[SystemZ][z/OS] Refactor AutoConvert.h to remove large MVS guard (llvm#143174)

This AutoConvert.h header frequently gets mislabeled as an unused
include because it is guarded by MVS internally and every usage is also
guarded. This refactors the change to remove this guard and instead make
these functions a noop on other non-z/OS platforms.

Author: abhina-sree

llvm/include/llvm/Support/AutoConvert.h

@@ -16,6 +16,7 @@
 
 #ifdef __MVS__
 #include <_Ccsid.h>
+#endif
 #ifdef __cplusplus
 #include "llvm/Support/ErrorOr.h"
 #include <system_error>
@@ -28,16 +29,58 @@
 #ifdef __cplusplus
 extern "C" {
 #endif /* __cplusplus */
+
 int enablezOSAutoConversion(int FD);
 int disablezOSAutoConversion(int FD);
 int restorezOSStdHandleAutoConversion(int FD);
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */
 
 #ifdef __cplusplus
 namespace llvm {
 
+inline std::error_code disableAutoConversion(int FD) {
+#ifdef __MVS__
+  if (::disablezOSAutoConversion(FD) == -1)
+    return errnoAsErrorCode();
+#endif
+  return std::error_code();
+}
+
+inline std::error_code enableAutoConversion(int FD) {
+#ifdef __MVS__
+  if (::enablezOSAutoConversion(FD) == -1)
+    return errnoAsErrorCode();
+#endif
+  return std::error_code();
+}
+
+inline std::error_code restoreStdHandleAutoConversion(int FD) {
+#ifdef __MVS__
+  if (::restorezOSStdHandleAutoConversion(FD) == -1)
+    return errnoAsErrorCode();
+#endif
+  return std::error_code();
+}
+
+inline std::error_code setFileTag(int FD, int CCSID, bool Text) {
+#ifdef __MVS__
+  return setzOSFileTag(FD, CCSID, Text);
+#endif
+  return std::error_code();
+}
+
+inline ErrorOr<bool> needConversion(const char *FileName, const int FD = -1) {
+#ifdef __MVS__
+  return needzOSConversion(FileName, FD);
+#endif
+  return false;
+}
+
+#ifdef __MVS__
+
 /** \brief Disable the z/OS enhanced ASCII auto-conversion for the file
  * descriptor.
  */
@@ -63,9 +106,8 @@ ErrorOr<__ccsid_t> getzOSFileTag(const char *FileName, const int FD = -1);
  */
 ErrorOr<bool> needzOSConversion(const char *FileName, const int FD = -1);
 
+#endif /* __MVS__*/
 } /* namespace llvm */
 #endif /* __cplusplus */
 
-#endif /* __MVS__ */
-
 #endif /* LLVM_SUPPORT_AUTOCONVERT_H */

llvm/lib/Support/AutoConvert.cpp

@@ -83,27 +83,6 @@ int enablezOSAutoConversion(int FD) {
   return fcntl(FD, F_CONTROL_CVT, &Query);
 }
 
-std::error_code llvm::disablezOSAutoConversion(int FD) {
-  if (::disablezOSAutoConversion(FD) == -1)
-    return errnoAsErrorCode();
-
-  return std::error_code();
-}
-
-std::error_code llvm::enablezOSAutoConversion(int FD) {
-  if (::enablezOSAutoConversion(FD) == -1)
-    return errnoAsErrorCode();
-
-  return std::error_code();
-}
-
-std::error_code llvm::restorezOSStdHandleAutoConversion(int FD) {
-  if (::restorezOSStdHandleAutoConversion(FD) == -1)
-    return errnoAsErrorCode();
-
-  return std::error_code();
-}
-
 std::error_code llvm::setzOSFileTag(int FD, int CCSID, bool Text) {
   assert((!Text || (CCSID != FT_UNTAGGED && CCSID != FT_BINARY)) &&
          "FT_UNTAGGED and FT_BINARY are not allowed for text files");

llvm/lib/Support/InitLLVM.cpp

@@ -18,18 +18,28 @@
 #include "llvm/Support/Windows/WindowsSupport.h"
 #endif
 
-#ifdef __MVS__
+#if defined(HAVE_UNISTD_H)
 #include <unistd.h>
+#else
+#ifndef STDIN_FILENO
+#define STDIN_FILENO 0
+#endif
+#ifndef STDOUT_FILENO
+#define STDOUT_FILENO 1
+#endif
+#ifndef STDERR_FILENO
+#define STDERR_FILENO 2
+#endif
+#endif
 
