[clang] e3b9af9 - [Driver] -gsplit-dwarf: Produce .dwo regardless of -gN for IR input

[Fangrui Song via cfe-commits]

Author: Fangrui Song
Date: 2021-01-14T11:46:22-08:00
New Revision: e3b9af92a4821fec25c207e2d1e443e09ff6b11e

URL: https://github.com/llvm/llvm-project/commit/e3b9af92a4821fec25c207e2d1e443e09ff6b11e
DIFF: https://github.com/llvm/llvm-project/commit/e3b9af92a4821fec25c207e2d1e443e09ff6b11e.diff

LOG: [Driver] -gsplit-dwarf: Produce .dwo regardless of -gN for IR input

This generalizes D94647 to IR input, as suggested by @tejohnson.
Ideally the driver should just forward split dwarf options, but doing this currently will cause `clang -gsplit-dwarf -c a.c` to create a .dwo with just `.strtab`.

Reviewed By: dblaikie, tejohnson

Differential Revision: https://reviews.llvm.org/D94655

Added: 
    

Modified: 
    clang/lib/Driver/ToolChains/Clang.cpp
    clang/test/Driver/split-debug.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 0c821b85c229..8d6e8c42053f 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3728,9 +3728,10 @@ static DwarfFissionKind getDebugFissionKind(const Driver &D,
   return DwarfFissionKind::None;
 }
 
-static void RenderDebugOptions(const ToolChain &TC, const Driver &D,
+static void renderDebugOptions(const ToolChain &TC, const Driver &D,
                                const llvm::Triple &T, const ArgList &Args,
-                               bool EmitCodeView, ArgStringList &CmdArgs,
+                               bool EmitCodeView, bool IRInput,
+                               ArgStringList &CmdArgs,
                                codegenoptions::DebugInfoKind &DebugInfoKind,
                                DwarfFissionKind &DwarfFission) {
   if (Args.hasFlag(options::OPT_fdebug_info_for_profiling,
@@ -3754,12 +3755,10 @@ static void RenderDebugOptions(const ToolChain &TC, const Driver &D,
       Args.hasFlag(options::OPT_fsplit_dwarf_inlining,
                    options::OPT_fno_split_dwarf_inlining, false);
 
-  // Normally -gsplit-dwarf is only useful with -gN. For -gsplit-dwarf in the
-  // backend phase of a distributed ThinLTO which does object file generation
-  // and no IR generation, -gN should not be needed. So allow -gsplit-dwarf with
-  // either -gN or -fthinlto-index=.
-  if (Args.hasArg(options::OPT_g_Group) ||
-      Args.hasArg(options::OPT_fthinlto_index_EQ)) {
+  // Normally -gsplit-dwarf is only useful with -gN. For IR input, Clang does
+  // object file generation and no IR generation, -gN should not be needed. So
+  // allow -gsplit-dwarf with either -gN or IR input.
+  if (IRInput || Args.hasArg(options::OPT_g_Group)) {
     Arg *SplitDWARFArg;
     DwarfFission = getDebugFissionKind(D, Args, SplitDWARFArg);
     if (DwarfFission != DwarfFissionKind::None &&
@@ -4956,8 +4955,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     AddClangCLArgs(Args, InputType, CmdArgs, &DebugInfoKind, &EmitCodeView);
 
   DwarfFissionKind DwarfFission = DwarfFissionKind::None;
-  RenderDebugOptions(TC, D, RawTriple, Args, EmitCodeView, CmdArgs,
-                     DebugInfoKind, DwarfFission);
+  renderDebugOptions(TC, D, RawTriple, Args, EmitCodeView,
+                     types::isLLVMIR(InputType), CmdArgs, DebugInfoKind,
+                     DwarfFission);
 
   // Add the split debug info name to the command lines here so we
   // can propagate it to the backend.

diff  --git a/clang/test/Driver/split-debug.c b/clang/test/Driver/split-debug.c
index 2ce4ca980c3f..d4511574da4d 100644
--- a/clang/test/Driver/split-debug.c
+++ b/clang/test/Driver/split-debug.c
@@ -26,11 +26,12 @@
 
 /// ... unless -fthinlto-index= is specified.
 // RUN: echo > %t.bc
-// RUN: %clang -### -c -target x86_64 -fthinlto-index=dummy -gsplit-dwarf %t.bc 2>&1 | FileCheck %s --check-prefix=THINLTO
+// RUN: %clang -### -c -target x86_64 -fthinlto-index=dummy -gsplit-dwarf %t.bc 2>&1 | FileCheck %s --check-prefix=IR
+// RUN: %clang -### -c -target x86_64 -gsplit-dwarf -x ir %t.bc 2>&1 | FileCheck %s --check-prefix=IR
 
-// THINLTO-NOT:  "-debug-info-kind=
-// THINLTO:      "-ggnu-pubnames"
-// THINLTO-SAME: "-split-dwarf-file" "{{.*}}.dwo" "-split-dwarf-output" "{{.*}}.dwo"
+// IR-NOT:  "-debug-info-kind=
+// IR:      "-ggnu-pubnames"
+// IR-SAME: "-split-dwarf-file" "{{.*}}.dwo" "-split-dwarf-output" "{{.*}}.dwo"
 
 /// -gno-split-dwarf disables debug fission.
 // RUN: %clang -### -c -target x86_64 -gsplit-dwarf -g -gno-split-dwarf %s 2>&1 | FileCheck %s --check-prefix=NOSPLIT