[FPEnv][Clang][Driver] Use MarshallingInfoFlag for -fexperimental-strict-floating-point

[kpn]

Summary

As of D80952 we are disabling strict floating point on all hosts except those that are explicitly listed as supported. Use of strict floating point on other hosts requires use of the -fexperimental-strict-floating-point flag. This is to avoid bugs like "https://bugs.llvm.org/show_bug.cgi?id=45329" (which has an incorrect link in the previous review).

In the review for D80952 I was asked to mark the -fexperimental option as a MarshallingInfoFlag. This patch does exactly that.

The previous tests continue to work correctly so I haven't included a new one here. I can if needed, but I would need guidance since I don't know what would need to be tested.

[kpn]

Ping

[jansvoboda11]

Hi Kevin, sorry for the late response.

I don't think adding new tests is necessary as long as the flag is used in existing ones.

clang/include/clang/Driver/Options.td

1311

In D82756, we've replaced the "default value" argument with a list of options that can imply the current flag. If empty or omitted, we set the default value to false automatically. Could you please remove the "false" argument?

[kpn]

No worries!

The option does already have tests that verify correct operation.

clang/include/clang/Driver/Options.td

1311

Will do.

[kpn]

Update for review comments.

[jansvoboda11]

LGTM

clang/include/clang/Driver/Options.td

def fglobal_isel : Flag<["-"], "fglobal-isel">, Group<f_clang_Group>,
   HelpText<"Enables the global instruction selector">;
 def fexperimental_isel : Flag<["-"], "fexperimental-isel">, Group<f_clang_Group>,
   Alias<fglobal_isel>;
 def fexperimental_new_pass_manager : Flag<["-"], "fexperimental-new-pass-manager">,
   Group<f_clang_Group>, Flags<[CC1Option]>,
   HelpText<"Enables an experimental new pass manager in LLVM.">;
 def fexperimental_strict_floating_point : Flag<["-"], "fexperimental-strict-floating-point">,
   Group<f_clang_Group>, Flags<[CC1Option]>,
-  HelpText<"Enables experimental strict floating point in LLVM.">;
+  HelpText<"Enables experimental strict floating point in LLVM.">,
+  MarshallingInfoFlag<"LangOpts->ExpStrictFP">;
 def finput_charset_EQ : Joined<["-"], "finput-charset=">, Group<f_Group>;
 def fexec_charset_EQ : Joined<["-"], "fexec-charset=">, Group<f_Group>;
 def finstrument_functions : Flag<["-"], "finstrument-functions">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Generate calls to instrument function entry and exit">;
 def finstrument_functions_after_inlining : Flag<["-"], "finstrument-functions-after-inlining">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Like -finstrument-functions, but insert the calls after inlining">;
 def finstrument_function_entry_bare : Flag<["-"], "finstrument-function-entry-bare">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Instrument function entry only, after inlining, without arguments to the instrumentation call">;

clang/lib/Frontend/CompilerInvocation.cpp

if (Arg *A = Args.getLastArg(OPT_ffp_contract)) {
     else if (Val == "on")
       Opts.setDefaultFPContractMode(LangOptions::FPM_On);
     else if (Val == "off")
       Opts.setDefaultFPContractMode(LangOptions::FPM_Off);
     else
       Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Val;
   }
 
-  if (Args.hasArg(OPT_fexperimental_strict_floating_point))
-    Opts.ExpStrictFP = true;
-
   auto FPRM = llvm::RoundingMode::NearestTiesToEven;
   if (Args.hasArg(OPT_frounding_math)) {
     FPRM = llvm::RoundingMode::Dynamic;
   }
   Opts.setFPRoundingMode(FPRM);
 
   if (Args.hasArg(OPT_ftrapping_math)) {
     Opts.setFPExceptionMode(LangOptions::FPE_Strict);