[Driver] -noprofilelib flag

This flag is analoguous to other flags like -nostdlib or -nolibc
and could be used to disable linking of profile runtime library.
This is useful in certain environments like kernel, where profile
instrumentation is still desirable, but we cannot use the standard
runtime library.

llvm-svn: 365808

clang/docs/ClangCommandLineReference.rst

@@ -346,6 +346,8 @@ Disable builtin #include directories
 
 .. option:: -noprebind
 
+.. option:: -noprofilelib
+
 .. option:: -noseglinkedit
 
 .. option:: -nostartfiles

clang/include/clang/Driver/Options.td

@@ -2512,6 +2512,7 @@ def nomultidefs : Flag<["-"], "nomultidefs">;
 def nopie : Flag<["-"], "nopie">;
 def no_pie : Flag<["-"], "no-pie">, Alias<nopie>;
 def noprebind : Flag<["-"], "noprebind">;
+def noprofilelib : Flag<["-"], "noprofilelib">;
 def noseglinkedit : Flag<["-"], "noseglinkedit">;
 def nostartfiles : Flag<["-"], "nostartfiles">;
 def nostdinc : Flag<["-"], "nostdinc">, Flags<[CoreOption]>;

clang/lib/Driver/ToolChain.cpp

@@ -450,6 +450,9 @@ std::string ToolChain::getArchSpecificLibPath() const {
 }
 
 bool ToolChain::needsProfileRT(const ArgList &Args) {
+  if (Args.hasArg(options::OPT_noprofilelib))
+    return false;
+
   if (needsGCovInstrumentation(Args) ||
       Args.hasArg(options::OPT_fprofile_generate) ||
       Args.hasArg(options::OPT_fprofile_generate_EQ) ||

clang/test/Driver/noprofilelib.c

@@ -0,0 +1,5 @@
+// RUN: %clang -target i686-pc-linux-gnu -### %s 2>&1 \
+// RUN:     -fprofile-generate -noprofilelib | FileCheck %s
+// RUN: %clang -target i686-pc-linux-gnu -### %s 2>&1 \
+// RUN:     -fprofile-instr-generate -noprofilelib | FileCheck %s
+// CHECK-NOT: clang_rt.profile