Expose -mllvm -accurate-sample-profile to clang.

Summary: With accurate sample profile, we can do more aggressive size optimization. For some size-critical application, this can reduce the text size by 20%

Reviewers: davidxl, rsmith

Reviewed By: davidxl, rsmith

Subscribers: mehdi_amini, eraman, sanjoy, cfe-commits

Differential Revision: https://reviews.llvm.org/D37091

llvm-svn: 311707
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 24a08e8..aea3af9 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -652,6 +652,8 @@
 
   Opts.NoUseJumpTables = Args.hasArg(OPT_fno_jump_tables);
 
+  Opts.ProfileSampleAccurate = Args.hasArg(OPT_fprofile_sample_accurate);
+
   Opts.PrepareForLTO = Args.hasArg(OPT_flto, OPT_flto_EQ);
   Opts.EmitSummaryIndex = false;
   if (Arg *A = Args.getLastArg(OPT_flto_EQ)) {