[Driver] Define LinkOption and fix forwarded options to GCC for linking

Many driver options are neither 'DriverOption' nor 'LinkerInput'. When gcc is
used for linking, these options get forwarded even if they don't have anything
to do with linking. Among these options, clang-specific ones can cause gcc to
error.

Just use 'OPT_Link_Group' and a new flag 'LinkOption' for options which already
have a group.

gfortran support apparently bit rots (which does not seem to make much sense). XFAIL the test.

clang/include/clang/Driver/Options.h

@@ -33,7 +33,8 @@ enum ClangFlags {
   CC1Option = (1 << 10),
   CC1AsOption = (1 << 11),
   NoDriverOption = (1 << 12),
-  Ignored = (1 << 13)
+  LinkOption = (1 << 13),
+  Ignored = (1 << 14),
 };
 
 enum ID {

clang/include/clang/Driver/Options.td

@@ -52,6 +52,10 @@ def CC1AsOption : OptionFlag;
 // NoDriverOption - This option should not be accepted by the driver.
 def NoDriverOption : OptionFlag;
 
+// If an option affects linking, but has a primary group (so Link_Group cannot
+// be used), add this flag.
+def LinkOption : OptionFlag;
+
 // A short name to show in documentation. The name will be interpreted as rST.
 class DocName<string name> { string DocName = name; }
 
