trans: initial implementation of MIR debuginfo.

Author: eddyb

src/librustc_trans/base.rs

@@ -1276,7 +1276,7 @@ pub fn alloca(cx: Block, ty: Type, name: &str) -> ValueRef {
             return llvm::LLVMGetUndef(ty.ptr_to().to_ref());
         }
     }
-    debuginfo::clear_source_location(cx.fcx);
+    DebugLoc::None.apply(cx.fcx);
     Alloca(cx, ty, name)
 }
 
@@ -1739,7 +1739,7 @@ impl<'blk, 'tcx> FunctionContext<'blk, 'tcx> {
 
         self.build_return_block(ret_cx, ret_debug_loc);
 
-        debuginfo::clear_source_location(self);
+        DebugLoc::None.apply(self);
         self.cleanup();
     }
 

src/librustc_trans/controlflow.rs

@@ -167,11 +167,11 @@ pub fn trans_if<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
         if cv == 1 {
             // if true { .. } [else { .. }]
             bcx = trans_block(bcx, &thn, dest);
-            debuginfo::clear_source_location(bcx.fcx);
+            DebugLoc::None.apply(bcx.fcx);
         } else {
             if let Some(elexpr) = els {
                 bcx = expr::trans_into(bcx, &elexpr, dest);
-                debuginfo::clear_source_location(bcx.fcx);
+                DebugLoc::None.apply(bcx.fcx);
             }
         }
 
@@ -181,7 +181,7 @@ pub fn trans_if<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
     let name = format!("then-block-{}-", thn.id);
     let then_bcx_in = bcx.fcx.new_id_block(&name[..], thn.id);
     let then_bcx_out = trans_block(then_bcx_in, &thn, dest);
-    debuginfo::clear_source_location(bcx.fcx);
+    DebugLoc::None.apply(bcx.fcx);
 
     let cond_source_loc = cond.debug_loc();
 
@@ -204,7 +204,7 @@ pub fn trans_if<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 
     // Clear the source location because it is still set to whatever has been translated
     // right before.
-    debuginfo::clear_source_location(next_bcx.fcx);
+    DebugLoc::None.apply(next_bcx.fcx);
 
     next_bcx
 }

src/librustc_trans/debuginfo/create_scope_map.rs

@@ -8,19 +8,24 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use super::FunctionDebugContext;
 use super::metadata::file_metadata;
-use super::utils::DIB;
+use super::utils::{DIB, span_start};
 
 use llvm;
 use llvm::debuginfo::{DIScope, DISubprogram};
-use common::CrateContext;
+use common::{CrateContext, FunctionContext};
 use rustc::hir::pat_util;
+use rustc::mir::repr::{Mir, ScopeId};
 use rustc::util::nodemap::NodeMap;
 
 use libc::c_uint;
+use std::ptr;
+
 use syntax::codemap::{Span, Pos};
 use syntax::{ast, codemap};
 
+use rustc_data_structures::bitvec::BitVector;
 use rustc::hir::{self, PatKind};
 
 // This procedure builds the *scope map* for a given function, which maps any
@@ -65,6 +70,74 @@ pub fn create_scope_map(cx: &CrateContext,
     return scope_map;
 }
 
