From fe533e862cd2d2d65e14970d327365dfe593aa27 Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@fb.com>
Date: Tue, 7 Jun 2022 13:38:35 -0700
Subject: [PATCH] Specify DWARF alignment in bits, not bytes.

In DWARF, alignment of types is specified in bits, as is made clear by the
parameter name `AlignInBits`. However, `rustc` was incorrectly passing a byte
alignment. This commit fixes that.

This was noticed in upstream LLVM when I tried to check in a test consisting of
LLVM IR generated from `rustc` and it triggered assertions [1].

[1]: https://reviews.llvm.org/D126835
---
 compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs | 2 +-
 src/test/codegen/debug-alignment.rs                   | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)
 create mode 100644 src/test/codegen/debug-alignment.rs

diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
index dd3adbf70a6..f5cbbc7ca91 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
@@ -1365,7 +1365,7 @@ pub fn build_global_var_di_node<'ll>(cx: &CodegenCx<'ll, '_>, def_id: DefId, glo
             is_local_to_unit,
             global,
             None,
-            global_align.bytes() as u32,
+            global_align.bits() as u32,
         );
     }
 }
diff --git a/src/test/codegen/debug-alignment.rs b/src/test/codegen/debug-alignment.rs
new file mode 100644
index 00000000000..f6c1062e0fc
--- /dev/null
+++ b/src/test/codegen/debug-alignment.rs
@@ -0,0 +1,8 @@
+// Verifies that DWARF alignment is specified properly.
+//
+// compile-flags: -C debuginfo=2
+#![crate_type = "lib"]
+
+// CHECK: !DIGlobalVariable
+// CHECK: align: 32
+pub static A: u32 = 1;