Special case aliases in GlobalValue::getAlignment.

An alias has the address of what it points to, so it also has the same
alignment.

This allows a few optimizations to see past aliases for free.

llvm-svn: 208103

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/AArch64/global-alignment.ll b/llvm/test/CodeGen/AArch64/global-alignment.ll
index 24e6618e98b..36b74e5a57c 100644
--- a/llvm/test/CodeGen/AArch64/global-alignment.ll
+++ b/llvm/test/CodeGen/AArch64/global-alignment.ll
@@ -4,6 +4,7 @@
 @var32 = global [3 x i32] zeroinitializer
 @var64 = global [3 x i64] zeroinitializer
 @var32_align64 = global [3 x i32] zeroinitializer, align 8
+@alias = alias [3 x i32]* @var32_align64
 
 define i64 @test_align32() {
 ; CHECK-LABEL: test_align32:
@@ -47,6 +48,19 @@ define i64 @test_var32_align64() {
   ret i64 %val
 }
 
+define i64 @test_var32_alias() {
+; CHECK-LABEL: test_var32_alias:
+  %addr = bitcast [3 x i32]* @alias to i64*
+
+  ; Test that we can find the alignment for aliases.
+  %val = load i64* %addr
+; CHECK: adrp x[[HIBITS:[0-9]+]], alias
+; CHECK-NOT: add x[[HIBITS]]
+; CHECK: ldr x0, [x[[HIBITS]], {{#?}}:lo12:alias]
+
+  ret i64 %val
+}
+
 @yet_another_var = external global {i32, i32}
 
 define i64 @test_yet_another_var() {