+/// Produce 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(fcx: &FunctionContext) -> Vec<DIScope> {
+    let mir = fcx.mir.clone().expect("create_mir_scopes: missing MIR for fn");
+    let mut scopes = vec![ptr::null_mut(); mir.scopes.len()];
+
+    let fn_metadata = match fcx.debug_context {
+        FunctionDebugContext::RegularContext(box ref data) => data.fn_metadata,
+        FunctionDebugContext::DebugInfoDisabled |
+        FunctionDebugContext::FunctionWithoutDebugInfo => {
+            return scopes;
+        }
+    };
+
+    // Find all the scopes with variables defined in them.
+    let mut has_variables = BitVector::new(mir.scopes.len());
+    for var in &mir.var_decls {
+        has_variables.insert(var.scope.index());
+    }
+
+    // Instantiate all scopes.
+    for idx in 0..mir.scopes.len() {
+        let scope = ScopeId::new(idx);
+        make_mir_scope(fcx.ccx, &mir, &has_variables, fn_metadata, scope, &mut scopes);
+    }
+
+    scopes
+}
+
+fn make_mir_scope(ccx: &CrateContext,
+                  mir: &Mir,
+                  has_variables: &BitVector,
+                  fn_metadata: DISubprogram,
+                  scope: ScopeId,
+                  scopes: &mut [DIScope]) {
+    let idx = scope.index();
+    if !scopes[idx].is_null() {
+        return;
+    }
+
+    let scope_data = &mir.scopes[scope];
+    let parent_scope = if let Some(parent) = scope_data.parent_scope {
+        make_mir_scope(ccx, mir, has_variables, fn_metadata, parent, scopes);
+        scopes[parent.index()]
+    } else {
+        // The root is the function itself.
+        scopes[idx] = fn_metadata;
+        return;
+    };
+
+    scopes[idx] = if !has_variables.contains(idx) {
+        // Do not create a DIScope if there are no variables
+        // defined in this MIR Scope, to avoid debuginfo bloat.
+        parent_scope
+    } else {
+        let loc = span_start(ccx, scope_data.span);
+        let file_metadata = file_metadata(ccx, &loc.file.name);
+        unsafe {
+            llvm::LLVMDIBuilderCreateLexicalBlock(
+                DIB(ccx),
+                parent_scope,
+                file_metadata,
+                loc.line as c_uint,
+                loc.col.to_usize() as c_uint)
+        }
+    };
+}
+
 // local helper functions for walking the AST.
 fn with_new_scope<F>(cx: &CrateContext,
                      scope_span: Span,
@@ -74,7 +147,7 @@ fn with_new_scope<F>(cx: &CrateContext,
     F: FnOnce(&CrateContext, &mut Vec<ScopeStackEntry>, &mut NodeMap<DIScope>),
 {
     // Create a new lexical scope and push it onto the stack
-    let loc = cx.sess().codemap().lookup_char_pos(scope_span.lo);
+    let loc = span_start(cx, scope_span);
     let file_metadata = file_metadata(cx, &loc.file.name);
     let parent_scope = scope_stack.last().unwrap().scope_metadata;
 
@@ -199,7 +272,7 @@ fn walk_pattern(cx: &CrateContext,
 
                 if need_new_scope {
                     // Create a new lexical scope and push it onto the stack
-                    let loc = cx.sess().codemap().lookup_char_pos(pat.span.lo);
+                    let loc = span_start(cx, pat.span);
                     let file_metadata = file_metadata(cx, &loc.file.name);
                     let parent_scope = scope_stack.last().unwrap().scope_metadata;
 

src/librustc_trans/debuginfo/mod.rs

@@ -20,7 +20,7 @@ use self::namespace::mangled_name_of_item;
 use self::type_names::compute_debuginfo_type_name;
 use self::metadata::{type_metadata, diverging_type_metadata};
 use self::metadata::{file_metadata, scope_metadata, TypeMap, compile_unit_metadata};
-use self::source_loc::InternalDebugLocation;
+use self::source_loc::InternalDebugLocation::{self, UnknownLocation};
 
 use llvm;
 use llvm::{ModuleRef, ContextRef, ValueRef};
@@ -32,7 +32,7 @@ use rustc::ty::subst::Substs;
 use rustc::hir;
 
 use abi::Abi;
-use common::{NodeIdAndSpan, CrateContext, FunctionContext, Block};
+use common::{NodeIdAndSpan, CrateContext, FunctionContext, Block, BlockAndBuilder};
 use monomorphize::Instance;
 use rustc::ty::{self, Ty};
 use session::config::{self, FullDebugInfo, LimitedDebugInfo, NoDebugInfo};
@@ -55,8 +55,7 @@ mod metadata;
 mod create_scope_map;
 mod source_loc;
 
