Auto merge of #115139 - cjgillot:llvm-fragment, r=nikic

Do not forget to pass DWARF fragment information to LLVM.

Fixes https://github.com/rust-lang/rust/issues/115113 for the rustc part

1 files changed, 28 insertions, 9 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
index 564b5da32cc..526c16a59de 100644
--- a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
@@ -435,9 +435,23 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             bx.store(place.llval, alloca.llval, alloca.align);
 
             // Point the debug info to `*alloca` for the current variable
-            bx.dbg_var_addr(dbg_var, dbg_loc, alloca.llval, Size::ZERO, &[Size::ZERO], None);
+            bx.dbg_var_addr(
+                dbg_var,
+                dbg_loc,
+                alloca.llval,
+                Size::ZERO,
+                &[Size::ZERO],
+                var.fragment,
+            );
         } else {
-            bx.dbg_var_addr(dbg_var, dbg_loc, base.llval, direct_offset, &indirect_offsets, None);
+            bx.dbg_var_addr(
+                dbg_var,
+                dbg_loc,
+                base.llval,
+                direct_offset,
+                &indirect_offsets,
+                var.fragment,
+            );
         }
     }
 
@@ -560,17 +574,22 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         }
 
                         let place = fragment.contents;
+                        let fragment = if fragment_layout.size == Size::ZERO {
+                            // Fragment is a ZST, so does not represent anything.
+                            continue;
+                        } else if fragment_layout.size == var_layout.size {
+                            // Fragment covers entire variable, so as far as
+                            // DWARF is concerned, it's not really a fragment.
+                            None
+                        } else {
+                            Some(fragment_start..fragment_start + fragment_layout.size)
+                        };
+
                         per_local[place.local].push(PerLocalVarDebugInfo {
                             name: var.name,
                             source_info: var.source_info,
                             dbg_var,
-                            fragment: if fragment_layout.size == var_layout.size {
-                                // Fragment covers entire variable, so as far as
-                                // DWARF is concerned, it's not really a fragment.
-                                None
-                            } else {
-                                Some(fragment_start..fragment_start + fragment_layout.size)
-                            },
+                            fragment,
                             projection: place.projection,
                         });
                     }