[Driver] Add a cc1 flag for the new TBAA metadata format

This patch starts a series of changes to add support for the new
TBAA metadata format proposed in this llvm-dev thread:

http://lists.llvm.org/pipermail/llvm-dev/2017-November/118748.html

Differential Revision: https://reviews.llvm.org/D39955


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@318644 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Ivan A. Kosarev

include/clang/Driver/CC1Options.td

@@ -244,6 +244,8 @@ def relaxed_aliasing : Flag<["-"], "relaxed-aliasing">,
   HelpText<"Turn off Type Based Alias Analysis">;
 def no_struct_path_tbaa : Flag<["-"], "no-struct-path-tbaa">,
   HelpText<"Turn off struct-path aware Type Based Alias Analysis">;
+def new_struct_path_tbaa : Flag<["-"], "new-struct-path-tbaa">,
+  HelpText<"Enable enhanced struct-path aware Type Based Alias Analysis">;
 def masm_verbose : Flag<["-"], "masm-verbose">,
   HelpText<"Generate verbose assembly output">;
 def mcode_model : Separate<["-"], "mcode-model">,

include/clang/Frontend/CodeGenOptions.def

@@ -144,6 +144,7 @@ ENUM_CODEGENOPT(StructReturnConvention, StructReturnConventionKind, 2, SRCK_Defa
 CODEGENOPT(RelaxAll          , 1, 0) ///< Relax all machine code instructions.
 CODEGENOPT(RelaxedAliasing   , 1, 0) ///< Set when -fno-strict-aliasing is enabled.
 CODEGENOPT(StructPathTBAA    , 1, 0) ///< Whether or not to use struct-path TBAA.
+CODEGENOPT(NewStructPathTBAA , 1, 0) ///< Whether or not to use enhanced struct-path TBAA.
 CODEGENOPT(SaveTempLabels    , 1, 0) ///< Save temporary labels.
 CODEGENOPT(SanitizeAddressUseAfterScope , 1, 0) ///< Enable use-after-scope detection
                                                 ///< in AddressSanitizer

lib/Frontend/CompilerInvocation.cpp

@@ -546,6 +546,8 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
     OPT_fuse_register_sized_bitfield_access);
   Opts.RelaxedAliasing = Args.hasArg(OPT_relaxed_aliasing);
   Opts.StructPathTBAA = !Args.hasArg(OPT_no_struct_path_tbaa);
+  Opts.NewStructPathTBAA = !Args.hasArg(OPT_no_struct_path_tbaa) &&
+                           Args.hasArg(OPT_new_struct_path_tbaa);
   Opts.FineGrainedBitfieldAccesses =
       Args.hasFlag(OPT_ffine_grained_bitfield_accesses,
                    OPT_fno_fine_grained_bitfield_accesses, false);