[SystemZ][z/OS] Add z/OS customization file

clang/include/clang/Driver/Driver.h

@@ -741,6 +741,11 @@ class Driver {
   /// \returns true if error occurred.
   bool loadDefaultConfigFiles(llvm::cl::ExpansionContext &ExpCtx);
 
+  /// Tries to load options from customization file.
+  ///
+  /// \returns true if error occurred.
+  bool loadZOSCustomizationFile(llvm::cl::ExpansionContext &);
+
   /// Read options from the specified file.
   ///
   /// \param [in] FileName File to read.

clang/lib/Driver/Driver.cpp

@@ -1002,6 +1002,34 @@ void Driver::CreateOffloadingDeviceToolChains(Compilation &C,
   //
 }
 
+bool Driver::loadZOSCustomizationFile(llvm::cl::ExpansionContext &ExpCtx) {
+  if (IsCLMode() || IsDXCMode() || IsFlangMode())
+    return false;
+
+  SmallString<128> CustomizationFile;
+  StringRef PathLIBEnv = StringRef(getenv("CLANG_CONFIG_PATH")).trim();
+  // If the env var is a directory then append "/clang.cfg" and treat
+  // that as the config file.  Otherwise treat the env var as the
+  // config file.
+  if (!PathLIBEnv.empty()) {
+    llvm::sys::path::append(CustomizationFile, PathLIBEnv);
+    if (llvm::sys::fs::is_directory(PathLIBEnv))
+      llvm::sys::path::append(CustomizationFile, "/clang.cfg");
+    if (llvm::sys::fs::is_regular_file(CustomizationFile))
+      return readConfigFile(CustomizationFile, ExpCtx);
+    Diag(diag::err_drv_config_file_not_found) << CustomizationFile;
+    return true;
+  }
+
+  SmallString<128> BaseDir(llvm::sys::path::parent_path(Dir));
+  llvm::sys::path::append(CustomizationFile, BaseDir + "/etc/clang.cfg");
+  if (llvm::sys::fs::is_regular_file(CustomizationFile))
+    return readConfigFile(CustomizationFile, ExpCtx);
+
+  // If no customization file, just return
+  return false;
+}
+
 static void appendOneArg(InputArgList &Args, const Arg *Opt) {
   // The args for config files or /clang: flags belong to different InputArgList
   // objects than Args. This copies an Arg from one of those other InputArgLists
@@ -1223,11 +1251,18 @@ bool Driver::loadDefaultConfigFiles(llvm::cl::ExpansionContext &ExpCtx) {
   }
 
   // Otherwise, use the real triple as used by the driver.
+  llvm::Triple RealTriple =
+      computeTargetTriple(*this, TargetTriple, *CLOptions);
   if (Triple.str().empty()) {
-    Triple = computeTargetTriple(*this, TargetTriple, *CLOptions);
+    Triple = RealTriple;
     assert(!Triple.str().empty());
   }
 
+  // On z/OS, start by loading the customization file before loading
+  // the usual default config file(s).
+  if (RealTriple.isOSzOS() && loadZOSCustomizationFile(ExpCtx))
+    return true;
+
   // Search for config files in the following order:
   // 1. <triple>-<mode>.cfg using real driver mode
   //    (e.g. i386-pc-linux-gnu-clang++.cfg).

clang/test/Driver/Inputs/config-zos/clang.cfg

@@ -0,0 +1 @@
+-DABC=123

clang/test/Driver/Inputs/config-zos/def.cfg

@@ -0,0 +1 @@
+-DDEF=456

clang/test/Driver/Inputs/config-zos/tst/def.cfg

@@ -0,0 +1 @@
+-DDEF=456

clang/test/Driver/config-zos.c

@@ -0,0 +1,17 @@
+// REQUIRES: shell
+// REQUIRES: systemz-registered-target
+
+// RUN: unset CLANG_NO_DEFAULT_CONFIG
+// RUN: rm -rf %t && mkdir %t
+
+// RUN: mkdir -p %t/testbin
+// RUN: mkdir -p %t/etc
+// RUN: ln -s %clang %t/testbin/clang
+// RUN: echo "-DXYZ=789" >%t/etc/clang.cfg
+// RUN: %t/testbin/clang --target=s390x-ibm-zos -c -### -no-canonical-prefixes %s 2>&1 | FileCheck -DDIR=%t %s 
+// RUN: %t/testbin/clang --target=s390x-ibm-zos -c -### -no-canonical-prefixes --no-default-config %s 2>&1 | FileCheck -check-prefix=NOCONFIG %s 
+//
+// CHECK: Configuration file: [[DIR]]/etc/clang.cfg
+// CHECK: "-D" "XYZ=789"
+// NOCONFIG-NOT: Configuration file: {{.*}}/etc/clang.cfg
+// NOCONFIG-NOT: "-D" "XYZ=789"

clang/test/Driver/config-zos1.c

@@ -0,0 +1,23 @@
+// REQUIRES: shell
+// REQUIRES: systemz-registered-target
+
+// RUN: unset CLANG_NO_DEFAULT_CONFIG
+
+// RUN: export CLANG_CONFIG_PATH=%S/Inputs/config-zos
+// RUN: %clang --target=s390x-ibm-zos -c -### %s 2>&1 | FileCheck %s 
+// CHECK: Configuration file: {{.*}}/Inputs/config-zos/clang.cfg
+// CHECK: "-D" "ABC=123"
+
+// RUN: export CLANG_CONFIG_PATH=%S/Inputs/config-zos/def.cfg
+// RUN: %clang --target=s390x-ibm-zos -c -### %s 2>&1 | FileCheck %s -check-prefix=CHECK-DEF
+// CHECK-DEF: Configuration file: {{.*}}/Inputs/config-zos/def.cfg
+// CHECK-DEF: "-D" "DEF=456"
+
+// RUN: export CLANG_CONFIG_PATH=%S/Inputs/config-zos/Garbage
+// RUN: not %clang --target=s390x-ibm-zos -c -### %s 2>&1 | FileCheck %s  -check-prefix=CHECK-ERR
+// CHECK-ERR:  error: configuration file '{{.*}}/Inputs/config-zos/Garbage' cannot be found
+
+// The directory exists but no clang.cfg in it
+// RUN: export CLANG_CONFIG_PATH=%S/Inputs/config-zos/tst
+// RUN: not %clang --target=s390x-ibm-zos -c -### %s 2>&1 | FileCheck %s  -check-prefix=CHECK-ERRDIR
+// CHECK-ERRDIR:  error: configuration file '{{.*}}/Inputs/config-zos/tst/clang.cfg' cannot be found