[clang] [clang] Add deprecation warning for `-Ofast` driver option (PR #98736)
Vlad Serebrennikov via cfe-commits
cfe-commits at lists.llvm.org
Sat Jul 13 03:14:02 PDT 2024
https://github.com/Endilll created https://github.com/llvm/llvm-project/pull/98736
This patch implements consensus on the corresponding RFC documented here: https://discourse.llvm.org/t/rfc-deprecate-ofast/78687/72
Specifically, I added a deprecation warning for `-Ofast`, that suggests to use `-O3` or `-O3` with `-ffast-math`, and a new diagnostic group for aforementioned warning.
>From 44b4a682f2b3d7e140f7b1bd124e7aabdbf439ad Mon Sep 17 00:00:00 2001
From: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Date: Sat, 13 Jul 2024 13:10:25 +0300
Subject: [PATCH] [clang] Add deprecation warning for `-Ofast` driver option
---
clang/docs/ReleaseNotes.rst | 3 +++
clang/include/clang/Basic/DiagnosticDriverKinds.td | 3 +++
clang/include/clang/Basic/DiagnosticGroups.td | 2 ++
clang/include/clang/Driver/Options.td | 3 ++-
clang/lib/Driver/ToolChains/Clang.cpp | 2 ++
clang/test/Driver/Ofast.c | 4 ++++
6 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index ceead8c362e9c..2f5f40f355901 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -470,6 +470,9 @@ New Compiler Flags
Deprecated Compiler Flags
-------------------------
+- ``-Ofast`` is deprecated in favor of ``-O3``, possibly combined with ``-ffast-math``.
+ See `RFC <https://discourse.llvm.org/t/rfc-deprecate-ofast/78687>`_ for details.
+
Modified Compiler Flags
-----------------------
- Added a new diagnostic flag ``-Wreturn-mismatch`` which is grouped under
diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 359c0de7f811c..3857f2f3a33ce 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -442,6 +442,9 @@ def warn_drv_deprecated_arg : Warning<
def warn_drv_deprecated_arg_no_relaxed_template_template_args : Warning<
"argument '-fno-relaxed-template-template-args' is deprecated">,
InGroup<DeprecatedNoRelaxedTemplateTemplateArgs>;
+def warn_drv_deprecated_arg_ofast : Warning<
+ "argument '-Ofast' is deprecated; use '-O3', possibly with '-ffast-math'">,
+ InGroup<DeprecatedOFast>;
def warn_drv_deprecated_custom : Warning<
"argument '%0' is deprecated, %1">, InGroup<Deprecated>;
def warn_drv_assuming_mfloat_abi_is : Warning<
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 2241f8481484e..d7dba76a0fcf8 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -103,6 +103,7 @@ def EnumConversion : DiagGroup<"enum-conversion",
EnumFloatConversion,
EnumCompareConditional]>;
def DeprecatedNoRelaxedTemplateTemplateArgs : DiagGroup<"deprecated-no-relaxed-template-template-args">;
+def DeprecatedOFast : DiagGroup<"deprecated-ofast">;
def ObjCSignedCharBoolImplicitIntConversion :
DiagGroup<"objc-signed-char-bool-implicit-int-conversion">;
def Shorten64To32 : DiagGroup<"shorten-64-to-32">;
@@ -228,6 +229,7 @@ def Deprecated : DiagGroup<"deprecated", [DeprecatedAnonEnumEnumConversion,
DeprecatedPragma,
DeprecatedRegister,
DeprecatedNoRelaxedTemplateTemplateArgs,
+ DeprecatedOFast,
DeprecatedThisCapture,
DeprecatedType,
DeprecatedVolatile,
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index f1e8cb87e5321..269790476c1c3 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -931,7 +931,8 @@ def O : Joined<["-"], "O">, Group<O_Group>,
def O_flag : Flag<["-"], "O">, Visibility<[ClangOption, CC1Option, FC1Option]>,
Alias<O>, AliasArgs<["1"]>;
def Ofast : Joined<["-"], "Ofast">, Group<O_Group>,
- Visibility<[ClangOption, CC1Option, FlangOption]>;
+ Visibility<[ClangOption, CC1Option, FlangOption]>,
+ HelpText<"Deprecated; use -O3, possibly with -ffast-math">;
def P : Flag<["-"], "P">,
Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>,
Group<Preprocessor_Group>,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index bc21d03a627b9..33e7152343171 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5712,6 +5712,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
options::OPT_fno_zero_initialized_in_bss);
bool OFastEnabled = isOptimizationLevelFast(Args);
+ if (OFastEnabled)
+ D.Diag(diag::warn_drv_deprecated_arg_ofast);
// If -Ofast is the optimization level, then -fstrict-aliasing should be
// enabled. This alias option is being used to simplify the hasFlag logic.
OptSpecifier StrictAliasingAliasOption =
diff --git a/clang/test/Driver/Ofast.c b/clang/test/Driver/Ofast.c
index 8b7f2217eca2f..f5a2aabe257f1 100644
--- a/clang/test/Driver/Ofast.c
+++ b/clang/test/Driver/Ofast.c
@@ -10,6 +10,7 @@
// RUN: %clang -Ofast -fno-strict-aliasing -### %s 2>&1 | FileCheck -check-prefix=CHECK-OFAST-NO-STRICT-ALIASING %s
// RUN: %clang -Ofast -fno-vectorize -### %s 2>&1 | FileCheck -check-prefix=CHECK-OFAST-NO-VECTORIZE %s
+// CHECK-OFAST: warning: argument '-Ofast' is deprecated; use '-O3', possibly with '-ffast-math'
// CHECK-OFAST: -cc1
// CHECK-OFAST-NOT: -relaxed-aliasing
// CHECK-OFAST: -ffast-math
@@ -23,18 +24,21 @@
// CHECK-OFAST-O2-NOT: -Ofast
// CHECK-OFAST-O2: -vectorize-loops
+// CHECK-OFAST-NO-FAST-MATH: warning: argument '-Ofast' is deprecated; use '-O3', possibly with '-ffast-math'
// CHECK-OFAST-NO-FAST-MATH: -cc1
// CHECK-OFAST-NO-FAST-MATH-NOT: -relaxed-aliasing
// CHECK-OFAST-NO-FAST-MATH-NOT: -ffast-math
// CHECK-OFAST-NO-FAST-MATH: -Ofast
// CHECK-OFAST-NO-FAST-MATH: -vectorize-loops
+// CHECK-OFAST-NO-STRICT-ALIASING: warning: argument '-Ofast' is deprecated; use '-O3', possibly with '-ffast-math'
// CHECK-OFAST-NO-STRICT-ALIASING: -cc1
// CHECK-OFAST-NO-STRICT-ALIASING: -relaxed-aliasing
// CHECK-OFAST-NO-STRICT-ALIASING: -ffast-math
// CHECK-OFAST-NO-STRICT-ALIASING: -Ofast
// CHECK-OFAST-NO-STRICT-ALIASING: -vectorize-loops
+// CHECK-OFAST-NO-VECTORIZE: warning: argument '-Ofast' is deprecated; use '-O3', possibly with '-ffast-math'
// CHECK-OFAST-NO-VECTORIZE: -cc1
// CHECK-OFAST-NO-VECTORIZE-NOT: -relaxed-aliasing
// CHECK-OFAST-NO-VECTORIZE: -ffast-math
More information about the cfe-commits
mailing list