[Driver] Remove -fno-experimental-new-pass-manager

[MaskRay]

Summary

to give users a final warning that they need to migrate away. They could still
use -flegacy-pass-manager for Clang 14.0.0, but the functionality may not work
for 15.0.0.

-fexperimental-new-pass-manager is a no-op for default builds, so not urgent to
be removed for 14.0.0.

clang/test/Frontend/optimization-remark-with-hotness.c is removed because its
new PM replacement optimization-remark-with-hotness-new-pm.c exists.

[aeubanks]

can we also remove the -cc1 option?

[MaskRay]

In D118313#3274709, @aeubanks wrote:

can we also remove the -cc1 option?

Some tests will fail if -DLLVM_ENABLE_NEW_PASS_MANAGER=off is specified. But I see 5 tests have failed with -DLLVM_ENABLE_NEW_PASS_MANAGER=off, so perhaps we should not worry too much now.

[MaskRay]

rg 'clang_cc1.*fexperimental-new-pass-manager' -l => 41

I think the CC1 option can be removed separately.

[nikic]

So this just forces you to change -fno-experimental-new-pass-manager to -flegacy-pass-manager? I'm not sure I see the point.

Note that removal of middle-end LegacyPM functionality is currently blocked on https://reviews.llvm.org/D98481 landing, which prevents NewPM deployment in the Rust ecosystem.

[MaskRay]

In D118313#3275059, @nikic wrote:

So this just forces you to change -fno-experimental-new-pass-manager to -flegacy-pass-manager? I'm not sure I see the point.

Note that removal of middle-end LegacyPM functionality is currently blocked on https://reviews.llvm.org/D98481 landing, which prevents NewPM deployment in the Rust ecosystem.

-flegacy-pass-manager is a new option added in 13.0.0. It did not exist in older releases.
So by making -fno-experimental-new-pass-manager non-functional, it forces the remaining users to migrate, or at least, accept the big warning.

[aeubanks]

I think this is fine, it gives clang users another chance to report new PM blockers

[MaskRay]

In D118313#3280822, @aeubanks wrote:

I think this is fine, it gives clang users another chance to report new PM blockers

Yes. Thanks for accepting this before 14.0.0 branching:)

[MaskRay]

Add -fno-experimental-new-pass-manager to Removed Compiler Flags in release notes

[nikic]

clang/docs/ReleaseNotes.rst

112

Would be good to mention -flegacy-pass-manager as the alternative here.

[MaskRay]

Mention -flegacy-pass-manager as a makeshift for 14.0.0

[kda]

This looks like it is breaking the sanitizer buildbot for android:
https://lab.llvm.org/buildbot/#/builders/77/builds/13756/steps/21/logs/stdio

Failed Tests (1):
  HWAddressSanitizer-aarch64 :: TestCases/stack-uas.c

[MaskRay]

In D118313#3288651, @kda wrote:

This looks like it is breaking the sanitizer buildbot for android:
https://lab.llvm.org/buildbot/#/builders/77/builds/13756/steps/21/logs/stdio

Failed Tests (1):
  HWAddressSanitizer-aarch64 :: TestCases/stack-uas.c

Sorry for the breakage. I cannot test Android. Should be fixed by 9477a308ca6b8536044c9d31a8c89062b514431e, though.

clang/docs/ReleaseNotes.rst

- Support has been added for the following architectures (``-march`` identifiers in parentheses):
 
   - Armv9-A (``armv9-a``).
   - Armv9.1-A (``armv9.1-a``).
   - Armv9.2-A (``armv9.2-a``).
 
 Removed Compiler Flags
 -------------------------
 
-- ...
+- ``-fno-experimental-new-pass-manager`` has been removed.
+  ``-flegacy-pass-manager`` can be used as a makeshift,
+  Using the legacy pass manager for the optimization pipeline was deprecated in
+  13.0.0 and will be removed after 14.0.0.
 
 New Pragmas in Clang
 --------------------
 
 - ...
 
