Auto merge of #68965 - eddyb:mir-inline-scope, r=nagisa,oli-obk

 rustc_mir: track inlined callees in SourceScopeData.

We now record which MIR scopes are the roots of *other* (inlined) functions's scope trees, which allows us to generate the correct debuginfo in codegen, similar to what LLVM inlining generates.
This PR makes the `ui` test `backtrace-debuginfo` pass, if the MIR inliner is turned on by default.

Also, `#[track_caller]` is now correct in the face of MIR inlining (cc `@anp).`

Fixes #76997.

r? `@rust-lang/wg-mir-opt`

compiler/rustc_codegen_llvm/src/builder.rs

@@ -56,6 +56,7 @@ impl BackendTypes for Builder<'_, 'll, 'tcx> {
     type Funclet = <CodegenCx<'ll, 'tcx> as BackendTypes>::Funclet;
 
     type DIScope = <CodegenCx<'ll, 'tcx> as BackendTypes>::DIScope;
+    type DILocation = <CodegenCx<'ll, 'tcx> as BackendTypes>::DILocation;
     type DIVariable = <CodegenCx<'ll, 'tcx> as BackendTypes>::DIVariable;
 }
 

compiler/rustc_codegen_llvm/src/common.rs

@@ -80,13 +80,15 @@ impl Funclet<'ll> {
 
 impl BackendTypes for CodegenCx<'ll, 'tcx> {
     type Value = &'ll Value;
+    // FIXME(eddyb) replace this with a `Function` "subclass" of `Value`.
     type Function = &'ll Value;
 
     type BasicBlock = &'ll BasicBlock;
     type Type = &'ll Type;
     type Funclet = Funclet<'ll>;
 
     type DIScope = &'ll llvm::debuginfo::DIScope;
+    type DILocation = &'ll llvm::debuginfo::DILocation;
     type DIVariable = &'ll llvm::debuginfo::DIVariable;
 }
 

compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs

@@ -3,21 +3,26 @@ use super::utils::DIB;
 use rustc_codegen_ssa::mir::debuginfo::{DebugScope, FunctionDebugContext};
 use rustc_codegen_ssa::traits::*;
 
+use crate::abi::FnAbi;
 use crate::common::CodegenCx;
 use crate::llvm;
-use crate::llvm::debuginfo::{DIScope, DISubprogram};
+use crate::llvm::debuginfo::{DILocation, DIScope};
 use rustc_middle::mir::{Body, SourceScope};
+use rustc_middle::ty::layout::FnAbiExt;
+use rustc_middle::ty::{self, Instance};
 use rustc_session::config::DebugInfo;
 
 use rustc_index::bit_set::BitSet;
 use rustc_index::vec::Idx;
 
 /// Produces DIScope DIEs for each MIR Scope which has variables defined in it.
+// FIXME(eddyb) almost all of this should be in `rustc_codegen_ssa::mir::debuginfo`.
 pub fn compute_mir_scopes(
-    cx: &CodegenCx<'ll, '_>,
-    mir: &Body<'_>,
-    fn_metadata: &'ll DISubprogram,
-    debug_context: &mut FunctionDebugContext<&'ll DIScope>,
+    cx: &CodegenCx<'ll, 'tcx>,
+    instance: Instance<'tcx>,
+    mir: &Body<'tcx>,
+    fn_dbg_scope: &'ll DIScope,
+    debug_context: &mut FunctionDebugContext<&'ll DIScope, &'ll DILocation>,
 ) {
     // Find all the scopes with variables defined in them.
     let mut has_variables = BitSet::new_empty(mir.source_scopes.len());
@@ -37,58 +42,82 @@ pub fn compute_mir_scopes(
     // Instantiate all scopes.
     for idx in 0..mir.source_scopes.len() {
         let scope = SourceScope::new(idx);
-        make_mir_scope(cx, &mir, fn_metadata, &has_variables, debug_context, scope);
+        make_mir_scope(cx, instance, &mir, fn_dbg_scope, &has_variables, debug_context, scope);
     }
 }
 
