[RFC 07/12] Add randstruct-seed compiler argument

[Connor Kuehl via cfe-commits]

To create reproducible builds, the randstruct feature
can (and should) operate on a seed provided at compile
time.

Co-authored-by: Cole Nixon <nixontcole at gmail.com>
Co-authored-by: Connor Kuehl <cipkuehl at gmail.com>
Co-authored-by: James Foster <jafosterja at gmail.com>
Co-authored-by: Jeff Takahashi <jeffrey.takahashi at gmail.com>
Co-authored-by: Jordan Cantrell <jordan.cantrell at mail.com>
Co-authored-by: Nikk Forbus <nicholas.forbus at gmail.com>
Co-authored-by: Tim Pugh <nwtpugh at gmail.com>
---
 clang/include/clang/Driver/CC1Options.td  | 2 ++
 clang/include/clang/Driver/Options.td     | 1 +
 clang/lib/Driver/ToolChains/Clang.cpp     | 6 ++++++
 clang/lib/Frontend/CompilerInvocation.cpp | 5 +++++
 4 files changed, 14 insertions(+)

diff --git a/clang/include/clang/Driver/CC1Options.td b/clang/include/clang/Driver/CC1Options.td
index f4f8fae39e3..541a8e74a0c 100644
--- a/clang/include/clang/Driver/CC1Options.td
+++ b/clang/include/clang/Driver/CC1Options.td
@@ -422,6 +422,8 @@ def fcaret_diagnostics_max_lines :
   HelpText<"Set the maximum number of source lines to show in a caret diagnostic">;
 def fmessage_length : Separate<["-"], "fmessage-length">, MetaVarName<"<N>">,
   HelpText<"Format message diagnostics so that they fit within N columns or fewer, when possible.">;
+def randstruct_seed : Separate<["-"], "randstruct-seed">, MetaVarName<"<N>">,
+  HelpText<"Randomization seed for random struct layouts">;
 def verify_EQ : CommaJoined<["-"], "verify=">,
   MetaVarName<"<prefixes>">,
   HelpText<"Verify diagnostic output using comment directives that start with"
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 81e4ce75b02..735ec11e221 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1267,6 +1267,7 @@ def fmacro_backtrace_limit_EQ : Joined<["-"], "fmacro-backtrace-limit=">,
 def fmerge_all_constants : Flag<["-"], "fmerge-all-constants">, Group<f_Group>,
   Flags<[CC1Option, CoreOption]>, HelpText<"Allow merging of constants">;
 def fmessage_length_EQ : Joined<["-"], "fmessage-length=">, Group<f_Group>;
+def randstruct_seed_EQ : Joined<["-"], "randstruct-seed=">, Group<f_Group>;
 def fms_extensions : Flag<["-"], "fms-extensions">, Group<f_Group>, Flags<[CC1Option, CoreOption]>,
   HelpText<"Accept some non-standard constructs supported by the Microsoft compiler">;
 def fms_compatibility : Flag<["-"], "fms-compatibility">, Group<f_Group>, Flags<[CC1Option, CoreOption]>,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 3bc7412911b..52daed9fe36 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4427,6 +4427,12 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back(Args.MakeArgString(Twine(N)));
   }
 
+  // -randstruct-seed parent process
+  if (Arg *A = Args.getLastArg(options::OPT_randstruct_seed_EQ)) {
+    CmdArgs.push_back( "-randstruct-seed" );
+    CmdArgs.push_back(A->getValue(0));
+  }
+
   // -fvisibility= and -fvisibility-ms-compat are of a piece.
   if (const Arg *A = Args.getLastArg(options::OPT_fvisibility_EQ,
                                      options::OPT_fvisibility_ms_compat)) {
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 1cd1cb1ff47..b4423dabbe7 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "clang/AST/RandstructSeed.h"
 #include "clang/Frontend/CompilerInvocation.h"
 #include "TestModuleFileExtension.h"
 #include "clang/Basic/Builtins.h"
@@ -1673,6 +1674,10 @@ static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
     Opts.ProgramAction = frontend::PluginAction;
     Opts.ActionName = A->getValue();
   }
+  // child process handle arguments
+  if (const Arg* A = Args.getLastArg(OPT_randstruct_seed)) {
+    RandstructSeed = A->getValue(0);
+  }
   Opts.AddPluginActions = Args.getAllArgValues(OPT_add_plugin);
   for (const auto *AA : Args.filtered(OPT_plugin_arg))
     Opts.PluginArgs[AA->getValue(0)].emplace_back(AA->getValue(1));
-- 
2.17.1