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| 1 | +From 10b69dde3fd15334ea2382d2dc9e9a261de1afaf Mon Sep 17 00:00:00 2001 |
| 2 | +From: Josh Stone < [email protected]> |
| 3 | +Date: Wed, 3 May 2023 15:52:31 -0700 |
| 4 | +Subject: [PATCH] debuginfo: split method declaration and definition |
| 5 | + |
| 6 | +When we're adding a method to a type DIE, we only want a DW_AT_declaration |
| 7 | +there, because LLVM LTO can't unify type definitions when a child DIE is a |
| 8 | +full subprogram definition. Now the subprogram definition gets added at the |
| 9 | +CU level with a specification link back to the abstract declaration. |
| 10 | +--- |
| 11 | + .../rustc_codegen_llvm/src/debuginfo/mod.rs | 85 +++++++++++-------- |
| 12 | + compiler/rustc_codegen_llvm/src/llvm/ffi.rs | 15 ++++ |
| 13 | + .../rustc_llvm/llvm-wrapper/RustWrapper.cpp | 22 +++++ |
| 14 | + .../issue-109934-lto-debuginfo/Makefile | 12 +++ |
| 15 | + .../issue-109934-lto-debuginfo/lib.rs | 9 ++ |
| 16 | + 5 files changed, 109 insertions(+), 34 deletions(-) |
| 17 | + create mode 100644 tests/run-make/issue-109934-lto-debuginfo/Makefile |
| 18 | + create mode 100644 tests/run-make/issue-109934-lto-debuginfo/lib.rs |
| 19 | + |
| 20 | +diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs |
| 21 | +index 2e9f89f419696..b138b0c0e70a1 100644 |
| 22 | +--- a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs |
| 23 | ++++ b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs |
| 24 | +@@ -322,7 +322,7 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> { |
| 25 | + let tcx = self.tcx; |
| 26 | + |
| 27 | + let def_id = instance.def_id(); |
| 28 | +- let containing_scope = get_containing_scope(self, instance); |
| 29 | ++ let (containing_scope, is_method) = get_containing_scope(self, instance); |
| 30 | + let span = tcx.def_span(def_id); |
| 31 | + let loc = self.lookup_debug_loc(span.lo()); |
| 32 | + let file_metadata = file_metadata(self, &loc.file); |
| 33 | +@@ -378,8 +378,29 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> { |
| 34 | + } |
| 35 | + } |
| 36 | + |
| 37 | +- unsafe { |
| 38 | +- return llvm::LLVMRustDIBuilderCreateFunction( |
| 39 | ++ // When we're adding a method to a type DIE, we only want a DW_AT_declaration there, because |
| 40 | ++ // LLVM LTO can't unify type definitions when a child DIE is a full subprogram definition. |
| 41 | ++ // When we use this `decl` below, the subprogram definition gets created at the CU level |
| 42 | ++ // with a DW_AT_specification pointing back to the type's declaration. |
| 43 | ++ let decl = is_method.then(|| unsafe { |
| 44 | ++ llvm::LLVMRustDIBuilderCreateMethod( |
| 45 | ++ DIB(self), |
| 46 | ++ containing_scope, |
| 47 | ++ name.as_ptr().cast(), |
| 48 | ++ name.len(), |
| 49 | ++ linkage_name.as_ptr().cast(), |
| 50 | ++ linkage_name.len(), |
| 51 | ++ file_metadata, |
| 52 | ++ loc.line, |
| 53 | ++ function_type_metadata, |
| 54 | ++ flags, |
| 55 | ++ spflags & !DISPFlags::SPFlagDefinition, |
| 56 | ++ template_parameters, |
| 57 | ++ ) |
| 58 | ++ }); |
| 59 | ++ |
| 60 | ++ return unsafe { |
| 61 | ++ llvm::LLVMRustDIBuilderCreateFunction( |
| 62 | + DIB(self), |
| 63 | + containing_scope, |
| 64 | + name.as_ptr().cast(), |
| 65 | +@@ -394,9 +415,9 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> { |
| 66 | + spflags, |
| 67 | + maybe_definition_llfn, |
| 68 | + template_parameters, |
| 69 | +- None, |
| 70 | +- ); |
| 71 | +- } |
| 72 | ++ decl, |
| 73 | ++ ) |
| 74 | ++ }; |
| 75 | + |
| 76 | + fn get_function_signature<'ll, 'tcx>( |
| 77 | + cx: &CodegenCx<'ll, 'tcx>, |
| 78 | +@@ -493,14 +514,16 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> { |
