[clang] Deprecate order file instrumentation (PR #121514)

[Ellis Hoag via cfe-commits]

https://github.com/ellishg created https://github.com/llvm/llvm-project/pull/121514

`-forder-file-instrumentation` is used to instrument a startup function order, but this feature is also in IRPGO as Temporal Profiling. As discussed in https://discourse.llvm.org/t/rfc-temporal-profiling-extension-for-irpgo/68068, this PR deprecates this flag.

>From 432c55783cbb5d4a9675f1f6018b58ffc4fe636d Mon Sep 17 00:00:00 2001
From: Ellis Hoag <ellis.sparky.hoag at gmail.com>
Date: Thu, 2 Jan 2025 10:51:54 -0800
Subject: [PATCH] Deprecate order file instrumentation

---
 clang/include/clang/Driver/Options.td | 2 +-
 clang/lib/Driver/ToolChains/Clang.cpp | 6 +++++-
 clang/test/Driver/clang_f_opts.c      | 2 ++
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index d922709db17786..7e419fb889488d 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1888,7 +1888,7 @@ defm pseudo_probe_for_profiling : BoolFOption<"pseudo-probe-for-profiling",
           " pseudo probes for sample profiling">>;
 def forder_file_instrumentation : Flag<["-"], "forder-file-instrumentation">,
     Group<f_Group>, Visibility<[ClangOption, CC1Option, CLOption]>,
-    HelpText<"Generate instrumented code to collect order file into default.profraw file (overridden by '=' form of option or LLVM_PROFILE_FILE env var)">;
+    HelpText<"Generate instrumented code to collect order file into default.profraw file (overridden by '=' form of option or LLVM_PROFILE_FILE env var). Deprecated, please use temporal profiling.">;
 def fprofile_list_EQ : Joined<["-"], "fprofile-list=">,
     Group<f_Group>, Visibility<[ClangOption, CC1Option, CLOption]>,
     HelpText<"Filename defining the list of functions/files to instrument. "
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index a020e00cd17392..4f1bf64e8cb7e8 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -8010,7 +8010,11 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     }
   }
 
-  if (Args.hasArg(options::OPT_forder_file_instrumentation)) {
+  if (const Arg *A =
+          Args.getLastArg(options::OPT_forder_file_instrumentation)) {
+     D.Diag(diag::warn_drv_deprecated_arg)
+         << A->getAsString(Args) << /*hasReplacement=*/true
+         << "-mllvm -pgo-temporal-instrumentation";
      CmdArgs.push_back("-forder-file-instrumentation");
      // Enable order file instrumentation when ThinLTO is not on. When ThinLTO is
      // on, we need to pass these flags as linker flags and that will be handled
diff --git a/clang/test/Driver/clang_f_opts.c b/clang/test/Driver/clang_f_opts.c
index ddbf1fd951c84e..2b72068eae1eeb 100644
--- a/clang/test/Driver/clang_f_opts.c
+++ b/clang/test/Driver/clang_f_opts.c
@@ -364,6 +364,7 @@
 // RUN: -fno-devirtualize-speculatively                                       \
 // RUN: -fslp-vectorize-aggressive                                            \
 // RUN: -fno-slp-vectorize-aggressive                                         \
+// RUN: -forder-file-instrumentation                                          \
 // RUN: %s 2>&1 | FileCheck --check-prefix=CHECK-WARNING %s
 // CHECK-WARNING-DAG: optimization flag '-finline-limit=1000' is not supported
 // CHECK-WARNING-DAG: optimization flag '-finline-limit' is not supported
@@ -423,6 +424,7 @@
 // CHECK-WARNING-DAG: optimization flag '-fno-devirtualize-speculatively' is not supported
 // CHECK-WARNING-DAG: the flag '-fslp-vectorize-aggressive' has been deprecated and will be ignored
 // CHECK-WARNING-DAG: the flag '-fno-slp-vectorize-aggressive' has been deprecated and will be ignored
+// CHECK-WARNING-DAG: argument '-forder-file-instrumentation' is deprecated, use '-mllvm -pgo-temporal-instrumentation' instead
 
 // Test that we mute the warning on these
 // RUN: %clang -### -finline-limit=1000 -Wno-invalid-command-line-argument              \