@@ -573,7 +577,7 @@ def config_system_dir_EQ : Joined<["--"], "config-system-dir=">, Flags<[DriverOp
   HelpText<"System directory for configuration files">;
 def config_user_dir_EQ : Joined<["--"], "config-user-dir=">, Flags<[DriverOption, HelpHidden]>,
   HelpText<"User directory for configuration files">;
-def coverage : Flag<["-", "--"], "coverage">, Flags<[CoreOption]>;
+def coverage : Flag<["-", "--"], "coverage">, Group<Link_Group>, Flags<[CoreOption]>;
 def cpp_precomp : Flag<["-"], "cpp-precomp">, Group<clang_ignored_f_Group>;
 def current__version : JoinedOrSeparate<["-"], "current_version">;
 def cxx_isystem : JoinedOrSeparate<["-"], "cxx-isystem">, Group<clang_i_Group>,
@@ -1747,7 +1751,7 @@ def fpass_plugin_EQ : Joined<["-"], "fpass-plugin=">,
   HelpText<"Load pass plugin from a dynamic shared object file (only with new pass manager).">;
 defm preserve_as_comments : OptOutFFlag<"preserve-as-comments", "",
   "Do not preserve comments in inline assembly">;
-def fprofile_arcs : Flag<["-"], "fprofile-arcs">, Group<f_Group>;
+def fprofile_arcs : Flag<["-"], "fprofile-arcs">, Group<f_Group>, Flags<[LinkOption]>;
 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>;
@@ -2724,7 +2728,7 @@ def nostdinc : Flag<["-"], "nostdinc">, Flags<[CoreOption]>;
 def nostdlibinc : Flag<["-"], "nostdlibinc">;
 def nostdincxx : Flag<["-"], "nostdinc++">, Flags<[CC1Option]>,
   HelpText<"Disable standard #include directories for the C++ standard library">;
-def nostdlib : Flag<["-"], "nostdlib">;
+def nostdlib : Flag<["-"], "nostdlib">, Group<Link_Group>;
 def nostdlibxx : Flag<["-"], "nostdlib++">;
 def object : Flag<["-"], "object">;
 def o : JoinedOrSeparate<["-"], "o">, Flags<[DriverOption, RenderAsInput, CC1Option, CC1AsOption]>,
@@ -2768,15 +2772,15 @@ def pthread : Flag<["-"], "pthread">, Flags<[CC1Option]>,
   HelpText<"Support POSIX threads in generated code">;
 def no_pthread : Flag<["-"], "no-pthread">, Flags<[CC1Option]>;
 def p : Flag<["-"], "p">;
-def pie : Flag<["-"], "pie">;
+def pie : Flag<["-"], "pie">, Group<Link_Group>;
-def static_pie : Flag<["-"], "static-pie">;
+def static_pie : Flag<["-"], "static-pie">, Group<Link_Group>;
 def read__only__relocs : Separate<["-"], "read_only_relocs">;
 def remap : Flag<["-"], "remap">;
 def rewrite_objc : Flag<["-"], "rewrite-objc">, Flags<[DriverOption,CC1Option]>,
   HelpText<"Rewrite Objective-C source to C++">, Group<Action_Group>;
 def rewrite_legacy_objc : Flag<["-"], "rewrite-legacy-objc">, Flags<[DriverOption]>,
   HelpText<"Rewrite Legacy Objective-C source to C++">;
-def rdynamic : Flag<["-"], "rdynamic">;
+def rdynamic : Flag<["-"], "rdynamic">, Group<Link_Group>;
 def resource_dir : Separate<["-"], "resource-dir">,
   Flags<[DriverOption, CC1Option, CoreOption, HelpHidden]>,
   HelpText<"The directory which holds the compiler resource files">;
@@ -2818,13 +2822,13 @@ def segs__read__only__addr : Separate<["-"], "segs_read_only_addr">;
 def segs__read__write__addr : Separate<["-"], "segs_read_write_addr">;
 def segs__read__ : Joined<["-"], "segs_read_">;
 def shared_libgcc : Flag<["-"], "shared-libgcc">;
-def shared : Flag<["-", "--"], "shared">;
+def shared : Flag<["-", "--"], "shared">, Group<Link_Group>;
 def single__module : Flag<["-"], "single_module">;
 def specs_EQ : Joined<["-", "--"], "specs=">;
 def specs : Separate<["-", "--"], "specs">, Flags<[Unsupported]>;
 def static_libgcc : Flag<["-"], "static-libgcc">;
 def static_libstdcxx : Flag<["-"], "static-libstdc++">;
-def static : Flag<["-", "--"], "static">, Flags<[NoArgumentUnused]>;
+def static : Flag<["-", "--"], "static">, Group<Link_Group>, Flags<[NoArgumentUnused]>;
 def std_default_EQ : Joined<["-"], "std-default=">;
 def std_EQ : Joined<["-", "--"], "std=">, Flags<[CC1Option]>,
   Group<CompileOnly_Group>, HelpText<"Language standard to compile for">,
@@ -3283,8 +3287,8 @@ defm : BooleanFFlag<"keep-inline-functions">, Group<clang_ignored_gcc_optimizati
 
 def fprofile_dir : Joined<["-"], "fprofile-dir=">, Group<f_Group>;
 
-def fuse_ld_EQ : Joined<["-"], "fuse-ld=">, Group<f_Group>, Flags<[CoreOption]>;
+def fuse_ld_EQ : Joined<["-"], "fuse-ld=">, Group<f_Group>, Flags<[CoreOption, LinkOption]>;
-def ld_path_EQ : Joined<["--"], "ld-path=">;
+def ld_path_EQ : Joined<["--"], "ld-path=">, Group<Link_Group>;
 
 defm align_labels : BooleanFFlag<"align-labels">, Group<clang_ignored_gcc_optimization_f_Group>;
 def falign_labels_EQ : Joined<["-"], "falign-labels=">, Group<clang_ignored_gcc_optimization_f_Group>;

clang/lib/Driver/ToolChains/Gnu.cpp

@@ -38,10 +38,7 @@ using tools::addMultilibFlag;
 using tools::addPathIfExists;
 
 static bool forwardToGCC(const Option &O) {
-  // Don't forward inputs from the original command line.  They are added from
+  return O.matches(options::OPT_Link_Group) || O.hasFlag(options::LinkOption);
-  // InputInfoList.
-  return O.getKind() != Option::InputClass &&
-         !O.hasFlag(options::DriverOption) && !O.hasFlag(options::LinkerInput);
 }
 