| 79 | + names |
| 80 | + } |
| 81 | + |
| 82 | ++ /// Returns a scope, plus `true` if that's a type scope for "class" methods, |
| 83 | ++ /// otherwise `false` for plain namespace scopes. |
| 84 | + fn get_containing_scope<'ll, 'tcx>( |
| 85 | + cx: &CodegenCx<'ll, 'tcx>, |
| 86 | + instance: Instance<'tcx>, |
| 87 | +- ) -> &'ll DIScope { |
| 88 | ++ ) -> (&'ll DIScope, bool) { |
| 89 | + // First, let's see if this is a method within an inherent impl. Because |
| 90 | + // if yes, we want to make the result subroutine DIE a child of the |
| 91 | + // subroutine's self-type. |
| 92 | +- let self_type = cx.tcx.impl_of_method(instance.def_id()).and_then(|impl_def_id| { |
| 93 | ++ if let Some(impl_def_id) = cx.tcx.impl_of_method(instance.def_id()) { |
| 94 | + // If the method does *not* belong to a trait, proceed |
| 95 | + if cx.tcx.trait_id_of_impl(impl_def_id).is_none() { |
| 96 | + let impl_self_ty = cx.tcx.subst_and_normalize_erasing_regions( |
| 97 | +@@ -511,39 +534,33 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> { |
| 98 | + |
| 99 | + // Only "class" methods are generally understood by LLVM, |
| 100 | + // so avoid methods on other types (e.g., `<*mut T>::null`). |
| 101 | +- match impl_self_ty.kind() { |
| 102 | +- ty::Adt(def, ..) if !def.is_box() => { |
| 103 | +- // Again, only create type information if full debuginfo is enabled |
| 104 | +- if cx.sess().opts.debuginfo == DebugInfo::Full |
| 105 | +- && !impl_self_ty.needs_subst() |
| 106 | +- { |
| 107 | +- Some(type_di_node(cx, impl_self_ty)) |
| 108 | +- } else { |
| 109 | +- Some(namespace::item_namespace(cx, def.did())) |
| 110 | +- } |
| 111 | ++ if let ty::Adt(def, ..) = impl_self_ty.kind() && !def.is_box() { |
| 112 | ++ // Again, only create type information if full debuginfo is enabled |
| 113 | ++ if cx.sess().opts.debuginfo == DebugInfo::Full && !impl_self_ty.needs_subst() |
| 114 | ++ { |
| 115 | ++ return (type_di_node(cx, impl_self_ty), true); |
| 116 | ++ } else { |
| 117 | ++ return (namespace::item_namespace(cx, def.did()), false); |
| 118 | + } |
| 119 | +- _ => None, |
| 120 | + } |
| 121 | + } else { |
| 122 | + // For trait method impls we still use the "parallel namespace" |
| 123 | + // strategy |
| 124 | +- None |
| 125 | + } |
| 126 | +- }); |
| 127 | ++ } |
| 128 | + |
| 129 | +- self_type.unwrap_or_else(|| { |
| 130 | +- namespace::item_namespace( |
| 131 | +- cx, |
| 132 | +- DefId { |
| 133 | +- krate: instance.def_id().krate, |
| 134 | +- index: cx |
| 135 | +- .tcx |
| 136 | +- .def_key(instance.def_id()) |
| 137 | +- .parent |
| 138 | +- .expect("get_containing_scope: missing parent?"), |
| 139 | +- }, |
| 140 | +- ) |
| 141 | +- }) |
| 142 | ++ let scope = namespace::item_namespace( |
| 143 | ++ cx, |
| 144 | ++ DefId { |
| 145 | ++ krate: instance.def_id().krate, |
| 146 | ++ index: cx |
| 147 | ++ .tcx |
| 148 | ++ .def_key(instance.def_id()) |
| 149 | ++ .parent |
| 150 | ++ .expect("get_containing_scope: missing parent?"), |
| 151 | ++ }, |
| 152 | ++ ); |
| 153 | ++ (scope, false) |
| 154 | + } |
| 155 | + } |
| 156 | + |
| 157 | +diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs |
| 158 | +index c95148013eb74..1f98d91c32054 100644 |
| 159 | +--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs |
| 160 | ++++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs |
| 161 | +@@ -1987,6 +1987,21 @@ extern "C" { |
| 162 | + Decl: Option<&'a DIDescriptor>, |
| 163 | + ) -> &'a DISubprogram; |
| 164 | + |
| 165 | ++ pub fn LLVMRustDIBuilderCreateMethod<'a>( |
| 166 | ++ Builder: &DIBuilder<'a>, |
| 167 | ++ Scope: &'a DIDescriptor, |
| 168 | ++ Name: *const c_char, |