 fn make_mir_scope(
-    cx: &CodegenCx<'ll, '_>,
-    mir: &Body<'_>,
-    fn_metadata: &'ll DISubprogram,
+    cx: &CodegenCx<'ll, 'tcx>,
+    instance: Instance<'tcx>,
+    mir: &Body<'tcx>,
+    fn_dbg_scope: &'ll DIScope,
     has_variables: &BitSet<SourceScope>,
-    debug_context: &mut FunctionDebugContext<&'ll DISubprogram>,
+    debug_context: &mut FunctionDebugContext<&'ll DIScope, &'ll DILocation>,
     scope: SourceScope,
 ) {
-    if debug_context.scopes[scope].is_valid() {
+    if debug_context.scopes[scope].dbg_scope.is_some() {
         return;
     }
 
     let scope_data = &mir.source_scopes[scope];
     let parent_scope = if let Some(parent) = scope_data.parent_scope {
-        make_mir_scope(cx, mir, fn_metadata, has_variables, debug_context, parent);
+        make_mir_scope(cx, instance, mir, fn_dbg_scope, has_variables, debug_context, parent);
         debug_context.scopes[parent]
     } else {
         // The root is the function itself.
         let loc = cx.lookup_debug_loc(mir.span.lo());
         debug_context.scopes[scope] = DebugScope {
-            scope_metadata: Some(fn_metadata),
+            dbg_scope: Some(fn_dbg_scope),
+            inlined_at: None,
             file_start_pos: loc.file.start_pos,
             file_end_pos: loc.file.end_pos,
         };
         return;
     };
 
-    if !has_variables.contains(scope) {
-        // Do not create a DIScope if there are no variables
-        // defined in this MIR Scope, to avoid debuginfo bloat.
+    if !has_variables.contains(scope) && scope_data.inlined.is_none() {
+        // Do not create a DIScope if there are no variables defined in this
+        // MIR `SourceScope`, and it's not `inlined`, to avoid debuginfo bloat.
         debug_context.scopes[scope] = parent_scope;
         return;
     }
 
     let loc = cx.lookup_debug_loc(scope_data.span.lo());
-    let file_metadata = file_metadata(cx, &loc.file, debug_context.defining_crate);
+    let file_metadata = file_metadata(cx, &loc.file);
 
-    let scope_metadata = unsafe {
-        Some(llvm::LLVMRustDIBuilderCreateLexicalBlock(
-            DIB(cx),
-            parent_scope.scope_metadata.unwrap(),
-            file_metadata,
-            loc.line.unwrap_or(UNKNOWN_LINE_NUMBER),
-            loc.col.unwrap_or(UNKNOWN_COLUMN_NUMBER),
-        ))
+    let dbg_scope = match scope_data.inlined {
+        Some((callee, _)) => {
+            // FIXME(eddyb) this would be `self.monomorphize(&callee)`
+            // if this is moved to `rustc_codegen_ssa::mir::debuginfo`.
+            let callee = cx.tcx.subst_and_normalize_erasing_regions(
+                instance.substs,
+                ty::ParamEnv::reveal_all(),
+                &callee,
+            );
+            let callee_fn_abi = FnAbi::of_instance(cx, callee, &[]);
+            cx.dbg_scope_fn(callee, &callee_fn_abi, None)
+        }
+        None => unsafe {
+            llvm::LLVMRustDIBuilderCreateLexicalBlock(
+                DIB(cx),
+                parent_scope.dbg_scope.unwrap(),
+                file_metadata,
+                loc.line.unwrap_or(UNKNOWN_LINE_NUMBER),
+                loc.col.unwrap_or(UNKNOWN_COLUMN_NUMBER),
+            )
+        },
     };
+
+    let inlined_at = scope_data.inlined.map(|(_, callsite_span)| {
+        // FIXME(eddyb) this doesn't account for the macro-related
+        // `Span` fixups that `rustc_codegen_ssa::mir::debuginfo` does.
+        let callsite_scope = parent_scope.adjust_dbg_scope_for_span(cx, callsite_span);
+        cx.dbg_loc(callsite_scope, parent_scope.inlined_at, callsite_span)
+    });
+
     debug_context.scopes[scope] = DebugScope {
-        scope_metadata,
+        dbg_scope: Some(dbg_scope),
+        inlined_at: inlined_at.or(parent_scope.inlined_at),
         file_start_pos: loc.file.start_pos,
         file_end_pos: loc.file.end_pos,
     };

