Deprecation flag group + use for BB vectorizer options

[joerg]

Summary

As discussed on IRC when D34846 came up, removing flags is problematic from a UX experience.

This change introduces a new option group similar to the group GCC optimizer flags like -fexpensive-optimizations. This gives a warning by default, but can be silenced appropriately. Move the two BB vectorizer flags into this option group, test them and add a release note entry.

[hfinkel]

LGTM

docs/ReleaseNotes.rst

69

There was only one pass, so maybe say, "... to enable the basic-block-vectorization pass."

docs/ReleaseNotes.rst

 -  -Wunused-lambda-capture warns when a variable explicitly captured
    by a lambda is not used in the body of the lambda.
 
 New Compiler Flags
 ------------------
 
 The option ....
 
+Deprecated Compiler Flags
+-------------------------
+
+The following options are deprecated and ignored. They will be removed in
+future versions of Clang.
+
+- -fslp-vectorize-aggressive used to enable the BB vectorizing passes. They have been superseeded
+  by the normal SLP vectorizer.
+- -fno-slp-vectorize-aggressive used to be the default behavior of clang.
+
 New Pragmas in Clang
 -----------------------
 
 Clang now supports the ...
 
 
 Attribute Changes in Clang
 --------------------------

include/clang/Basic/DiagnosticDriverKinds.td

 def err_drv_bitcode_unsupported_on_toolchain : Error<
   "-fembed-bitcode is not supported on versions of iOS prior to 6.0">;
 
 def warn_O4_is_O3 : Warning<"-O4 is equivalent to -O3">, InGroup<Deprecated>;
 def warn_drv_optimization_value : Warning<"optimization level '%0' is not supported; using '%1%2' instead">,
   InGroup<InvalidCommandLineArgument>;
 def warn_ignored_gcc_optimization : Warning<"optimization flag '%0' is not supported">,
   InGroup<IgnoredOptimizationArgument>;
+def warn_ignored_clang_option : Warning<"the flag '%0' has been deprecated and will be ignored">,
+  InGroup<UnusedCommandLineArgument>;
 def warn_drv_unsupported_opt_for_target : Warning<
   "optimization flag '%0' is not supported for target '%1'">,
   InGroup<IgnoredOptimizationArgument>;
 def warn_c_kext : Warning<
   "ignoring -fapple-kext which is valid for C++ and Objective-C++ only">;
 def warn_drv_input_file_unused : Warning<
   "%0: '%1' input unused%select{ when '%3' is present|}2">,
   InGroup<UnusedCommandLineArgument>;

include/clang/Driver/Options.td

 
 // Temporary groups for clang options which we know we don't support,
 // but don't want to verbosely warn the user about.
 def clang_ignored_f_Group : OptionGroup<"<clang ignored f group>">,
   Group<f_Group>, Flags<[Ignored]>;
 def clang_ignored_m_Group : OptionGroup<"<clang ignored m group>">,
   Group<m_Group>, Flags<[Ignored]>;
 
+// Group for clang options in the process of deprecation.
+// Please include the version that deprecated the flag as comment to allow
+// easier garbage collection.
+def clang_ignored_legacy_options_Group : OptionGroup<"<clang legacy flags>">,
+  Group<f_Group>, Flags<[Ignored]>;
+
+// Retired with clang-5.0
+def : Flag<["-"], "fslp-vectorize-aggressive">, Group<clang_ignored_legacy_options_Group>;
+def : Flag<["-"], "fno-slp-vectorize-aggressive">, Group<clang_ignored_legacy_options_Group>;
+
 // Group that ignores all gcc optimizations that won't be implemented
 def clang_ignored_gcc_optimization_f_Group : OptionGroup<
   "<clang_ignored_gcc_optimization_f_Group>">, Group<f_Group>, Flags<[Ignored]>;
 
 /////////
 // Options
 
 // The internal option ID must be a valid C++ identifier and results in a

lib/Driver/ToolChains/Clang.cpp

 
   // Warn about ignored options to clang.
   for (const Arg *A :
        Args.filtered(options::OPT_clang_ignored_gcc_optimization_f_Group)) {
     D.Diag(diag::warn_ignored_gcc_optimization) << A->getAsString(Args);
     A->claim();
   }
 
+  for (const Arg *A :
+       Args.filtered(options::OPT_clang_ignored_legacy_options_Group)) {
+    D.Diag(diag::warn_ignored_clang_option) << A->getAsString(Args);
+    A->claim();
+  }
+
   claimNoWarnArgs(Args);
 
   Args.AddAllArgs(CmdArgs, options::OPT_R_Group);
 
   Args.AddAllArgs(CmdArgs, options::OPT_W_Group);
   if (Args.hasFlag(options::OPT_pedantic, options::OPT_no_pedantic, false))
     CmdArgs.push_back("-pedantic");
   Args.AddLastArg(CmdArgs, options::OPT_pedantic_errors);

test/Driver/clang_f_opts.c

 // RUN: -ffat-lto-objects                                                     \
 // RUN: -fmerge-constants                                                     \
 // RUN: -finline-small-functions                                              \
 // RUN: -ftree-dce                                                            \
 // RUN: -ftree-ter                                                            \
 // RUN: -ftree-vrp                                                            \
 // RUN: -fno-devirtualize                                                     \
 // RUN: -fno-devirtualize-speculatively                                       \
+// RUN: -fslp-vectorize-aggressive                                            \
+// RUN: -fno-slp-vectorize-aggressive                                         \
 // RUN: %s 2>&1 | FileCheck --check-prefix=CHECK-WARNING %s
 // CHECK-WARNING-DAG: optimization flag '-finline-limit=1000' is not supported
 // CHECK-WARNING-DAG: optimization flag '-finline-limit' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fexpensive-optimizations' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fno-expensive-optimizations' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fno-defer-pop' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fkeep-inline-functions' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fno-keep-inline-functions' is not supported

 // CHECK-WARNING-DAG: optimization flag '-ffat-lto-objects' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fmerge-constants' is not supported
 // CHECK-WARNING-DAG: optimization flag '-finline-small-functions' is not supported
 // CHECK-WARNING-DAG: optimization flag '-ftree-dce' is not supported
 // CHECK-WARNING-DAG: optimization flag '-ftree-ter' is not supported
 // CHECK-WARNING-DAG: optimization flag '-ftree-vrp' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fno-devirtualize' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fno-devirtualize-speculatively' is not supported
+// CHECK-WARNING-DAG: the flag '-fslp-vectorize-aggressive' has been deprecated and will be ignored
+// CHECK-WARNING-DAG: the flag '-fno-slp-vectorize-aggressive' has been deprecated and will be ignored
 
 // Test that we mute the warning on these
 // RUN: %clang -### -finline-limit=1000 -Wno-invalid-command-line-argument              \
 // RUN:     %s 2>&1 | FileCheck --check-prefix=CHECK-NO-WARNING1 %s
 // RUN: %clang -### -finline-limit -Wno-invalid-command-line-argument                   \
 // RUN:     %s 2>&1 | FileCheck --check-prefix=CHECK-NO-WARNING2 %s
 // RUN: %clang -### -finline-limit \
 // RUN:     -Winvalid-command-line-argument -Wno-ignored-optimization-argument          \