Add a new -fglobal-isel option and make -fexperimental-isel an alias for it.

[aemerson]

Summary

Since GlobalISel is maturing and is already on at -O0 for AArch64, it's not completely "experimental". Create a more appropriate driver flag and make the older option an alias for it.

[aemerson]

Sorry, forgot to add cfe-commits to the original diff.

[dsanders]

LGTM

clang/include/clang/Basic/DiagnosticDriverKinds.td

 def warn_drv_fine_grained_bitfield_accesses_ignored : Warning<
   "option '-ffine-grained-bitfield-accesses' cannot be enabled together with a sanitizer; flag ignored">,
   InGroup<OptionIgnored>;
 
 def note_drv_verify_prefix_spelling : Note<
   "-verify prefixes must start with a letter and contain only alphanumeric"
   " characters, hyphens, and underscores">;
 
-def warn_drv_experimental_isel_incomplete : Warning<
-  "-fexperimental-isel support for the '%0' architecture is incomplete">,
-  InGroup<ExperimentalISel>;
-
-def warn_drv_experimental_isel_incomplete_opt : Warning<
-  "-fexperimental-isel support is incomplete for this architecture at the current optimization level">,
-  InGroup<ExperimentalISel>;
+def warn_drv_global_isel_incomplete : Warning<
+  "-fglobal-isel support for the '%0' architecture is incomplete">,
+  InGroup<GlobalISel>;
+
+def warn_drv_global_isel_incomplete_opt : Warning<
+  "-fglobal-isel support is incomplete for this architecture at the current optimization level">,
+  InGroup<GlobalISel>;
 
 def warn_drv_moutline_unsupported_opt : Warning<
   "The '%0' architecture does not support -moutline; flag ignored">,
   InGroup<OptionIgnored>;
 
 def warn_drv_darwin_sdk_invalid_settings : Warning<
   "SDK settings were ignored as 'SDKSettings.json' could not be parsed">,
   InGroup<DiagGroup<"darwin-sdk-settings">>;

clang/include/clang/Basic/DiagnosticGroups.td

 def OptionIgnored : DiagGroup<"option-ignored">;
 
 def UnknownArgument : DiagGroup<"unknown-argument">;
 
 // A warning group for warnings about code that clang accepts when
 // compiling OpenCL C/C++ but which is not compatible with the SPIR spec.
 def SpirCompat : DiagGroup<"spir-compat">;
 
-// Warning for the experimental-isel options.
-def ExperimentalISel : DiagGroup<"experimental-isel">;
+// Warning for the GlobalISel options.
+def GlobalISel : DiagGroup<"global-isel">;
 
 // A warning group specifically for warnings related to function
 // multiversioning.
 def FunctionMultiVersioning : DiagGroup<"function-multiversion">;
 
 def NoDeref : DiagGroup<"noderef">;
 
 // A group for cross translation unit static analysis related warnings.

