[compiler-rt] [builtins] Update HAVE_SYSCONF configure check to adapt CMake [NFC] (PR #79847)

[via llvm-commits]

https://github.com/piggynl updated https://github.com/llvm/llvm-project/pull/79847

>From 17103cc4339886c2cfdc6d24a69d7dd78068f8ba Mon Sep 17 00:00:00 2001
From: ZHU Zijia <piggynl at outlook.com>
Date: Tue, 30 Jan 2024 01:03:35 +0800
Subject: [PATCH] [builtins] Update HAVE_SYSCONF configure check to adapt CMake

The cleans up the HAVE_SYSCONF check in enable_execute_stack.c from
2dbae9c and 40268af. Those two commits were made when the CMake build
system was not ready yet.
---
 compiler-rt/CMakeLists.txt                      |  4 ++++
 compiler-rt/cmake/config-ix.cmake               |  1 +
 compiler-rt/include/config/config.h.cmake       |  6 ++++++
 compiler-rt/lib/builtins/CMakeLists.txt         |  2 ++
 compiler-rt/lib/builtins/enable_execute_stack.c | 11 ++++-------
 5 files changed, 17 insertions(+), 7 deletions(-)
 create mode 100644 compiler-rt/include/config/config.h.cmake

diff --git a/compiler-rt/CMakeLists.txt b/compiler-rt/CMakeLists.txt
index bbb4e8d7c333e4f..332cab71f579d35 100644
--- a/compiler-rt/CMakeLists.txt
+++ b/compiler-rt/CMakeLists.txt
@@ -282,6 +282,10 @@ option(COMPILER_RT_USE_BUILTINS_LIBRARY
 
 include(config-ix)
 
+configure_file(
+  ${COMPILER_RT_SOURCE_DIR}/include/config/config.h.cmake
+  ${COMPILER_RT_BINARY_DIR}/include/config/config.h)
+
 #================================
 # Setup Compiler Flags
 #================================
diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake
index 2ca18ebb4ad4896..f69078fe57fcf49 100644
--- a/compiler-rt/cmake/config-ix.cmake
+++ b/compiler-rt/cmake/config-ix.cmake
@@ -168,6 +168,7 @@ check_cxx_compiler_flag(-Werror -Wsizeof-pointer-div COMPILER_RT_HAS_SIZEOF_POIN
 
 # Symbols.
 check_symbol_exists(__func__ "" COMPILER_RT_HAS_FUNC_SYMBOL)
+check_symbol_exists(sysconf unistd.h COMPILER_RT_HAS_SYSCONF)
 
 # Includes.
 check_cxx_compiler_flag(-nostdinc++ COMPILER_RT_HAS_NOSTDINCXX_FLAG)
diff --git a/compiler-rt/include/config/config.h.cmake b/compiler-rt/include/config/config.h.cmake
new file mode 100644
index 000000000000000..7d76a869a478f58
--- /dev/null
+++ b/compiler-rt/include/config/config.h.cmake
@@ -0,0 +1,6 @@
+#ifndef CONFIG_H
+#define CONFIG_H
+
+#cmakedefine COMPILER_RT_HAS_SYSCONF
+
+#endif
diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
index 28ded8766f2533a..21fff14fbe749b0 100644
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -64,6 +64,8 @@ include(CMakePushCheckState)
 option(COMPILER_RT_BUILTINS_HIDE_SYMBOLS
   "Do not export any symbols from the static library." ON)
 
+include_directories(${COMPILER_RT_BINARY_DIR}/include/config)
+
 # TODO: Need to add a mechanism for logging errors when builtin source files are
 # added to a sub-directory and not this CMakeLists file.
 set(GENERIC_SOURCES
diff --git a/compiler-rt/lib/builtins/enable_execute_stack.c b/compiler-rt/lib/builtins/enable_execute_stack.c
index e18de4eaebf2a76..535053e572a55b7 100644
--- a/compiler-rt/lib/builtins/enable_execute_stack.c
+++ b/compiler-rt/lib/builtins/enable_execute_stack.c
@@ -12,10 +12,7 @@
 #include <sys/mman.h>
 #endif
 
-// #include "config.h"
-// FIXME: CMake - include when cmake system is ready.
-// Remove #define HAVE_SYSCONF 1 line.
-#define HAVE_SYSCONF 1
+#include "config.h"
 
 #ifdef _WIN32
 #define WIN32_LEAN_AND_MEAN
@@ -50,11 +47,11 @@ COMPILER_RT_ABI void __enable_execute_stack(void *addr) {
 #if __APPLE__
   // On Darwin, pagesize is always 4096 bytes
   const uintptr_t pageSize = 4096;
-#elif !defined(HAVE_SYSCONF)
-#error "HAVE_SYSCONF not defined! See enable_execute_stack.c"
+#elif !defined(COMPILER_RT_HAS_SYSCONF)
+#error "COMPILER_RT_HAS_SYSCONF not defined! See enable_execute_stack.c"
 #else
   const uintptr_t pageSize = sysconf(_SC_PAGESIZE);
-#endif // __APPLE__
+#endif
 
   const uintptr_t pageAlignMask = ~(pageSize - 1);
   uintptr_t p = (uintptr_t)addr;