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[mips][mips64r6] Add support for mips-img-linux-gnu GCC toolchains
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Authored by dsanders on Jul 9 2014, 7:08 AM.

Details

Summary
  • Support the multilib layout used by the mips-img-linux-gnu
  • Recognize mips{,64}{,el}-img-linux-gnu as being aliases of mips-img-linux-gnu
  • Use the correct dynamic linker for mips-img-linux-gnu
  • Make mips32r6/mips64r6 the default CPU for mips-img-linux-gnu

Diff Detail

Event Timeline

dsanders updated this revision to Diff 11196.Jul 9 2014, 7:08 AM
dsanders retitled this revision from to [mips][mips64r6] Add support for mips-img-linux-gnu GCC toolchains.
dsanders updated this object.
dsanders edited the test plan for this revision. (Show Details)
dsanders added a reviewer: atanasyan.
dsanders added a subscriber: mpf.

I'm still working on the test case but I thought it would be sensible to upload the patch anyway so you can look at it sooner.

atanasyan edited edge metadata.Jul 9 2014, 8:45 AM

Some notes are below:

lib/Driver/ToolChains.cpp
1937

Before call findMIPSMultilibs() we check that the current architecture is mips or mipsel or mips64 or mips64el. So the first four conditions are redundant here.

lib/Driver/Tools.cpp
7022

We do not need to check that getOS() == llvm::Triple::Linux here. The getLinuxDynamicLinker() function is called on Linux only.

7033

Is the path prefix /lib correct? Maybe /lib64?

dsanders added a comment.EditedJul 9 2014, 9:17 AM

I've nearly finished the testcase. I'm currently pruning the files that aren't really needed from the dummy toolchain.

lib/Driver/ToolChains.cpp
1937

Ok

lib/Driver/Tools.cpp
7022

Ok

7033

It's /lib in all cases for the mips-img-linux-gnu toolchain I currently have.

dsanders updated this revision to Diff 11201.Jul 9 2014, 9:35 AM
dsanders edited edge metadata.

Made requested changes and added a testcase.

A couple more comments.

lib/Driver/ToolChains.cpp
1943

I think we can replace the getEnvironment() == llvm::Triple::GNU condition by the corresponding assert. Should we catch the case when user provide something like mips-img-linux-android?

lib/Driver/Tools.cpp
7025

Are there any toolchains except the mips-img-linux-gnu which use the ld-linux-mipsn8.so.1 dynamic linker? If there is no such toolchains I suggest to write all these conditions as follows:

else if (ToolChain.getArch() == llvm::Triple::mips ||
         ToolChain.getArch() == llvm::Triple::mipsel ||
         ToolChain.getArch() == llvm::Triple::mips64 ||
         ToolChain.getArch() == llvm::Triple::mips64el) {
  if (ToolChain.getTriple().getVendor() == llvm::Triple::ImaginationTechnologies) {
    assert(ToolChain.getTriple().getEnvironment() == llvm::Triple::GNU &&
           "Unexpected environment value");
    return "/lib/ld-linux-mipsn8.so.1";
  }

  if (ToolChain.getArch() == llvm::Triple::mips ||
      ToolChain.getArch() == llvm::Triple::mipsel)
    return "/lib/ld.so.1";

  if (mips::hasMipsAbiArg(Args, "n32"))
    return "/lib32/ld.so.1";

  return "/lib64/ld.so.1";
}
dsanders added inline comments.Jul 9 2014, 11:20 AM
lib/Driver/ToolChains.cpp
1943

The downside to that is that a NDEBUG build would silently act as if the user had specified gnu regardless of what the user specified (except for the android case which is caught by the previous if-statement on line 1928). I'm not sure if that's really a problem though since using an undefined triple is likely to result in undefined defaults.

lib/Driver/Tools.cpp
7025

Yes, any toolchain with a NaN2008 multilib will use ld-linux-mipsn8.so.1 when given -mnan=2008. mips-mti-linux-gnu is one example but I think there are others.

mpf added inline comments.Jul 9 2014, 1:37 PM
lib/Driver/ToolChains.cpp
1361

Why is mti missing from this list. Either there should be both mti and img or neither

lib/Driver/Tools.cpp
7023

can't R6 just imply isNan2008 is true and therefore just use the logic below?

