Add support to -Wa,--version in clang

[jcai19]

Summary

Clang currently only supports -Wa,--version when -no-integrated-as is
used. This adds support to -Wa,--version with -integrated-as.

Link:
https://github.com/ClangBuiltLinux/linux/issues/1320

[MaskRay]

gcc does not understand options in -Wa, so -Wa,--version needs to be used this way: gcc -Wa,--version -c -x assembler /dev/null -o /dev/null
The verbose syntax makes it not that useful. If the kernel really wants to use it, I have no issue with it.

-integrated-as => -fintegrated-as. -i* options are generally used for include related features.
Similarly, -no-integrated-as => -fno-integrated-as

[MaskRay]

clang/test/Driver/as-options.s

40 ↗

(On Diff #334027)

Drop 2>&1 because you specifically want to test stdout.

[nickdesaulniers]

In D99556#2657509, @MaskRay wrote:

gcc does not understand options in -Wa, so -Wa,--version needs to be used this way: gcc -Wa,--version -c -x assembler /dev/null -o /dev/null
The verbose syntax makes it not that useful. If the kernel really wants to use it, I have no issue with it.

I agree; the kernel only uses the compiler as the driver for assembler sources, as the kernel assembler is almost entirely -x assembler-with-cpp, so the C pre processor must be run first over the sources. This is done to share important constants like the PAGE_SIZE between C and assembler. For this reason, the maintainer of the kernel build system (Kbuild) would prefer to detect assembler version via $(CC) -Wa,--version.

@jcai19 would you mind adding a test like clang/test/Driver/version.c? clang/test/Driver/version.s perhaps? Testing that there is some output from -Wa,--version might be helpful.

[jcai19]

Update tests to address comments.

[nickdesaulniers]

clang/test/Driver/as-version.s

10

What happens if we run this on windows (where I suspect that GAS isn't available)? Perhaps a CHECK-NOT: clang would be better?

[jcai19]

Update tests.

clang/test/Driver/as-version.s

10

CHECK-NOT does sound safer in this case. I've updated the test. Thanks.

[MaskRay]

clang/test/Driver/as-version.s

4

Delete excess spaces

[thakis]

Looks like the test fails on non-linux:
http://45.33.8.238/macm1/6631/step_6.txt

Please take a look and revert for now if it takes a while to fix.

[thakis]

Different error on windows: http://45.33.8.238/win/36132/step_7.txt

[nickdesaulniers]

ah, sorry, I think we're missing a // REQUIRES: linux in the newly added test? I've pushed a revert for now.

[dyung]

It also fails with the PS4 triple because we default to an external assembler that isn't present: https://lab.llvm.org/buildbot/#/builders/139/builds/2161/steps/6/logs/FAIL__Clang__as-version_s

[jcai19]

We can probably remove the -fno-integraetd-as case.

[nickdesaulniers]

In D99556#2662990, @jcai19 wrote:

We can probably remove the -fno-integraetd-as case.

Or split it out into a separate test file with // REQUIRES: linux. Either actually is fine by me.

[MaskRay]

In D99556#2664426, @nickdesaulniers wrote:

In D99556#2662990, @jcai19 wrote:

We can probably remove the -fno-integraetd-as case.

Or split it out into a separate test file with // REQUIRES: linux. Either actually is fine by me.

No, we should reduce reliance on the host system. Printing ....as is fine (with -B), but invoking it to get the output is not something we should do in isolated tests.

[jcai19]

Relanded without -fno-initegrated-as case at https://reviews.llvm.org/rG76d9bc72784d88f4dd57b9939e52c73739438af5.

[MaskRay]

In the future, please include Differential Revision: for relands so that the Commits line displays the associated commits :)

clang/lib/Driver/ToolChains/Clang.cpp

for (StringRef Value : A->getValues()) {
         CmdArgs.push_back("-fdebug-compilation-dir");
         TakeNextArg = true;
       } else if (Value.consume_front("-fdebug-compilation-dir=")) {
         // The flag is a -Wa / -Xassembler argument and Options doesn't
         // parse the argument, so this isn't automatically aliased to
         // -fdebug-compilation-dir (without '=') here.
         CmdArgs.push_back("-fdebug-compilation-dir");
         CmdArgs.push_back(Value.data());
+      } else if (Value == "--version") {
+        D.PrintVersion(C, llvm::outs());
       } else {
         D.Diag(diag::err_drv_unsupported_option_argument)
             << A->getOption().getName() << Value;
       }
     }
   }
   if (UseRelaxRelocations)
     CmdArgs.push_back("--mrelax-relocations");

clang/test/Driver/as-version.s

+// Test version information.
+
+// RUN: %clang -Wa,--version -c -fintegrated-as %s -o /dev/null \
+// RUN:   | FileCheck --check-prefix=IAS %s
+// IAS: clang version
+
+// RUN: %clang -Wa,--version -c -fno-integrated-as %s -o /dev/null \
+// RUN:   | FileCheck --check-prefix=GAS %s
+// GAS-NOT: clang