rust/src/librustc_trans/trans/debuginfo/utils.rs

// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// Utility Functions.

use super::{FunctionDebugContext, CrateDebugContext};
use super::namespace::namespace_for_item;
use super::metadata::file_metadata;

use llvm;
use llvm::debuginfo::{DIScope, DISubprogram, DIBuilderRef};
use trans::machine;
use trans::common::{CrateContext, FunctionContext};
use trans::type_::Type;
use middle::pat_util;
use util::nodemap::NodeMap;

use libc::c_uint;
use syntax::codemap::{Span, Pos};
use syntax::{ast, codemap, ast_util};


pub fn contains_nodebug_attribute(attributes: &[ast::Attribute]) -> bool {
    attributes.iter().any(|attr| {
        let meta_item: &ast::MetaItem = &*attr.node.value;
        match meta_item.node {
            ast::MetaWord(ref value) => &value[..] == "no_debug",
            _ => false
        }
    })
}

/// Return codemap::Loc corresponding to the beginning of the span
pub fn span_start(cx: &CrateContext, span: Span) -> codemap::Loc {
    cx.sess().codemap().lookup_char_pos(span.lo)
}

pub fn size_and_align_of(cx: &CrateContext, llvm_type: Type) -> (u64, u64) {
    (machine::llsize_of_alloc(cx, llvm_type), machine::llalign_of_min(cx, llvm_type) as u64)
}

pub fn bytes_to_bits(bytes: u64) -> u64 {
    bytes * 8
}

#[inline]
pub fn debug_context<'a, 'tcx>(cx: &'a CrateContext<'a, 'tcx>)
                           -> &'a CrateDebugContext<'tcx> {
    let debug_context: &'a CrateDebugContext<'tcx> = cx.dbg_cx().as_ref().unwrap();
    debug_context
}

#[inline]
#[allow(non_snake_case)]
pub fn DIB(cx: &CrateContext) -> DIBuilderRef {
    cx.dbg_cx().as_ref().unwrap().builder
}

pub fn fn_should_be_ignored(fcx: &FunctionContext) -> bool {
    match fcx.debug_context {
        FunctionDebugContext::RegularContext(_) => false,
        _ => true
    }
}

pub fn assert_type_for_node_id(cx: &CrateContext,
                           node_id: ast::NodeId,
                           error_reporting_span: Span) {
    if !cx.tcx().node_types().contains_key(&node_id) {
        cx.sess().span_bug(error_reporting_span,
                           "debuginfo: Could not find type for node id!");
    }
}

pub fn get_namespace_and_span_for_item(cx: &CrateContext, def_id: ast::DefId)
                                   -> (DIScope, Span) {
    let containing_scope = namespace_for_item(cx, def_id).scope;
    let definition_span = if def_id.krate == ast::LOCAL_CRATE {
        cx.tcx().map.span(def_id.node)
    } else {
        // For external items there is no span information
        codemap::DUMMY_SP
    };

    (containing_scope, definition_span)
}

// This procedure builds the *scope map* for a given function, which maps any
// given ast::NodeId in the function's AST to the correct DIScope metadata instance.
//
// This builder procedure walks the AST in execution order and keeps track of
// what belongs to which scope, creating DIScope DIEs along the way, and
// introducing *artificial* lexical scope descriptors where necessary. These
// artificial scopes allow GDB to correctly handle name shadowing.
pub fn create_scope_map(cx: &CrateContext,
                        args: &[ast::Arg],
                        fn_entry_block: &ast::Block,
                        fn_metadata: DISubprogram,
                        fn_ast_id: ast::NodeId)
                        -> NodeMap<DIScope> {
    let mut scope_map = NodeMap();

    let def_map = &cx.tcx().def_map;

    struct ScopeStackEntry {
        scope_metadata: DIScope,
        name: Option<ast::Name>
    }

    let mut scope_stack = vec!(ScopeStackEntry { scope_metadata: fn_metadata, name: None });
    scope_map.insert(fn_ast_id, fn_metadata);

