[Driver] Allow -mnop-mcount for SystemZ and -mfentry for X86 and SystemZ

gcc/config/{i386,s390} support -mnop-mcount. We currently only support
-mnop-mcount for SystemZ. The function attribute "mnop-mcount" is
ignored on other targets.

gcc/config/{i386,s390} support -mfentry. We currently only support
-mfentry for X86 and SystemZ. TargetOpcode::FENTRY_CALL is not handled
on other targets.

  % clang -target aarch64 -pg -mfentry a.c -c
  fatal error: error in backend: Not supported instr: <MCInst 21>

-mfentry, -mrecord-mcount, and -mnop-mcount were invented for Linux
ftrace. Linux uses $(call cc-option-yn,-mrecord-mcount) to detect if the
specific feature is available. Reject unsupported features so that Linux
build system will not wrongly consider them available and cause
build/runtime failures.

Note, GCC has stricter checks that we do not implement, e.g. -fpic/-fpie
-fnop-mcount is not allowed on x86, -fpic/-fpie -mfentry is not allowed
on x86-32.

1 files changed, 18 insertions, 9 deletions

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 03100948f56..1b8eca0ea0d 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4986,18 +4986,27 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   const XRayArgs &XRay = TC.getXRayArgs();
   XRay.addArgs(TC, Args, CmdArgs, InputType);
 
-  if (TC.SupportsProfiling())
+  if (TC.SupportsProfiling()) {
     Args.AddLastArg(CmdArgs, options::OPT_pg);
 
-  if (TC.SupportsProfiling())
-    Args.AddLastArg(CmdArgs, options::OPT_mfentry);
-
-  if (TC.SupportsProfiling())
-    Args.AddLastArg(CmdArgs, options::OPT_mnop_mcount);
-
-  if (TC.SupportsProfiling()) {
+    llvm::Triple::ArchType Arch = TC.getArch();
+    if (Arg *A = Args.getLastArg(options::OPT_mfentry)) {
+      if (Arch == llvm::Triple::systemz || Arch == llvm::Triple::x86 ||
+          Arch == llvm::Triple::x86_64)
+        A->render(Args, CmdArgs);
+      else
+        D.Diag(diag::err_drv_unsupported_opt_for_target)
+            << A->getAsString(Args) << TripleStr;
+    }
+    if (Arg *A = Args.getLastArg(options::OPT_mnop_mcount)) {
+      if (Arch == llvm::Triple::systemz)
+        A->render(Args, CmdArgs);
+      else
+        D.Diag(diag::err_drv_unsupported_opt_for_target)
+            << A->getAsString(Args) << TripleStr;
+    }
     if (Arg *A = Args.getLastArg(options::OPT_mrecord_mcount)) {
-      if (TC.getArch() == llvm::Triple::systemz)
+      if (Arch == llvm::Triple::systemz)
         A->render(Args, CmdArgs);
       else
         D.Diag(diag::err_drv_unsupported_opt_for_target)