From 08428aadad19b01f3d3b5a9f8c2247fc5ed50aea Mon Sep 17 00:00:00 2001
From: Rodrigo Tobar <rtobarc@gmail.com>
Date: Thu, 14 Oct 2021 21:36:22 +0800
Subject: [PATCH] LibSymbolication: Skip source position calculation if
 requested

Calculating source code positions can be expensive, and some
applications (like SystemMonitor's Stack tab) don't even show this
information, making these calculations wasteful.

This commit adds a new enumerated flag to the `symbolicate` functions
for callers to specify whether source positions should be included in
the results; it defaults to "Yes" to preserve old behavior for existing
applications.
---
 .../LibSymbolication/Symbolication.cpp        | 23 +++++++++++--------
 .../LibSymbolication/Symbolication.h          |  9 ++++++--
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/Userland/Libraries/LibSymbolication/Symbolication.cpp b/Userland/Libraries/LibSymbolication/Symbolication.cpp
index 50f78acb528..ef883044292 100644
--- a/Userland/Libraries/LibSymbolication/Symbolication.cpp
+++ b/Userland/Libraries/LibSymbolication/Symbolication.cpp
@@ -61,7 +61,7 @@ Optional<FlatPtr> kernel_base()
     return s_kernel_base;
 }
 
-Optional<Symbol> symbolicate(String const& path, FlatPtr address)
+Optional<Symbol> symbolicate(String const& path, FlatPtr address, IncludeSourcePosition include_source_positions)
 {
     String full_path = path;
     if (!path.starts_with('/')) {
@@ -106,16 +106,19 @@ Optional<Symbol> symbolicate(String const& path, FlatPtr address)
 
     u32 offset = 0;
     auto symbol = cached_elf->debug_info->elf().symbolicate(address, &offset);
-    auto source_position_with_inlines = cached_elf->debug_info->get_source_position_with_inlines(address);
 
     Vector<Debug::DebugInfo::SourcePosition> positions;
-    for (auto& position : source_position_with_inlines.inline_chain) {
-        if (!positions.contains_slow(position))
-            positions.append(position);
-    }
+    if (include_source_positions == IncludeSourcePosition::Yes) {
+        auto source_position_with_inlines = cached_elf->debug_info->get_source_position_with_inlines(address);
 
-    if (source_position_with_inlines.source_position.has_value() && !positions.contains_slow(source_position_with_inlines.source_position.value())) {
-        positions.insert(0, source_position_with_inlines.source_position.value());
+        for (auto& position : source_position_with_inlines.inline_chain) {
+            if (!positions.contains_slow(position))
+                positions.append(position);
+        }
+
+        if (source_position_with_inlines.source_position.has_value() && !positions.contains_slow(source_position_with_inlines.source_position.value())) {
+            positions.insert(0, source_position_with_inlines.source_position.value());
+        }
     }
 
     return Symbol {
@@ -127,7 +130,7 @@ Optional<Symbol> symbolicate(String const& path, FlatPtr address)
     };
 }
 
-Vector<Symbol> symbolicate_thread(pid_t pid, pid_t tid)
+Vector<Symbol> symbolicate_thread(pid_t pid, pid_t tid, IncludeSourcePosition include_source_positions)
 {
     struct RegionWithSymbols {
         FlatPtr base { 0 };
@@ -245,7 +248,7 @@ Vector<Symbol> symbolicate_thread(pid_t pid, pid_t tid)
         // However, because the first frame represents the current
         // instruction pointer rather than the return address we don't
         // subtract 1 for that.
-        auto result = symbolicate(found_region->path, adjusted_address - (first_frame ? 0 : 1));
+        auto result = symbolicate(found_region->path, adjusted_address - (first_frame ? 0 : 1), include_source_positions);
         first_frame = false;
         if (!result.has_value()) {
             symbols.append(Symbol {
diff --git a/Userland/Libraries/LibSymbolication/Symbolication.h b/Userland/Libraries/LibSymbolication/Symbolication.h
index 7b5535c4f5c..b52af72487b 100644
--- a/Userland/Libraries/LibSymbolication/Symbolication.h
+++ b/Userland/Libraries/LibSymbolication/Symbolication.h
@@ -20,8 +20,13 @@ struct Symbol {
     bool operator==(Symbol const&) const = default;
 };
 
+enum class IncludeSourcePosition {
+    Yes,
+    No
+};
+
 Optional<FlatPtr> kernel_base();
-Vector<Symbol> symbolicate_thread(pid_t pid, pid_t tid);
-Optional<Symbol> symbolicate(String const& path, FlatPtr address);
+Vector<Symbol> symbolicate_thread(pid_t pid, pid_t tid, IncludeSourcePosition = IncludeSourcePosition::Yes);
+Optional<Symbol> symbolicate(String const& path, FlatPtr address, IncludeSourcePosition = IncludeSourcePosition::Yes);
 
 }