[llvm] [BOLT] Simple hugify fixes and refactoring (PR #202609)

[via llvm-commits]

https://github.com/DmitriiMartynov updated https://github.com/llvm/llvm-project/pull/202609

>From efab4bd96f2d7d0a1548a274e60cd62a9222ecd0 Mon Sep 17 00:00:00 2001
From: Dmitrii Martynov <martynovdmitryvladimirovich at yandex.ru>
Date: Tue, 5 May 2026 09:25:41 -0400
Subject: [PATCH] [BOLT] hugify: macro constants instead of hardcoded values

All hardcoded values have been replaced with macro constants defined
in bolt/runtime/common.h to improve code readability.
---
 bolt/runtime/common.h   |  5 +++++
 bolt/runtime/hugify.cpp | 25 +++++++++++--------------
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/bolt/runtime/common.h b/bolt/runtime/common.h
index 8689bc8b72041..8547cad2c7a6d 100644
--- a/bolt/runtime/common.h
+++ b/bolt/runtime/common.h
@@ -64,6 +64,11 @@ typedef int int32_t;
 
 #define MAP_FAILED ((void *)-1)
 
+#define MADV_HUGEPAGE 14 /* Worth backing with hugepages */
+
+/* set the state of the "THP disable" flags for the calling thread */
+#define PR_SET_THP_DISABLE 41
+
 #define SEEK_SET 0 /* Seek from beginning of file.  */
 #define SEEK_CUR 1 /* Seek from current position.  */
 #define SEEK_END 2 /* Seek from end of file.  */
diff --git a/bolt/runtime/hugify.cpp b/bolt/runtime/hugify.cpp
index de896307f24fc..34edf3cb1d03b 100644
--- a/bolt/runtime/hugify.cpp
+++ b/bolt/runtime/hugify.cpp
@@ -64,8 +64,8 @@ static void getKernelVersion(uint32_t *Val) {
 static bool hasPagecacheTHPSupport() {
   char Buf[64];
 
-  int FD = __open("/sys/kernel/mm/transparent_hugepage/enabled",
-                  0 /* O_RDONLY */, 0);
+  const int FD =
+      __open("/sys/kernel/mm/transparent_hugepage/enabled", O_RDONLY, 0);
   if (FD < 0)
     return false;
 
@@ -98,11 +98,10 @@ static bool hasPagecacheTHPSupport() {
 static void hugifyForOldKernel(uint8_t *From, uint8_t *To) {
   const size_t Size = To - From;
 
-  uint8_t *Mem = reinterpret_cast<uint8_t *>(
-      __mmap(0, Size, 0x3 /* PROT_READ | PROT_WRITE */,
-             0x22 /* MAP_PRIVATE | MAP_ANONYMOUS */, -1, 0));
+  void *Mem = __mmap(0, Size, PROT_READ | PROT_WRITE,
+                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 
-  if (Mem == ((void *)-1) /* MAP_FAILED */) {
+  if (Mem == MAP_FAILED) {
     char Msg[] = "[hugify] could not allocate memory for text move\n";
     reportError(Msg, sizeof(Msg));
   }
@@ -114,19 +113,17 @@ static void hugifyForOldKernel(uint8_t *From, uint8_t *To) {
   // Copy the hot code to a temporary location.
   memcpy(Mem, From, Size);
 
-  __prctl(41 /* PR_SET_THP_DISABLE */, 0, 0, 0, 0);
+  __prctl(PR_SET_THP_DISABLE, 0, 0, 0, 0);
   // Maps out the existing hot code.
-  if (__mmap(reinterpret_cast<uint64_t>(From), Size,
-             0x3 /* PROT_READ | PROT_WRITE */,
-             0x32 /* MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE */, -1,
-             0) == ((void *)-1) /*MAP_FAILED*/) {
+  if (__mmap(reinterpret_cast<uint64_t>(From), Size, PROT_READ | PROT_WRITE,
+             MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0) == MAP_FAILED) {
     char Msg[] =
         "[hugify] failed to mmap memory for large page move terminating\n";
     reportError(Msg, sizeof(Msg));
   }
 
   // Mark the hot code page to be huge page.
-  if (__madvise(From, Size, 14 /* MADV_HUGEPAGE */) == -1) {
+  if (__madvise(From, Size, MADV_HUGEPAGE) == -1) {
     char Msg[] = "[hugify] setting MADV_HUGEPAGE is failed\n";
     reportError(Msg, sizeof(Msg));
   }
@@ -135,7 +132,7 @@ static void hugifyForOldKernel(uint8_t *From, uint8_t *To) {
   memcpy(From, Mem, Size);
 
   // Change permission back to read-only, ignore failure
-  __mprotect(From, Size, 0x5 /* PROT_READ | PROT_EXEC */);
+  __mprotect(From, Size, PROT_READ | PROT_EXEC);
 
   __munmap(Mem, Size);
 }
@@ -161,7 +158,7 @@ extern "C" void __bolt_hugify_self_impl() {
     return;
   }
 
-  if (__madvise(From, (To - From), 14 /* MADV_HUGEPAGE */) == -1) {
+  if (__madvise(From, (To - From), MADV_HUGEPAGE) == -1) {
     char Msg[] = "[hugify] failed to allocate large page\n";
     // TODO: allow user to control the failure behavior.
     reportError(Msg, sizeof(Msg));