[AIX] Pass the -b option to linker on AIX

[anjankgk]

Summary

We want to parse the -b option in the driver and pass it to the linker if the target OS is AIX. This will establish compatibility with the other AIX compilers.

[anjankgk]

Gentle ping..

[ZarkoCA]

clang/lib/Driver/ToolChains/CommonArgs.cpp

262–269

Can this be reversed so the error check is first for (!T.isOSAIX()) instead? Then you don't need the else.

clang/test/Driver/Xlinker-args.c

15–16

Does this mean that we need space between -b and the linker option when using clang normally? Or this an artifact of the way we need to write tests?

[anjankgk]

Addressed review comments

[anjankgk]

clang/test/Driver/Xlinker-args.c

15–16

Yes, since the option is defined as "JoinedOrSeparate" in the td file it wouldn't actually need the space.

[ZarkoCA]

LGTM with small nit, thanks.

clang/lib/Driver/ToolChains/CommonArgs.cpp

263

nit, I prefer this error message but it's up to you.

[anjankgk]

Thank you reviewing Zarko!

clang/lib/Driver/ToolChains/CommonArgs.cpp

263

I intentionally chose that error msg (without target mention) since that's the one the original option threw (existing '-b' option which was defined as unsupported for all the platforms).

[ZarkoCA]

clang/lib/Driver/ToolChains/CommonArgs.cpp

263

I see, that makes sense.

But now with your patch this option is supported even if only for the AIX target. So we could make the case to use the suggested error message. That said, I am still fine with what you choose.

[anjankgk]

clang/lib/Driver/ToolChains/CommonArgs.cpp

263

I actually agree on your point. So, eventhough my intention was to leave the behavior on other (non-AIX) platforms unaffected, the change causes the behavior of the option to be more target-specific - since it's now valid/supported option on AIX. So, I am going to change this error message as suggested. Thanks!

[anjankgk]

Change the error msg to include target information.

[thakis]

This seems to break tests everywhere, see e.g. https://lab.llvm.org/buildbot/#/builders/109/builds/19680

PTAL.

clang/include/clang/Driver/Options.td

 def arch__errors__fatal : Flag<["-"], "arch_errors_fatal">;
 def arch : Separate<["-"], "arch">, Flags<[NoXarchOption]>;
 def arch__only : Separate<["-"], "arch_only">;
 def a : Joined<["-"], "a">;
 def autocomplete : Joined<["--"], "autocomplete=">;
 def bind__at__load : Flag<["-"], "bind_at_load">;
 def bundle__loader : Separate<["-"], "bundle_loader">;
 def bundle : Flag<["-"], "bundle">;
-def b : JoinedOrSeparate<["-"], "b">, Flags<[Unsupported]>;
+def b : JoinedOrSeparate<["-"], "b">, Flags<[LinkerInput, RenderAsInput]>,
+  HelpText<"Pass -b <arg> to the linker on AIX (only).">, MetaVarName<"<arg>">,
+  Group<Link_Group>;
 def cl_opt_disable : Flag<["-"], "cl-opt-disable">, Group<opencl_Group>, Flags<[CC1Option]>,
   HelpText<"OpenCL only. This option disables all optimizations. By default optimizations are enabled.">;
 def cl_strict_aliasing : Flag<["-"], "cl-strict-aliasing">, Group<opencl_Group>, Flags<[CC1Option]>,
   HelpText<"OpenCL only. This option is added for compatibility with OpenCL 1.0.">;
 def cl_single_precision_constant : Flag<["-"], "cl-single-precision-constant">, Group<opencl_Group>, Flags<[CC1Option]>,
   HelpText<"OpenCL only. Treat double precision floating-point constant as single precision constant.">,
   MarshallingInfoFlag<LangOpts<"SinglePrecisionConstants">>;
 def cl_finite_math_only : Flag<["-"], "cl-finite-math-only">, Group<opencl_Group>, Flags<[CC1Option]>,

clang/lib/Driver/ToolChains/CommonArgs.cpp

for (const auto &II : Inputs) {
     if (II.isFilename()) {
       CmdArgs.push_back(II.getFilename());
       continue;
     }
 
     // Otherwise, this is a linker input argument.
     const Arg &A = II.getInputArg();
 
+    if (A.getOption().matches(options::OPT_b)) {
+      const llvm::Triple &T = TC.getTriple();
+      if (!T.isOSAIX()) {
+        TC.getDriver().Diag(diag::err_drv_unsupported_opt_for_target)
+            << A.getAsString(Args);
+      }
+      // Pass -b prefix for AIX linker.
+      A.claim();
+      A.render(Args, CmdArgs);
+    }
+
     // Handle reserved library options.
     if (A.getOption().matches(options::OPT_Z_reserved_lib_stdcxx))
       TC.AddCXXStdlibLibArgs(Args, CmdArgs);
     else if (A.getOption().matches(options::OPT_Z_reserved_lib_cckext))
       TC.AddCCKextLibArgs(Args, CmdArgs);
     else if (A.getOption().matches(options::OPT_z)) {
       // Pass -z prefix for gcc linker compatibility.
       A.claim();

clang/test/Driver/Xlinker-args.c

 // Check that we extract --no-demangle from '-Xlinker' and '-Wl,', since that
 // was a collect2 argument.
 
 // RUN: %clang -target i386-apple-darwin9 -### \
 // RUN:   -Xlinker one -Xlinker --no-demangle \
 // RUN:   -Wl,two,--no-demangle,three -Xlinker four -z five -r %s 2> %t
 // RUN: FileCheck -check-prefix=DARWIN < %t %s
 
 /// -T is reordered to the last to make sure -L takes precedence.
 // RUN: %clang -target x86_64-pc-linux-gnu -### \
 // RUN:   -e _start -T a.lds -Xlinker one -Xlinker --no-demangle \
 // RUN:   -Wl,two,--no-demangle,three -Xlinker four -z five -r %s 2> %t
 // RUN: FileCheck -check-prefix=LINUX < %t %s
-//
+
+// RUN: %clang -target powerpc-unknown-aix -### \
+// RUN:   -b one %s 2> %t
+// RUN: FileCheck -check-prefix=AIX < %t %s
+
+// RUN: %clang -target powerpc-unknown-linux -### \
+// RUN:   -b one %s 2> %t
+// RUN: FileCheck -check-prefix=NOT-AIX < %t %s
+
 // DARWIN-NOT: --no-demangle
 // DARWIN: "one" "two" "three" "four" "-z" "five" "-r"
 // LINUX: "--no-demangle" "-e" "_start" "one" "two" "three" "four" "-z" "five" "-r" {{.*}} "-T" "a.lds"
+// AIX: "-b" "one" 
+// NOT-AIX: error: unsupported option '-b one'
 
 // Check that we forward '-Xlinker' and '-Wl,' on Windows.
 // RUN: %clang -target i686-pc-win32 -fuse-ld=link -### \
 // RUN:   -Xlinker one -Wl,two %s 2>&1 | \
 // RUN:   FileCheck -check-prefix=WIN %s
 // WIN: link.exe
 // WIN: "one"
 // WIN: "two"