From 39f924a7315470da26d293fa4e6ecfedbf982828 Mon Sep 17 00:00:00 2001
From: Brian Gianforcaro <bgianf@serenityos.org>
Date: Thu, 31 Mar 2022 00:07:06 -0700
Subject: [PATCH] LibELF: Skip DynamicObject::dump() if logging isn't enabled

I noticed that we were populating this StringBuilder and then throwing
away the result while profiling `true` with UserSpace emulator.

Before:

    courage:~ $ time -n 1000 true
    Timing report: 3454 ms
    ==============
    Command:         true
    Average time:    3.45 ms (median: 3, stddev: 3.42, min: 0, max:11)
    Excluding first: 3.45 ms (median: 3, stddev: 3.42, min: 0, max:11)

After:

    courage:~ $ time -n 1000 true
    Timing report: 3308 ms
    ==============
    Command:         true
    Average time:    3.30 ms (median: 3, stddev: 3.28, min: 0, max:12)
    Excluding first: 3.30 ms (median: 3, stddev: 3.29, min: 0, max:12)
---
 Userland/Libraries/LibELF/DynamicObject.cpp | 34 +++++++++++----------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/Userland/Libraries/LibELF/DynamicObject.cpp b/Userland/Libraries/LibELF/DynamicObject.cpp
index f56b1b6aea..22ec378e7d 100644
--- a/Userland/Libraries/LibELF/DynamicObject.cpp
+++ b/Userland/Libraries/LibELF/DynamicObject.cpp
@@ -39,25 +39,27 @@ DynamicObject::~DynamicObject()
 
 void DynamicObject::dump() const
 {
-    StringBuilder builder;
-    builder.append("\nd_tag      tag_name         value\n");
-    size_t num_dynamic_sections = 0;
+    if constexpr (DYNAMIC_LOAD_DEBUG) {
+        StringBuilder builder;
+        builder.append("\nd_tag      tag_name         value\n");
+        size_t num_dynamic_sections = 0;
 
-    for_each_dynamic_entry([&](const DynamicObject::DynamicEntry& entry) {
-        String name_field = String::formatted("({})", name_for_dtag(entry.tag()));
-        builder.appendff("{:#08x} {:17} {:#08x}\n", entry.tag(), name_field, entry.val());
-        num_dynamic_sections++;
-    });
+        for_each_dynamic_entry([&](const DynamicObject::DynamicEntry& entry) {
+            String name_field = String::formatted("({})", name_for_dtag(entry.tag()));
+            builder.appendff("{:#08x} {:17} {:#08x}\n", entry.tag(), name_field, entry.val());
+            num_dynamic_sections++;
+        });
 
-    if (m_has_soname)
-        builder.appendff("DT_SONAME: {}\n", soname()); // FIXME: Validate that this string is null terminated?
-    if (m_has_rpath)
-        builder.appendff("DT_RPATH: {}\n", rpath());
-    if (m_has_runpath)
-        builder.appendff("DT_RUNPATH: {}\n", runpath());
+        if (m_has_soname)
+            builder.appendff("DT_SONAME: {}\n", soname()); // FIXME: Validate that this string is null terminated?
+        if (m_has_rpath)
+            builder.appendff("DT_RPATH: {}\n", rpath());
+        if (m_has_runpath)
+            builder.appendff("DT_RUNPATH: {}\n", runpath());
 
-    dbgln_if(DYNAMIC_LOAD_DEBUG, "Dynamic section at address {} contains {} entries:", m_dynamic_address.as_ptr(), num_dynamic_sections);
-    dbgln_if(DYNAMIC_LOAD_DEBUG, "{}", builder.string_view());
+        dbgln("Dynamic section at address {} contains {} entries:", m_dynamic_address.as_ptr(), num_dynamic_sections);
+        dbgln("{}", builder.string_view());
+    }
 }
 
 void DynamicObject::parse()