[AIX][pg] Add Correct Search Paths for Profiled Libraries

[francii]

Summary

On AIX, profiled system libraries are stored at /lib/profiled and /usr/lib/profiled. When compiling with -pg, we want to link against libraries in those directories. This PR modifies the AIX toolchain to add those directories to the linker search paths.

[MaskRay]

This needs a clang/test/Driver test. And, does this work with --sysroot= ?

[francii]

Including test case

[francii]

In D137375#3906777, @MaskRay wrote:

This needs a clang/test/Driver test. And, does this work with --sysroot= ?

Thanks for your comment!
It does not work with --sysroot. From my initial findings, the compiler recognizes sysroot but the linker does not respect it for any of the libraries it links against.

On xlc, passing --sysroot= does not change the path used for these libraries. The driver will emit the same link flags: -L/lib/profiled,-L/usr/lib/profiled. As of now, this patch follows the same standard for consistency.

[francii]

Update the recently-created test cases

[francii]

Add support for --sysroot

[francii]

Removed unnecessary variables

[francii]

Soft reset

[francii]

Removed check for sysroot, it is not needed.

[francii]

Fix mixup

[francii]

Remove check for -p

[francii]

Add sysroot to test cases

[cebowleratibm]

Looks good but I just want to confirm that the profiled -L paths are appended in the correct order with respect to the non-profiled paths.

clang/test/Driver/aix-ld.c

192 ↗

(On Diff #475203)

I don't currently see the test checking for the usual /lib and /usr/lib directories. Should we check that the new profiled -L paths are correctly positioned relative to the non-profiled directories, or does it matter?

[francii]

In D137375#3943751, @cebowleratibm wrote:

Looks good but I just want to confirm that the profiled -L paths are appended in the correct order with respect to the non-profiled paths.

In the AIX ld manpage, we find:

Libraries

       Libraries are files whose names end in .a, or possibly .so. To designate a library, you can specify an absolute or relative path name or use the -l (lowercase
       letter L) flag in the form -lName. The last form designates a libName.a file, or when the rtl option is used, a libName.so file to be searched for in several
       directories. These search directories include any directories that are specified by -L flags and the standard library directories /usr/lib and /lib.

So the addition of -L/usr/lib/profiled and -L/lib/profiled comes before the implicit linking of /usr/lib and /lib, so the linker will resolve the profiled libraries first.

[cebowleratibm]

LGTM.

[francii]

Closing as this revision has landed
https://reviews.llvm.org/rG0fae851824bc1b64a727aeb331b7a0787599bd1f

clang/lib/Driver/ToolChains/AIX.cpp

if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
     // Support POSIX threads if "-pthreads" or "-pthread" is present.
     if (Args.hasArg(options::OPT_pthreads, options::OPT_pthread))
       CmdArgs.push_back("-lpthreads");
 
     if (D.CCCIsCXX())
       CmdArgs.push_back("-lm");
 
     CmdArgs.push_back("-lc");
+
+    if (Args.hasArg(options::OPT_pg)) {
+      const char *libProfiled;
+      const char *usrLibProfiled;
+
+      if (!D.SysRoot.empty()) {
+        libProfiled = Args.MakeArgString((llvm::Twine("-L") + D.SysRoot) +
+                                         "/lib/profiled");
+        usrLibProfiled = Args.MakeArgString((llvm::Twine("-L") + D.SysRoot) +
+                                            "/usr/lib/profiled");
+      } else {
+        libProfiled = Args.MakeArgString(llvm::Twine("-L/lib/profiled"));
+        usrLibProfiled = Args.MakeArgString(llvm::Twine("-L/usr/lib/profiled"));
+      }
+      CmdArgs.push_back(libProfiled);
+      CmdArgs.push_back(usrLibProfiled);
+    }
   }
 
   const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath());
   C.addCommand(std::make_unique<Command>(JA, *this, ResponseFileSupport::None(),
                                          Exec, CmdArgs, Inputs, Output));
 }
 
 /// AIX - AIX tool chain which can call as(1) and ld(1) directly.