    // Push argument identifiers onto the stack so arguments integrate nicely
    // with variable shadowing.
    for arg in args {
        pat_util::pat_bindings(def_map, &*arg.pat, |_, node_id, _, path1| {
            scope_stack.push(ScopeStackEntry { scope_metadata: fn_metadata,
                                               name: Some(path1.node.name) });
            scope_map.insert(node_id, fn_metadata);
        })
    }

    // Clang creates a separate scope for function bodies, so let's do this too.
    with_new_scope(cx,
                   fn_entry_block.span,
                   &mut scope_stack,
                   &mut scope_map,
                   |cx, scope_stack, scope_map| {
        walk_block(cx, fn_entry_block, scope_stack, scope_map);
    });

    return scope_map;


    // local helper functions for walking the AST.
    fn with_new_scope<F>(cx: &CrateContext,
                         scope_span: Span,
                         scope_stack: &mut Vec<ScopeStackEntry> ,
                         scope_map: &mut NodeMap<DIScope>,
                         inner_walk: F) where
        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 file_metadata = file_metadata(cx, &loc.file.name);
        let parent_scope = scope_stack.last().unwrap().scope_metadata;

        let scope_metadata = unsafe {
            llvm::LLVMDIBuilderCreateLexicalBlock(
                DIB(cx),
                parent_scope,
                file_metadata,
                loc.line as c_uint,
                loc.col.to_usize() as c_uint)
        };

        scope_stack.push(ScopeStackEntry { scope_metadata: scope_metadata, name: None });

        inner_walk(cx, scope_stack, scope_map);

        // pop artificial scopes
        while scope_stack.last().unwrap().name.is_some() {
            scope_stack.pop();
        }

        if scope_stack.last().unwrap().scope_metadata != scope_metadata {
            cx.sess().span_bug(scope_span, "debuginfo: Inconsistency in scope management.");
        }

        scope_stack.pop();
    }

    fn walk_block(cx: &CrateContext,
                  block: &ast::Block,
                  scope_stack: &mut Vec<ScopeStackEntry> ,
                  scope_map: &mut NodeMap<DIScope>) {
        scope_map.insert(block.id, scope_stack.last().unwrap().scope_metadata);

        // The interesting things here are statements and the concluding expression.
        for statement in &block.stmts {
            scope_map.insert(ast_util::stmt_id(&**statement),
                             scope_stack.last().unwrap().scope_metadata);

            match statement.node {
                ast::StmtDecl(ref decl, _) =>
                    walk_decl(cx, &**decl, scope_stack, scope_map),
                ast::StmtExpr(ref exp, _) |
                ast::StmtSemi(ref exp, _) =>
                    walk_expr(cx, &**exp, scope_stack, scope_map),
                ast::StmtMac(..) => () // Ignore macros (which should be expanded anyway).
            }
        }

        if let Some(ref exp) = block.expr {
            walk_expr(cx, &**exp, scope_stack, scope_map);
        }
    }

    fn walk_decl(cx: &CrateContext,
                 decl: &ast::Decl,
                 scope_stack: &mut Vec<ScopeStackEntry> ,
                 scope_map: &mut NodeMap<DIScope>) {
        match *decl {
            codemap::Spanned { node: ast::DeclLocal(ref local), .. } => {
                scope_map.insert(local.id, scope_stack.last().unwrap().scope_metadata);

                walk_pattern(cx, &*local.pat, scope_stack, scope_map);

                if let Some(ref exp) = local.init {
                    walk_expr(cx, &**exp, scope_stack, scope_map);
                }
            }
            _ => ()
        }
    }

    fn walk_pattern(cx: &CrateContext,
                    pat: &ast::Pat,
                    scope_stack: &mut Vec<ScopeStackEntry> ,
                    scope_map: &mut NodeMap<DIScope>) {

        let def_map = &cx.tcx().def_map;

        // Unfortunately, we cannot just use pat_util::pat_bindings() or
        // ast_util::walk_pat() here because we have to visit *all* nodes in
        // order to put them into the scope map. The above functions don't do that.
        match pat.node {
            ast::PatIdent(_, ref path1, ref sub_pat_opt) => {

