Merge pull request #18874 from lnicola/sync-from-rust

minor: Sync from downstream

4 files changed, 86 insertions, 41 deletions

diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/dwarf_const.rs b/compiler/rustc_codegen_llvm/src/debuginfo/dwarf_const.rs
new file mode 100644
index 00000000000..40842915222
--- /dev/null
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/dwarf_const.rs
@@ -0,0 +1,37 @@
+//! Definitions of various DWARF-related constants.
+
+use libc::c_uint;
+
+/// Helper macro to let us redeclare gimli's constants as our own constants
+/// with a different type, with less risk of copy-paste errors.
+macro_rules! declare_constant {
+    (
+        $name:ident : $type:ty
+    ) => {
+        #[allow(non_upper_case_globals)]
+        pub(crate) const $name: $type = ::gimli::constants::$name.0 as $type;
+
+        // Assert that as-cast probably hasn't changed the value.
+        const _: () = assert!($name as i128 == ::gimli::constants::$name.0 as i128);
+    };
+}
+
+declare_constant!(DW_TAG_const_type: c_uint);
+
+// DWARF languages.
+declare_constant!(DW_LANG_Rust: c_uint);
+
+// DWARF attribute type encodings.
+declare_constant!(DW_ATE_boolean: c_uint);
+declare_constant!(DW_ATE_float: c_uint);
+declare_constant!(DW_ATE_signed: c_uint);
+declare_constant!(DW_ATE_unsigned: c_uint);
+declare_constant!(DW_ATE_UTF: c_uint);
+
+// DWARF expression operators.
+declare_constant!(DW_OP_deref: u64);
+declare_constant!(DW_OP_plus_uconst: u64);
+/// Defined by LLVM in `llvm/include/llvm/BinaryFormat/Dwarf.h`.
+/// Double-checked by a static assertion in `RustWrapper.cpp`.
+#[allow(non_upper_case_globals)]
+pub(crate) const DW_OP_LLVM_fragment: u64 = 0x1000;
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
index 40248a9009a..88e43e1c678 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
@@ -22,6 +22,7 @@ use rustc_target::spec::DebuginfoKind;
 use smallvec::smallvec;
 use tracing::{debug, instrument};
 
+pub(crate) use self::type_map::TypeMap;
 use self::type_map::{DINodeCreationResult, Stub, UniqueTypeId};
 use super::CodegenUnitDebugContext;
 use super::namespace::mangled_name_of_instance;
@@ -30,6 +31,7 @@ use super::utils::{
     DIB, create_DIArray, debug_context, get_namespace_for_item, is_node_local_to_unit,
 };
 use crate::common::{AsCCharPtr, CodegenCx};
+use crate::debuginfo::dwarf_const;
 use crate::debuginfo::metadata::type_map::build_type_with_children;
 use crate::debuginfo::utils::{WidePtrKind, wide_pointer_kind};
 use crate::llvm::debuginfo::{
@@ -59,20 +61,6 @@ impl fmt::Debug for llvm::Metadata {
     }
 }
 
-// From DWARF 5.
-// See http://www.dwarfstd.org/ShowIssue.php?issue=140129.1.
-const DW_LANG_RUST: c_uint = 0x1c;
-#[allow(non_upper_case_globals)]
-const DW_ATE_boolean: c_uint = 0x02;
-#[allow(non_upper_case_globals)]
-const DW_ATE_float: c_uint = 0x04;
-#[allow(non_upper_case_globals)]
-const DW_ATE_signed: c_uint = 0x05;
-#[allow(non_upper_case_globals)]
-const DW_ATE_unsigned: c_uint = 0x07;
-#[allow(non_upper_case_globals)]
-const DW_ATE_UTF: c_uint = 0x10;
-
 pub(super) const UNKNOWN_LINE_NUMBER: c_uint = 0;
 pub(super) const UNKNOWN_COLUMN_NUMBER: c_uint = 0;
 
@@ -87,8 +75,6 @@ type SmallVec<T> = smallvec::SmallVec<[T; 16]>;
 mod enums;
 mod type_map;
 
-pub(crate) use type_map::TypeMap;
-
 /// Returns from the enclosing function if the type debuginfo node with the given
 /// unique ID can be found in the type map.
 macro_rules! return_if_di_node_created_in_meantime {
@@ -519,7 +505,7 @@ fn recursion_marker_type_di_node<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>) -> &'ll D
                 name.as_c_char_ptr(),
                 name.len(),
                 cx.tcx.data_layout.pointer_size.bits(),
-                DW_ATE_unsigned,
+                dwarf_const::DW_ATE_unsigned,
             )
         }
     })
@@ -778,6 +764,8 @@ fn build_basic_type_di_node<'ll, 'tcx>(
     // .natvis visualizers (and perhaps other existing native debuggers?)
     let cpp_like_debuginfo = cpp_like_debuginfo(cx.tcx);
 
+    use dwarf_const::{DW_ATE_UTF, DW_ATE_boolean, DW_ATE_float, DW_ATE_signed, DW_ATE_unsigned};
+
     let (name, encoding) = match t.kind() {
         ty::Never => ("!", DW_ATE_unsigned),
         ty::Tuple(elements) if elements.is_empty() => {
@@ -958,7 +946,7 @@ pub(crate) fn build_compile_unit_di_node<'ll, 'tcx>(
 
         let unit_metadata = llvm::LLVMRustDIBuilderCreateCompileUnit(
             debug_context.builder,
-            DW_LANG_RUST,
+            dwarf_const::DW_LANG_Rust,
             compile_unit_file,
             producer.as_c_char_ptr(),
             producer.len(),
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs
index 23e11748e52..a72e205c9b2 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs
@@ -12,6 +12,7 @@ use rustc_middle::ty::{self, AdtDef, CoroutineArgs, CoroutineArgsExt, Ty};
 use smallvec::smallvec;
 
 use crate::common::{AsCCharPtr, CodegenCx};
+use crate::debuginfo::dwarf_const::DW_TAG_const_type;
 use crate::debuginfo::metadata::enums::DiscrResult;
 use crate::debuginfo::metadata::type_map::{self, Stub, UniqueTypeId};
 use crate::debuginfo::metadata::{
@@ -566,22 +567,39 @@ fn build_variant_struct_wrapper_type_di_node<'ll, 'tcx>(
                 None,
             ));
 
