[Flang] Add debug flag to enable current debug information pass

While a pass exists to generate basic debug information, currently there is not a corresponding flag to enable it.
This patch adds support for activating this pass at any debug level >= -g1, as well as emiting a warning for higher levels that the functionality is not yet fully implemented.

This patch also adds -g and -gline-tables-only to appear when `flang-new` --help is run

Depends on D142347.

Reviewed By: awarzynski

Differential Revision: https://reviews.llvm.org/D146814

8 files changed, 153 insertions, 4 deletions

diff --git a/flang/include/flang/Frontend/CodeGenOptions.def b/flang/include/flang/Frontend/CodeGenOptions.def
index c6bd7a5..dbdfe07 100644
--- a/flang/include/flang/Frontend/CodeGenOptions.def
+++ b/flang/include/flang/Frontend/CodeGenOptions.def
@@ -34,6 +34,7 @@ CODEGENOPT(StackArrays, 1, 0) ///< -fstack-arrays (enable the stack-arrays pass)
 
 CODEGENOPT(Underscoring, 1, 1)
 ENUM_CODEGENOPT(RelocationModel, llvm::Reloc::Model, 3, llvm::Reloc::PIC_) ///< Name of the relocation model to use.
+ENUM_CODEGENOPT(DebugInfo,  llvm::codegenoptions::DebugInfoKind, 4,  llvm::codegenoptions::NoDebugInfo) ///< Level of debug info to generate
 
 #undef CODEGENOPT
 #undef ENUM_CODEGENOPT
diff --git a/flang/include/flang/Frontend/CodeGenOptions.h b/flang/include/flang/Frontend/CodeGenOptions.h
index 925de7f..60aa38a 100644
--- a/flang/include/flang/Frontend/CodeGenOptions.h
+++ b/flang/include/flang/Frontend/CodeGenOptions.h
@@ -15,6 +15,7 @@
 #ifndef LLVM_CLANG_BASIC_CODEGENOPTIONS_H
 #define LLVM_CLANG_BASIC_CODEGENOPTIONS_H
 
+#include "llvm/Frontend/Debug/Options.h"
 #include "llvm/Support/CodeGen.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Target/TargetOptions.h"
diff --git a/flang/include/flang/Tools/CLOptions.inc b/flang/include/flang/Tools/CLOptions.inc
index 3058162..8a1f7eb 100644
--- a/flang/include/flang/Tools/CLOptions.inc
+++ b/flang/include/flang/Tools/CLOptions.inc
@@ -16,6 +16,7 @@
 #include "flang/Optimizer/CodeGen/CodeGen.h"
 #include "flang/Optimizer/HLFIR/Passes.h"
 #include "flang/Optimizer/Transforms/Passes.h"
+#include "llvm/Frontend/Debug/Options.h"
 #include "llvm/Passes/OptimizationLevel.h"
 #include "llvm/Support/CommandLine.h"
 
@@ -56,6 +57,9 @@ namespace {
 const static llvm::OptimizationLevel &defaultOptLevel{
     llvm::OptimizationLevel::O0};
 
+const static llvm::codegenoptions::DebugInfoKind &NoDebugInfo{
+    llvm::codegenoptions::NoDebugInfo};
+
 /// Optimizer Passes
 DisableOption(CfgConversion, "cfg-conversion", "disable FIR to CFG pass");
 DisableOption(FirAvc, "avc", "array value copy analysis and transformation");
@@ -228,9 +232,28 @@ inline void createHLFIRToFIRPassPipeline(
 }
 
