[mips][mips64r6] Add support for mips-img-linux-gnu GCC toolchains

[dsanders]

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

[dsanders]

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]

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.

7034

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

[dsanders]

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

7034

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

[dsanders]

Made requested changes and added a testcase.

[atanasyan]

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

7026

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]

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

7026

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]

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?

7034

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]

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.

7034

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]

lib/Driver/Tools.cpp

7034

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]

lib/Driver/Tools.cpp

7034

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.

[atanasyan]

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]

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]

Ensure directories are present.

[atanasyan]

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]

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]

LGTM

lib/Driver/ToolChains.cpp

static const char *const X86Triples[] = {
     "i686-linux-gnu", "i686-pc-linux-gnu", "i486-linux-gnu", "i386-linux-gnu",
     "i386-redhat-linux6E", "i686-redhat-linux", "i586-redhat-linux",
     "i386-redhat-linux", "i586-suse-linux", "i486-slackware-linux",
     "i686-montavista-linux", "i686-linux-android"
   };
 
   static const char *const MIPSLibDirs[] = { "/lib" };
   static const char *const MIPSTriples[] = { "mips-linux-gnu",
-                                             "mips-mti-linux-gnu" };
+                                             "mips-mti-linux-gnu",
+                                             "mips-img-linux-gnu" };
   static const char *const MIPSELLibDirs[] = { "/lib" };
   static const char *const MIPSELTriples[] = { "mipsel-linux-gnu",
-                                               "mipsel-linux-android" };
+                                               "mipsel-linux-android",
+                                               "mips-img-linux-gnu" };
 
   static const char *const MIPS64LibDirs[] = { "/lib64", "/lib" };
   static const char *const MIPS64Triples[] = { "mips64-linux-gnu",
                                                "mips-mti-linux-gnu",
+                                               "mips-img-linux-gnu",
                                                "mips64-linux-gnuabi64" };
   static const char *const MIPS64ELLibDirs[] = { "/lib64", "/lib" };
   static const char *const MIPS64ELTriples[] = { "mips64el-linux-gnu",
                                                  "mips-mti-linux-gnu",
+                                                 "mips-img-linux-gnu",
                                                  "mips64el-linux-android",
                                                  "mips64el-linux-gnuabi64" };
 
   static const char *const PPCLibDirs[] = { "/lib32", "/lib" };
   static const char *const PPCTriples[] = {
     "powerpc-linux-gnu", "powerpc-unknown-linux-gnu", "powerpc-linux-gnuspe",
     "powerpc-suse-linux", "powerpc-montavista-linuxspe"
   };
MultilibSet DebianMipsMultilibs;
     Multilib M32 = Multilib()
       .flag("-m64").flag("+m32").flag("-mabi=n32");
 
     DebianMipsMultilibs = MultilibSet()
       .Either(M32, M64, MAbiN32)
       .FilterOut(NonExistent);
   }
 
+  MultilibSet ImgMultilibs;
+  {
+    Multilib Mips64r6 = Multilib()
+      .gccSuffix("/mips64r6")
+      .osSuffix("/mips64r6")
+      .includeSuffix("/mips64r6")
+      .flag("+m64").flag("-m32");
+
+    Multilib LittleEndian = Multilib()
+      .gccSuffix("/el")
+      .osSuffix("/el")
+      .includeSuffix("/el")
+      .flag("+EL").flag("-EB");
+
+    Multilib MAbi64 = Multilib()
+      .gccSuffix("/64")
+      .osSuffix("/64")
+      .includeSuffix("/64")
+      .flag("+mabi=64").flag("-mabi=n32").flag("-m32");
+
+    ImgMultilibs = MultilibSet()
+      .Maybe(Mips64r6)
+      .Maybe(MAbi64)
+      .Maybe(LittleEndian)
+      .FilterOut(NonExistent);
+  }
+
   llvm::Triple::ArchType TargetArch = TargetTriple.getArch();
 
   Multilib::flags_list Flags;
   addMultilibFlag(isMips32(TargetArch), "m32", Flags);
   addMultilibFlag(isMips64(TargetArch), "m64", Flags);
   addMultilibFlag(isMips16(Args), "mips16", Flags);
   addMultilibFlag(isMips32r2(Args), "march=mips32r2", Flags);
   addMultilibFlag(isMips64r2(Args), "march=mips64r2", Flags);
if (TargetTriple.getEnvironment() == llvm::Triple::Android) {
     // Select Android toolchain. It's the only choice in that case.
     if (AndroidMipsMultilibs.select(Flags, Result.SelectedMultilib)) {
       Result.Multilibs = AndroidMipsMultilibs;
       return true;
     }
     return false;
   }
 
