r189369 - Warn that -O4 is the same as -O3.

[Daniel Dunbar]

Hi Rafael,

This is a behavior change, -O4 used to imply LTO. Maybe I missed a
discussion about changing this, but this is unexpected to me.

 - Daniel


On Tue, Aug 27, 2013 at 9:58 AM, Rafael Espindola <
rafael.espindola at gmail.com> wrote:

> Author: rafael
> Date: Tue Aug 27 11:58:15 2013
> New Revision: 189369
>
> URL: http://llvm.org/viewvc/llvm-project?rev=189369&view=rev
> Log:
> Warn that -O4 is the same as -O3.
>
> We error on -O5 and higher. While it is tempting to do the same for -O4, I
> agree with Jordan Rose: we should warn for a release at least first.
>
> Modified:
>     cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td
>     cfe/trunk/include/clang/Driver/Options.td
>     cfe/trunk/lib/Driver/Tools.cpp
>     cfe/trunk/test/Driver/clang_f_opts.c
>
> Modified: cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td?rev=189369&r1=189368&r2=189369&view=diff
>
> ==============================================================================
> --- cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td Tue Aug 27
> 11:58:15 2013
> @@ -112,6 +112,7 @@ def err_drv_unknown_objc_runtime : Error
>  def err_drv_emit_llvm_link : Error<
>     "-emit-llvm cannot be used when linking">;
>
> +def warn_O4_is_O3 : Warning<"-O4 is equivalent to -O3">,
> InGroup<Deprecated>;
>  def warn_c_kext : Warning<
>    "ignoring -fapple-kext which is valid for C++ and Objective-C++ only">;
>  def warn_drv_input_file_unused : Warning<
>
> Modified: cfe/trunk/include/clang/Driver/Options.td
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Driver/Options.td?rev=189369&r1=189368&r2=189369&view=diff
>
> ==============================================================================
> --- cfe/trunk/include/clang/Driver/Options.td (original)
> +++ cfe/trunk/include/clang/Driver/Options.td Tue Aug 27 11:58:15 2013
> @@ -214,13 +214,13 @@ def MT : JoinedOrSeparate<["-"], "MT">,
>  def Mach : Flag<["-"], "Mach">;
>  def M : Flag<["-"], "M">, Group<M_Group>;
>  def O0 : Flag<["-"], "O0">, Group<O_Group>, Flags<[CC1Option]>;
> +def O4 : Flag<["-"], "O4">, Group<O_Group>, Flags<[CC1Option]>;
>  def ObjCXX : Flag<["-"], "ObjC++">, Flags<[DriverOption]>,
>    HelpText<"Treat source input files as Objective-C++ inputs">;
>  def ObjC : Flag<["-"], "ObjC">, Flags<[DriverOption]>,
>    HelpText<"Treat source input files as Objective-C inputs">;
>  def O : Joined<["-"], "O">, Group<O_Group>, Flags<[CC1Option]>;
>  def O_flag : Flag<["-"], "O">, Flags<[CC1Option]>, Alias<O>,
> AliasArgs<["2"]>;
> -def O4 : Flag<["-"], "O4">, Alias<O>, AliasArgs<["3"]>;
>  def Ofast : Joined<["-"], "Ofast">, Group<O_Group>, Flags<[CC1Option]>;
>  def P : Flag<["-"], "P">, Flags<[CC1Option]>,
>    HelpText<"Disable linemarker output in -E mode">;
>
> Modified: cfe/trunk/lib/Driver/Tools.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=189369&r1=189368&r2=189369&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Driver/Tools.cpp (original)
> +++ cfe/trunk/lib/Driver/Tools.cpp Tue Aug 27 11:58:15 2013
> @@ -1863,7 +1863,8 @@ static bool isOptimizationLevelFast(cons
>  /// \brief Vectorize at all optimization levels greater than 1 except for
> -Oz.
>  static bool shouldEnableVectorizerAtOLevel(const ArgList &Args) {
>    if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
> -    if (A->getOption().matches(options::OPT_Ofast))
> +    if (A->getOption().matches(options::OPT_O4) ||
> +        A->getOption().matches(options::OPT_Ofast))
>        return true;
>
>      if (A->getOption().matches(options::OPT_O0))
> @@ -2622,8 +2623,15 @@ void Clang::ConstructJob(Compilation &C,
>    // preprocessed inputs and configure concludes that -fPIC is not
> supported.
>    Args.ClaimAllArgs(options::OPT_D);
>
> -  if (Arg *A = Args.getLastArg(options::OPT_O_Group))
> -    A->render(Args, CmdArgs);
> +  // Manually translate -O4 to -O3; let clang reject others.
> +  if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
> +    if (A->getOption().matches(options::OPT_O4)) {
> +      CmdArgs.push_back("-O3");
> +      D.Diag(diag::warn_O4_is_O3);
> +    } else {
> +      A->render(Args, CmdArgs);
> +    }
> +  }
>
>    // Don't warn about unused -flto.  This can happen when we're
> preprocessing or
>    // precompiling.
>
> Modified: cfe/trunk/test/Driver/clang_f_opts.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/clang_f_opts.c?rev=189369&r1=189368&r2=189369&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/Driver/clang_f_opts.c (original)
> +++ cfe/trunk/test/Driver/clang_f_opts.c Tue Aug 27 11:58:15 2013
> @@ -97,4 +97,5 @@
>  // CHECK-NO-M-PASCAL-STRINGS-NOT: "-fpascal-strings"
>
>  // RUN: %clang -### -S -O4 %s 2>&1 | FileCheck -check-prefix=CHECK-MAX-O
> %s
> +// CHECK-MAX-O: warning: -O4 is equivalent to -O3
>  // CHECK-MAX-O: -O3
>
>
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