-            let build_assoc_const =
-                |name: &str, type_di_node: &'ll DIType, value: u64, align: Align| unsafe {
-                    llvm::LLVMRustDIBuilderCreateStaticMemberType(
-                        DIB(cx),
-                        wrapper_struct_type_di_node,
-                        name.as_c_char_ptr(),
-                        name.len(),
-                        unknown_file_metadata(cx),
-                        UNKNOWN_LINE_NUMBER,
-                        type_di_node,
-                        DIFlags::FlagZero,
-                        Some(cx.const_u64(value)),
-                        align.bits() as u32,
-                    )
+            let build_assoc_const = |name: &str,
+                                     type_di_node_: &'ll DIType,
+                                     value: u64,
+                                     align: Align| unsafe {
+                // FIXME: Currently we force all DISCR_* values to be u64's as LLDB seems to have
+                // problems inspecting other value types. Since DISCR_* is typically only going to be
+                // directly inspected via the debugger visualizer - which compares it to the `tag` value
+                // (whose type is not modified at all) it shouldn't cause any real problems.
+                let (t_di, align) = if name == ASSOC_CONST_DISCR_NAME {
+                    (type_di_node_, align.bits() as u32)
+                } else {
+                    let ty_u64 = Ty::new_uint(cx.tcx, ty::UintTy::U64);
+                    (type_di_node(cx, ty_u64), Align::EIGHT.bits() as u32)
                 };
 
+                // must wrap type in a `const` modifier for LLDB to be able to inspect the value of the member
+                let field_type =
+                    llvm::LLVMRustDIBuilderCreateQualifiedType(DIB(cx), DW_TAG_const_type, t_di);
+
+                llvm::LLVMRustDIBuilderCreateStaticMemberType(
+                    DIB(cx),
+                    wrapper_struct_type_di_node,
+                    name.as_c_char_ptr(),
+                    name.len(),
+                    unknown_file_metadata(cx),
+                    UNKNOWN_LINE_NUMBER,
+                    field_type,
+                    DIFlags::FlagZero,
+                    Some(cx.const_u64(value)),
+                    align,
+                )
+            };
+
             // We also always have an associated constant for the discriminant value
             // of the variant.
             fields.push(build_assoc_const(
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
index fae698bea2a..755f4816acf 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
@@ -39,6 +39,7 @@ use crate::llvm::debuginfo::{
 use crate::value::Value;
 
 mod create_scope_map;
+mod dwarf_const;
 mod gdb;
 pub(crate) mod metadata;
 mod namespace;
@@ -47,6 +48,10 @@ mod utils;
 use self::create_scope_map::compute_mir_scopes;
 pub(crate) use self::metadata::build_global_var_di_node;
 
+// FIXME(Zalathar): These `DW_TAG_*` constants are fake values that were
+// removed from LLVM in 2015, and are only used by our own `RustWrapper.cpp`
+// to decide which C++ API to call. Instead, we should just have two separate
+// FFI functions and choose the correct one on the Rust side.
 #[allow(non_upper_case_globals)]
 const DW_TAG_auto_variable: c_uint = 0x100;
 #[allow(non_upper_case_globals)]
@@ -152,29 +157,26 @@ impl<'ll> DebugInfoBuilderMethods for Builder<'_, 'll, '_> {
         indirect_offsets: &[Size],
         fragment: Option<Range<Size>>,
     ) {
+        use dwarf_const::{DW_OP_LLVM_fragment, DW_OP_deref, DW_OP_plus_uconst};
+
         // Convert the direct and indirect offsets and fragment byte range to address ops.
-        // FIXME(eddyb) use `const`s instead of getting the values via FFI,
-        // the values should match the ones in the DWARF standard anyway.
-        let op_deref = || unsafe { llvm::LLVMRustDIBuilderCreateOpDeref() };
-        let op_plus_uconst = || unsafe { llvm::LLVMRustDIBuilderCreateOpPlusUconst() };
-        let op_llvm_fragment = || unsafe { llvm::LLVMRustDIBuilderCreateOpLLVMFragment() };
         let mut addr_ops = SmallVec::<[u64; 8]>::new();
 
         if direct_offset.bytes() > 0 {
-            addr_ops.push(op_plus_uconst());
+            addr_ops.push(DW_OP_plus_uconst);
             addr_ops.push(direct_offset.bytes() as u64);
         }
         for &offset in indirect_offsets {
-            addr_ops.push(op_deref());
+            addr_ops.push(DW_OP_deref);
             if offset.bytes() > 0 {
-                addr_ops.push(op_plus_uconst());
+                addr_ops.push(DW_OP_plus_uconst);
                 addr_ops.push(offset.bytes() as u64);
             }
         }
         if let Some(fragment) = fragment {
             // `DW_OP_LLVM_fragment` takes as arguments the fragment's
             // offset and size, both of them in bits.
-            addr_ops.push(op_llvm_fragment());
+            addr_ops.push(DW_OP_LLVM_fragment);
             addr_ops.push(fragment.start.bits() as u64);
             addr_ops.push((fragment.end - fragment.start).bits() as u64);
         }