                // Check if this is a binding. If so we need to put it on the
                // scope stack and maybe introduce an artificial scope
                if pat_util::pat_is_binding(def_map, &*pat) {

                    let name = path1.node.name;

                    // LLVM does not properly generate 'DW_AT_start_scope' fields
                    // for variable DIEs. For this reason we have to introduce
                    // an artificial scope at bindings whenever a variable with
                    // the same name is declared in *any* parent scope.
                    //
                    // Otherwise the following error occurs:
                    //
                    // let x = 10;
                    //
                    // do_something(); // 'gdb print x' correctly prints 10
                    //
                    // {
                    //     do_something(); // 'gdb print x' prints 0, because it
                    //                     // already reads the uninitialized 'x'
                    //                     // from the next line...
                    //     let x = 100;
                    //     do_something(); // 'gdb print x' correctly prints 100
                    // }

                    // Is there already a binding with that name?
                    // N.B.: this comparison must be UNhygienic... because
                    // gdb knows nothing about the context, so any two
                    // variables with the same name will cause the problem.
                    let need_new_scope = scope_stack
                        .iter()
                        .any(|entry| entry.name == Some(name));

                    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 file_metadata = file_metadata(cx, &loc.file.name);
                        let parent_scope = scope_stack.last().unwrap().scope_metadata;

                        let scope_metadata = unsafe {
                            llvm::LLVMDIBuilderCreateLexicalBlock(
                                DIB(cx),
                                parent_scope,
                                file_metadata,
                                loc.line as c_uint,
                                loc.col.to_usize() as c_uint)
                        };

                        scope_stack.push(ScopeStackEntry {
                            scope_metadata: scope_metadata,
                            name: Some(name)
                        });

                    } else {
                        // Push a new entry anyway so the name can be found
                        let prev_metadata = scope_stack.last().unwrap().scope_metadata;
                        scope_stack.push(ScopeStackEntry {
                            scope_metadata: prev_metadata,
                            name: Some(name)
                        });
                    }
                }

                scope_map.insert(pat.id, scope_stack.last().unwrap().scope_metadata);

                if let Some(ref sub_pat) = *sub_pat_opt {
                    walk_pattern(cx, &**sub_pat, scope_stack, scope_map);
                }
            }

            ast::PatWild(_) => {
                scope_map.insert(pat.id, scope_stack.last().unwrap().scope_metadata);
            }

            ast::PatEnum(_, ref sub_pats_opt) => {
                scope_map.insert(pat.id, scope_stack.last().unwrap().scope_metadata);

                if let Some(ref sub_pats) = *sub_pats_opt {
                    for p in sub_pats {
                        walk_pattern(cx, &**p, scope_stack, scope_map);
                    }
                }
            }

            ast::PatQPath(..) => {
                scope_map.insert(pat.id, scope_stack.last().unwrap().scope_metadata);
            }

            ast::PatStruct(_, ref field_pats, _) => {
                scope_map.insert(pat.id, scope_stack.last().unwrap().scope_metadata);

                for &codemap::Spanned {
                    node: ast::FieldPat { pat: ref sub_pat, .. },
                    ..
                } in field_pats.iter() {
                    walk_pattern(cx, &**sub_pat, scope_stack, scope_map);
                }
            }

            ast::PatTup(ref sub_pats) => {
                scope_map.insert(pat.id, scope_stack.last().unwrap().scope_metadata);

                for sub_pat in sub_pats {
                    walk_pattern(cx, &**sub_pat, scope_stack, scope_map);
                }
            }

            ast::PatBox(ref sub_pat) | ast::PatRegion(ref sub_pat, _) => {
                scope_map.insert(pat.id, scope_stack.last().unwrap().scope_metadata);
                walk_pattern(cx, &**sub_pat, scope_stack, scope_map);
            }

            ast::PatLit(ref exp) => {
                scope_map.insert(pat.id, scope_stack.last().unwrap().scope_metadata);
                walk_expr(cx, &**exp, scope_stack, scope_map);
            }

