[NewPM] Add Clang cc1 flag -fdebug-pass-manager for printing debug information.

[chandlerc]

clang/include/clang/Driver/Options.td

971–973 ↗

(On Diff #104550)

I don't think we want to expose this flag in the driver -- it should really be a CC1-only thing for debugging.

As such, I think I'd just make it an independent flag:

-fexperimental-new-pass-manager-debug-logging

Or some such. This also seems easier than having to define a new kind.

[timshen]

clang/include/clang/Driver/Options.td

971–973 ↗

(On Diff #104550)

The two small disadvantages of your suggestion is that

1. It's more verbose to type: clang -fexperimental-new-pass-manager -fexperimental-new-pass-manager-debug-logging
2. it's the 3 states vs 4 states pattern: clang -fno-experimental-new-pass-manager -fexperimental-new-pass-manager-debug-logging doesn't make sense to me, and it's good to avoid that.

What do you think about these trade offs?

[joerg]

As I said in the discussion about similar flags for GVN, I'm generally fine with. We should have a big fat warning in the Release Notes that all -fexperimental-* flags are exactly that -- temporary and not intended for long term consumption. I.e. "we can and will remove them whenever it creates the most havoc".

[timshen]

Use a cc1 flag -fdebug-pass-manager instead.

[timshen]

Also add @tejohnson as a reviewer, since the LTO test changed

[timshen]

clang/include/clang/Driver/Options.td

971–973 ↗

(On Diff #104550)

As discussed offline, (2) isn't a practical issue, and (1) makes sense since -fexperimental-new-pass-manager will ultimately go away, but the debug flag remains.

[chandlerc]

This looks great to me with a CC1-layer flag. But check that others are happy as well, thanks!

[tejohnson]

LGTM. Just one minor nit on the option help string below. Thanks

clang/include/clang/Driver/CC1Options.td

329 ↗

(On Diff #104753)

s/the debug prints/debug printing/

[timshen]

s/the debug prints/debug printing/

cfe/trunk/include/clang/Driver/CC1Options.td

 def flto_visibility_public_std:
     Flag<["-"], "flto-visibility-public-std">,
     HelpText<"Use public LTO visibility for classes in std and stdext namespaces">;
 def flto_unit: Flag<["-"], "flto-unit">,
     HelpText<"Emit IR to support LTO unit features (CFI, whole program vtable opt)">;
 def fno_lto_unit: Flag<["-"], "fno-lto-unit">;
 def fthin_link_bitcode_EQ : Joined<["-"], "fthin-link-bitcode=">,
     HelpText<"Write minimized bitcode to <file> for the ThinLTO thin link only">;
+def fdebug_pass_manager : Flag<["-"], "fdebug-pass-manager">,
+    HelpText<"Prints debug information for the new pass manager">;
+def fno_debug_pass_manager : Flag<["-"], "fno-debug-pass-manager">,
+    HelpText<"Disables debug printing for the new pass manager">;
 
 //===----------------------------------------------------------------------===//
 // Dependency Output Options
 //===----------------------------------------------------------------------===//
 
 def sys_header_deps : Flag<["-"], "sys-header-deps">,
   HelpText<"Include system headers in dependency output">;
 def module_file_deps : Flag<["-"], "module-file-deps">,

cfe/trunk/include/clang/Frontend/CodeGenOptions.def

 CODEGENOPT(DisableGCov       , 1, 0) ///< Don't run the GCov pass, for testing.
 CODEGENOPT(DisableLLVMPasses , 1, 0) ///< Don't run any LLVM IR passes to get
                                      ///< the pristine IR generated by the
                                      ///< frontend.
 CODEGENOPT(DisableLifetimeMarkers, 1, 0) ///< Don't emit any lifetime markers
 CODEGENOPT(DisableO0ImplyOptNone , 1, 0) ///< Don't annonate function with optnone at O0
 CODEGENOPT(ExperimentalNewPassManager, 1, 0) ///< Enables the new, experimental
                                              ///< pass manager.
+CODEGENOPT(DebugPassManager, 1, 0) ///< Prints debug information for the new
+                                   ///< pass manager.
 CODEGENOPT(DisableRedZone    , 1, 0) ///< Set when -mno-red-zone is enabled.
 CODEGENOPT(DisableTailCalls  , 1, 0) ///< Do not emit tail calls.
 CODEGENOPT(EmitDeclMetadata  , 1, 0) ///< Emit special metadata indicating what
                                      ///< Decl* various IR entities came from.
                                      ///< Only useful when running CodeGen as a
                                      ///< subroutine.
 CODEGENOPT(EmitGcovArcs      , 1, 0) ///< Emit coverage data files, aka. GCDA.
 CODEGENOPT(EmitGcovNotes     , 1, 0) ///< Emit coverage "notes" files, aka GCNO.

cfe/trunk/lib/CodeGen/BackendUtil.cpp

void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
 
   // Register all the basic analyses with the managers.
   PB.registerModuleAnalyses(MAM);
   PB.registerCGSCCAnalyses(CGAM);
   PB.registerFunctionAnalyses(FAM);
   PB.registerLoopAnalyses(LAM);
   PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
 