 #if !defined(FLANG_EXCLUDE_CODEGEN)
+inline void createDebugPasses(
+    mlir::PassManager &pm, llvm::codegenoptions::DebugInfoKind debugLevel) {
+  // Currently only -g1, -g, -gline-tables-only supported
+  switch (debugLevel) {
+  case llvm::codegenoptions::DebugLineTablesOnly:
+    addDebugFoundationPass(pm);
+    return;
+  case llvm::codegenoptions::NoDebugInfo:
+    return;
+  default:
+    // TODO: Add cases and passes for other debug options.
+    // All other debug options not implemented yet, currently emits warning
+    // and generates as much debug information as possible.
+    addDebugFoundationPass(pm);
+    return;
+  }
+}
+
 inline void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
     llvm::OptimizationLevel optLevel = defaultOptLevel,
-    bool underscoring = true) {
+    bool underscoring = true,
+    llvm::codegenoptions::DebugInfoKind debugInfo = NoDebugInfo) {
   fir::addBoxedProcedurePass(pm);
   pm.addNestedPass<mlir::func::FuncOp>(
       fir::createAbstractResultOnFuncOptPass());
@@ -238,6 +261,7 @@ inline void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
   fir::addCodeGenRewritePass(pm);
   fir::addTargetRewritePass(pm);
   fir::addExternalNameConversionPass(pm, underscoring);
+  fir::createDebugPasses(pm, debugInfo);
   fir::addFIRToLLVMPass(pm, optLevel);
 }
 
@@ -248,14 +272,16 @@ inline void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
 ///   passes pipeline
 inline void createMLIRToLLVMPassPipeline(mlir::PassManager &pm,
     llvm::OptimizationLevel optLevel = defaultOptLevel,
-    bool stackArrays = false, bool underscoring = true) {
+    bool stackArrays = false, bool underscoring = true,
+    llvm::codegenoptions::DebugInfoKind debugInfo = NoDebugInfo) {
   fir::createHLFIRToFIRPassPipeline(pm, optLevel);
 
   // Add default optimizer pass pipeline.
   fir::createDefaultFIROptimizerPassPipeline(pm, optLevel, stackArrays);
 
   // Add codegen pass pipeline.
-  fir::createDefaultFIRCodeGenPassPipeline(pm, optLevel, underscoring);
+  fir::createDefaultFIRCodeGenPassPipeline(
+      pm, optLevel, underscoring, debugInfo);
 }
 #undef FLANG_EXCLUDE_CODEGEN
 #endif
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 49dfeed..9fbf5bb 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -25,6 +25,7 @@
 #include "clang/Driver/Options.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/Frontend/Debug/Options.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/OptTable.h"
@@ -117,6 +118,38 @@ bool Fortran::frontend::parseDiagnosticArgs(clang::DiagnosticOptions &opts,
   return true;
 }
 
+static bool parseDebugArgs(Fortran::frontend::CodeGenOptions &opts,
+                           llvm::opt::ArgList &args,
+                           clang::DiagnosticsEngine &diags) {
+  using DebugInfoKind = llvm::codegenoptions::DebugInfoKind;
+  if (llvm::opt::Arg *arg =
+          args.getLastArg(clang::driver::options::OPT_debug_info_kind_EQ)) {
+    std::optional<DebugInfoKind> val =
+        llvm::StringSwitch<std::optional<DebugInfoKind>>(arg->getValue())
+            .Case("line-tables-only", llvm::codegenoptions::DebugLineTablesOnly)
+            .Case("line-directives-only",
+                  llvm::codegenoptions::DebugDirectivesOnly)
+            .Case("constructor", llvm::codegenoptions::DebugInfoConstructor)
+            .Case("limited", llvm::codegenoptions::LimitedDebugInfo)
+            .Case("standalone", llvm::codegenoptions::FullDebugInfo)
+            .Case("unused-types", llvm::codegenoptions::UnusedTypeInfo)
+            .Default(std::nullopt);
+    if (!val.has_value()) {
+      diags.Report(clang::diag::err_drv_invalid_value)
+          << arg->getAsString(args) << arg->getValue();
+      return false;
+    }
+    opts.setDebugInfo(val.value());
+    if (val != llvm::codegenoptions::DebugLineTablesOnly &&
+        val != llvm::codegenoptions::NoDebugInfo) {
+      const auto debugWarning = diags.getCustomDiagID(
+          clang::DiagnosticsEngine::Warning, "Unsupported debug option: %0");
+      diags.Report(debugWarning) << arg->getValue();
+    }
+  }
+  return true;
+}
+
 static void parseCodeGenArgs(Fortran::frontend::CodeGenOptions &opts,
                              llvm::opt::ArgList &args,
                              clang::DiagnosticsEngine &diags) {
@@ -830,6 +863,7 @@ bool CompilerInvocation::createFromArgs(
   parseTargetArgs(res.getTargetOpts(), args);
   parsePreprocessorArgs(res.getPreprocessorOpts(), args);
   parseCodeGenArgs(res.getCodeGenOpts(), args, diags);
+  success &= parseDebugArgs(res.getCodeGenOpts(), args, diags);
   success &= parseSemaArgs(res, args, diags);
   success &= parseDialectArgs(res, args, diags);
   success &= parseDiagArgs(res, args, diags);
diff --git a/flang/lib/Frontend/FrontendActions.cpp b/flang/lib/Frontend/FrontendActions.cpp
index 8b2055e..3e8bebd 100644
--- a/flang/lib/Frontend/FrontendActions.cpp
+++ b/flang/lib/Frontend/FrontendActions.cpp
@@ -662,7 +662,7 @@ void CodeGenAction::generateLLVMIR() {
 