 Attribute Changes in Clang
 --------------------------

clang/include/clang/Driver/Options.td

 defm legacy_pass_manager : BoolOption<"f", "legacy-pass-manager",
   CodeGenOpts<"LegacyPassManager">, Default<"!static_cast<unsigned>(LLVM_ENABLE_NEW_PASS_MANAGER)">,
   PosFlag<SetTrue, [], "Use the legacy pass manager in LLVM (deprecated, to be removed in a future release)">,
   NegFlag<SetFalse, [], "Use the new pass manager in LLVM">,
   BothFlags<[CC1Option]>>, Group<f_clang_Group>;
 def fexperimental_new_pass_manager : Flag<["-"], "fexperimental-new-pass-manager">,
   Group<f_clang_Group>, Flags<[CC1Option]>, Alias<fno_legacy_pass_manager>;
 def fno_experimental_new_pass_manager : Flag<["-"], "fno-experimental-new-pass-manager">,
-  Group<f_clang_Group>, Flags<[CC1Option]>, Alias<flegacy_pass_manager>;
+  Group<f_clang_Group>, Flags<[CC1Option,NoDriverOption]>, Alias<flegacy_pass_manager>;
 def fexperimental_strict_floating_point : Flag<["-"], "fexperimental-strict-floating-point">,
   Group<f_clang_Group>, Flags<[CC1Option]>,
   HelpText<"Enables experimental strict floating point in LLVM.">,
   MarshallingInfoFlag<LangOpts<"ExpStrictFP">>;
 def finput_charset_EQ : Joined<["-"], "finput-charset=">, Flags<[FlangOption, FC1Option]>, Group<f_Group>,
   HelpText<"Specify the default character set for source files">;
 def fexec_charset_EQ : Joined<["-"], "fexec-charset=">, Group<f_Group>;
 def finstrument_functions : Flag<["-"], "finstrument-functions">, Group<f_Group>, Flags<[CC1Option]>,

clang/test/Driver/flegacy-pass-manager.c

 // RUN: %clang -### -c -flegacy-pass-manager -fno-legacy-pass-manager %s 2>&1 | FileCheck --check-prefixes=NOWARN,NEW %s
 // RUN: %clang -### -c -fno-legacy-pass-manager -flegacy-pass-manager %s 2>&1 | FileCheck --check-prefixes=NOWARN,LEGACY %s
 
-/// -f[no-]experimental-new-pass-manager are legacy aliases when the new PM was still experimental.
-// RUN: %clang -### -c -fno-experimental-new-pass-manager -fexperimental-new-pass-manager %s 2>&1 | FileCheck --check-prefixes=NOWARN,NEW %s
-// RUN: %clang -### -c -fexperimental-new-pass-manager -fno-experimental-new-pass-manager %s 2>&1 | FileCheck --check-prefixes=NOWARN,LEGACY %s
+/// -fexperimental-new-pass-manager is a legacy alias. -fno-experimental-new-pass-manager has been removed.
+// RUN: %clang -### -c -fexperimental-new-pass-manager %s 2>&1 | FileCheck --check-prefixes=NOWARN,NEW %s
+// RUN: not %clang -### -fno-experimental-new-pass-manager %s
 
 // NOWARN-NOT: warning: argument unused
 
 // NEW:        -fno-legacy-pass-manager
 // NEW-NOT:    -flegacy-pass-manager
 
 // LEGACY:     -flegacy-pass-manager
 // LEGACY-NOT: -fno-legacy-pass-manager
 
 /// For full/Thin LTO, -fno-legacy-pass-manager passes -plugin-opt=new-pass-manager to the linker (which may not be LLD).
 // RUN: %clang -### -target x86_64-linux -flto -fno-legacy-pass-manager %s 2>&1 | FileCheck --check-prefix=LTO_NEW %s
 // RUN: %clang -### -target x86_64-linux -flto=thin -fexperimental-new-pass-manager %s 2>&1 | FileCheck --check-prefix=LTO_NEW %s
 
