[clang] 85c18d3 - [Driver] Add -gno-split-dwarf which can disable debug fission

[Fangrui Song via cfe-commits]

Author: Fangrui Song
Date: 2020-12-08T13:24:59-08:00
New Revision: 85c18d3521e87a22c742be512245665d6bb5bfe2

URL: https://github.com/llvm/llvm-project/commit/85c18d3521e87a22c742be512245665d6bb5bfe2
DIFF: https://github.com/llvm/llvm-project/commit/85c18d3521e87a22c742be512245665d6bb5bfe2.diff

LOG: [Driver] Add -gno-split-dwarf which can disable debug fission

Currently when -gsplit-dwarf is specified (could be buried in a build system),
there is no convenient way to cancel debug fission without affecting the debug
information amount (all of -g0, -g1 -fsplit-dwarf-inlining and -gline-directives-only
can, but they affect the debug information amount).

Reviewed By: #debug-info, dblaikie

Differential Revision: https://reviews.llvm.org/D92809

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 8cabcd671161..896ccbe3b275 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -2213,6 +2213,7 @@ def gsplit_dwarf : Flag<["-"], "gsplit-dwarf">, Group<g_flags_Group>;
 def gsplit_dwarf_EQ : Joined<["-"], "gsplit-dwarf=">, Group<g_flags_Group>,
   HelpText<"Set DWARF fission mode to either 'split' or 'single'">,
   Values<"split,single">;
+def gno_split_dwarf : Flag<["-"], "gno-split-dwarf">, Group<g_flags_Group>;
 def ggnu_pubnames : Flag<["-"], "ggnu-pubnames">, Group<g_flags_Group>, Flags<[CC1Option]>;
 def gno_gnu_pubnames : Flag<["-"], "gno-gnu-pubnames">, Group<g_flags_Group>;
 def gpubnames : Flag<["-"], "gpubnames">, Group<g_flags_Group>, Flags<[CC1Option]>;

diff  --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index f3a6b12609e2..6c78a5d9555c 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3705,9 +3705,9 @@ enum class DwarfFissionKind { None, Split, Single };
 
 static DwarfFissionKind getDebugFissionKind(const Driver &D,
                                             const ArgList &Args, Arg *&Arg) {
-  Arg =
-      Args.getLastArg(options::OPT_gsplit_dwarf, options::OPT_gsplit_dwarf_EQ);
-  if (!Arg)
+  Arg = Args.getLastArg(options::OPT_gsplit_dwarf, options::OPT_gsplit_dwarf_EQ,
+                        options::OPT_gno_split_dwarf);
+  if (!Arg || Arg->getOption().matches(options::OPT_gno_split_dwarf))
     return DwarfFissionKind::None;
 
   if (Arg->getOption().matches(options::OPT_gsplit_dwarf))

diff  --git a/clang/test/Driver/split-debug.c b/clang/test/Driver/split-debug.c
index bd9ec32e0010..7d3fcf078c56 100644
--- a/clang/test/Driver/split-debug.c
+++ b/clang/test/Driver/split-debug.c
@@ -17,12 +17,22 @@
 // RUN: %clang -### -c -target amdgcn-amd-amdhsa -gsplit-dwarf -g %s 2>&1 | FileCheck %s --check-prefix=SPLIT
 
 /// -gsplit-dwarf is a no-op on a non-ELF platform.
-// RUN: %clang -### -c -target x86_64-apple-darwin  -gsplit-dwarf -g %s 2>&1 | FileCheck %s --check-prefix=NOSPLIT
-// NOSPLIT-NOT: "-split-dwarf
+// RUN: %clang -### -c -target x86_64-apple-darwin  -gsplit-dwarf -g %s 2>&1 | FileCheck %s --check-prefix=DARWIN
+// DARWIN:     "-debug-info-kind=standalone"
+// DARWIN-NOT: "-split-dwarf
 
 /// -gsplit-dwarf is a no-op if no -g is specified.
 // RUN: %clang -### -c -target x86_64 -gsplit-dwarf %s 2>&1 | FileCheck %s --check-prefix=G0
 
+/// -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
+// RUN: %clang -### -c -target x86_64 -gsplit-dwarf=single -g -gno-split-dwarf %s 2>&1 | FileCheck %s --check-prefix=NOSPLIT
+// RUN: %clang -### -c -target x86_64 -gno-split-dwarf -g -gsplit-dwarf %s 2>&1 | FileCheck %s --check-prefixes=NOINLINE,SPLIT
+
+// NOSPLIT:     "-debug-info-kind=limited"
+// NOSPLIT-NOT: "-ggnu-pubnames"
+// NOSPLIT-NOT: "-split-dwarf
+
 /// Test -gsplit-dwarf=single.
 // RUN: %clang -### -c -target x86_64 -gsplit-dwarf=single -g %s 2>&1 | FileCheck %s --check-prefix=SINGLE