[Frontend] 'Show hotness' can be used with a sampling profile

Summary:
Prior to this change, using `-fdiagnostics-show-hotness` with a sampling
profile specified via `-fprofile-sample-use=` would result in the Clang
frontend emitting a warning: "argument '-fdiagnostics-show-hotness' requires
profile-guided optimization information". Of course, a sampling profile
*is* profile-guided optimization information, so the warning is misleading.
Furthermore, despite the warning, hotness was displayed based on the data in
the sampling profile.

Prevent the warning from being emitted when a sampling profile is used, and
add a test that verifies this.

Reviewers: anemet, davidxl

Reviewed By: davidxl

Subscribers: danielcdh, cfe-commits

Differential Revision: https://reviews.llvm.org/D34082

llvm-svn: 306079

1 files changed, 6 insertions, 2 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index e6feaf7447d..203723953a6 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -892,14 +892,18 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
 
   Opts.DiagnosticsWithHotness =
       Args.hasArg(options::OPT_fdiagnostics_show_hotness);
+  bool UsingSampleProfile = !Opts.SampleProfileFile.empty();
+
   if (Opts.DiagnosticsWithHotness &&
-      Opts.getProfileUse() == CodeGenOptions::ProfileNone)
+      Opts.getProfileUse() == CodeGenOptions::ProfileNone &&
+      !UsingSampleProfile) {
     Diags.Report(diag::warn_drv_fdiagnostics_show_hotness_requires_pgo);
+  }
 
   // If the user requested to use a sample profile for PGO, then the
   // backend will need to track source location information so the profile
   // can be incorporated into the IR.
-  if (!Opts.SampleProfileFile.empty())
+  if (UsingSampleProfile)
     NeedLocTracking = true;
 
   // If the user requested a flag that requires source locations available in