[llvm] [BOLT] Add an option to remove pseudo probe sections (PR #218662)

[via llvm-commits]

https://github.com/Thrrreeee created https://github.com/llvm/llvm-project/pull/218662

Add the --remove-pseudo-probes option to strip the `.pseudo_probe` and `.pseudo_probe_desc` sections from the output binary when pseudo-probe metadata is no longer needed after BOLT optimization.

When enabled, this option skips pseudo-probe rewriting and prevents both sections from being emitted, reducing output binary size and avoiding unnecessary metadata processing. The default behavior remains unchanged, preserving pseudo-probe sections unless the option is set to true.

>From f9569520200c05be552dd3d72c854c1bfc2ac36e Mon Sep 17 00:00:00 2001
From: shijinrui <shijinrui at bytedance.com>
Date: Tue, 25 Aug 2026 19:45:41 +0800
Subject: [PATCH] [BOLT] Add an option to remove pseudo probe sections

---
 bolt/lib/Rewrite/RewriteInstance.cpp    | 20 ++++++++++++++++++--
 bolt/test/X86/remove-pseudo-probes.test | 23 +++++++++++++++++++++++
 2 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 bolt/test/X86/remove-pseudo-probes.test

diff --git a/bolt/lib/Rewrite/RewriteInstance.cpp b/bolt/lib/Rewrite/RewriteInstance.cpp
index 4486efe926d01..96b1fbfd6f559 100644
--- a/bolt/lib/Rewrite/RewriteInstance.cpp
+++ b/bolt/lib/Rewrite/RewriteInstance.cpp
@@ -114,6 +114,11 @@ static cl::opt<bool> MergeTextSections(
              "instead of separate .text/.text.cold sections (relocation mode)"),
     cl::init(false), cl::cat(BoltCategory));
 
+static cl::opt<bool> RemovePseudoProbes(
+    "remove-pseudo-probes",
+    cl::desc("remove pseudo probe sections from the output binary"),
+    cl::init(false), cl::cat(BoltOutputCategory));
+
 static cl::opt<std::string>
     BoltID("bolt-id",
            cl::desc("add any string to tag this execution in the "
@@ -345,6 +350,11 @@ cl::opt<RuntimeLibInitHookTarget> RuntimeLibInitHook(
 
 } // namespace opts
 
+static bool shouldRemovePseudoProbeSection(StringRef SectionName) {
+  return opts::RemovePseudoProbes && (SectionName == ".pseudo_probe" ||
+                                      SectionName == ".pseudo_probe_desc");
+}
+
 // FIXME: implement a better way to mark sections for replacement.
 std::vector<std::string> RewriteInstance::DebugSectionsToOverwrite = {
     ".debug_abbrev", ".debug_aranges",  ".debug_line",   ".debug_line_str",
@@ -3843,8 +3853,8 @@ void RewriteInstance::initializeMetadataManager() {
     MetadataManager.registerRewriter(createLinuxKernelRewriter(*BC));
 
   MetadataManager.registerRewriter(createBuildIDRewriter(*BC));
-
-  MetadataManager.registerRewriter(createPseudoProbeRewriter(*BC));
+  if (!opts::RemovePseudoProbes)
+    MetadataManager.registerRewriter(createPseudoProbeRewriter(*BC));
 
   MetadataManager.registerRewriter(createRSeqRewriter(*BC));
 
@@ -5176,6 +5186,8 @@ void RewriteInstance::rewriteNoteSections(ELFObjectFile<ELFT> *File) {
 
   // Write new note sections.
   for (BinarySection &Section : BC->nonAllocatableSections()) {
+    if (shouldRemovePseudoProbeSection(Section.getOutputName()))
+      continue;
     if (Section.getOutputFileOffset() || !Section.getAllocAddress())
       continue;
 
@@ -5258,6 +5270,10 @@ void RewriteInstance::encodeBATSection() {
 template <typename ELFShdrTy>
 bool RewriteInstance::shouldStrip(const ELFShdrTy &Section,
                                   StringRef SectionName) {
+  // Do not emit pseudo probe metadata when its removal is requested.
+  if (shouldRemovePseudoProbeSection(SectionName))
+    return true;
+
   // Strip non-allocatable relocation sections.
   if (!(Section.sh_flags & ELF::SHF_ALLOC) &&
       (Section.sh_type == ELF::SHT_RELA || Section.sh_type == ELF::SHT_CREL))
diff --git a/bolt/test/X86/remove-pseudo-probes.test b/bolt/test/X86/remove-pseudo-probes.test
new file mode 100644
index 0000000000000..da294693a97d2
--- /dev/null
+++ b/bolt/test/X86/remove-pseudo-probes.test
@@ -0,0 +1,23 @@
+## Check that BOLT omits pseudo probe metadata only when requested.
+
+# REQUIRES: system-linux
+
+# RUN: llvm-readelf -SW \
+# RUN:   %S/../../../llvm/test/tools/llvm-profgen/X86/Inputs/noinline-cs-pseudoprobe.perfbin \
+# RUN:   | FileCheck %s --check-prefix=CHECK
+# RUN: llvm-bolt \
+# RUN:   %S/../../../llvm/test/tools/llvm-profgen/X86/Inputs/noinline-cs-pseudoprobe.perfbin \
+# RUN:   -o %t.default
+# RUN: llvm-readelf -SW %t.default | FileCheck %s --check-prefix=CHECK
+# RUN: llvm-bolt \
+# RUN:   %S/../../../llvm/test/tools/llvm-profgen/X86/Inputs/noinline-cs-pseudoprobe.perfbin \
+# RUN:   -o %t.removed --remove-pseudo-probes
+# RUN: llvm-readelf -SW %t.removed | FileCheck %s --check-prefix=CHECK-PROBES
+
+# CHECK-DAG: .pseudo_probe PROGBITS
+# CHECK-DAG: .pseudo_probe_desc PROGBITS
+
+# CHECK-PROBES: Section Headers:
+# CHECK-PROBES-NOT: .pseudo_probe
+# CHECK-PROBES-NOT: .pseudo_probe_desc
+# CHECK-PROBES: Key to Flags: