Move Split DWARF handling to an MC option/command line argument rather than using metadata

Since Split DWARF needs to name the actual .dwo file that is generated,
it can't be known at the time the llvm::Module is produced as it may be
merged with other Modules before the object is generated and that object
may be generated with any name.

By passing the Split DWARF file name when LLVM is producing object code
the .dwo file name in the object file can match correctly.

The support for Split DWARF for implicit modules remains the same -
using metadata to store the dwo name and dwo id so that potentially
multiple skeleton CUs referring to different dwo files can be generated
from one llvm::Module.

llvm-svn: 301063

8 files changed, 27 insertions, 15 deletions

diff --git a/clang/include/clang/Driver/CC1Options.td b/clang/include/clang/Driver/CC1Options.td
index ba09bccfe1c..63348c094c9 100644
--- a/clang/include/clang/Driver/CC1Options.td
+++ b/clang/include/clang/Driver/CC1Options.td
@@ -573,6 +573,8 @@ def fblocks_runtime_optional : Flag<["-"], "fblocks-runtime-optional">,
   HelpText<"Weakly link in the blocks runtime">;
 def fexternc_nounwind : Flag<["-"], "fexternc-nounwind">,
   HelpText<"Assume all functions with C linkage do not unwind">;
+def enable_split_dwarf : Flag<["-"], "enable-split-dwarf">,
+  HelpText<"Use split dwarf/Fission">;
 def split_dwarf_file : Separate<["-"], "split-dwarf-file">,
   HelpText<"File name to use for split dwarf debug info output">;
 def fno_wchar : Flag<["-"], "fno-wchar">,
diff --git a/clang/include/clang/Frontend/CodeGenOptions.def b/clang/include/clang/Frontend/CodeGenOptions.def
index 9565b22e705..0b7d466ab3d 100644
--- a/clang/include/clang/Frontend/CodeGenOptions.def
+++ b/clang/include/clang/Frontend/CodeGenOptions.def
@@ -199,6 +199,7 @@ CODEGENOPT(DebugTypeExtRefs, 1, 0) ///< Whether or not debug info should contain
 CODEGENOPT(DebugExplicitImport, 1, 0)  ///< Whether or not debug info should
                                        ///< contain explicit imports for
                                        ///< anonymous namespaces
+CODEGENOPT(EnableSplitDwarf, 1, 0) ///< Whether to enable split DWARF
 CODEGENOPT(SplitDwarfInlining, 1, 1) ///< Whether to include inlining info in the
                                      ///< skeleton CU to allow for symbolication
 				     ///< of inline stack frames without .dwo files.
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 20059d922f9..7de0eaca19a 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -407,6 +407,8 @@ static void initTargetOptions(llvm::TargetOptions &Options,
   Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
 
+  if (CodeGenOpts.EnableSplitDwarf)
+    Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
   Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 2f6a2b95fb6..dd32a44393c 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -528,12 +528,14 @@ void CGDebugInfo::CreateCompileUnit() {
   // Create new compile unit.
   // FIXME - Eliminate TheCU.
   TheCU = DBuilder.createCompileUnit(
-      LangTag, DBuilder.createFile(remapDIPath(MainFileName),
-                                   remapDIPath(getCurrentDirname()), CSKind,
-                                   Checksum),
+      LangTag,
+      DBuilder.createFile(remapDIPath(MainFileName),
+                          remapDIPath(getCurrentDirname()), CSKind, Checksum),
       Producer, LO.Optimize, CGM.getCodeGenOpts().DwarfDebugFlags, RuntimeVers,
-      CGM.getCodeGenOpts().SplitDwarfFile, EmissionKind, 0 /* DWOid */,
-      CGM.getCodeGenOpts().SplitDwarfInlining,
+      CGM.getCodeGenOpts().EnableSplitDwarf
+          ? ""
+          : CGM.getCodeGenOpts().SplitDwarfFile,
+      EmissionKind, 0 /* DWOid */, CGM.getCodeGenOpts().SplitDwarfInlining,
       CGM.getCodeGenOpts().DebugInfoForProfiling);
 }
 
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 49708e7d724..6e1e4ccf44f 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2778,8 +2778,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
       CmdArgs.push_back("-fno-split-dwarf-inlining");
     if (DebugInfoKind == codegenoptions::NoDebugInfo)
       DebugInfoKind = codegenoptions::LimitedDebugInfo;
-    CmdArgs.push_back("-backend-option");
-    CmdArgs.push_back("-split-dwarf=Enable");
+    CmdArgs.push_back("-enable-split-dwarf");
   }
 
