[driver] Add support for the --param ssp-buffer-size= driver option.

PR9673


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162285 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Driver/CC1Options.td

@@ -415,6 +415,8 @@ def static_define : Flag<"-static-define">,
   HelpText<"Should __STATIC__ be defined">;
 def stack_protector : Separate<"-stack-protector">,
   HelpText<"Enable stack protectors">;
+def stack_protector_buffer_size : Separate<"-stack-protector-buffer-size">,
+  HelpText<"Lower bound for a buffer to be considered for stack protection">;
 def fvisibility : Separate<"-fvisibility">,
   HelpText<"Default symbol visibility">;
 def ftemplate_depth : Separate<"-ftemplate-depth">,

include/clang/Frontend/CodeGenOptions.h

@@ -185,6 +185,9 @@ public:
   /// The run-time penalty for bounds checking, or 0 to disable.
   unsigned char BoundsChecking;
 
+  /// The lower bound for a buffer to be considered for stack protection.
+  unsigned SSPBufferSize;
+
   /// The default TLS model to use.
   TLSModel DefaultTLSModel;
 
@@ -241,6 +244,7 @@ public:
     StackRealignment = 0;
     StackAlignment = 0;
     BoundsChecking = 0;
+    SSPBufferSize = 8;
     UseInitArray = 0;
 
     DebugInfo = NoDebugInfo;

lib/CodeGen/BackendUtil.cpp

@@ -375,6 +375,7 @@ bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
   Options.DisableTailCalls = CodeGenOpts.DisableTailCalls;
   Options.TrapFuncName = CodeGenOpts.TrapFuncName;
   Options.PositionIndependentExecutable = LangOpts.PIELevel != 0;
+  Options.SSPBufferSize = CodeGenOpts.SSPBufferSize;
 
   TargetMachine *TM = TheTarget->createTargetMachine(Triple, TargetOpts.CPU,
                                                      FeaturesStr, Options,

lib/Driver/Tools.cpp

@@ -2353,6 +2353,18 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   if (StackProtectorLevel) {
     CmdArgs.push_back("-stack-protector");
     CmdArgs.push_back(Args.MakeArgString(Twine(StackProtectorLevel)));
+
+    // --param ssp-buffer-size=
+    for (arg_iterator it = Args.filtered_begin(options::OPT__param),
+           ie = Args.filtered_end(); it != ie; ++it) {
+      StringRef Str((*it)->getValue(Args));
+      if (Str.startswith("ssp-buffer-size=")) {
+        CmdArgs.push_back("-stack-protector-buffer-size");
+        // FIXME: Verify the argument is a valid integer.
+        CmdArgs.push_back(Args.MakeArgString(Str.drop_front(16)));
+        (*it)->claim();
+      }
+    }
   }
 
   // Translate -mstackrealign

lib/Frontend/CompilerInvocation.cpp

@@ -1267,6 +1267,8 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.CoverageFile = Args.getLastArgValue(OPT_coverage_file);
   Opts.DebugCompilationDir = Args.getLastArgValue(OPT_fdebug_compilation_dir);
   Opts.LinkBitcodeFile = Args.getLastArgValue(OPT_mlink_bitcode_file);
+  Opts.SSPBufferSize =
+    Args.getLastArgIntValue(OPT_stack_protector_buffer_size, 8, Diags);
   Opts.StackRealignment = Args.hasArg(OPT_mstackrealign);
   if (Arg *A = Args.getLastArg(OPT_mstack_alignment)) {
     StringRef Val = A->getValue(Args);

test/Driver/stack-protector.c

@@ -0,0 +1,11 @@
+// RUN: %clang -fno-stack-protector -### %s 2>&1 | FileCheck %s -check-prefix=NOSSP
+// NOSSP-NOT: "-stack-protector" "1"
+// NOSSP-NOT: "-stack-protector-buffer-size" 
+
+// RUN: %clang -fstack-protector -### %s 2>&1 | FileCheck %s -check-prefix=SSP
+// SSP: "-stack-protector" "1"
+// SSP-NOT: "-stack-protector-buffer-size" 
+
+// RUN: %clang -fstack-protector --param ssp-buffer-size=16 -### %s 2>&1 | FileCheck %s -check-prefix=SSP-BUF
+// SSP-BUF: "-stack-protector" "1"
+// SSP-BUF: "-stack-protector-buffer-size" "16"