-  ModulePassManager MPM;
+  ModulePassManager MPM(CodeGenOpts.DebugPassManager);
 
   if (!CodeGenOpts.DisableLLVMPasses) {
     bool IsThinLTO = CodeGenOpts.EmitSummaryIndex;
     bool IsLTO = CodeGenOpts.PrepareForLTO;
 
     if (CodeGenOpts.OptimizationLevel == 0) {
       // Build a minimal pipeline based on the semantics required by Clang,
       // which is just that always inlining occurs.
       MPM.addPass(AlwaysInlinerPass());
       if (IsThinLTO)
         MPM.addPass(NameAnonGlobalPass());
     } else {
       // Map our optimization levels into one of the distinct levels used to
       // configure the pipeline.
       PassBuilder::OptimizationLevel Level = mapToLevel(CodeGenOpts);
 
       if (IsThinLTO) {
-        MPM = PB.buildThinLTOPreLinkDefaultPipeline(Level);
+        MPM = PB.buildThinLTOPreLinkDefaultPipeline(
+            Level, CodeGenOpts.DebugPassManager);
         MPM.addPass(NameAnonGlobalPass());
       } else if (IsLTO) {
-        MPM = PB.buildLTOPreLinkDefaultPipeline(Level);
+        MPM = PB.buildLTOPreLinkDefaultPipeline(Level,
+                                                CodeGenOpts.DebugPassManager);
       } else {
-        MPM = PB.buildPerModuleDefaultPipeline(Level);
+        MPM = PB.buildPerModuleDefaultPipeline(Level,
+                                               CodeGenOpts.DebugPassManager);
       }
     }
   }
 
   // FIXME: We still use the legacy pass manager to do code generation. We
   // create that pass manager here and use it as needed below.
   legacy::PassManager CodeGenPasses;
   bool NeedCodeGen = false;

cfe/trunk/lib/Frontend/CompilerInvocation.cpp

if (Opts.OptimizationLevel > 0) {
         Opts.setInlining(CodeGenOptions::OnlyAlwaysInlining);
     }
   }
 
   Opts.ExperimentalNewPassManager = Args.hasFlag(
       OPT_fexperimental_new_pass_manager, OPT_fno_experimental_new_pass_manager,
       /* Default */ false);
 
+  Opts.DebugPassManager =
+      Args.hasFlag(OPT_fdebug_pass_manager, OPT_fno_debug_pass_manager,
+                   /* Default */ false);
+
   if (Arg *A = Args.getLastArg(OPT_fveclib)) {
     StringRef Name = A->getValue();
     if (Name == "Accelerate")
       Opts.setVecLib(CodeGenOptions::Accelerate);
     else if (Name == "SVML")
       Opts.setVecLib(CodeGenOptions::SVML);
     else if (Name == "none")
       Opts.setVecLib(CodeGenOptions::NoLibrary);

cfe/trunk/test/CodeGen/lto-newpm-pipeline.c

+// REQUIRES: x86-registered-target
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -O0 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-O0
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -O0 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-O0
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -O1 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -O1 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -O2 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -O2 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -O3 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -O3 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -Os %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -Os %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -Oz %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -Oz %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-OPTIMIZED
+
+// CHECK-FULL-O0: Starting llvm::Module pass manager run.
+// CHECK-FULL-O0: Running pass: AlwaysInlinerPass
+// CHECK-FULL-O0-NEXT: Running pass: BitcodeWriterPass
+// CHECK-FULL-O0: Finished llvm::Module pass manager run.
+
+// CHECK-THIN-O0: Starting llvm::Module pass manager run.
+// CHECK-THIN-O0: Running pass: AlwaysInlinerPass
+// CHECK-THIN-O0-NEXT: Running pass: NameAnonGlobalPass
+// CHECK-THIN-O0-NEXT: Running pass: ThinLTOBitcodeWriterPass
+// CHECK-THIN-O0: Finished llvm::Module pass manager run.
+
+// TODO: The LTO pre-link pipeline currently invokes
+//       buildPerModuleDefaultPipeline(), which contains LoopVectorizePass.
+//       This may change as the pipeline gets implemented.
+// CHECK-FULL-OPTIMIZED: Starting llvm::Function pass manager run.
+// CHECK-FULL-OPTIMIZED: Running pass: LoopVectorizePass
+// CHECK-FULL-OPTIMIZED: Running pass: BitcodeWriterPass
+
+// The ThinLTO pre-link pipeline shouldn't contain passes like
+// LoopVectorizePass.
+// CHECK-THIN-OPTIMIZED: Starting llvm::Function pass manager run.
+// CHECK-THIN-OPTIMIZED-NOT: Running pass: LoopVectorizePass
+// CHECK-THIN-OPTIMIZED: Running pass: NameAnonGlobalPass
+// CHECK-THIN-OPTIMIZED: Running pass: ThinLTOBitcodeWriterPass
+
+void Foo() {}