[SystemZ][z/OS] Fix build errors on z/OS in the Unix .inc files (#74758)

This patch resolves the following errors on z/OS:

error: no member named 'wait4' in the global namespace
error: no member named 'ru_maxrss' in 'rusage'
error: use of undeclared identifier 'strsignal'
error: Cannot get usage times on this platform
error: Cannot get malloc info on this platform

Author: abhina-sree

llvm/include/llvm/Support/SystemZ/zOSSupport.h

@@ -0,0 +1,39 @@
+//===- zOSSupport.h - Common z/OS Include File ------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines z/OS implementations for common functions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_ZOSSUPPORT_H
+#define LLVM_SUPPORT_ZOSSUPPORT_H
+
+#ifdef __MVS__
+#include <sys/resource.h>
+#include <sys/wait.h>
+
+// z/OS Unix System Services does not have strsignal() support, so the
+// strsignal() function is implemented here.
+inline char *strsignal(int sig) {
+  static char msg[256];
+  sprintf(msg, "%d", sig);
+  return msg;
+}
+
+// z/OS Unix System Services does not have wait4() support, so the wait4
+// function is implemented here.
+inline pid_t wait4(pid_t pid, int *wstatus, int options,
+                   struct rusage *rusage) {
+  pid_t Result = waitpid(pid, wstatus, options);
+  int GetrusageRC = getrusage(RUSAGE_CHILDREN, rusage);
+  assert(!GetrusageRC && "Must have valid measure of the resources!");
+  return Result;
+}
+
+#endif
+#endif

llvm/lib/Support/Unix/Process.inc

@@ -62,7 +62,9 @@ getRUsageTimes() {
   ::getrusage(RUSAGE_SELF, &RU);
   return {toDuration(RU.ru_utime), toDuration(RU.ru_stime)};
 #else
+#ifndef __MVS__ // Exclude for MVS in case -pedantic is used
 #warning Cannot get usage times on this platform
+#endif
   return {std::chrono::microseconds::zero(), std::chrono::microseconds::zero()};
 #endif
 }
@@ -117,7 +119,9 @@ size_t Process::GetMallocUsage() {
     return EndOfMemory - StartOfMemory;
   return 0;
 #else
+#ifndef __MVS__ // Exclude for MVS in case -pedantic is used
 #warning Cannot get malloc info on this platform
+#endif
   return 0;
 #endif
 }

llvm/lib/Support/Unix/Program.inc

@@ -25,6 +25,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/StringSaver.h"
+#include "llvm/Support/SystemZ/zOSSupport.h"
 #include "llvm/Support/raw_ostream.h"
 #if HAVE_SYS_STAT_H
 #include <sys/stat.h>
@@ -466,7 +467,7 @@ ProcessInfo llvm::sys::Wait(const ProcessInfo &PI,
     std::chrono::microseconds UserT = toDuration(Info.ru_utime);
     std::chrono::microseconds KernelT = toDuration(Info.ru_stime);
     uint64_t PeakMemory = 0;
-#ifndef __HAIKU__
+#if !defined(__HAIKU__) && !defined(__MVS__)
     PeakMemory = static_cast<uint64_t>(Info.ru_maxrss);
 #endif
     *ProcStat = ProcessStatistics{UserT + KernelT, UserT, PeakMemory};