 // LTO_NEW:    "-plugin-opt=new-pass-manager"
 
 // RUN: %clang -### -target x86_64-linux -flto -flegacy-pass-manager %s 2>&1 | FileCheck --check-prefix=LTO_LEGACY %s
-// RUN: %clang -### -target x86_64-linux -flto=thin -fno-experimental-new-pass-manager %s 2>&1 | FileCheck --check-prefix=LTO_LEGACY %s
 
 // LTO_LEGACY: "-plugin-opt=legacy-pass-manager"
 
 // RUN: %clang -### -target x86_64-linux -flto %s 2>&1 | FileCheck --check-prefix=DEFAULT %s
 //
 // DEFAULT-NOT: "-plugin-opt=new-pass-manager"
 // DEFAULT-NOT: "-plugin-opt=legacy-pass-manager"

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

-// Generate instrumentation and sampling profile data.
-// RUN: llvm-profdata merge \
-// 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:     -fno-experimental-new-pass-manager \
-// 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 \
-// RUN:     -fno-experimental-new-pass-manager \
-// RUN:     -Rpass-analysis=inline -Rpass-missed=inline \
-// RUN:     -fdiagnostics-show-hotness -Xclang -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:     -fno-experimental-new-pass-manager \
-// RUN:     -Rpass-analysis=inline -Rpass-missed=inline \
-// RUN:     -fdiagnostics-show-hotness -fdiagnostics-hotness-threshold=10 \
-// RUN:     -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-instrument-use-path=%t.profdata -Rpass=inline \
-// RUN:     -fno-experimental-new-pass-manager \
-// RUN:     -Rpass-analysis=inline -Rpass-missed=inline \
-// RUN:     -fdiagnostics-show-hotness -fdiagnostics-hotness-threshold=10 -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-instrument-use-path=%t.profdata -Rpass=inline \
-// RUN:     -fno-experimental-new-pass-manager \
-// RUN:     -Rpass-analysis=inline 2>&1 | FileCheck -check-prefix=HOTNESS_OFF %s
-// 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:     -fno-experimental-new-pass-manager \
-// RUN:     -Rpass-analysis=inline -Rno-pass-with-hotness 2>&1 | FileCheck \
-// RUN:     -check-prefix=HOTNESS_OFF %s
-// 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 -fdiagnostics-show-hotness \
-// RUN:     -fdiagnostics-hotness-threshold=100 2>&1 \
-// RUN:     | FileCheck -allow-empty -check-prefix=THRESHOLD %s
-// RUN: %clang_cc1 -triple x86_64-apple-macosx10.9 -main-file-name \
-// RUN:     optimization-remark-with-hotness.c %s -emit-llvm-only \
-// RUN:     -Rpass=inline -Rpass-analysis=inline \
-// RUN:     -fdiagnostics-show-hotness -fdiagnostics-hotness-threshold=10 2>&1 \
-// RUN:     | FileCheck -check-prefix=NO_PGO %s
-
-int foo(int x, int y) __attribute__((always_inline));
-int foo(int x, int y) { return x + y; }
-
-int sum = 0;
-
-void bar(int x) {
-  // HOTNESS_OFF: 'foo' inlined into 'bar'
-  // HOTNESS_OFF-NOT: hotness:
-  // THRESHOLD-NOT: inlined
-  // THRESHOLD-NOT: hotness
-  // NO_PGO: '-fdiagnostics-show-hotness' requires profile-guided optimization information
-  // NO_PGO: '-fdiagnostics-hotness-threshold=' requires profile-guided optimization information
-  // expected-remark@+1 {{'foo' inlined into 'bar' with (cost=always): always inliner at callsite bar:8:10; (hotness:}}
-  sum += foo(x, x - 2);
-}
-
-int main(int argc, const char *argv[]) {
-  for (int i = 0; i < 30; i++)
-    // expected-remark@+1 {{'bar' not inlined into 'main' because it should never be inlined (cost=never): no alwaysinline attribute (hotness:}}
-    bar(argc);
-  return sum;
-}