r279687 - DebugInfo: Let -gsplit-dwarf and -gmlt compose if -fno-split-dwarf-inlining is used

[David Blaikie via cfe-commits]

Author: dblaikie
Date: Wed Aug 24 18:22:36 2016
New Revision: 279687

URL: http://llvm.org/viewvc/llvm-project?rev=279687&view=rev
Log:
DebugInfo: Let -gsplit-dwarf and -gmlt compose if -fno-split-dwarf-inlining is used

If the inline info is not duplicated into the skeleton CU, then there's
value in using -gsplit-dwarf and -gmlt together (to keep all those extra
subprograms out of the skeleton CU, while also producing smaller .dwo
files)

Modified:
    cfe/trunk/lib/Driver/Tools.cpp
    cfe/trunk/test/Driver/split-debug.c

Modified: cfe/trunk/lib/Driver/Tools.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=279687&r1=279686&r2=279687&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/Tools.cpp (original)
+++ cfe/trunk/lib/Driver/Tools.cpp Wed Aug 24 18:22:36 2016
@@ -4597,6 +4597,12 @@ void Clang::ConstructJob(Compilation &C,
                                                  : "-");
   }
 
+  bool splitDwarfInlining =
+      Args.hasFlag(options::OPT_fsplit_dwarf_inlining,
+                   options::OPT_fno_split_dwarf_inlining, true);
+  if (!splitDwarfInlining)
+    CmdArgs.push_back("-fno-split-dwarf-inlining");
+
   Args.ClaimAllArgs(options::OPT_g_Group);
   Arg *SplitDwarfArg = Args.getLastArg(options::OPT_gsplit_dwarf);
   if (Arg *A = Args.getLastArg(options::OPT_g_Group)) {
@@ -4606,8 +4612,15 @@ void Clang::ConstructJob(Compilation &C,
       // If you say "-gsplit-dwarf -gline-tables-only", -gsplit-dwarf loses.
       // But -gsplit-dwarf is not a g_group option, hence we have to check the
       // order explicitly. (If -gsplit-dwarf wins, we fix DebugInfoKind later.)
-      if (SplitDwarfArg && DebugInfoKind < codegenoptions::LimitedDebugInfo &&
-          A->getIndex() > SplitDwarfArg->getIndex())
+      // This gets a bit more complicated if you've disabled inline info in the
+      // skeleton CUs (splitDwarfInlining) - then there's value in composing
+      // split-dwarf and line-tables-only, so let those compose naturally in
+      // that case.
+      // And if you just turned off debug info, (-gsplit-dwarf -g0) - do that.
+      if (SplitDwarfArg && A->getIndex() > SplitDwarfArg->getIndex() &&
+          ((DebugInfoKind == codegenoptions::DebugLineTablesOnly &&
+            splitDwarfInlining) ||
+           DebugInfoKind == codegenoptions::NoDebugInfo))
         SplitDwarfArg = nullptr;
     } else
       // For any other 'g' option, use Limited.
@@ -4659,7 +4672,8 @@ void Clang::ConstructJob(Compilation &C,
   // splitting and extraction.
   // FIXME: Currently only works on Linux.
   if (getToolChain().getTriple().isOSLinux() && SplitDwarfArg) {
-    DebugInfoKind = codegenoptions::LimitedDebugInfo;
+    if (splitDwarfInlining)
+      DebugInfoKind = codegenoptions::LimitedDebugInfo;
     CmdArgs.push_back("-backend-option");
     CmdArgs.push_back("-split-dwarf=Enable");
   }
@@ -4697,10 +4711,6 @@ void Clang::ConstructJob(Compilation &C,
     CmdArgs.push_back("-generate-type-units");
   }
 
-  if (!Args.hasFlag(options::OPT_fsplit_dwarf_inlining,
-                    options::OPT_fno_split_dwarf_inlining, true))
-    CmdArgs.push_back("-fno-split-dwarf-inlining");
-
   // CloudABI and WebAssembly use -ffunction-sections and -fdata-sections by
   // default.
   bool UseSeparateSections = Triple.getOS() == llvm::Triple::CloudABI ||

Modified: cfe/trunk/test/Driver/split-debug.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/split-debug.c?rev=279687&r1=279686&r2=279687&view=diff
==============================================================================
--- cfe/trunk/test/Driver/split-debug.c (original)
+++ cfe/trunk/test/Driver/split-debug.c Wed Aug 24 18:22:36 2016
@@ -33,11 +33,25 @@
 //
 // CHECK-IAS: objcopy
 
+// 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: "-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: "-debug-info-kind=line-tables-only"
+// CHECK-SPLIT-WITH-GMLT: "-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: "-debug-info-kind=line-tables-only"
 // CHECK-GMLT-OVER-SPLIT-NOT: "-split-dwarf=Enable"
+// 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
@@ -46,11 +60,18 @@
 // CHECK-SPLIT-OVER-GMLT: "-split-dwarf=Enable" "-debug-info-kind=limited"
 // CHECK-SPLIT-OVER-GMLT: "-split-dwarf-file"
 
-// RUN: %clang -target x86_64-unknown-linux-gnu -gsplit-dwarf -g0 -S -### %s 2> %t
+// 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: "-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: "-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