[Clang] Harmonize Split DWARF options with llc

Summary:
With Split DWARF the resulting object file (then called skeleton CU)
contains the file name of another ("DWO") file with the debug info.
This can be a problem for remote compilation, as it will contain the
name of the file on the compilation server, not on the client.

To use Split DWARF with remote compilation, one needs to either

* make sure only relative paths are used, and mirror the build directory
  structure of the client on the server,
* inject the desired file name on the client directly.

Since llc already supports the latter solution, we're just copying that
over. We allow setting the actual output filename separately from the
value of the DW_AT_[GNU_]dwo_name attribute in the skeleton CU.

Fixes PR40276.

Reviewers: dblaikie, echristo, tejohnson

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D59673

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@363496 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/CodeGenOptions.h

@@ -185,8 +185,11 @@ public:
   /// file, for example with -save-temps.
   std::string MainFileName;
 
-  /// The name for the split debug info file that we'll break out. This is used
-  /// in the backend for setting the name in the skeleton cu.
+  /// The name for the split debug info file used for the DW_AT_[GNU_]dwo_name
+  /// attribute in the skeleton CU.
+  std::string SplitDwarfFile;
+
+  /// Output filename for the split debug info, not used in the skeleton CU.
   std::string SplitDwarfOutput;
 
   /// The name of the relocation model to use.

include/clang/Driver/CC1Options.td

@@ -696,6 +696,8 @@ def enable_split_dwarf : Flag<["-"], "enable-split-dwarf">,
   HelpText<"Use DWARF fission in 'split' mode">;
 def enable_split_dwarf_EQ : Joined<["-"], "enable-split-dwarf=">,
   HelpText<"Set DWARF fission mode to either 'split' or 'single'">, Values<"split,single">;
+def split_dwarf_file : Separate<["-"], "split-dwarf-file">,
+  HelpText<"Name of the split dwarf debug info file to encode in the object file">;
 def fno_wchar : Flag<["-"], "fno-wchar">,
   HelpText<"Disable C++ builtin type wchar_t">;
 def fconstant_string_class : Separate<["-"], "fconstant-string-class">,

lib/CodeGen/BackendUtil.cpp

@@ -472,7 +472,7 @@ static void initTargetOptions(llvm::TargetOptions &Options,
   Options.EmitAddrsig = CodeGenOpts.Addrsig;
 
   if (CodeGenOpts.getSplitDwarfMode() != CodeGenOptions::NoFission)
-    Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfOutput;
+    Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
   Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
@@ -1428,7 +1428,8 @@ static void runThinLTOBackend(ModuleSummaryIndex *CombinedIndex, Module *M,
   Conf.RemarksWithHotness = CGOpts.DiagnosticsWithHotness;
   Conf.RemarksFilename = CGOpts.OptRecordFile;
   Conf.RemarksPasses = CGOpts.OptRecordPasses;
-  Conf.DwoPath = CGOpts.SplitDwarfOutput;
+  Conf.SplitDwarfFile = CGOpts.SplitDwarfFile;
+  Conf.SplitDwarfOutput = CGOpts.SplitDwarfOutput;
   switch (Action) {
   case Backend_EmitNothing:
     Conf.PreCodeGenModuleHook = [](size_t Task, const Module &Mod) {

lib/CodeGen/CGDebugInfo.cpp

@@ -616,7 +616,7 @@ void CGDebugInfo::CreateCompileUnit() {
       CGOpts.DwarfDebugFlags, RuntimeVers,
       (CGOpts.getSplitDwarfMode() != CodeGenOptions::NoFission)
           ? ""
-          : CGOpts.SplitDwarfOutput,
+          : CGOpts.SplitDwarfFile,
       EmissionKind, DwoId, CGOpts.SplitDwarfInlining,
       CGOpts.DebugInfoForProfiling,
       CGM.getTarget().getTriple().isNVPTX()

lib/Driver/ToolChains/Clang.cpp

@@ -4108,11 +4108,14 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                     TC.getTriple().isOSBinFormatELF() &&
                     (isa<AssembleJobAction>(JA) || isa<CompileJobAction>(JA) ||
                      isa<BackendJobAction>(JA));
-  const char *SplitDWARFOut;
   if (SplitDWARF) {
-    CmdArgs.push_back("-split-dwarf-output");
-    SplitDWARFOut = SplitDebugName(Args, Input, Output);
+    const char *SplitDWARFOut = SplitDebugName(Args, Input, Output);
+    CmdArgs.push_back("-split-dwarf-file");
     CmdArgs.push_back(SplitDWARFOut);
+    if (DwarfFission == DwarfFissionKind::Split) {
+      CmdArgs.push_back("-split-dwarf-output");
+      CmdArgs.push_back(SplitDWARFOut);
+    }
   }
 
   // Pass the linker version in use.

