[llvm] [llvm][DebugInfo] Attach object-pointer to DISubprogram declarations (PR #122742)
Michael Buch via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 14 02:47:39 PST 2025
https://github.com/Michael137 updated https://github.com/llvm/llvm-project/pull/122742
>From c1e4faf70993f59734882d9a98024d44eb50d82d Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12 at gmail.com>
Date: Thu, 9 Jan 2025 14:37:41 +0000
Subject: [PATCH 1/2] [llvm][DebugInfo] Attach object-pointer to DISubprogram
declarations
Currently Clang only attaches `DW_AT_object_pointer` to
`DW_TAG_subprogram` definitions. LLDB constructs C++ method
types from their `DW_TAG_subprogram` declaration, which is also
the point at which it needs to determine whether a method is
static or not. LLDB's heuristic for this could be very simple if we
emitted `DW_AT_object_pointer` on declarations. But since we don't,
LLDB has to guess whether an argument is an implicit object parameter
based on the DW_AT_name and DW_AT_type.
To simplify LLDB's job (and to eventually support C++23's explicit
object parameters), this patch adds the `DIFlagObjectPointer` to
`DISubprogram` declarations.
For reference, GCC attaches the object-pointer DIE to both the
definition and declaration: https://godbolt.org/z/3TWjTfWon
Fixes https://github.com/llvm/llvm-project/issues/120973
---
llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp | 13 +++++++++++--
llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h | 4 +++-
llvm/test/DebugInfo/X86/DW_AT_object_pointer.ll | 10 +++++++++-
llvm/test/DebugInfo/X86/dwarf-public-names.ll | 2 +-
4 files changed, 24 insertions(+), 5 deletions(-)
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 0a8a1ad38c959f..d3450b8b0556fd 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -849,7 +849,9 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DIDerivedType *DTy) {
}
}
-void DwarfUnit::constructSubprogramArguments(DIE &Buffer, DITypeRefArray Args) {
+DIE *DwarfUnit::constructSubprogramArguments(DIE &Buffer, DITypeRefArray Args) {
+ // Args[0] is the return type.
+ DIE *ObjectPointer = nullptr;
for (unsigned i = 1, N = Args.size(); i < N; ++i) {
const DIType *Ty = Args[i];
if (!Ty) {
@@ -860,8 +862,14 @@ void DwarfUnit::constructSubprogramArguments(DIE &Buffer, DITypeRefArray Args) {
addType(Arg, Ty);
if (Ty->isArtificial())
addFlag(Arg, dwarf::DW_AT_artificial);
+ if (Ty->isObjectPointer()) {
+ assert(!ObjectPointer && "Can't have more than one object pointer");
+ ObjectPointer = &Arg;
+ }
}
}
+
+ return ObjectPointer;
}
void DwarfUnit::constructTypeDIE(DIE &Buffer, const DISubroutineType *CTy) {
@@ -1358,7 +1366,8 @@ void DwarfUnit::applySubprogramAttributes(const DISubprogram *SP, DIE &SPDie,
// Add arguments. Do not add arguments for subprogram definition. They will
// be handled while processing variables.
- constructSubprogramArguments(SPDie, Args);
+ if (auto *ObjectPointer = constructSubprogramArguments(SPDie, Args))
+ addDIEEntry(SPDie, dwarf::DW_AT_object_pointer, *ObjectPointer);
}
addThrownTypes(SPDie, SP->getThrownTypes());
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index 163205378fb4b6..7a5295d826a483 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -268,7 +268,9 @@ class DwarfUnit : public DIEUnit {
void constructContainingTypeDIEs();
/// Construct function argument DIEs.
- void constructSubprogramArguments(DIE &Buffer, DITypeRefArray Args);
+ ///
+ /// \returns DIE of the object pointer if one exists. Nullptr otherwise.
+ DIE *constructSubprogramArguments(DIE &Buffer, DITypeRefArray Args);
/// Create a DIE with the given Tag, add the DIE to its parent, and
/// call insertDIE if MD is not null.
