/X86/alias-error.ll
@@ -0,0 +1,5 @@
+; RUN: not llc < %s -mtriple=i686-pc-linux-gnu %s 2>&1 | FileCheck %s
+
+@a = external global i32
+@b = alias i32* @a
+; CHECK: b: Target doesn't support aliases to declarations
diff --git a/llvm/test/CodeGen/X86/aliases.ll b/llvm/test/CodeGen/X86/aliases.ll
index 025dcfedb62..d0a262d390d 100644
--- a/llvm/test/CodeGen/X86/aliases.ll
+++ b/llvm/test/CodeGen/X86/aliases.ll
@@ -1,6 +1,6 @@
 ; RUN: llc < %s -mtriple=i686-pc-linux-gnu -asm-verbose=false | FileCheck %s
 
-@bar = external global i32
+@bar = global i32 42
 
 ; CHECK-DAG: .globl	foo1
 @foo1 = alias i32* @bar
@@ -10,7 +10,9 @@
 
 %FunTy = type i32()
 
-declare i32 @foo_f()
+define i32 @foo_f() {
+  ret i32 0
+}
 ; CHECK-DAG: .weak	bar_f
 @bar_f = alias weak %FunTy* @foo_f
 
diff --git a/llvm/test/CodeGen/X86/x86-64-pic-10.ll b/llvm/test/CodeGen/X86/x86-64-pic-10.ll
index 3ec172b2b65..da8082b9251 100644
--- a/llvm/test/CodeGen/X86/x86-64-pic-10.ll
+++ b/llvm/test/CodeGen/X86/x86-64-pic-10.ll
@@ -9,4 +9,6 @@ entry:
         ret void
 }
 
-declare extern_weak i32 @f()
+define weak i32 @f() {
+  ret i32 42
+}