| 169 | ++ NameLen: size_t, |
| 170 | ++ LinkageName: *const c_char, |
| 171 | ++ LinkageNameLen: size_t, |
| 172 | ++ File: &'a DIFile, |
| 173 | ++ LineNo: c_uint, |
| 174 | ++ Ty: &'a DIType, |
| 175 | ++ Flags: DIFlags, |
| 176 | ++ SPFlags: DISPFlags, |
| 177 | ++ TParam: &'a DIArray, |
| 178 | ++ ) -> &'a DISubprogram; |
| 179 | ++ |
| 180 | + pub fn LLVMRustDIBuilderCreateBasicType<'a>( |
| 181 | + Builder: &DIBuilder<'a>, |
| 182 | + Name: *const c_char, |
| 183 | +diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp |
| 184 | +index cadb6b1e23fe9..49acd71b3e106 100644 |
| 185 | +--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp |
| 186 | ++++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp |
| 187 | +@@ -831,6 +831,28 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateFunction( |
| 188 | + return wrap(Sub); |
| 189 | + } |
| 190 | + |
| 191 | ++extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateMethod( |
| 192 | ++ LLVMRustDIBuilderRef Builder, LLVMMetadataRef Scope, |
| 193 | ++ const char *Name, size_t NameLen, |
| 194 | ++ const char *LinkageName, size_t LinkageNameLen, |
| 195 | ++ LLVMMetadataRef File, unsigned LineNo, |
| 196 | ++ LLVMMetadataRef Ty, LLVMRustDIFlags Flags, |
| 197 | ++ LLVMRustDISPFlags SPFlags, LLVMMetadataRef TParam) { |
| 198 | ++ DITemplateParameterArray TParams = |
| 199 | ++ DITemplateParameterArray(unwrap<MDTuple>(TParam)); |
| 200 | ++ DISubprogram::DISPFlags llvmSPFlags = fromRust(SPFlags); |
| 201 | ++ DINode::DIFlags llvmFlags = fromRust(Flags); |
| 202 | ++ DISubprogram *Sub = Builder->createMethod( |
| 203 | ++ unwrapDI<DIScope>(Scope), |
| 204 | ++ StringRef(Name, NameLen), |
| 205 | ++ StringRef(LinkageName, LinkageNameLen), |
| 206 | ++ unwrapDI<DIFile>(File), LineNo, |
| 207 | ++ unwrapDI<DISubroutineType>(Ty), |
| 208 | ++ 0, 0, nullptr, // VTable params aren't used |
| 209 | ++ llvmFlags, llvmSPFlags, TParams); |
| 210 | ++ return wrap(Sub); |
| 211 | ++} |
| 212 | ++ |
| 213 | + extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateBasicType( |
| 214 | + LLVMRustDIBuilderRef Builder, const char *Name, size_t NameLen, |
| 215 | + uint64_t SizeInBits, unsigned Encoding) { |
| 216 | +diff --git a/tests/run-make/issue-109934-lto-debuginfo/Makefile b/tests/run-make/issue-109934-lto-debuginfo/Makefile |
| 217 | +new file mode 100644 |
| 218 | +index 0000000000000..3b7a99d3dbc62 |
| 219 | +--- /dev/null |
| 220 | ++++ b/tests/run-make/issue-109934-lto-debuginfo/Makefile |
| 221 | +@@ -0,0 +1,12 @@ |
| 222 | ++# ignore-cross-compile |
| 223 | ++include ../tools.mk |
| 224 | ++ |
| 225 | ++# With the upgrade to LLVM 16, this was getting: |
| 226 | ++# |
| 227 | ++# error: Cannot represent a difference across sections |
| 228 | ++# |
| 229 | ++# The error stemmed from DI function definitions under type scopes, fixed by |
| 230 | ++# only declaring in type scope and defining the subprogram elsewhere. |
| 231 | ++ |
| 232 | ++all: |
| 233 | ++ $(RUSTC) lib.rs --test -C lto=fat -C debuginfo=2 -C incremental=$(TMPDIR)/inc-fat |
| 234 | +diff --git a/tests/run-make/issue-109934-lto-debuginfo/lib.rs b/tests/run-make/issue-109934-lto-debuginfo/lib.rs |
| 235 | +new file mode 100644 |
| 236 | +index 0000000000000..c405928bd1824 |
| 237 | +--- /dev/null |
| 238 | ++++ b/tests/run-make/issue-109934-lto-debuginfo/lib.rs |
| 239 | +@@ -0,0 +1,9 @@ |
| 240 | ++extern crate alloc; |
| 241 | ++ |
| 242 | ++#[cfg(test)] |
| 243 | ++mod tests { |
| 244 | ++ #[test] |
| 245 | ++ fn something_alloc() { |
| 246 | ++ assert_eq!(Vec::<u32>::new(), Vec::<u32>::new()); |
| 247 | ++ } |
| 248 | ++} |
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