diff --git a/llvm/test/DebugInfo/X86/DW_AT_object_pointer.ll b/llvm/test/DebugInfo/X86/DW_AT_object_pointer.ll
index d9988ac31451e2..30d4203466766e 100644
--- a/llvm/test/DebugInfo/X86/DW_AT_object_pointer.ll
+++ b/llvm/test/DebugInfo/X86/DW_AT_object_pointer.ll
@@ -5,7 +5,15 @@
; CHECK-NOT: ""
; CHECK: DW_TAG
; CHECK: DW_TAG_class_type
-; CHECK: DW_AT_object_pointer [DW_FORM_ref4] (cu + 0x{{[0-9a-f]*}} => {[[PARAM:0x[0-9a-f]*]]})
+; CHECK: [[DECL:0x[0-9a-f]+]]: DW_TAG_subprogram
+; CHECK: DW_AT_name {{.*}} "A"
+; CHECK: DW_AT_object_pointer [DW_FORM_ref4]
+; CHECK-SAME: (cu + 0x{{[0-9a-f]*}} => {[[DECL_PARAM:0x[0-9a-f]*]]})
+; CHECK: [[DECL_PARAM]]: DW_TAG_formal_parameter
+;
+; CHECK: DW_TAG_subprogram
+; CHECK: DW_AT_specification [DW_FORM_ref4] (cu + {{.*}} => {[[DECL]]}
+; CHECK: DW_AT_object_pointer [DW_FORM_ref4] (cu + 0x{{[0-9a-f]*}} => {[[PARAM:0x[0-9a-f]*]]})
; CHECK: [[PARAM]]: DW_TAG_formal_parameter
; CHECK-NOT: DW_TAG
; CHECK: DW_AT_name [DW_FORM_strp] ( .debug_str[0x{{[0-9a-f]*}}] = "this")
diff --git a/llvm/test/DebugInfo/X86/dwarf-public-names.ll b/llvm/test/DebugInfo/X86/dwarf-public-names.ll
index c2274511d4191f..a484c094892d0c 100644
--- a/llvm/test/DebugInfo/X86/dwarf-public-names.ll
+++ b/llvm/test/DebugInfo/X86/dwarf-public-names.ll
@@ -61,7 +61,7 @@
; Skip the output to the header of the pubnames section.
; LINUX: debug_pubnames
-; LINUX-NEXT: unit_size = 0x00000128
+; LINUX-NEXT: unit_size =
; Check for each name in the output.
; LINUX-DAG: "ns"
>From 05243239d04b85c803780f3d4eaf6bfadd9498de Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12 at gmail.com>
Date: Tue, 14 Jan 2025 10:47:27 +0000
Subject: [PATCH 2/2] fixup! fix nvptx and dwarfdump test
---
llvm/test/DebugInfo/NVPTX/debug-info.ll | 29 ++++++++++++++++++-
.../tools/llvm-dwarfdump/X86/statistics.ll | 4 +--
2 files changed, 30 insertions(+), 3 deletions(-)
diff --git a/llvm/test/DebugInfo/NVPTX/debug-info.ll b/llvm/test/DebugInfo/NVPTX/debug-info.ll
index c926229f96e38b..3e6dd935102ba1 100644
--- a/llvm/test/DebugInfo/NVPTX/debug-info.ll
+++ b/llvm/test/DebugInfo/NVPTX/debug-info.ll
@@ -199,6 +199,8 @@ if.end: ; preds = %if.then, %entry
; CHECK-NEXT:.b8 19 // DW_FORM_ref4
; CHECK-NEXT:.b8 60 // DW_AT_declaration
; CHECK-NEXT:.b8 12 // DW_FORM_flag
+; CHECK-NEXT:.b8 100 // DW_AT_object_pointer
+; CHECK-NEXT:.b8 19 // DW_FORM_ref4
; CHECK-NEXT:.b8 63 // DW_AT_external
; CHECK-NEXT:.b8 12 // DW_FORM_flag
; CHECK-NEXT:.b8 0 // EOM(1)
@@ -223,6 +225,8 @@ if.end: ; preds = %if.then, %entry
; CHECK-NEXT:.b8 11 // DW_FORM_data1
; CHECK-NEXT:.b8 60 // DW_AT_declaration
; CHECK-NEXT:.b8 12 // DW_FORM_flag
+; CHECK-NEXT:.b8 100 // DW_AT_object_pointer
+; CHECK-NEXT:.b8 19 // DW_FORM_ref4
; CHECK-NEXT:.b8 63 // DW_AT_external
; CHECK-NEXT:.b8 12 // DW_FORM_flag
; CHECK-NEXT:.b8 50 // DW_AT_accessibility
@@ -250,6 +254,8 @@ if.end: ; preds = %if.then, %entry
; CHECK-NEXT:.b8 11 // DW_FORM_data1
; CHECK-NEXT:.b8 60 // DW_AT_declaration
; CHECK-NEXT:.b8 12 // DW_FORM_flag
+; CHECK-NEXT:.b8 100 // DW_AT_object_pointer
+; CHECK-NEXT:.b8 19 // DW_FORM_ref4
; CHECK-NEXT:.b8 63 // DW_AT_external
; CHECK-NEXT:.b8 12 // DW_FORM_flag
