Auto merge of #65718 - eddyb:codegen-var-debuginfo, r=nikomatsakis

rustc_codegen_ssa: introduce MIR VarDebugInfo, but only for codegen.

These are all the codegen changes necessary for #56231.

The refactors were performed locally to codegen, and in several steps, to ease reviewing and avoid introducing changes in behavior (as I'm not sure our debuginfo tests cover enough).

r? @michaelwoerister cc @nagisa @rkruppe @oli-obk

1 files changed, 21 insertions, 37 deletions

diff --git a/src/librustc_codegen_llvm/debuginfo/create_scope_map.rs b/src/librustc_codegen_llvm/debuginfo/create_scope_map.rs
index bdb7467a101..6ee76b71fce 100644
--- a/src/librustc_codegen_llvm/debuginfo/create_scope_map.rs
+++ b/src/librustc_codegen_llvm/debuginfo/create_scope_map.rs
@@ -1,4 +1,4 @@
-use rustc_codegen_ssa::debuginfo::{FunctionDebugContext, FunctionDebugContextData, MirDebugScope};
+use rustc_codegen_ssa::mir::debuginfo::{FunctionDebugContext, DebugScope};
 use super::metadata::file_metadata;
 use super::utils::{DIB, span_start};
 
@@ -12,34 +12,20 @@ use libc::c_uint;
 use syntax_pos::Pos;
 
 use rustc_index::bit_set::BitSet;
-use rustc_index::vec::{Idx, IndexVec};
-
-use syntax_pos::BytePos;
+use rustc_index::vec::Idx;
 
 /// Produces DIScope DIEs for each MIR Scope which has variables defined in it.
-/// If debuginfo is disabled, the returned vector is empty.
-pub fn create_mir_scopes(
+pub fn compute_mir_scopes(
     cx: &CodegenCx<'ll, '_>,
     mir: &Body<'_>,
-    debug_context: &FunctionDebugContext<&'ll DISubprogram>,
-) -> IndexVec<SourceScope, MirDebugScope<&'ll DIScope>> {
-    let null_scope = MirDebugScope {
-        scope_metadata: None,
-        file_start_pos: BytePos(0),
-        file_end_pos: BytePos(0)
-    };
-    let mut scopes = IndexVec::from_elem(null_scope, &mir.source_scopes);
-
-    let debug_context = match *debug_context {
-        FunctionDebugContext::RegularContext(ref data) => data,
-        FunctionDebugContext::DebugInfoDisabled |
-        FunctionDebugContext::FunctionWithoutDebugInfo => {
-            return scopes;
-        }
-    };
-
+    fn_metadata: &'ll DISubprogram,
+    debug_context: &mut FunctionDebugContext<&'ll DIScope>,
+) {
     // Find all the scopes with variables defined in them.
     let mut has_variables = BitSet::new_empty(mir.source_scopes.len());
+    // FIXME(eddyb) base this on `decl.name`, or even better, on debuginfo.
+    // FIXME(eddyb) take into account that arguments always have debuginfo,
+    // irrespective of their name (assuming full debuginfo is enabled).
     for var in mir.vars_iter() {
         let decl = &mir.local_decls[var];
         has_variables.insert(decl.visibility_scope);
@@ -48,31 +34,29 @@ pub fn create_mir_scopes(
     // Instantiate all scopes.
     for idx in 0..mir.source_scopes.len() {
         let scope = SourceScope::new(idx);
-        make_mir_scope(cx, &mir, &has_variables, debug_context, scope, &mut scopes);
+        make_mir_scope(cx, &mir, fn_metadata, &has_variables, debug_context, scope);
     }
-
-    scopes
 }
 
 fn make_mir_scope(cx: &CodegenCx<'ll, '_>,
                   mir: &Body<'_>,
+                  fn_metadata: &'ll DISubprogram,
                   has_variables: &BitSet<SourceScope>,
-                  debug_context: &FunctionDebugContextData<&'ll DISubprogram>,
-                  scope: SourceScope,
-                  scopes: &mut IndexVec<SourceScope, MirDebugScope<&'ll DIScope>>) {
-    if scopes[scope].is_valid() {
+                  debug_context: &mut FunctionDebugContext<&'ll DISubprogram>,
+                  scope: SourceScope) {
+    if debug_context.scopes[scope].is_valid() {
         return;
     }
 
     let scope_data = &mir.source_scopes[scope];
     let parent_scope = if let Some(parent) = scope_data.parent_scope {
-        make_mir_scope(cx, mir, has_variables, debug_context, parent, scopes);
-        scopes[parent]
+        make_mir_scope(cx, mir, fn_metadata, has_variables, debug_context, parent);
+        debug_context.scopes[parent]
     } else {
         // The root is the function itself.
         let loc = span_start(cx, mir.span);
-        scopes[scope] = MirDebugScope {
-            scope_metadata: Some(debug_context.fn_metadata),
+        debug_context.scopes[scope] = DebugScope {
+            scope_metadata: Some(fn_metadata),
             file_start_pos: loc.file.start_pos,
             file_end_pos: loc.file.end_pos,
         };
@@ -86,8 +70,8 @@ fn make_mir_scope(cx: &CodegenCx<'ll, '_>,
         // However, we don't skip creating a nested scope if
         // our parent is the root, because we might want to
         // put arguments in the root and not have shadowing.
-        if parent_scope.scope_metadata.unwrap() != debug_context.fn_metadata {
-            scopes[scope] = parent_scope;
+        if parent_scope.scope_metadata.unwrap() != fn_metadata {
+            debug_context.scopes[scope] = parent_scope;
             return;
         }
     }
@@ -105,7 +89,7 @@ fn make_mir_scope(cx: &CodegenCx<'ll, '_>,
             loc.line as c_uint,
             loc.col.to_usize() as c_uint))
     };
-    scopes[scope] = MirDebugScope {
+    debug_context.scopes[scope] = DebugScope {
         scope_metadata,
         file_start_pos: loc.file.start_pos,
         file_end_pos: loc.file.end_pos,