   // After we've dealt with all combinations of things that could
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 0e0eb40eb33..8cdb8298ee9 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -519,6 +519,7 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.MacroDebugInfo = Args.hasArg(OPT_debug_info_macro);
   Opts.WholeProgramVTables = Args.hasArg(OPT_fwhole_program_vtables);
   Opts.LTOVisibilityPublicStd = Args.hasArg(OPT_flto_visibility_public_std);
+  Opts.EnableSplitDwarf = Args.hasArg(OPT_enable_split_dwarf);
   Opts.SplitDwarfFile = Args.getLastArgValue(OPT_split_dwarf_file);
   Opts.SplitDwarfInlining = !Args.hasArg(OPT_fno_split_dwarf_inlining);
   Opts.DebugTypeExtRefs = Args.hasArg(OPT_dwarf_ext_refs);
diff --git a/clang/test/CodeGen/split-debug-filename.c b/clang/test/CodeGen/split-debug-filename.c
index 43daeada96a..9ca7b0f3287 100644
--- a/clang/test/CodeGen/split-debug-filename.c
+++ b/clang/test/CodeGen/split-debug-filename.c
@@ -1,7 +1,12 @@
 // RUN: %clang_cc1 -debug-info-kind=limited -split-dwarf-file foo.dwo -S -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -debug-info-kind=limited -enable-split-dwarf -split-dwarf-file foo.dwo -S -emit-llvm -o - %s | FileCheck --check-prefix=VANILLA %s
 int main (void) {
   return 0;
 }
 
 // Testing to ensure that the dwo name gets output into the compile unit.
 // CHECK: !DICompileUnit({{.*}}, splitDebugFilename: "foo.dwo"
+
+// Testing to ensure that the dwo name is not output into the compile unit if
+// it's for vanilla split-dwarf rather than split-dwarf for implicit modules.
+// VANILLA-NOT: splitDebugFilename
diff --git a/clang/test/Driver/split-debug.c b/clang/test/Driver/split-debug.c
index eaa1e990c04..c12164b4e2f 100644
--- a/clang/test/Driver/split-debug.c
+++ b/clang/test/Driver/split-debug.c
@@ -36,53 +36,53 @@
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -gmlt -fno-split-dwarf-inlining -S -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-GMLT-WITH-SPLIT < %t %s
 //
-// CHECK-GMLT-WITH-SPLIT: "-split-dwarf=Enable"
+// CHECK-GMLT-WITH-SPLIT: "-enable-split-dwarf"
 // CHECK-GMLT-WITH-SPLIT: "-debug-info-kind=line-tables-only"
 // CHECK-GMLT-WITH-SPLIT: "-split-dwarf-file"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gmlt -gsplit-dwarf -fno-split-dwarf-inlining -S -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-SPLIT-WITH-GMLT < %t %s
 //
-// CHECK-SPLIT-WITH-GMLT: "-split-dwarf=Enable"
+// CHECK-SPLIT-WITH-GMLT: "-enable-split-dwarf"
 // CHECK-SPLIT-WITH-GMLT: "-debug-info-kind=line-tables-only"
 // CHECK-SPLIT-WITH-GMLT: "-split-dwarf-file"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -fno-split-dwarf-inlining -S -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-SPLIT-WITH-NOINL < %t %s
 //
-// CHECK-SPLIT-WITH-NOINL: "-split-dwarf=Enable"
+// CHECK-SPLIT-WITH-NOINL: "-enable-split-dwarf"
 // CHECK-SPLIT-WITH-NOINL: "-debug-info-kind=limited"
 // CHECK-SPLIT-WITH-NOINL: "-split-dwarf-file"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -gmlt -S -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-GMLT-OVER-SPLIT < %t %s
 //
-// CHECK-GMLT-OVER-SPLIT-NOT: "-split-dwarf=Enable"
+// CHECK-GMLT-OVER-SPLIT-NOT: "-enable-split-dwarf"
 // CHECK-GMLT-OVER-SPLIT: "-debug-info-kind=line-tables-only"
 // CHECK-GMLT-OVER-SPLIT-NOT: "-split-dwarf-file"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gmlt -gsplit-dwarf -S -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-SPLIT-OVER-GMLT < %t %s
 //
-// CHECK-SPLIT-OVER-GMLT: "-split-dwarf=Enable" "-debug-info-kind=limited"
+// CHECK-SPLIT-OVER-GMLT: "-enable-split-dwarf" "-debug-info-kind=limited"
 // CHECK-SPLIT-OVER-GMLT: "-split-dwarf-file"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -g0 -fno-split-dwarf-inlining -S -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-G0-OVER-SPLIT < %t %s
 //
-// CHECK-G0-OVER-SPLIT-NOT: "-split-dwarf=Enable"
+// CHECK-G0-OVER-SPLIT-NOT: "-enable-split-dwarf"
 // CHECK-G0-OVER-SPLIT-NOT: "-debug-info-kind
 // CHECK-G0-OVER-SPLIT-NOT: "-split-dwarf-file"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -g0 -S -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-G0-OVER-SPLIT < %t %s
 //
-// CHECK-G0-OVER-SPLIT-NOT: "-split-dwarf=Enable"
+// CHECK-G0-OVER-SPLIT-NOT: "-enable-split-dwarf"
 // CHECK-G0-OVER-SPLIT-NOT: "-debug-info-kind
 // CHECK-G0-OVER-SPLIT-NOT: "-split-dwarf-file"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -g0 -gsplit-dwarf -S -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-SPLIT-OVER-G0 < %t %s
 //
-// CHECK-SPLIT-OVER-G0: "-split-dwarf=Enable" "-debug-info-kind=limited"
+// CHECK-SPLIT-OVER-G0: "-enable-split-dwarf" "-debug-info-kind=limited"
 // CHECK-SPLIT-OVER-G0: "-split-dwarf-file"