compiler/rustc_codegen_llvm/src/debuginfo/doc.rs

@@ -28,7 +28,7 @@
 //! utilizing a cache. The way to get a shared metadata node when needed is
 //! thus to just call the corresponding function in this module:
 //!
-//!     let file_metadata = file_metadata(crate_context, path);
+//!     let file_metadata = file_metadata(cx, file);
 //!
 //! The function will take care of probing the cache for an existing node for
 //! that exact file path.

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -26,7 +26,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_fs_util::path_to_c_string;
 use rustc_hir::def::CtorKind;
-use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
+use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_middle::ich::NodeIdHashingMode;
 use rustc_middle::mir::interpret::truncate;
@@ -760,16 +760,12 @@ fn hex_encode(data: &[u8]) -> String {
     hex_string
 }
 
-pub fn file_metadata(
-    cx: &CodegenCx<'ll, '_>,
-    source_file: &SourceFile,
-    defining_crate: CrateNum,
-) -> &'ll DIFile {
-    debug!("file_metadata: file_name: {}, defining_crate: {}", source_file.name, defining_crate);
+pub fn file_metadata(cx: &CodegenCx<'ll, '_>, source_file: &SourceFile) -> &'ll DIFile {
+    debug!("file_metadata: file_name: {}", source_file.name);
 
     let hash = Some(&source_file.src_hash);
     let file_name = Some(source_file.name.to_string());
-    let directory = if defining_crate == LOCAL_CRATE {
+    let directory = if source_file.is_real_file() && !source_file.is_imported() {
         Some(cx.sess().working_dir.0.to_string_lossy().to_string())
     } else {
         // If the path comes from an upstream crate we assume it has been made
@@ -1835,7 +1831,7 @@ impl<'tcx> VariantInfo<'_, 'tcx> {
                 if !span.is_dummy() {
                     let loc = cx.lookup_debug_loc(span.lo());
                     return Some(SourceInfo {
-                        file: file_metadata(cx, &loc.file, def_id.krate),
+                        file: file_metadata(cx, &loc.file),
                         line: loc.line.unwrap_or(UNKNOWN_LINE_NUMBER),
                     });
                 }
@@ -2474,7 +2470,7 @@ pub fn create_global_var_metadata(cx: &CodegenCx<'ll, '_>, def_id: DefId, global
 
     let (file_metadata, line_number) = if !span.is_dummy() {
         let loc = cx.lookup_debug_loc(span.lo());
-        (file_metadata(cx, &loc.file, LOCAL_CRATE), loc.line)
+        (file_metadata(cx, &loc.file), loc.line)
     } else {
         (unknown_file_metadata(cx), None)
     };
@@ -2576,9 +2572,8 @@ pub fn create_vtable_metadata(cx: &CodegenCx<'ll, 'tcx>, ty: Ty<'tcx>, vtable: &
 pub fn extend_scope_to_file(
     cx: &CodegenCx<'ll, '_>,
     scope_metadata: &'ll DIScope,
-    file: &rustc_span::SourceFile,
-    defining_crate: CrateNum,
+    file: &SourceFile,
 ) -> &'ll DILexicalBlock {
-    let file_metadata = file_metadata(cx, &file, defining_crate);
+    let file_metadata = file_metadata(cx, file);
     unsafe { llvm::LLVMRustDIBuilderCreateLexicalBlockFile(DIB(cx), scope_metadata, file_metadata) }
 }