7033

This looks like a bug somewhere. The layout should be the same as the existing code. Perhaps the GNU toolchain for 'img' is wrong.

dsanders added inline comments.Jul 9 2014, 1:56 PM
lib/Driver/ToolChains.cpp
1361

I don't know why mti is missing. I haven't added it because this patch only aims to add support for the img triple.

lib/Driver/Tools.cpp
7023

No because the mips64r6 multilibs will try to use /lib64/ld-linux-mipsn8.so.1 when it's actually in /lib. Although, as you suggest below, it could be that the GNU toolchain is wrong.

7033

It's possible that the GNU toolchain is wrong. Here are all the ld-linux-mipsn8.so.1's in the toolchain I have:

$ find -name ld-linux-mipsn8.so.1
./sysroot/el/usr/lib/ld-linux-mipsn8.so.1
./sysroot/usr/lib/ld-linux-mipsn8.so.1
./sysroot/mips64r6/el/usr/lib/ld-linux-mipsn8.so.1
./sysroot/mips64r6/64/el/usr/lib/ld-linux-mipsn8.so.1
./sysroot/mips64r6/64/usr/lib/ld-linux-mipsn8.so.1
./sysroot/mips64r6/usr/lib/ld-linux-mipsn8.so.1
mpf added inline comments.Jul 9 2014, 2:21 PM
lib/Driver/Tools.cpp
7033

Yes but I believe that is true of mti as well. I need to check but it will be tomorrow now.

The paths used for the dynamic linker are those which would exist on a target filesystem and I think they are different from the paths used in the toolchain.

dsanders added inline comments.Jul 10 2014, 3:47 AM
lib/Driver/Tools.cpp
7033

As we discussed off-review, it seems you are correct. The sysroot layout and the expected filesystem layout on the target differ so we have to account for the difference in qemu instead.

We do not need so many files under the test/Driver/Inputs/mips_img_tree directory. Let's keep the following list because other files are not used by the test case.

  • crt1.o
  • crti.o
  • crtbegin.o
  • crtend.o
  • crtn.o
dsanders updated this revision to Diff 11259.Jul 10 2014, 4:34 AM

Further reduced the number of files in the dummy toolchain.

Corrected ld-linux-mipsn8.so.1 path

Made mips32r6/mips64r6 the default for mips-img-linux-gnu and mips64-img-linux-gnu.

dsanders updated this revision to Diff 11260.Jul 10 2014, 4:35 AM

Ensure directories are present.

dsanders updated this object.Jul 10 2014, 4:38 AM

A couple more redundant file/folders:

  • test/Driver/Inputs/mips_img_tree/include/dejagnu.h
  • test/Driver/Inputs/mips_img_tree/sysroot/usr/lib/audit
lib/Driver/Tools.cpp
943

Suppose the driver gets the following command line options:

clang -target mips-img-linux-gnu -mabi=o32 -c main.c

In that case the CPU name becomes mips32r2. Is that expected? I think we need to configure default CPU names in the lines 916-917.

dsanders updated this revision to Diff 11268.Jul 10 2014, 6:28 AM

Removed redundant files/folders

Fixed bug Simon spotted

lib/Driver/Tools.cpp
943

No, it's not expected. I've fixed this in the latest version

atanasyan accepted this revision.Jul 10 2014, 6:39 AM
atanasyan edited edge metadata.

LGTM

This revision is now accepted and ready to land.Jul 10 2014, 6:39 AM
dsanders closed this revision.Jul 10 2014, 7:49 AM