[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

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

clang/test/Frontend/Inputs/optimization-remark-with-hotness-sample.proftext

@@ -0,0 +1,7 @@
+foo:0:0
+ 0: 0
+bar:29:29
+ 6: foo:0
+main:0:0
+ 0: 0 bar:0
+

clang/test/Frontend/optimization-remark-with-hotness.c

@@ -1,11 +1,21 @@
+// Generate instrumentation and sampling profile data.
 // RUN: llvm-profdata merge \
-// RUN:     %S/Inputs/optimization-remark-with-hotness.proftext   \
+// RUN:     %S/Inputs/optimization-remark-with-hotness.proftext \
 // RUN:     -o %t.profdata
+// RUN: llvm-profdata merge -sample \
+// RUN:     %S/Inputs/optimization-remark-with-hotness-sample.proftext \
+// RUN:     -o %t-sample.profdata
+//
 // RUN: %clang_cc1 -triple x86_64-apple-macosx10.9 -main-file-name \
 // RUN:     optimization-remark-with-hotness.c %s -emit-llvm-only \
 // RUN:     -fprofile-instrument-use-path=%t.profdata -Rpass=inline \
 // RUN:     -Rpass-analysis=inline -Rpass-missed=inline \
 // RUN:     -fdiagnostics-show-hotness -verify
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.9 -main-file-name \
+// RUN:     optimization-remark-with-hotness.c %s -emit-llvm-only \
+// RUN:     -fprofile-sample-use=%t-sample.profdata -Rpass=inline \
+// RUN:     -Rpass-analysis=inline -Rpass-missed=inline \
+// RUN:     -fdiagnostics-show-hotness -verify
 // The clang version of the previous test.
 // RUN: %clang -target x86_64-apple-macosx10.9 %s -c -emit-llvm -o /dev/null \
 // RUN:     -fprofile-instr-use=%t.profdata -Rpass=inline \