From a45b5ccd969443aef7a4afce8bd43d512ca74b1a Mon Sep 17 00:00:00 2001
From: Itamar <itamar8910@gmail.com>
Date: Sat, 19 Jun 2021 12:12:52 +0300
Subject: [PATCH] LibDebug: Add DebugInfo::get_source_position_with_inlines

This function returns the source position of a given address in the
program. If that address exists in an inline chain, then it also returns
the source positions that are in the chain.
---
 Userland/Libraries/LibDebug/DebugInfo.cpp | 75 ++++++++++++++++++++++-
 Userland/Libraries/LibDebug/DebugInfo.h   | 11 +++-
 2 files changed, 84 insertions(+), 2 deletions(-)

diff --git a/Userland/Libraries/LibDebug/DebugInfo.cpp b/Userland/Libraries/LibDebug/DebugInfo.cpp
index cf11542d1b0..3600ef22645 100644
--- a/Userland/Libraries/LibDebug/DebugInfo.cpp
+++ b/Userland/Libraries/LibDebug/DebugInfo.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * Copyright (c) 2020-2021, Itamar S. <itamar8910@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -380,4 +380,77 @@ DebugInfo::SourcePosition DebugInfo::SourcePosition::from_line_info(const Dwarf:
     return { line.file, line.line, { line.address } };
 }
 
+DebugInfo::SourcePositionWithInlines DebugInfo::get_source_position_with_inlines(u32 address) const
+{
+    // If the address is in an "inline chain", this is the inner-most inlined position.
+    auto inner_source_position = get_source_position(address);
+
+    auto die = m_dwarf_info.get_die_at_address(address);
+    if (!die.has_value() || die->tag() == Dwarf::EntryTag::SubroutineType) {
+        // Inline chain is empty
+        return SourcePositionWithInlines { inner_source_position, {} };
+    }
+
+    Vector<SourcePosition> inline_chain;
+
+    auto insert_to_chain = [&](const Dwarf::DIE& die) {
+        auto caller_source_path = get_source_path_of_inline(die);
+        auto caller_line = get_line_of_inline(die);
+
+        if (!caller_source_path.has_value() || !caller_line.has_value()) {
+            return;
+        }
+
+        inline_chain.append({ String::formatted("{}/{}", caller_source_path->directory, caller_source_path->filename), caller_line.value() });
+    };
+
+    while (die->tag() == Dwarf::EntryTag::InlinedSubroutine) {
+        insert_to_chain(*die);
+
+        if (!die->parent_offset().has_value()) {
+            break;
+        }
+
+        auto parent = die->compilation_unit().dwarf_info().get_cached_die_at_offset(die->parent_offset().value());
+        if (!parent.has_value()) {
+            break;
+        }
+        die = *parent;
+    }
+
+    return SourcePositionWithInlines { inner_source_position, inline_chain };
+}
+
+Optional<Dwarf::LineProgram::DirectoryAndFile> DebugInfo::get_source_path_of_inline(const Dwarf::DIE& die) const
+{
+    auto caller_file = die.get_attribute(Dwarf::Attribute::CallFile);
+    if (caller_file.has_value()) {
+        u32 file_index = 0;
+
+        if (caller_file->type == Dwarf::AttributeValue::Type::UnsignedNumber) {
+            file_index = caller_file->data.as_u32;
+        } else if (caller_file->type == Dwarf::AttributeValue::Type::SignedNumber) {
+            // For some reason, the file_index is sometimes stored as a signed number.
+            VERIFY(caller_file->data.as_i32 >= 0);
+            file_index = (u32)caller_file->data.as_i32;
+        } else {
+            return {};
+        }
+
+        return die.compilation_unit().line_program().get_directory_and_file(file_index);
+    }
+    return {};
+}
+
+Optional<uint32_t> DebugInfo::get_line_of_inline(const Dwarf::DIE& die) const
+{
+    auto caller_line = die.get_attribute(Dwarf::Attribute::CallLine);
+    if (!caller_line.has_value())
+        return {};
+
+    if (caller_line->type != Dwarf::AttributeValue::Type::UnsignedNumber)
+        return {};
+    return caller_line.value().data.as_u32;
+}
+
 }
diff --git a/Userland/Libraries/LibDebug/DebugInfo.h b/Userland/Libraries/LibDebug/DebugInfo.h
index 3922729b4a6..2d774539a83 100644
--- a/Userland/Libraries/LibDebug/DebugInfo.h
+++ b/Userland/Libraries/LibDebug/DebugInfo.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * Copyright (c) 2020-2021, Itamar S. <itamar8910@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -95,6 +95,12 @@ public:
 
     Optional<SourcePosition> get_source_position(u32 address) const;
 
+    struct SourcePositionWithInlines {
+        Optional<SourcePosition> source_position;
+        Vector<SourcePosition> inline_chain;
+    };
+    SourcePositionWithInlines get_source_position_with_inlines(u32 address) const;
+
     struct SourcePositionAndAddress {
         String file;
         size_t line;
@@ -115,6 +121,9 @@ private:
     static bool is_variable_tag_supported(const Dwarf::EntryTag& tag);
     void add_type_info_to_variable(const Dwarf::DIE& type_die, const PtraceRegisters& regs, DebugInfo::VariableInfo* parent_variable) const;
 
+    Optional<Dwarf::LineProgram::DirectoryAndFile> get_source_path_of_inline(const Dwarf::DIE&) const;
+    Optional<uint32_t> get_line_of_inline(const Dwarf::DIE&) const;
+
     NonnullOwnPtr<const ELF::Image> m_elf;
     String m_source_root;
     FlatPtr m_base_address { 0 };