lib/Frontend/CompilerInvocation.cpp

@@ -726,6 +726,7 @@ 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.SplitDwarfFile = Args.getLastArgValue(OPT_split_dwarf_file);
   Opts.SplitDwarfOutput = Args.getLastArgValue(OPT_split_dwarf_output);
   Opts.SplitDwarfInlining = !Args.hasArg(OPT_fno_split_dwarf_inlining);
 

test/CodeGen/split-debug-filename.c

@@ -1,7 +1,7 @@
 // REQUIRES: x86-registered-target
-// RUN: %clang_cc1 -debug-info-kind=limited -split-dwarf-output foo.dwo -S -emit-llvm -o - %s | FileCheck %s
-// RUN: %clang_cc1 -debug-info-kind=limited -enable-split-dwarf -split-dwarf-output foo.dwo -S -emit-llvm -o - %s | FileCheck --check-prefix=VANILLA %s
-// RUN: %clang_cc1 -triple x86_64-unknown-linux -debug-info-kind=limited -enable-split-dwarf -split-dwarf-output %t.dwo -emit-obj -o - %s | llvm-readobj -S - | FileCheck --check-prefix=O %s
+// 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
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -debug-info-kind=limited -enable-split-dwarf -split-dwarf-file %t.dwo -split-dwarf-output %t.dwo -emit-obj -o - %s | llvm-readobj -S - | FileCheck --check-prefix=O %s
 // RUN: llvm-readobj -S %t.dwo | FileCheck --check-prefix=DWO %s
 
 int main (void) {

test/CodeGen/split-debug-output.c

@@ -0,0 +1,7 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -debug-info-kind=limited -enable-split-dwarf -split-dwarf-file foo.dwo -split-dwarf-output %t -emit-obj -o - %s | llvm-dwarfdump -debug-info - | FileCheck %s
+// RUN: llvm-dwarfdump -debug-info %t | FileCheck %s
+
+int f() { return 0; }
+
+// CHECK: DW_AT_GNU_dwo_name ("foo.dwo")

test/CodeGen/split-debug-single-file.c

@@ -2,19 +2,19 @@
 
 // Testing to ensure -enable-split-dwarf=single allows to place .dwo sections into regular output object.
 //  RUN: %clang_cc1 -debug-info-kind=limited -triple x86_64-unknown-linux \
-//  RUN:   -enable-split-dwarf=single -split-dwarf-output %t.o -emit-obj -o %t.o %s -fno-experimental-new-pass-manager
+//  RUN:   -enable-split-dwarf=single -split-dwarf-file %t.o -emit-obj -o %t.o %s -fno-experimental-new-pass-manager
 //  RUN: llvm-readobj -S %t.o | FileCheck --check-prefix=MODE-SINGLE %s
 //  RUN: %clang_cc1 -debug-info-kind=limited -triple x86_64-unknown-linux \
-//  RUN:   -enable-split-dwarf=single -split-dwarf-output %t.o -emit-obj -o %t.o %s -fexperimental-new-pass-manager
+//  RUN:   -enable-split-dwarf=single -split-dwarf-file %t.o -emit-obj -o %t.o %s -fexperimental-new-pass-manager
 //  RUN: llvm-readobj -S %t.o | FileCheck --check-prefix=MODE-SINGLE %s
 //  MODE-SINGLE: .dwo
 
 // Testing to ensure -enable-split-dwarf=split does not place .dwo sections into regular output object.
 //  RUN: %clang_cc1 -debug-info-kind=limited -triple x86_64-unknown-linux \
-//  RUN:   -enable-split-dwarf=split -split-dwarf-output %t.o -emit-obj -o %t.o %s -fno-experimental-new-pass-manager
+//  RUN:   -enable-split-dwarf=split -split-dwarf-file %t.dwo -split-dwarf-output %t.dwo -emit-obj -o %t.o %s -fno-experimental-new-pass-manager
 //  RUN: llvm-readobj -S %t.o | FileCheck --check-prefix=MODE-SPLIT %s
 //  RUN: %clang_cc1 -debug-info-kind=limited -triple x86_64-unknown-linux \
-//  RUN:   -enable-split-dwarf=split -split-dwarf-output %t.o -emit-obj -o %t.o %s -fexperimental-new-pass-manager
+//  RUN:   -enable-split-dwarf=split -split-dwarf-file %t.dwo -split-dwarf-output %t.dwo -emit-obj -o %t.o %s -fexperimental-new-pass-manager
 //  RUN: llvm-readobj -S %t.o | FileCheck --check-prefix=MODE-SPLIT %s
 //  MODE-SPLIT-NOT: .dwo
 

test/CodeGen/thinlto-split-dwarf.c

@@ -10,12 +10,14 @@
 
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu \
 // RUN:   -emit-obj -fthinlto-index=%t.o.thinlto.bc \
-// RUN:   -o %t.native.o -split-dwarf-output %t.native.dwo -x ir %t.o
+// RUN:   -o %t.native.o -split-dwarf-file %t.file.dwo \
+// RUN:   -split-dwarf-output %t.output.dwo -x ir %t.o
 