-pub use self::source_loc::set_source_location;
-pub use self::source_loc::clear_source_location;
+pub use self::create_scope_map::create_mir_scopes;
 pub use self::source_loc::start_emitting_source_locations;
 pub use self::source_loc::get_cleanup_debug_loc_for_ast_node;
 pub use self::source_loc::with_source_location_override;
@@ -218,7 +217,7 @@ pub fn empty_function_debug_context<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>)
     }
 
     // Clear the debug location so we don't assign them in the function prelude.
-    source_loc::set_debug_location(cx, InternalDebugLocation::UnknownLocation);
+    source_loc::set_debug_location(cx, None, UnknownLocation);
     FunctionDebugContext::FunctionWithoutDebugInfo
 }
 
@@ -239,7 +238,7 @@ pub fn create_function_debug_context<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 
     // Clear the debug location so we don't assign them in the function prelude.
     // Do this here already, in case we do an early exit from this function.
-    source_loc::set_debug_location(cx, InternalDebugLocation::UnknownLocation);
+    source_loc::set_debug_location(cx, None, UnknownLocation);
 
     // This can be the case for functions inlined from another crate
     let (containing_scope, span) = get_namespace_and_span_for_item(cx, instance.def);
@@ -425,13 +424,13 @@ pub fn fill_scope_map_for_function<'a, 'tcx>(fcx: &FunctionContext<'a, 'tcx>,
     }
 }
 
-fn declare_local<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
-                             variable_name: ast::Name,
-                             variable_type: Ty<'tcx>,
-                             scope_metadata: DIScope,
-                             variable_access: VariableAccess,
-                             variable_kind: VariableKind,
-                             span: Span) {
+pub fn declare_local<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
+                                 variable_name: ast::Name,
+                                 variable_type: Ty<'tcx>,
+                                 scope_metadata: DIScope,
+                                 variable_access: VariableAccess,
+                                 variable_kind: VariableKind,
+                                 span: Span) {
     let cx: &CrateContext = bcx.ccx();
 
     let filename = span_start(cx, span).file.name.clone();
@@ -465,9 +464,8 @@ fn declare_local<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
                     address_operations.len() as c_uint,
                     argument_index)
             };
-            source_loc::set_debug_location(cx, InternalDebugLocation::new(scope_metadata,
-                                                                          loc.line,
-                                                                          loc.col.to_usize()));
+            source_loc::set_debug_location(cx, None,
+                InternalDebugLocation::new(scope_metadata, loc.line, loc.col.to_usize()));
             unsafe {
                 let debug_loc = llvm::LLVMGetCurrentDebugLocation(cx.raw_builder());
                 let instr = llvm::LLVMDIBuilderInsertDeclareAtEnd(
@@ -491,7 +489,7 @@ fn declare_local<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
                         .get_ref(span)
                         .source_locations_enabled
                         .get());
-            source_loc::set_debug_location(cx, InternalDebugLocation::UnknownLocation);
+            source_loc::set_debug_location(cx, None, UnknownLocation);
         }
         _ => { /* nothing to do */ }
     }
@@ -500,19 +498,17 @@ fn declare_local<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum DebugLoc {
     At(ast::NodeId, Span),
+    ScopeAt(DIScope, Span),
     None
 }
 
 impl DebugLoc {
-    pub fn apply(&self, fcx: &FunctionContext) {
-        match *self {
-            DebugLoc::At(node_id, span) => {
-                source_loc::set_source_location(fcx, node_id, span);
-            }
-            DebugLoc::None => {
-                source_loc::clear_source_location(fcx);
-            }
-        }
+    pub fn apply(self, fcx: &FunctionContext) {
+        source_loc::set_source_location(fcx, None, self);
+    }
+
+    pub fn apply_to_bcx(self, bcx: &BlockAndBuilder) {
+        source_loc::set_source_location(bcx.fcx(), Some(bcx), self);
     }
 }