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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194705 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 44a8316..308b0e0 100644 (file)
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -949,6 +949,11 @@ bool AsmPrinter::doFinalization(Module &M) {
       MCSymbol *Name = getSymbol(I);
 
       const GlobalValue *GV = I->getAliasedGlobal();
+      if (GV->isDeclaration()) {
+        report_fatal_error(Name->getName() +
+                           ": Target doesn't support aliases to declarations");
+      }
+
       MCSymbol *Target = getSymbol(GV);
 
       if (I->hasExternalLinkage() || !MAI->getWeakRefDirective())

diff --git a/test/CodeGen/ARM/aliases.ll b/test/CodeGen/ARM/aliases.ll
index 4147bd0..f55ae10 100644 (file)
--- a/test/CodeGen/ARM/aliases.ll
+++ b/test/CodeGen/ARM/aliases.ll
@@ -16,13 +16,15 @@
 ; CHECK: .globl        A
 ; CHECK: A = bar
 
-@bar = external global i32
+@bar = global i32 42
 @foo1 = alias i32* @bar
 @foo2 = alias i32* @bar
 
 %FunTy = type i32()
 
-declare i32 @foo_f()
+define i32 @foo_f() {
+  ret i32 0
+}
 @bar_f = alias weak %FunTy* @foo_f
 
 @bar_i = alias internal i32* @bar

diff --git a/test/CodeGen/Generic/2009-03-17-LSR-APInt.ll b/test/CodeGen/Generic/2009-03-17-LSR-APInt.ll
index 6281ada..3f17ce1 100644 (file)
--- a/test/CodeGen/Generic/2009-03-17-LSR-APInt.ll
+++ b/test/CodeGen/Generic/2009-03-17-LSR-APInt.ll
@@ -63,30 +63,58 @@ bb47:               ; preds = %bb46, %bb44
        br label %bb44
 }
 
-declare i32 @pthread_once(i32*, void ()*)
+define i32 @pthread_once(i32*, void ()*) {
+  ret i32 0
+}
 
-declare i8* @pthread_getspecific(i32)
+define i8* @pthread_getspecific(i32) {
+  ret i8* null
+}
 
-declare i32 @pthread_setspecific(i32, i8*)
+define i32 @pthread_setspecific(i32, i8*) {
+  ret i32 0
+}
 
-declare i32 @pthread_create(i64*, %struct.pthread_attr_t*, i8* (i8*)*, i8*)
+define i32 @pthread_create(i64*, %struct.pthread_attr_t*, i8* (i8*)*, i8*) {
+  ret i32 0
+}
 
-declare i32 @pthread_cancel(i64)
+define i32 @pthread_cancel(i64) {
+  ret i32 0
+}
 
-declare i32 @pthread_mutex_lock(%struct.pthread_mutex_t*)
+define i32 @pthread_mutex_lock(%struct.pthread_mutex_t*) {
+  ret i32 0
+}
 
-declare i32 @pthread_mutex_trylock(%struct.pthread_mutex_t*)
+define i32 @pthread_mutex_trylock(%struct.pthread_mutex_t*) {
+  ret i32 0
+}
 
-declare i32 @pthread_mutex_unlock(%struct.pthread_mutex_t*)
+define i32 @pthread_mutex_unlock(%struct.pthread_mutex_t*) {
+  ret i32 0
+}
 
-declare i32 @pthread_mutex_init(%struct.pthread_mutex_t*, %struct.Alignment*)
+define i32 @pthread_mutex_init(%struct.pthread_mutex_t*, %struct.Alignment*) {
+  ret i32 0
+}
 
-declare i32 @pthread_key_create(i32*, void (i8*)*)
+define i32 @pthread_key_create(i32*, void (i8*)*) {
+  ret i32 0
+}
 
-declare i32 @pthread_key_delete(i32)
+define i32 @pthread_key_delete(i32) {
+  ret i32 0
+}
 
-declare i32 @pthread_mutexattr_init(%struct.Alignment*)
+define i32 @pthread_mutexattr_init(%struct.Alignment*) {
+  ret i32 0
+}
 
-declare i32 @pthread_mutexattr_settype(%struct.Alignment*, i32)
+define i32 @pthread_mutexattr_settype(%struct.Alignment*, i32) {
+  ret i32 0
+}
 
-declare i32 @pthread_mutexattr_destroy(%struct.Alignment*)
+define i32 @pthread_mutexattr_destroy(%struct.Alignment*) {
+  ret i32 0
+}

diff --git a/test/CodeGen/PowerPC/mcm-9.ll b/test/CodeGen/PowerPC/mcm-9.ll
index e587f61..7906b6a 100644 (file)
--- a/test/CodeGen/PowerPC/mcm-9.ll
+++ b/test/CodeGen/PowerPC/mcm-9.ll
@@ -7,8 +7,7 @@
 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-f128:128:128-v128:128:128-n32:64"
 target triple = "powerpc64-unknown-linux-gnu"
 
-@ei = external global i32
-@a = alias i32* @ei
+@a = external global i32
 
 define signext i32 @test_external() nounwind {
 entry:

diff --git a/test/CodeGen/X86/2007-09-06-ExtWeakAliasee.ll b/test/CodeGen/X86/2007-09-06-ExtWeakAliasee.ll
index c5d2a46..7e37ef5 100644 (file)
--- a/test/CodeGen/X86/2007-09-06-ExtWeakAliasee.ll
+++ b/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/test/CodeGen/X86/2008-03-14-SpillerCrash.ll b/test/CodeGen/X86/2008-03-14-SpillerCrash.ll
index 8946415..18b3714 100644 (file)
--- a/test/CodeGen/X86/2008-03-14-SpillerCrash.ll
+++ b/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/test/CodeGen/X86/alias-error.ll b/test/CodeGen/X86/alias-error.ll
new file mode 100644 (file)
index 0000000..89b0876
--- /dev/null
+++ b/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/test/CodeGen/X86/aliases.ll b/test/CodeGen/X86/aliases.ll
index 025dcfe..d0a262d 100644 (file)
--- a/test/CodeGen/X86/aliases.ll
+++ b/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/test/CodeGen/X86/x86-64-pic-10.ll b/test/CodeGen/X86/x86-64-pic-10.ll
index 3ec172b..da8082b 100644 (file)
--- a/test/CodeGen/X86/x86-64-pic-10.ll
+++ b/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
+}

diff --git a/test/CodeGen/XCore/aliases.ll b/test/CodeGen/XCore/aliases.ll
index d4da63c..b7ad416 100644 (file)
--- a/test/CodeGen/XCore/aliases.ll
+++ b/test/CodeGen/XCore/aliases.ll
@@ -1,7 +1,9 @@
 ; RUN: llc < %s -march=xcore | FileCheck %s
-declare void @a_val() nounwind
-@b_val = external constant i32, section ".cp.rodata"
-@c_val = external global i32
+define void @a_val() nounwind {
+  ret void
+}
+@b_val = constant i32 42, section ".cp.rodata"
+@c_val = global i32 42
 
 @a = alias void ()* @a_val
 @b = alias i32* @b_val