+  if ((TargetTriple.getArch() == llvm::Triple::mips ||
+       TargetTriple.getArch() == llvm::Triple::mipsel ||
+       TargetTriple.getArch() == llvm::Triple::mips64 ||
+       TargetTriple.getArch() == llvm::Triple::mips64el) &&
+      TargetTriple.getVendor() == llvm::Triple::ImaginationTechnologies &&
+      TargetTriple.getOS() == llvm::Triple::Linux &&
+      TargetTriple.getEnvironment() == llvm::Triple::GNU) {
+    // Select mips-img-linux-gnu toolchain.
+    if (ImgMultilibs.select(Flags, Result.SelectedMultilib)) {
+      Result.Multilibs = ImgMultilibs;
+      return true;
+    }
+    return false;
+  }
+
   // Sort candidates. Toolchain that best meets the directories goes first.
   // Then select the first toolchains matches command line flags.
   MultilibSet *candidates[] = { &DebianMipsMultilibs, &FSFMipsMultilibs,
                                 &CSMipsMultilibs };
   std::sort(
       std::begin(candidates), std::end(candidates),
       [](MultilibSet *a, MultilibSet *b) { return a->size() > b->size(); });
   for (const auto &candidate : candidates) {

lib/Driver/Tools.cpp

if (CPUName.empty() && ABIName.empty()) {
     switch (Triple.getArch()) {
     default:
       llvm_unreachable("Unexpected triple arch name");
     case llvm::Triple::mips:
     case llvm::Triple::mipsel:
       CPUName = DefMips32CPU;
       break;
     case llvm::Triple::mips64:
     case llvm::Triple::mips64el:
       CPUName = DefMips64CPU;
       break;
     }
   }
 
   if (ABIName.empty()) {
     // Deduce ABI name from the target triple.
     if (Triple.getArch() == llvm::Triple::mips ||
static StringRef getLinuxDynamicLinker(const ArgList &Args,
   } else if (ToolChain.getArch() == llvm::Triple::armeb ||
              ToolChain.getArch() == llvm::Triple::thumbeb) {
     if (ToolChain.getTriple().getEnvironment() == llvm::Triple::GNUEABIHF)
       return "/lib/ld-linux-armhf.so.3";        /* TODO: check which dynamic linker name.  */
     else
       return "/lib/ld-linux.so.3";              /* TODO: check which dynamic linker name.  */
   } else if (ToolChain.getArch() == llvm::Triple::mips ||
              ToolChain.getArch() == llvm::Triple::mipsel) {
+    if (ToolChain.getTriple().getVendor() ==
+            llvm::Triple::ImaginationTechnologies &&
+        ToolChain.getTriple().getOS() == llvm::Triple::Linux &&
+        ToolChain.getTriple().getEnvironment() == llvm::Triple::GNU)
+      return "/lib/ld-linux-mipsn8.so.1";
     if (mips::isNaN2008(Args))
       return "/lib/ld-linux-mipsn8.so.1";
     return "/lib/ld.so.1";
   } else if (ToolChain.getArch() == llvm::Triple::mips64 ||
              ToolChain.getArch() == llvm::Triple::mips64el) {
+    if (ToolChain.getTriple().getVendor() ==
+            llvm::Triple::ImaginationTechnologies &&
+        ToolChain.getTriple().getOS() == llvm::Triple::Linux &&
+        ToolChain.getTriple().getEnvironment() == llvm::Triple::GNU)
+      return "/lib/ld-linux-mipsn8.so.1";
     if (mips::hasMipsAbiArg(Args, "n32"))
       return mips::isNaN2008(Args) ? "/lib32/ld-linux-mipsn8.so.1"
                                    : "/lib32/ld.so.1";
     return mips::isNaN2008(Args) ? "/lib64/ld-linux-mipsn8.so.1"
                                  : "/lib64/ld.so.1";
   } else if (ToolChain.getArch() == llvm::Triple::ppc)
     return "/lib/ld.so.1";
   else if (ToolChain.getArch() == llvm::Triple::ppc64 ||