clang/include/clang/Driver/Options.td

 def filelist : Separate<["-"], "filelist">, Flags<[LinkerInput]>,
                Group<Link_Group>;
 def : Flag<["-"], "findirect-virtual-calls">, Alias<fapple_kext>;
 def finline_functions : Flag<["-"], "finline-functions">, Group<f_clang_Group>, Flags<[CC1Option]>,
   HelpText<"Inline suitable functions">;
 def finline_hint_functions: Flag<["-"], "finline-hint-functions">, Group<f_clang_Group>, Flags<[CC1Option]>,
   HelpText<"Inline functions which are (explicitly or implicitly) marked inline">;
 def finline : Flag<["-"], "finline">, Group<clang_ignored_f_Group>;
+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>,
-  HelpText<"Enables the experimental global instruction selector">;
+  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 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]>,
def fno_dollars_in_identifiers : Flag<["-"], "fno-dollars-in-identifiers">, Group<f_Group>,
   HelpText<"Disallow '$' in identifiers">, Flags<[CC1Option]>;
 def fno_elide_constructors : Flag<["-"], "fno-elide-constructors">, Group<f_Group>,
   HelpText<"Disable C++ copy constructor elision">, Flags<[CC1Option]>;
 def fno_eliminate_unused_debug_symbols : Flag<["-"], "fno-eliminate-unused-debug-symbols">, Group<f_Group>;
 def fno_exceptions : Flag<["-"], "fno-exceptions">, Group<f_Group>;
 def fno_gnu_keywords : Flag<["-"], "fno-gnu-keywords">, Group<f_Group>, Flags<[CC1Option]>;
 def fno_inline_functions : Flag<["-"], "fno-inline-functions">, Group<f_clang_Group>, Flags<[CC1Option]>;
 def fno_inline : Flag<["-"], "fno-inline">, Group<f_clang_Group>, Flags<[CC1Option]>;
+def fno_global_isel : Flag<["-"], "fno-global-isel">, Group<f_clang_Group>,
+  HelpText<"Disables the global instruction selector">;
 def fno_experimental_isel : Flag<["-"], "fno-experimental-isel">, Group<f_clang_Group>,
-  HelpText<"Disables the experimental global instruction selector">;
+  Alias<fno_global_isel>;
 def fno_experimental_new_pass_manager : Flag<["-"], "fno-experimental-new-pass-manager">,
   Group<f_clang_Group>, Flags<[CC1Option]>,
   HelpText<"Disables an experimental new pass manager in LLVM.">;
 def fveclib : Joined<["-"], "fveclib=">, Group<f_Group>, Flags<[CC1Option]>,
     HelpText<"Use the given vector functions library">, Values<"Accelerate,MASSV,SVML,none">;
 def fno_lax_vector_conversions : Flag<["-"], "fno-lax-vector-conversions">, Group<f_Group>,
   Alias<flax_vector_conversions_EQ>, AliasArgs<["none"]>;
 def fno_merge_all_constants : Flag<["-"], "fno-merge-all-constants">, Group<f_Group>,

clang/lib/Driver/ToolChains/Clang.cpp

bool SplitLTOUnit =
       Args.hasFlag(options::OPT_fsplit_lto_unit,
                    options::OPT_fno_split_lto_unit, DefaultsSplitLTOUnit);
   if (Sanitize.needsLTO() && !SplitLTOUnit)
     D.Diag(diag::err_drv_argument_not_allowed_with) << "-fno-split-lto-unit"
                                                     << "-fsanitize=cfi";
   if (SplitLTOUnit)
     CmdArgs.push_back("-fsplit-lto-unit");
 
-  if (Arg *A = Args.getLastArg(options::OPT_fexperimental_isel,
-                               options::OPT_fno_experimental_isel)) {
+  if (Arg *A = Args.getLastArg(options::OPT_fglobal_isel,
+                               options::OPT_fno_global_isel)) {
     CmdArgs.push_back("-mllvm");
-    if (A->getOption().matches(options::OPT_fexperimental_isel)) {
+    if (A->getOption().matches(options::OPT_fglobal_isel)) {
       CmdArgs.push_back("-global-isel=1");
 
       // GISel is on by default on AArch64 -O0, so don't bother adding
       // the fallback remarks for it. Other combinations will add a warning of
       // some kind.
       bool IsArchSupported = Triple.getArch() == llvm::Triple::aarch64;
       bool IsOptLevelSupported = false;
 
       Arg *A = Args.getLastArg(options::OPT_O_Group);
       if (Triple.getArch() == llvm::Triple::aarch64) {
         if (!A || A->getOption().matches(options::OPT_O0))
           IsOptLevelSupported = true;
       }
       if (!IsArchSupported || !IsOptLevelSupported) {
         CmdArgs.push_back("-mllvm");
         CmdArgs.push_back("-global-isel-abort=2");
 