 void CleanupStdHandles(void *Cookie) {
   llvm::raw_ostream *Outs = &llvm::outs(), *Errs = &llvm::errs();
   Outs->flush();
   Errs->flush();
-  llvm::restorezOSStdHandleAutoConversion(STDIN_FILENO);
-  llvm::restorezOSStdHandleAutoConversion(STDOUT_FILENO);
-  llvm::restorezOSStdHandleAutoConversion(STDERR_FILENO);
+  llvm::restoreStdHandleAutoConversion(STDIN_FILENO);
+  llvm::restoreStdHandleAutoConversion(STDOUT_FILENO);
+  llvm::restoreStdHandleAutoConversion(STDERR_FILENO);
 }
-#endif
 
 using namespace llvm;
 using namespace llvm::sys;
@@ -41,10 +51,10 @@ InitLLVM::InitLLVM(int &Argc, const char **&Argv,
   assert(!Initialized && "InitLLVM was already initialized!");
   Initialized = true;
 #endif
-#ifdef __MVS__
+
   // Bring stdin/stdout/stderr into a known state.
   sys::AddSignalHandler(CleanupStdHandles, nullptr);
-#endif
+
   if (InstallPipeSignalExitHandler)
     // The pipe signal handler must be installed before any other handlers are
     // registered. This is because the Unix \ref RegisterHandlers function does
@@ -68,8 +78,8 @@ InitLLVM::InitLLVM(int &Argc, const char **&Argv,
 
   // If turning on conversion for stderr fails then the error message
   // may be garbled. There is no solution to this problem.
-  ExitOnErr(errorCodeToError(llvm::enablezOSAutoConversion(STDERR_FILENO)));
-  ExitOnErr(errorCodeToError(llvm::enablezOSAutoConversion(STDOUT_FILENO)));
+  ExitOnErr(errorCodeToError(llvm::enableAutoConversion(STDERR_FILENO)));
+  ExitOnErr(errorCodeToError(llvm::enableAutoConversion(STDOUT_FILENO)));
 #endif
 
 #ifdef _WIN32
@@ -97,8 +107,6 @@ InitLLVM::InitLLVM(int &Argc, const char **&Argv,
 }
 
 InitLLVM::~InitLLVM() {
-#ifdef __MVS__
   CleanupStdHandles(nullptr);
-#endif
   llvm_shutdown();
 }

llvm/lib/Support/MemoryBuffer.cpp

@@ -15,6 +15,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Config/config.h"
 #include "llvm/Support/Alignment.h"
+#include "llvm/Support/AutoConvert.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -34,9 +35,6 @@
 #include <io.h>
 #endif
 
-#ifdef __MVS__
-#include "llvm/Support/AutoConvert.h"
-#endif
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
@@ -508,15 +506,15 @@ getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
   }
 
 #ifdef __MVS__
-  ErrorOr<bool> NeedConversion = needzOSConversion(Filename.str().c_str(), FD);
-  if (std::error_code EC = NeedConversion.getError())
+  ErrorOr<bool> NeedsConversion = needConversion(Filename.str().c_str(), FD);
+  if (std::error_code EC = NeedsConversion.getError())
     return EC;
   // File size may increase due to EBCDIC -> UTF-8 conversion, therefore we
   // cannot trust the file size and we create the memory buffer by copying
   // off the stream.
   // Note: This only works with the assumption of reading a full file (i.e,
   // Offset == 0 and MapSize == FileSize). Reading a file slice does not work.
-  if (Offset == 0 && MapSize == FileSize && *NeedConversion)
+  if (*NeedsConversion && Offset == 0 && MapSize == FileSize)
     return getMemoryBufferForStream(FD, Filename);
 #endif
 

llvm/lib/Support/raw_ostream.cpp

@@ -894,21 +894,24 @@ void raw_fd_ostream::anchor() {}
 raw_fd_ostream &llvm::outs() {
   // Set buffer settings to model stdout behavior.
   std::error_code EC;
-#ifdef __MVS__
-  EC = enablezOSAutoConversion(STDOUT_FILENO);
-  assert(!EC);
-#endif
+
+  // On z/OS we need to enable auto conversion
+  static std::error_code EC1 = enableAutoConversion(STDOUT_FILENO);
+  assert(!EC1);
+  (void)EC1;
+
   static raw_fd_ostream S("-", EC, sys::fs::OF_None);
   assert(!EC);
   return S;
 }
 
 raw_fd_ostream &llvm::errs() {
-  // Set standard error to be unbuffered.
-#ifdef __MVS__
-  std::error_code EC = enablezOSAutoConversion(STDERR_FILENO);
+  // On z/OS we need to enable auto conversion
+  static std::error_code EC = enableAutoConversion(STDERR_FILENO);
   assert(!EC);
-#endif
+  (void)EC;
+
+  // Set standard error to be unbuffered.
   static raw_fd_ostream S(STDERR_FILENO, false, true);
   return S;
 }