Add flags to toggle preservation of assembly comments

[niravd]

Summary

Add -fpreserve-as-comments and -fno-preserve-as-comments.

include/clang/Driver/Options.td

def fpcc_struct_return : Flag<["-"], "fpcc-struct-return">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Override the default ABI to return all structs on the stack">;
 def fpch_preprocess : Flag<["-"], "fpch-preprocess">, Group<f_Group>;
 def fpic : Flag<["-"], "fpic">, Group<f_Group>;
 def fno_pic : Flag<["-"], "fno-pic">, Group<f_Group>;
 def fpie : Flag<["-"], "fpie">, Group<f_Group>;
 def fno_pie : Flag<["-"], "fno-pie">, Group<f_Group>;
 def fplugin_EQ : Joined<["-"], "fplugin=">, Group<f_Group>, Flags<[DriverOption]>, MetaVarName<"<dsopath>">,
   HelpText<"Load the named plugin (dynamic shared object)">;
+def fpreserve_as_comments : Flag<["-"], "fpreserve-as-comments">, Group<f_Group>;
+def fno_preserve_as_comments : Flag<["-"], "fno-preserve-as-comments">, Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"Do not preserve comments in inline assembly">;
 def fprofile_arcs : Flag<["-"], "fprofile-arcs">, Group<f_Group>;
 def fno_profile_arcs : Flag<["-"], "fno-profile-arcs">, Group<f_Group>;
 def framework : Separate<["-"], "framework">, Flags<[LinkerInput]>;
 def frandom_seed_EQ : Joined<["-"], "frandom-seed=">, Group<clang_ignored_f_Group>;
 def freg_struct_return : Flag<["-"], "freg-struct-return">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Override the default ABI to return small structs in registers">;
 def frtti : Flag<["-"], "frtti">, Group<f_Group>;
 def : Flag<["-"], "fsched-interblock">, Group<clang_ignored_f_Group>;

include/clang/Frontend/CodeGenOptions.def

 #  define ENUM_CODEGENOPT(Name, Type, Bits, Default) \
 CODEGENOPT(Name, Bits, Default)
 #endif
 
 CODEGENOPT(DisableIntegratedAS, 1, 0) ///< -no-integrated-as
 CODEGENOPT(CompressDebugSections, 1, 0) ///< -Wa,-compress-debug-sections
 CODEGENOPT(RelaxELFRelocations, 1, 0) ///< -Wa,--mrelax-relocations
 CODEGENOPT(AsmVerbose        , 1, 0) ///< -dA, -fverbose-asm.
+CODEGENOPT(PreserveAsmComments, 1, 1) ///< -dA, -fno-preserve-as-comments.
 CODEGENOPT(AssumeSaneOperatorNew , 1, 1) ///< implicit __attribute__((malloc)) operator new
 CODEGENOPT(Autolink          , 1, 1) ///< -fno-autolink
 CODEGENOPT(ObjCAutoRefCountExceptions , 1, 0) ///< Whether ARC should be EH-safe.
 CODEGENOPT(Backchain         , 1, 0) ///< -mbackchain
 CODEGENOPT(CoverageExtraChecksum, 1, 0) ///< Whether we need a second checksum for functions in GCNO files.
 CODEGENOPT(CoverageNoFunctionNamesInData, 1, 0) ///< Do not include function names in GCDA files.
 CODEGENOPT(CoverageExitBlockBeforeBody, 1, 0) ///< Whether to emit the exit block before the body blocks in GCNO files.
 CODEGENOPT(CXAAtExit         , 1, 1) ///< Use __cxa_atexit for calling destructors.

lib/CodeGen/BackendUtil.cpp

void EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
   Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
   Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
   Options.MCOptions.MCIncrementalLinkerCompatible =
       CodeGenOpts.IncrementalLinkerCompatible;
   Options.MCOptions.MCFatalWarnings = CodeGenOpts.FatalWarnings;
   Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
+  Options.MCOptions.PreserveAsmComments = CodeGenOpts.PreserveAsmComments;
   Options.MCOptions.ABIName = TargetOpts.ABI;
 
   TM.reset(TheTarget->createTargetMachine(Triple, TargetOpts.CPU, FeaturesStr,
                                           Options, RM, CM, OptLevel));
 }
 
 bool EmitAssemblyHelper::AddEmitPasses(legacy::PassManager &CodeGenPasses,
                                        BackendAction Action,

lib/Driver/Tools.cpp

if (Arg *A = Args.getLastArg(options::OPT_Wframe_larger_than_EQ)) {
     CmdArgs.push_back(Args.MakeArgString("-warn-stack-size=" + v));
     A->claim();
   }
 
   if (!Args.hasFlag(options::OPT_fjump_tables, options::OPT_fno_jump_tables,
                     true))
     CmdArgs.push_back("-fno-jump-tables");
 
+  if (!Args.hasFlag(options::OPT_fpreserve_as_comments,
+                    options::OPT_fno_preserve_as_comments, true))
+    CmdArgs.push_back("-fno-preserve-as-comments");
+
   if (Arg *A = Args.getLastArg(options::OPT_mregparm_EQ)) {
     CmdArgs.push_back("-mregparm");
     CmdArgs.push_back(A->getValue());
   }
 
   if (Arg *A = Args.getLastArg(options::OPT_fpcc_struct_return,
                                options::OPT_freg_struct_return)) {
     if (getToolChain().getArch() != llvm::Triple::x86) {

lib/Frontend/CompilerInvocation.cpp

Opts.ProfileInstrumentUsePath =
       Args.getLastArgValue(OPT_fprofile_instrument_use_path_EQ);
   if (!Opts.ProfileInstrumentUsePath.empty())
     setPGOUseInstrumentor(Opts, Opts.ProfileInstrumentUsePath);
 
   Opts.CoverageMapping =
       Args.hasFlag(OPT_fcoverage_mapping, OPT_fno_coverage_mapping, false);
   Opts.DumpCoverageMapping = Args.hasArg(OPT_dump_coverage_mapping);
   Opts.AsmVerbose = Args.hasArg(OPT_masm_verbose);
+  Opts.PreserveAsmComments = !Args.hasArg(OPT_fno_preserve_as_comments);
   Opts.AssumeSaneOperatorNew = !Args.hasArg(OPT_fno_assume_sane_operator_new);
   Opts.ObjCAutoRefCountExceptions = Args.hasArg(OPT_fobjc_arc_exceptions);
   Opts.CXAAtExit = !Args.hasArg(OPT_fno_use_cxa_atexit);
   Opts.CXXCtorDtorAliases = Args.hasArg(OPT_mconstructor_aliases);
   Opts.CodeModel = getCodeModel(Args, Diags);
   Opts.DebugPass = Args.getLastArgValue(OPT_mdebug_pass);
   Opts.DisableFPElim =
       (Args.hasArg(OPT_mdisable_fp_elim) || Args.hasArg(OPT_pg));

test/CodeGen/preserve-as-comments.c

+// RUN: %clang_cc1 -S -fno-preserve-as-comments %s -o - | FileCheck %s --check-prefix=NOASM --check-prefix=CHECK
+// RUN: %clang_cc1 -S %s -o - | FileCheck %s --check-prefix=ASM --check-prefix=CHECK
+
+// CHECK-LABEL: main
+// CHECK: #APP
+// ASM: #comment
+// NOASM-NOT: #comment
+// CHECK: #NO_APP
+int main() {
+  __asm__("/*comment*/");
+  return 0;
+}