-// RUN: llvm-readobj -S %t.native.o | FileCheck --check-prefix=O %s
-// RUN: llvm-readobj -S %t.native.dwo | FileCheck --check-prefix=DWO %s
+// RUN: llvm-dwarfdump %t.native.o | FileCheck --check-prefix=O %s
+// RUN: llvm-dwarfdump %t.output.dwo | FileCheck --check-prefix=DWO %s
 
-// O-NOT: .dwo
-// DWO: .dwo
+// O: DW_AT_GNU_dwo_name ("{{.*}}.file.dwo")
+// O-NOT: DW_TAG_subprogram
+// DWO: DW_TAG_subprogram
 
 int main() {}

test/Driver/split-debug.c

@@ -3,7 +3,7 @@
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -c -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-ACTIONS < %t %s
 //
-// CHECK-ACTIONS: "-split-dwarf-output" "split-debug.dwo"
+// CHECK-ACTIONS: "-split-dwarf-file" "split-debug.dwo" "-split-dwarf-output" "split-debug.dwo"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -c -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-ACTIONS < %t %s
@@ -14,12 +14,14 @@
 // RUN: FileCheck -check-prefix=CHECK-ACTIONS-SINGLE-SPLIT < %t %s
 //
 // CHECK-ACTIONS-SINGLE-SPLIT: "-enable-split-dwarf=single"
-// CHECK-ACTIONS-SINGLE-SPLIT: "-split-dwarf-output" "split-debug.o"
+// CHECK-ACTIONS-SINGLE-SPLIT: "-split-dwarf-file" "split-debug.o"
+// CHECK-ACTIONS-SINGLE-SPLIT-NOT: "-split-dwarf-output"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf=single -c -### -o %tfoo.o %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-SINGLE-SPLIT-FILENAME < %t %s
 //
-// CHECK-SINGLE-SPLIT-FILENAME: "-split-dwarf-output" "{{.*}}foo.o"
+// CHECK-SINGLE-SPLIT-FILENAME: "-split-dwarf-file" "{{.*}}foo.o"
+// CHECK-SINGLE-SPLIT-FILENAME-NOT: "-split-dwarf-output"
 
 // RUN: %clang -target x86_64-macosx -gsplit-dwarf -c -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-NO-ACTIONS < %t %s
@@ -41,7 +43,7 @@
 // RUN: %clang -target amdgcn-amd-amdhsa -gsplit-dwarf -c -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-OPTION < %t %s
 //
-// CHECK-OPTION: "-split-dwarf-output" "split-debug.dwo"
+// CHECK-OPTION: "-split-dwarf-file" "split-debug.dwo" "-split-dwarf-output" "split-debug.dwo"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -S -### %s 2> %t
 // RUN: FileCheck -check-prefix=CHECK-ASM < %t %s
@@ -58,6 +60,7 @@
 //
 // CHECK-GMLT-WITH-SPLIT: "-enable-split-dwarf"
 // CHECK-GMLT-WITH-SPLIT: "-debug-info-kind=line-tables-only"
+// CHECK-GMLT-WITH-SPLIT: "-split-dwarf-file"
 // CHECK-GMLT-WITH-SPLIT: "-split-dwarf-output"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -g -fno-split-dwarf-inlining -S -### %s 2> %t
@@ -86,12 +89,14 @@
 //
 // 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"
 // CHECK-GMLT-OVER-SPLIT-NOT: "-split-dwarf-output"
 
 // 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: "-enable-split-dwarf" "-debug-info-kind=limited"
+// CHECK-SPLIT-OVER-GMLT: "-split-dwarf-file"
 // CHECK-SPLIT-OVER-GMLT: "-split-dwarf-output"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -g0 -fno-split-dwarf-inlining -S -### %s 2> %t
@@ -99,6 +104,7 @@
 //
 // CHECK-G0-OVER-SPLIT-NOT: "-enable-split-dwarf"
 // CHECK-G0-OVER-SPLIT-NOT: "-debug-info-kind
+// CHECK-G0-OVER-SPLIT-NOT: "-split-dwarf-file"
 // CHECK-G0-OVER-SPLIT-NOT: "-split-dwarf-output"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -g0 -S -### %s 2> %t
@@ -108,6 +114,7 @@
 //
 // CHECK-G0-OVER-SPLIT-NOT: "-enable-split-dwarf"
 // CHECK-G0-OVER-SPLIT-NOT: "-debug-info-kind
+// CHECK-G0-OVER-SPLIT-NOT: "-split-dwarf-file"
 // CHECK-G0-OVER-SPLIT-NOT: "-split-dwarf-output"
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -g0 -gsplit-dwarf -S -### %s 2> %t
@@ -116,4 +123,5 @@
 // RUN: FileCheck -check-prefix=CHECK-SPLIT-OVER-G0 < %t %s
 //
 // CHECK-SPLIT-OVER-G0: "-enable-split-dwarf" "-debug-info-kind=limited"
+// CHECK-SPLIT-OVER-G0: "-split-dwarf-file"
 // CHECK-SPLIT-OVER-G0: "-split-dwarf-output"