; CHECK-NEXT:.b8 50 // DW_AT_accessibility
@@ -272,6 +278,8 @@ if.end: ; preds = %if.then, %entry
; CHECK-NEXT:.b8 19 // DW_FORM_ref4
; CHECK-NEXT:.b8 60 // DW_AT_declaration
; CHECK-NEXT:.b8 12 // DW_FORM_flag
+; CHECK-NEXT:.b8 100 // DW_AT_object_pointer
+; CHECK-NEXT:.b8 19 // DW_FORM_ref4
; CHECK-NEXT:.b8 63 // DW_AT_external
; CHECK-NEXT:.b8 12 // DW_FORM_flag
; CHECK-NEXT:.b8 50 // DW_AT_accessibility
@@ -373,6 +381,8 @@ if.end: ; preds = %if.then, %entry
; CHECK-NEXT:.b8 5 // DW_FORM_data2
; CHECK-NEXT:.b8 60 // DW_AT_declaration
; CHECK-NEXT:.b8 12 // DW_FORM_flag
+; CHECK-NEXT:.b8 100 // DW_AT_object_pointer
+; CHECK-NEXT:.b8 19 // DW_FORM_ref4
; CHECK-NEXT:.b8 63 // DW_AT_external
; CHECK-NEXT:.b8 12 // DW_FORM_flag
; CHECK-NEXT:.b8 0 // EOM(1)
@@ -393,6 +403,8 @@ if.end: ; preds = %if.then, %entry
; CHECK-NEXT:.b8 19 // DW_FORM_ref4
; CHECK-NEXT:.b8 60 // DW_AT_declaration
; CHECK-NEXT:.b8 12 // DW_FORM_flag
+; CHECK-NEXT:.b8 100 // DW_AT_object_pointer
+; CHECK-NEXT:.b8 19 // DW_FORM_ref4
; CHECK-NEXT:.b8 63 // DW_AT_external
; CHECK-NEXT:.b8 12 // DW_FORM_flag
; CHECK-NEXT:.b8 0 // EOM(1)
@@ -727,6 +739,21 @@ if.end: ; preds = %if.then, %entry
; CHECK-NEXT:.b8 0 // EOM(2)
; CHECK-NEXT:.b8 45 // Abbreviation Code
; CHECK-NEXT:.b8 46 // DW_TAG_subprogram
+; CHECK-NEXT:.b8 1 // DW_CHILDREN_yes
+; CHECK-NEXT:.b8 3 // DW_AT_name
+; CHECK-NEXT:.b8 8 // DW_FORM_string
+; CHECK-NEXT:.b8 58 // DW_AT_decl_file
+; CHECK-NEXT:.b8 11 // DW_FORM_data1
+; CHECK-NEXT:.b8 59 // DW_AT_decl_line
+; CHECK-NEXT:.b8 5 // DW_FORM_data2
+; CHECK-NEXT:.b8 60 // DW_AT_declaration
+; CHECK-NEXT:.b8 12 // DW_FORM_flag
+; CHECK-NEXT:.b8 63 // DW_AT_external
+; CHECK-NEXT:.b8 12 // DW_FORM_flag
+; CHECK-NEXT:.b8 0 // EOM(1)
+; CHECK-NEXT:.b8 0 // EOM(2)
+; CHECK-NEXT:.b8 46 // Abbreviation Code
+; CHECK-NEXT:.b8 46 // DW_TAG_subprogram
; CHECK-NEXT:.b8 0 // DW_CHILDREN_no
; CHECK-NEXT:.b8 3 // DW_AT_name
; CHECK-NEXT:.b8 8 // DW_FORM_string
@@ -742,7 +769,7 @@ if.end: ; preds = %if.then, %entry
; CHECK-NEXT:.b8 12 // DW_FORM_flag
; CHECK-NEXT:.b8 0 // EOM(1)
; CHECK-NEXT:.b8 0 // EOM(2)
-; CHECK-NEXT:.b8 46 // Abbreviation Code
+; CHECK-NEXT:.b8 47 // Abbreviation Code
; CHECK-NEXT:.b8 46 // DW_TAG_subprogram
; CHECK-NEXT:.b8 1 // DW_CHILDREN_yes
; CHECK-NEXT:.b8 135 // DW_AT_MIPS_linkage_name
diff --git a/llvm/test/tools/llvm-dwarfdump/X86/statistics.ll b/llvm/test/tools/llvm-dwarfdump/X86/statistics.ll
index a454bf14c33532..9f3a00df2ffe75 100644
--- a/llvm/test/tools/llvm-dwarfdump/X86/statistics.ll
+++ b/llvm/test/tools/llvm-dwarfdump/X86/statistics.ll
@@ -55,8 +55,8 @@
; CHECK: "#bytes within functions": [[FUNCSIZE:[0-9]+]]
; CHECK: "#bytes within inlined functions": [[INLINESIZE:[0-9]+]]
; CHECK: "#bytes in __debug_loc": 35,
-; CHECK-NEXT: "#bytes in __debug_abbrev": 384,
-; CHECK-NEXT: "#bytes in __debug_info": 459,
+; CHECK-NEXT: "#bytes in __debug_abbrev": 386,
+; CHECK-NEXT: "#bytes in __debug_info": 463,
; CHECK-NEXT: "#bytes in __debug_str": 231,
; CHECK-NEXT: "#bytes in __apple_names": 348,
; CHECK-NEXT: "#bytes in __apple_objc": 36,
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