   // Create the pass pipeline
   fir::createMLIRToLLVMPassPipeline(pm, level, opts.StackArrays,
-                                    opts.Underscoring);
+                                    opts.Underscoring, opts.getDebugInfo());
   mlir::applyPassManagerCLOptions(pm);
 
   // run the pass manager
diff --git a/flang/test/Driver/driver-help-hidden.f90 b/flang/test/Driver/driver-help-hidden.f90
index 535bb82..1a5fb4e 100644
--- a/flang/test/Driver/driver-help-hidden.f90
+++ b/flang/test/Driver/driver-help-hidden.f90
@@ -60,6 +60,8 @@
 ! CHECK-NEXT: -fsyntax-only          Run the preprocessor, parser and semantic analysis stages
 ! CHECK-NEXT: -funderscoring         Appends one trailing underscore to external names
 ! CHECK-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
+! CHECK-NEXT: -gline-tables-only     Emit debug line number tables only
+! CHECK-NEXT: -g                     Generate source-level debug information
 ! CHECK-NEXT: -help     Display available options
 ! CHECK-NEXT: -I <dir>               Add directory to the end of the list of include search paths
 ! CHECK-NEXT: -mllvm=<arg>           Alias for -mllvm
diff --git a/flang/test/Driver/driver-help.f90 b/flang/test/Driver/driver-help.f90
index a1fdfb3..f50b14e 100644
--- a/flang/test/Driver/driver-help.f90
+++ b/flang/test/Driver/driver-help.f90
@@ -56,6 +56,8 @@
 ! HELP-NEXT: -fsyntax-only          Run the preprocessor, parser and semantic analysis stages
 ! HELP-NEXT: -funderscoring         Appends one trailing underscore to external names
 ! HELP-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
+! HELP-NEXT: -gline-tables-only     Emit debug line number tables only
+! HELP-NEXT: -g                     Generate source-level debug information
 ! HELP-NEXT: -help                  Display available options
 ! HELP-NEXT: -I <dir>               Add directory to the end of the list of include search paths
 ! HELP-NEXT: -mllvm=<arg>           Alias for -mllvm
diff --git a/flang/test/Driver/mlir-debug-pass-pipeline.f90 b/flang/test/Driver/mlir-debug-pass-pipeline.f90
new file mode 100644
index 0000000..d397b29
--- /dev/null
+++ b/flang/test/Driver/mlir-debug-pass-pipeline.f90
@@ -0,0 +1,83 @@
+! Test the debug pass pipeline
+
+! RUN: %flang -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline -o /dev/null %s 2>&1 | FileCheck --check-prefixes=ALL,NO-DEBUG %s
+
+! RUN: %flang -g0 -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -o /dev/null 2>&1 | FileCheck --check-prefixes=ALL,NO-DEBUG %s
+! RUN: %flang -g -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -o /dev/null 2>&1 | FileCheck --check-prefixes=ALL,DEBUG %s
+! RUN: %flang -g1 -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -o /dev/null 2>&1 | FileCheck --check-prefixes=ALL,DEBUG %s
+! RUN: %flang -gline-tables-only -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -o /dev/null 2>&1 | FileCheck --check-prefixes=ALL,DEBUG %s
