[Driver] Support multi /guard: options

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D150645

(cherry picked from commit 3b6f7e4)

Author: phoebewang

clang/lib/Driver/ToolChains/Clang.cpp

@@ -7782,7 +7782,7 @@ void Clang::AddClangCLArgs(const ArgList &Args, types::ID InputType,
   if (Args.hasArg(options::OPT__SLASH_kernel))
     CmdArgs.push_back("-fms-kernel");
 
-  if (Arg *A = Args.getLastArg(options::OPT__SLASH_guard)) {
+  for (const Arg *A : Args.filtered(options::OPT__SLASH_guard)) {
     StringRef GuardArgs = A->getValue();
     // The only valid options are "cf", "cf,nochecks", "cf-", "ehcont" and
     // "ehcont-".

clang/lib/Driver/ToolChains/MSVC.cpp

@@ -227,7 +227,7 @@ void visualstudio::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   Args.AddAllArgValues(CmdArgs, options::OPT__SLASH_link);
 
   // Control Flow Guard checks
-  if (Arg *A = Args.getLastArg(options::OPT__SLASH_guard)) {
+  for (const Arg *A : Args.filtered(options::OPT__SLASH_guard)) {
     StringRef GuardArgs = A->getValue();
     if (GuardArgs.equals_insensitive("cf") ||
         GuardArgs.equals_insensitive("cf,nochecks")) {

clang/test/Driver/cl-options.c

@@ -647,6 +647,10 @@
 // RUN: %clang_cl /guard:ehcont -### -- %s 2>&1 | FileCheck -check-prefix=EHCONTGUARD %s
 // EHCONTGUARD: -ehcontguard
 
+// RUN: %clang_cl /guard:cf /guard:ehcont -### -- %s 2>&1 | FileCheck -check-prefix=BOTHGUARD %s
+// BOTHGUARD: -cfguard
+// BOTHGUARD-SAME: -ehcontguard
+
 // RUN: %clang_cl /guard:foo -### -- %s 2>&1 | FileCheck -check-prefix=CFGUARDINVALID %s
 // CFGUARDINVALID: invalid value 'foo' in '/guard:'