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Improve debug symbol names to avoid ambiguity and work better with MSVC's debugger

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There are several cases where names of types and functions in the debug info are either ambiguous, or not helpful, such as including ambiguous placeholders (e.g., `{{impl}}`, `{{closure}}` or `dyn _'`) or dropping qualifications (e.g., for dynamic types).

Instead, each debug symbol name should be unique and useful:
* Include disambiguators for anonymous `DefPathDataName` (closures and generators), and unify their formatting when used as a path-qualifier vs item being qualified.
* Qualify the principal trait for dynamic types.
* If there is no principal trait for a dynamic type, emit all other traits instead.
* Respect the `qualified` argument when emitting ref and pointer types.
* For implementations, emit the disambiguator.
* Print const generics when emitting generic parameters or arguments.

Additionally, when targeting MSVC, its debugger treats many command arguments as C++ expressions, even when the argument is defined to be a symbol name. As such names in the debug info need to be more C++-like to be parsed correctly:
* Avoid characters with special meaning (`#`, `[`, `"`, `+`).
* Never start a name with `<` or `{` as this is treated as an operator.
* `>>` is always treated as a right-shift, even when parsing generic arguments (so add a space to avoid this).
* Emit function declarations using C/C++ style syntax (e.g., leading return type).
* Emit arrays as a synthetic `array$<type, size>` type.
* Include a `$` in all synthetic types as this is a legal character for C++, but not Rust (thus we avoid collisions with user types).
This commit is contained in:
Daniel Paoliello 2021-06-24 10:36:28 -07:00
parent 868c702d0c
commit aac8a88552
29 changed files with 855 additions and 357 deletions
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27
compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
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@ -5,7 +5,6 @@ use rustc_codegen_ssa::mir::debuginfo::VariableKind::*;
use self::metadata::{file_metadata, type_metadata, TypeMap};
use self::metadata::{UNKNOWN_COLUMN_NUMBER, UNKNOWN_LINE_NUMBER};
use self::namespace::mangled_name_of_instance;
use self::type_names::compute_debuginfo_type_name;
use self::utils::{create_DIArray, is_node_local_to_unit, DIB};
use crate::abi::FnAbi;
@ -311,10 +310,10 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
llvm::LLVMRustDIBuilderCreateSubroutineType(DIB(self), fn_signature)
};
// Find the enclosing function, in case this is a closure.
let def_key = self.tcx().def_key(def_id);
let mut name = def_key.disambiguated_data.data.to_string();
let mut name = String::new();
type_names::push_item_name(self.tcx(), def_id, false, &mut name);
// Find the enclosing function, in case this is a closure.
let enclosing_fn_def_id = self.tcx().closure_base_def_id(def_id);
// Get_template_parameters() will append a `<...>` clause to the function
@ -428,24 +427,16 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
substs: SubstsRef<'tcx>,
name_to_append_suffix_to: &mut String,
) -> &'ll DIArray {
type_names::push_generic_params(
cx.tcx,
cx.tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), substs),
name_to_append_suffix_to,
);
if substs.types().next().is_none() {
return create_DIArray(DIB(cx), &[]);
}
name_to_append_suffix_to.push('<');
for (i, actual_type) in substs.types().enumerate() {
if i != 0 {
name_to_append_suffix_to.push(',');
}
let actual_type =
cx.tcx.normalize_erasing_regions(ParamEnv::reveal_all(), actual_type);
// Add actual type name to <...> clause of function name
let actual_type_name = compute_debuginfo_type_name(cx.tcx(), actual_type, true);
name_to_append_suffix_to.push_str(&actual_type_name[..]);
}
name_to_append_suffix_to.push('>');
// Again, only create type information if full debuginfo is enabled
let template_params: Vec<_> = if cx.sess().opts.debuginfo == DebugInfo::Full {
let names = get_parameter_names(cx, generics);