[llvm] [Cygwin] Cygwin general (PR #74941)

[徐持恒 Xu Chiheng via llvm-commits]

https://github.com/xu-chiheng created https://github.com/llvm/llvm-project/pull/74941

Override Cygwin's buggy getpagesize() to Win32 computePageSize().


>From 444b7a3e7be7c04b8189e957607f40440ff211a7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=BE=90=E6=8C=81=E6=81=92=20Xu=20Chiheng?=
 <chiheng.xu at gmail.com>
Date: Sun, 10 Dec 2023 01:06:28 +0800
Subject: [PATCH] 1

---
 llvm/lib/Support/Process.cpp         | 19 +++++++++++++++++++
 llvm/lib/Support/Unix/Process.inc    |  4 +++-
 llvm/lib/Support/Windows/Process.inc | 13 -------------
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/llvm/lib/Support/Process.cpp b/llvm/lib/Support/Process.cpp
index 30c64d3ed9ed17..6d4a7275f5fa61 100644
--- a/llvm/lib/Support/Process.cpp
+++ b/llvm/lib/Support/Process.cpp
@@ -23,6 +23,10 @@
 #include <optional>
 #include <stdlib.h> // for _Exit
 
+#if defined(_WIN32) || defined(__CYGWIN__)
+#include <windows.h>
+#endif
+
 using namespace llvm;
 using namespace sys;
 
@@ -102,6 +106,21 @@ bool Process::AreCoreFilesPrevented() { return coreFilesPrevented; }
     ::exit(RetCode);
 }
 
+#if defined(_WIN32) || defined(__CYGWIN__)
+// This function retrieves the page size using GetNativeSystemInfo() and is
+// present solely so it can be called once to initialize the self_process member
+// below.
+static unsigned computePageSize() {
+  // GetNativeSystemInfo() provides the physical page size which may differ
+  // from GetSystemInfo() in 32-bit applications running under WOW64.
+  SYSTEM_INFO info;
+  GetNativeSystemInfo(&info);
+  // FIXME: FileOffset in MapViewOfFile() should be aligned to not dwPageSize,
+  // but dwAllocationGranularity.
+  return static_cast<unsigned>(info.dwPageSize);
+}
+#endif
+
 // Include the platform-specific parts of this class.
 #ifdef LLVM_ON_UNIX
 #include "Unix/Process.inc"
diff --git a/llvm/lib/Support/Unix/Process.inc b/llvm/lib/Support/Unix/Process.inc
index 2babf07944bf7b..2bf53ae188ebd3 100644
--- a/llvm/lib/Support/Unix/Process.inc
+++ b/llvm/lib/Support/Unix/Process.inc
@@ -76,7 +76,9 @@ Process::Pid Process::getProcessId() {
 // On Cygwin, getpagesize() returns 64k(AllocationGranularity) and
 // offset in mmap(3) should be aligned to the AllocationGranularity.
 Expected<unsigned> Process::getPageSize() {
-#if defined(HAVE_GETPAGESIZE)
+#if defined(__CYGWIN__)
+  static const int page_size = computePageSize();
+#elif defined(HAVE_GETPAGESIZE)
   static const int page_size = ::getpagesize();
 #elif defined(HAVE_SYSCONF)
   static long page_size = ::sysconf(_SC_PAGE_SIZE);
diff --git a/llvm/lib/Support/Windows/Process.inc b/llvm/lib/Support/Windows/Process.inc
index a54c06d46870b5..9addfa6ec805e3 100644
--- a/llvm/lib/Support/Windows/Process.inc
+++ b/llvm/lib/Support/Windows/Process.inc
@@ -50,19 +50,6 @@ Process::Pid Process::getProcessId() {
   return Pid(::GetCurrentProcessId());
 }
 
-// This function retrieves the page size using GetNativeSystemInfo() and is
-// present solely so it can be called once to initialize the self_process member
-// below.
-static unsigned computePageSize() {
-  // GetNativeSystemInfo() provides the physical page size which may differ
-  // from GetSystemInfo() in 32-bit applications running under WOW64.
-  SYSTEM_INFO info;
-  GetNativeSystemInfo(&info);
-  // FIXME: FileOffset in MapViewOfFile() should be aligned to not dwPageSize,
-  // but dwAllocationGranularity.
-  return static_cast<unsigned>(info.dwPageSize);
-}
-
 Expected<unsigned> Process::getPageSize() {
   static unsigned Ret = computePageSize();
   return Ret;