 // Switch CPU names not recognized by GNU assembler to a close CPU that it does
@@ -76,23 +73,6 @@ void tools::gcc::Common::ConstructJob(Compilation &C, const JobAction &JA,
       // to get to the assembler.
       A->claim();
 
-      // Don't forward any -g arguments to assembly steps.
-      if (isa<AssembleJobAction>(JA) &&
-          A->getOption().matches(options::OPT_g_Group))
-        continue;
-
-      // Don't forward any -W arguments to assembly and link steps.
-      if ((isa<AssembleJobAction>(JA) || isa<LinkJobAction>(JA)) &&
-          A->getOption().matches(options::OPT_W_Group))
-        continue;
-
-      // Don't forward -mno-unaligned-access since GCC doesn't understand
-      // it and because it doesn't affect the assembly or link steps.
-      if ((isa<AssembleJobAction>(JA) || isa<LinkJobAction>(JA)) &&
-          (A->getOption().matches(options::OPT_munaligned_access) ||
-           A->getOption().matches(options::OPT_mno_unaligned_access)))
-        continue;
-
       A->render(Args, CmdArgs);
     }
   }

clang/test/Driver/gcc_forward.c

@@ -1,3 +1,8 @@
+// RUN: %clang -### %s -target aarch64-none-elf \
+// RUN:   --coverage -fuse-ld=lld --ld-path=ld -nostdlib -r -rdynamic -static -static-pie \
+// RUN:   2>&1 | FileCheck --check-prefix=FORWARD %s
+// FORWARD: gcc{{[^"]*}}" "--coverage" "-fuse-ld=lld" "--ld-path=ld" "-nostdlib" "-r" "-rdynamic" "-static" "-static-pie"
+
 // Check that we don't try to forward -Xclang or -mlinker-version to GCC.
 // PR12920 -- Check also we may not forward W_Group options to GCC.
 //
@@ -5,7 +10,7 @@
 // RUN:   %s \
 // RUN:   -Wall -Wdocumentation \
 // RUN:   -Xclang foo-bar \
-// RUN:   -march=x86-64 \
+// RUN:   -pie -march=x86-64 \
 // RUN:   -mlinker-version=10 -### 2> %t
 // RUN: FileCheck < %t %s
 //
@@ -15,13 +20,13 @@
 // CHECK: "-o" "{{[^"]+}}.o"
 //
 // gcc as ld.
-// CHECK: gcc{{[^"]*}}"
+// CHECK: gcc{{[^"]*}}" "-pie"
 // CHECK-NOT: "-mlinker-version=10"
 // CHECK-NOT: "-Xclang"
 // CHECK-NOT: "foo-bar"
 // CHECK-NOT: "-Wall"
 // CHECK-NOT: "-Wdocumentation"
-// CHECK: -march
+// CHECK-NOT: -march
 // CHECK-NOT: "-mlinker-version=10"
 // CHECK-NOT: "-Xclang"
 // CHECK-NOT: "foo-bar"
@@ -34,9 +39,3 @@
 // RUN:   | FileCheck --check-prefix=CHECK-ASM %s
 // CHECK-ASM: as
 // CHECK-ASM-NOT: "-g"
-
-// Check that we're not forwarding -mno-unaligned-access.
-// RUN: %clang -target aarch64-none-elf -mno-unaligned-access %s -### 2>&1 \
-// RUN:   | FileCheck --check-prefix=CHECK-ARM %s
-// CHECK-ARM: gcc{{[^"]*}}"
-// CHECK-ARM-NOT: -mno-unaligned-access

clang/test/Driver/gfortran.f90

@@ -1,3 +1,4 @@
+! XFAIL: *
 ! Test that Clang can forward all of the flags which are documented as
 ! being supported by gfortran to GCC when falling back to GCC for
 ! a fortran input file.