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Include debug info for the allocator shim

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Issue Details:
In some cases it is necessary to generate an "allocator shim" to forward various Rust allocation functions (e.g., `__rust_alloc`) to an underlying function (e.g., `malloc`). However, since this allocator shim is a manually created LLVM module it is not processed via the normal module processing code and so no debug info is generated for it (if debugging info is enabled).

Fix Details:
* Modify the `debuginfo` code to allow creating debug info for a module without a `CodegenCx` (since it is difficult, and expensive, to create one just to emit some debug info).
* After creating the allocator shim add in basic debug info.
This commit is contained in:
Daniel Paoliello 2021-08-31 11:16:10 -07:00
parent 6cfa773583
commit 77a96ed564
5 changed files with 66 additions and 41 deletions
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72
compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
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@ -29,6 +29,7 @@ use rustc_middle::ty::layout::HasTyCtxt;
use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
use rustc_middle::ty::{self, Instance, ParamEnv, Ty, TypeFoldable};
use rustc_session::config::{self, DebugInfo};
use rustc_session::Session;
use rustc_span::symbol::Symbol;
use rustc_span::{self, BytePos, Pos, SourceFile, SourceFileAndLine, Span};
use rustc_target::abi::{LayoutOf, Primitive, Size};
@ -95,45 +96,52 @@ impl<'a, 'tcx> CrateDebugContext<'a, 'tcx> {
composite_types_completed: Default::default(),
}
}
pub fn finalize(&self, sess: &Session) {
unsafe {
llvm::LLVMRustDIBuilderFinalize(self.builder);
// Debuginfo generation in LLVM by default uses a higher
// version of dwarf than macOS currently understands. We can
// instruct LLVM to emit an older version of dwarf, however,
// for macOS to understand. For more info see #11352
// This can be overridden using --llvm-opts -dwarf-version,N.
// Android has the same issue (#22398)
if let Some(version) = sess.target.dwarf_version {
llvm::LLVMRustAddModuleFlag(self.llmod, "Dwarf Version\0".as_ptr().cast(), version)
}
// Indicate that we want CodeView debug information on MSVC
if sess.target.is_like_msvc {
llvm::LLVMRustAddModuleFlag(self.llmod, "CodeView\0".as_ptr().cast(), 1)
}
// Prevent bitcode readers from deleting the debug info.
let ptr = "Debug Info Version\0".as_ptr();
llvm::LLVMRustAddModuleFlag(
self.llmod,
ptr.cast(),
llvm::LLVMRustDebugMetadataVersion(),
);
}
}
}
/// Creates any deferred debug metadata nodes
pub fn finalize(cx: &CodegenCx<'_, '_>) {
if cx.dbg_cx.is_none() {
return;
}
if let Some(dbg_cx) = &cx.dbg_cx {
debug!("finalize");
debug!("finalize");
if gdb::needs_gdb_debug_scripts_section(cx) {
// Add a .debug_gdb_scripts section to this compile-unit. This will
// cause GDB to try and load the gdb_load_rust_pretty_printers.py file,
// which activates the Rust pretty printers for binary this section is
// contained in.
gdb::get_or_insert_gdb_debug_scripts_section_global(cx);
}
unsafe {
llvm::LLVMRustDIBuilderFinalize(DIB(cx));
// Debuginfo generation in LLVM by default uses a higher
// version of dwarf than macOS currently understands. We can
// instruct LLVM to emit an older version of dwarf, however,
// for macOS to understand. For more info see #11352
// This can be overridden using --llvm-opts -dwarf-version,N.
// Android has the same issue (#22398)
if let Some(version) = cx.sess().target.dwarf_version {
llvm::LLVMRustAddModuleFlag(cx.llmod, "Dwarf Version\0".as_ptr().cast(), version)
if gdb::needs_gdb_debug_scripts_section(cx) {
// Add a .debug_gdb_scripts section to this compile-unit. This will
// cause GDB to try and load the gdb_load_rust_pretty_printers.py file,
// which activates the Rust pretty printers for binary this section is
// contained in.
gdb::get_or_insert_gdb_debug_scripts_section_global(cx);
}
// Indicate that we want CodeView debug information on MSVC
if cx.sess().target.is_like_msvc {
llvm::LLVMRustAddModuleFlag(cx.llmod, "CodeView\0".as_ptr().cast(), 1)
}
// Prevent bitcode readers from deleting the debug info.
let ptr = "Debug Info Version\0".as_ptr();
llvm::LLVMRustAddModuleFlag(cx.llmod, ptr.cast(), llvm::LLVMRustDebugMetadataVersion());
};
dbg_cx.finalize(cx.sess());
}
}
impl DebugInfoBuilderMethods for Builder<'a, 'll, 'tcx> {