         if (!IsArchSupported)
-          D.Diag(diag::warn_drv_experimental_isel_incomplete) << Triple.getArchName();
+          D.Diag(diag::warn_drv_global_isel_incomplete) << Triple.getArchName();
         else
-          D.Diag(diag::warn_drv_experimental_isel_incomplete_opt);
+          D.Diag(diag::warn_drv_global_isel_incomplete_opt);
       }
     } else {
       CmdArgs.push_back("-global-isel=0");
     }
   }
 
   if (Args.hasArg(options::OPT_forder_file_instrumentation)) {
      CmdArgs.push_back("-forder-file-instrumentation");

clang/test/Driver/global-isel.c

 // REQUIRES: x86-registered-target,aarch64-registered-target
 
+// RUN: %clang -fglobal-isel -S -### %s 2>&1 | FileCheck --check-prefix=ENABLED %s
+// RUN: %clang -fno-global-isel -S -### %s 2>&1 | FileCheck --check-prefix=DISABLED %s
+
+// RUN: %clang -target aarch64 -fglobal-isel -S %s -### 2>&1 | FileCheck --check-prefix=ARM64-DEFAULT %s
+// RUN: %clang -target aarch64 -fglobal-isel -S -O0 %s -### 2>&1 | FileCheck --check-prefix=ARM64-O0 %s
+// RUN: %clang -target aarch64 -fglobal-isel -S -O2 %s -### 2>&1 | FileCheck --check-prefix=ARM64-O2 %s
+// RUN: %clang -target aarch64 -fglobal-isel -Wno-global-isel -S -O2 %s -### 2>&1 | FileCheck --check-prefix=ARM64-O2-NOWARN %s
+
+// RUN: %clang -target x86_64 -fglobal-isel -S %s -### 2>&1 | FileCheck --check-prefix=X86_64 %s
+
+// Now test the aliases.
+
 // RUN: %clang -fexperimental-isel -S -### %s 2>&1 | FileCheck --check-prefix=ENABLED %s
 // RUN: %clang -fno-experimental-isel -S -### %s 2>&1 | FileCheck --check-prefix=DISABLED %s
 
 // RUN: %clang -target aarch64 -fexperimental-isel -S %s -### 2>&1 | FileCheck --check-prefix=ARM64-DEFAULT %s
 // RUN: %clang -target aarch64 -fexperimental-isel -S -O0 %s -### 2>&1 | FileCheck --check-prefix=ARM64-O0 %s
 // RUN: %clang -target aarch64 -fexperimental-isel -S -O2 %s -### 2>&1 | FileCheck --check-prefix=ARM64-O2 %s
-// RUN: %clang -target aarch64 -fexperimental-isel -Wno-experimental-isel -S -O2 %s -### 2>&1 | FileCheck --check-prefix=ARM64-O2-NOWARN %s
 
 // RUN: %clang -target x86_64 -fexperimental-isel -S %s -### 2>&1 | FileCheck --check-prefix=X86_64 %s
 
 // ENABLED: "-mllvm" "-global-isel=1"
 // DISABLED: "-mllvm" "-global-isel=0"
 
-// ARM64-DEFAULT-NOT: warning: -fexperimental-sel
+// ARM64-DEFAULT-NOT: warning: -fglobal-isel
 // ARM64-DEFAULT-NOT: "-global-isel-abort=2"
-// ARM64-O0-NOT: warning: -fexperimental-sel
-// ARM64-O2: warning: -fexperimental-isel support is incomplete for this architecture at the current optimization level
+// ARM64-O0-NOT: warning: -fglobal-isel
+// ARM64-O2: warning: -fglobal-isel support is incomplete for this architecture at the current optimization level
 // ARM64-O2: "-mllvm" "-global-isel-abort=2"
-// ARM64-O2-NOWARN-NOT: warning: -fexperimental-isel
+// ARM64-O2-NOWARN-NOT: warning: -fglobal-isel
 
-// X86_64: -fexperimental-isel support for the 'x86_64' architecture is incomplete
+// X86_64: -fglobal-isel support for the 'x86_64' architecture is incomplete
 // X86_64: "-mllvm" "-global-isel-abort=2"