            ast::PatRange(ref exp1, ref exp2) => {
                scope_map.insert(pat.id, scope_stack.last().unwrap().scope_metadata);
                walk_expr(cx, &**exp1, scope_stack, scope_map);
                walk_expr(cx, &**exp2, scope_stack, scope_map);
            }

            ast::PatVec(ref front_sub_pats, ref middle_sub_pats, ref back_sub_pats) => {
                scope_map.insert(pat.id, scope_stack.last().unwrap().scope_metadata);

                for sub_pat in front_sub_pats {
                    walk_pattern(cx, &**sub_pat, scope_stack, scope_map);
                }

                if let Some(ref sub_pat) = *middle_sub_pats {
                    walk_pattern(cx, &**sub_pat, scope_stack, scope_map);
                }

                for sub_pat in back_sub_pats {
                    walk_pattern(cx, &**sub_pat, scope_stack, scope_map);
                }
            }

            ast::PatMac(_) => {
                cx.sess().span_bug(pat.span, "debuginfo::create_scope_map() - \
                                              Found unexpanded macro.");
            }
        }
    }

    fn walk_expr(cx: &CrateContext,
                 exp: &ast::Expr,
                 scope_stack: &mut Vec<ScopeStackEntry> ,
                 scope_map: &mut NodeMap<DIScope>) {

        scope_map.insert(exp.id, scope_stack.last().unwrap().scope_metadata);

        match exp.node {
            ast::ExprLit(_)   |
            ast::ExprBreak(_) |
            ast::ExprAgain(_) |
            ast::ExprPath(..) => {}

            ast::ExprCast(ref sub_exp, _)     |
            ast::ExprAddrOf(_, ref sub_exp)  |
            ast::ExprField(ref sub_exp, _) |
            ast::ExprTupField(ref sub_exp, _) |
            ast::ExprParen(ref sub_exp) =>
                walk_expr(cx, &**sub_exp, scope_stack, scope_map),

            ast::ExprBox(ref place, ref sub_expr) => {
                place.as_ref().map(
                    |e| walk_expr(cx, &**e, scope_stack, scope_map));
                walk_expr(cx, &**sub_expr, scope_stack, scope_map);
            }

            ast::ExprRet(ref exp_opt) => match *exp_opt {
                Some(ref sub_exp) => walk_expr(cx, &**sub_exp, scope_stack, scope_map),
                None => ()
            },

            ast::ExprUnary(_, ref sub_exp) => {
                walk_expr(cx, &**sub_exp, scope_stack, scope_map);
            }

            ast::ExprAssignOp(_, ref lhs, ref rhs) |
            ast::ExprIndex(ref lhs, ref rhs) |
            ast::ExprBinary(_, ref lhs, ref rhs)    => {
                walk_expr(cx, &**lhs, scope_stack, scope_map);
                walk_expr(cx, &**rhs, scope_stack, scope_map);
            }

            ast::ExprRange(ref start, ref end) => {
                start.as_ref().map(|e| walk_expr(cx, &**e, scope_stack, scope_map));
                end.as_ref().map(|e| walk_expr(cx, &**e, scope_stack, scope_map));
            }

            ast::ExprVec(ref init_expressions) |
            ast::ExprTup(ref init_expressions) => {
                for ie in init_expressions {
                    walk_expr(cx, &**ie, scope_stack, scope_map);
                }
            }

            ast::ExprAssign(ref sub_exp1, ref sub_exp2) |
            ast::ExprRepeat(ref sub_exp1, ref sub_exp2) => {
                walk_expr(cx, &**sub_exp1, scope_stack, scope_map);
                walk_expr(cx, &**sub_exp2, scope_stack, scope_map);
            }

            ast::ExprIf(ref cond_exp, ref then_block, ref opt_else_exp) => {
                walk_expr(cx, &**cond_exp, scope_stack, scope_map);

                with_new_scope(cx,
                               then_block.span,
                               scope_stack,
                               scope_map,
                               |cx, scope_stack, scope_map| {
                    walk_block(cx, &**then_block, scope_stack, scope_map);
                });

                match *opt_else_exp {
                    Some(ref else_exp) =>
                        walk_expr(cx, &**else_exp, scope_stack, scope_map),
                    _ => ()
                }
            }

