[LLVM-3.9] Setup the compile unit information immediately

Since LLVM reversed the order of the debug info graphs, we need to have
a compile unit that exists *before* any functions (`DISubprogram`s) are
created. This allows the LLVM debug info builder to automatically link
the functions to the compile unit.

src/librustc_trans/context.rs

@@ -532,7 +532,9 @@ impl<'tcx> LocalCrateContext<'tcx> {
                                                          &llmod_id[..]);

            let dbg_cx = if shared.tcx.sess.opts.debuginfo != NoDebugInfo {
                Some(debuginfo::CrateDebugContext::new(llmod))
                let dctx = debuginfo::CrateDebugContext::new(llmod);
                debuginfo::metadata::compile_unit_metadata(shared, &dctx, shared.tcx.sess);
                Some(dctx)
            } else {
                None
            };

src/librustc_trans/debuginfo/metadata.rs

@@ -18,7 +18,7 @@ use super::utils::{debug_context, DIB, span_start, bytes_to_bits, size_and_align
                   fn_should_be_ignored, is_node_local_to_unit};
use super::namespace::mangled_name_of_item;
use super::type_names::{compute_debuginfo_type_name, push_debuginfo_type_name};
use super::{declare_local, VariableKind, VariableAccess};
use super::{declare_local, VariableKind, VariableAccess, CrateDebugContext};

use llvm::{self, ValueRef};
use llvm::debuginfo::{DIType, DIFile, DIScope, DIDescriptor, DICompositeType};
@@ -980,14 +980,14 @@ fn pointer_type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
    return ptr_metadata;
}

pub fn compile_unit_metadata(cx: &CrateContext) -> DIDescriptor {
    let work_dir = &cx.sess().working_dir;
    let compile_unit_name = match cx.sess().local_crate_source_file {
        None => fallback_path(cx),
pub fn compile_unit_metadata(scc: &::context::SharedCrateContext, debug_context: &CrateDebugContext, sess: &::session::Session) -> DIDescriptor {
    let work_dir = &sess.working_dir;
    let compile_unit_name = match sess.local_crate_source_file {
        None => fallback_path(scc),
        Some(ref abs_path) => {
            if abs_path.is_relative() {
                cx.sess().warn("debuginfo: Invalid path to crate's local root source file!");
                fallback_path(cx)
                sess.warn("debuginfo: Invalid path to crate's local root source file!");
                fallback_path(scc)
            } else {
                match abs_path.strip_prefix(work_dir) {
                    Ok(ref p) if p.is_relative() => {
@@ -997,7 +997,7 @@ pub fn compile_unit_metadata(cx: &CrateContext) -> DIDescriptor {
                            path2cstr(&Path::new(".").join(p))
                        }
                    }
                    _ => fallback_path(cx)
                    _ => fallback_path(scc)
                }
            }
        }
@@ -1014,19 +1014,19 @@ pub fn compile_unit_metadata(cx: &CrateContext) -> DIDescriptor {
    let split_name = "\0";
    return unsafe {
        llvm::LLVMDIBuilderCreateCompileUnit(
            debug_context(cx).builder,
            debug_context.builder,
            DW_LANG_RUST,
            compile_unit_name,
            work_dir.as_ptr(),
            producer.as_ptr(),
            cx.sess().opts.optimize != config::OptLevel::No,
            sess.opts.optimize != config::OptLevel::No,
            flags.as_ptr() as *const _,
            0,
            split_name.as_ptr() as *const _)
    };

    fn fallback_path(cx: &CrateContext) -> CString {
        CString::new(cx.link_meta().crate_name.clone()).unwrap()
    fn fallback_path(scc: &::context::SharedCrateContext) -> CString {
        CString::new(scc.link_meta().crate_name.clone()).unwrap()
    }
}

src/librustc_trans/debuginfo/mod.rs

@@ -18,7 +18,7 @@ use self::utils::{DIB, span_start, create_DIArray, is_node_local_to_unit};
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::metadata::{file_metadata, scope_metadata, TypeMap};
use self::source_loc::InternalDebugLocation::{self, UnknownLocation};

use llvm;
@@ -50,7 +50,7 @@ pub mod gdb;
mod utils;
mod namespace;
mod type_names;
mod metadata;
pub mod metadata;
mod create_scope_map;
mod source_loc;

@@ -168,7 +168,7 @@ pub fn finalize(cx: &CrateContext) {
    }

    debug!("finalize");
    let _ = compile_unit_metadata(cx);
    //let _ = compile_unit_metadata(cx);

    if gdb::needs_gdb_debug_scripts_section(cx) {
        // Add a .debug_gdb_scripts section to this compile-unit. This will