Add -plugin-opt=sample-profile for thinLTO build.

[danielcdh]

Summary

ThinLTO needs to pass down the sample profile file path to linker.

[mehdi_amini]

Is this covered by a driver test usually?

[danielcdh]

add a test.

[bruno]

lib/Driver/Tools.cpp

2211

"fname" -> "FName", "FileName", etc, or any name that starts with a capital letter

[mehdi_amini]

LGTM, but fix what @bruno spotted before committing.

[danielcdh]

fix function name

lib/Driver/Tools.cpp

if (Args.hasFlag(options::OPT_ffunction_sections,
                    options::OPT_fno_function_sections, UseSeparateSections)) {
     CmdArgs.push_back("-plugin-opt=-function-sections");
   }
 
   if (Args.hasFlag(options::OPT_fdata_sections, options::OPT_fno_data_sections,
                    UseSeparateSections)) {
     CmdArgs.push_back("-plugin-opt=-data-sections");
   }
+
+  if (Arg *A = Args.getLastArg(options::OPT_fprofile_sample_use_EQ)) {
+    StringRef fname = A->getValue();
+    if (!llvm::sys::fs::exists(fname))
+      D.Diag(diag::err_drv_no_such_file) << fname;
+    else
+      CmdArgs.push_back(
+          Args.MakeArgString(Twine("-plugin-opt=sample-profile=") + fname));
+  }
 }
 
 /// This is a helper function for validating the optional refinement step
 /// parameter in reciprocal argument strings. Return false if there is an error
 /// parsing the refinement step. Otherwise, return true and set the Position
 /// of the refinement step in the input string.
 static bool getRefinementStep(StringRef In, const Driver &D,
                               const Arg &A, size_t &Position) {

test/Driver/gold-lto-samplepgo.c

+// RUN: touch %t.o
+//
+// RUN: %clang -target x86_64-unknown-linux -### %t.o -flto 2>&1 \
+// RUN:     -Wl,-plugin-opt=foo -O3 \
+// RUN:     -fprofile-sample-use=%s \
+// RUN:     | FileCheck %s
+// CHECK: -plugin-opt=sample-profile=