+! RUN: %flang -gline-directives-only -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -o /dev/null 2>&1 | FileCheck --check-prefixes=ALL,DEBUG,DEBUG-DIRECTIVES %s
+! RUN: %flang -g2 -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -o /dev/null 2>&1 | FileCheck --check-prefixes=ALL,DEBUG,DEBUG-CONSTRUCT %s
+! RUN: %flang -g3 -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -o /dev/null 2>&1 | FileCheck --check-prefixes=ALL,DEBUG,DEBUG-CONSTRUCT %s
+
+! RUN: not %flang_fc1 -debug-info-kind=invalid -S -mmlir --mlir-pass-statistics -mmlir --mlir-pass-statistics-display=pipeline %s -o /dev/null 2>&1 | FileCheck --check-prefixes=DEBUG-ERR %s
+
+! REQUIRES: asserts
+
+end program
+
+! DEBUG-CONSTRUCT: warning: Unsupported debug option: constructor
+! DEBUG-DIRECTIVES: warning: Unsupported debug option: line-directives-only
+!
+! DEBUG-ERR: error: invalid value 'invalid' in '-debug-info-kind=invalid'
+! DEBUG-ERR-NOT: Pass statistics report
+
+! ALL: Pass statistics report
+
+! ALL: Fortran::lower::VerifierPass
+! ALL-NEXT: LowerHLFIRIntrinsics
+! ALL-NEXT: BufferizeHLFIR
+! ALL-NEXT: ConvertHLFIRtoFIR
+! ALL-NEXT: CSE
+! Ideally, we need an output with only the pass names, but
+! there is currently no way to get that, so in order to
+! guarantee that the passes are in the expected order
+! (i.e. use -NEXT) we have to check the statistics output as well.
+! ALL-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
+! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
+
+! ALL-NEXT: 'func.func' Pipeline
+! ALL-NEXT:   ArrayValueCopy
+! ALL-NEXT:   CharacterConversion
+
+! ALL-NEXT: Canonicalizer
+! ALL-NEXT: SimplifyRegionLite
+! ALL-NEXT: CSE
+! ALL-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
+! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
+
+! ALL-NEXT: 'func.func' Pipeline
+! ALL-NEXT:   MemoryAllocationOpt
+
+! ALL-NEXT: Inliner
+! ALL-NEXT: SimplifyRegionLite
+! ALL-NEXT: CSE
+! ALL-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
+! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
+
+! ALL-NEXT: 'func.func' Pipeline
+! ALL-NEXT:   PolymorphicOpConversion
+! ALL-NEXT:   CFGConversion
+
+! ALL-NEXT: SCFToControlFlow
+! ALL-NEXT: Canonicalizer
+! ALL-NEXT: SimplifyRegionLite
+! ALL-NEXT: CSE
+! ALL-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
+! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
+! ALL-NEXT: BoxedProcedurePass
+
+! ALL-NEXT: Pipeline Collection : ['fir.global', 'func.func']
+! ALL-NEXT:   'fir.global' Pipeline
+! ALL-NEXT:    AbstractResultOnGlobalOpt
+! ALL-NEXT:  'func.func' Pipeline
+! ALL-NEXT:    AbstractResultOnFuncOpt
+
+! ALL-NEXT: CodeGenRewrite
+! ALL-NEXT:   (S) 0 num-dce'd - Number of operations eliminated
+! ALL-NEXT: TargetRewrite
+! ALL-NEXT: ExternalNameConversion
+! DEBUG-NEXT: AddDebugFoundation
+! NO-DEBUG-NOT: AddDebugFoundation
+! ALL-NEXT: FIRToLLVMLowering
+! ALL-NOT: LLVMIRLoweringPass