            ast::ExprIfLet(..) => {
                cx.sess().span_bug(exp.span, "debuginfo::create_scope_map() - \
                                              Found unexpanded if-let.");
            }

            ast::ExprWhile(ref cond_exp, ref loop_body, _) => {
                walk_expr(cx, &**cond_exp, scope_stack, scope_map);

                with_new_scope(cx,
                               loop_body.span,
                               scope_stack,
                               scope_map,
                               |cx, scope_stack, scope_map| {
                    walk_block(cx, &**loop_body, scope_stack, scope_map);
                })
            }

            ast::ExprWhileLet(..) => {
                cx.sess().span_bug(exp.span, "debuginfo::create_scope_map() - \
                                              Found unexpanded while-let.");
            }

            ast::ExprForLoop(..) => {
                cx.sess().span_bug(exp.span, "debuginfo::create_scope_map() - \
                                              Found unexpanded for loop.");
            }

            ast::ExprMac(_) => {
                cx.sess().span_bug(exp.span, "debuginfo::create_scope_map() - \
                                              Found unexpanded macro.");
            }

            ast::ExprLoop(ref block, _) |
            ast::ExprBlock(ref block)   => {
                with_new_scope(cx,
                               block.span,
                               scope_stack,
                               scope_map,
                               |cx, scope_stack, scope_map| {
                    walk_block(cx, &**block, scope_stack, scope_map);
                })
            }

            ast::ExprClosure(_, ref decl, ref block) => {
                with_new_scope(cx,
                               block.span,
                               scope_stack,
                               scope_map,
                               |cx, scope_stack, scope_map| {
                    for &ast::Arg { pat: ref pattern, .. } in &decl.inputs {
                        walk_pattern(cx, &**pattern, scope_stack, scope_map);
                    }

                    walk_block(cx, &**block, scope_stack, scope_map);
                })
            }

            ast::ExprCall(ref fn_exp, ref args) => {
                walk_expr(cx, &**fn_exp, scope_stack, scope_map);

                for arg_exp in args {
                    walk_expr(cx, &**arg_exp, scope_stack, scope_map);
                }
            }

            ast::ExprMethodCall(_, _, ref args) => {
                for arg_exp in args {
                    walk_expr(cx, &**arg_exp, scope_stack, scope_map);
                }
            }

            ast::ExprMatch(ref discriminant_exp, ref arms, _) => {
                walk_expr(cx, &**discriminant_exp, scope_stack, scope_map);

                // For each arm we have to first walk the pattern as these might
                // introduce new artificial scopes. It should be sufficient to
                // walk only one pattern per arm, as they all must contain the
                // same binding names.

                for arm_ref in arms {
                    let arm_span = arm_ref.pats[0].span;

                    with_new_scope(cx,
                                   arm_span,
                                   scope_stack,
                                   scope_map,
                                   |cx, scope_stack, scope_map| {
                        for pat in &arm_ref.pats {
                            walk_pattern(cx, &**pat, scope_stack, scope_map);
                        }

                        if let Some(ref guard_exp) = arm_ref.guard {
                            walk_expr(cx, &**guard_exp, scope_stack, scope_map)
                        }

                        walk_expr(cx, &*arm_ref.body, scope_stack, scope_map);
                    })
                }
            }

            ast::ExprStruct(_, ref fields, ref base_exp) => {
                for &ast::Field { expr: ref exp, .. } in fields {
                    walk_expr(cx, &**exp, scope_stack, scope_map);
                }

                match *base_exp {
                    Some(ref exp) => walk_expr(cx, &**exp, scope_stack, scope_map),
                    None => ()
                }
            }

            ast::ExprInlineAsm(ast::InlineAsm { ref inputs,
                                                ref outputs,
                                                .. }) => {
                // inputs, outputs: Vec<(String, P<Expr>)>
                for &(_, ref exp) in inputs {
                    walk_expr(cx, &**exp, scope_stack, scope_map);
                }

                for &(_, ref exp, _) in outputs {
                    walk_expr(cx, &**exp, scope_stack, scope_map);
                }
            }
        }
    }
}