[PATCH] D59923: [Driver] Simplify -g level computation and its interaction with -gsplit-dwarf

[Fangrui Song via Phabricator via cfe-commits]

MaskRay created this revision.
MaskRay added reviewers: dblaikie, echristo.
Herald added subscribers: cfe-commits, jdoerfert, aprantl.
Herald added a project: clang.

Computed debug info level:

-gsplit-dwarf -gmlt => 1
-gsplit-dwarf -gmlt -fno-split-dwarf-inlining => 1
-gmlt -gsplit-dwarf => 2
-gmlt -gsplit-dwarf -fno-split-dwarf-inlining => special: 1 (before) 2 (after)

This patch simplifies the computation and drops the
-fno-split-dwarf-inlining special case to make things simpler. If the
user want to compute 1, swap -gmlt and -gsplit-dwarf.

Some context:

In gcc, -gsplit-dwarf -g0 -g1 -g2 -g3 -ggdb* -gdwarf-* ... are applied
one by one and the last one decides the debug info level (-gsplit-dwarf
has level 2). It is a bit unfortunate that -gsplit-dwarf -gdwarf-* ...
participate in the level computation but that is the status quo.


Repository:
  rC Clang

https://reviews.llvm.org/D59923

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


Index: test/Driver/split-debug.c
===================================================================
--- test/Driver/split-debug.c
+++ test/Driver/split-debug.c
@@ -68,7 +68,7 @@
 // RUN: FileCheck -check-prefix=CHECK-SPLIT-WITH-GMLT < %t %s
 //
 // CHECK-SPLIT-WITH-GMLT: "-enable-split-dwarf"
-// CHECK-SPLIT-WITH-GMLT: "-debug-info-kind=line-tables-only"
+// CHECK-SPLIT-WITH-GMLT: "-debug-info-kind=limited"
 // 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
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -3155,9 +3155,11 @@
     SplitDWARFInlining = false;
   }
 
-  if (const Arg *A = Args.getLastArg(options::OPT_g_Group)) {
+  if (const Arg *A = Args.getLastArg(options::OPT_g_Group, options::OPT_gsplit_dwarf)) {
+    DebugInfoKind = codegenoptions::LimitedDebugInfo;
+
+    // If the last option explicitly specified a debug-info level, use it.
     if (checkDebugInfoOption(A, Args, D, TC)) {
-      // If the last option explicitly specified a debug-info level, use it.
       if (A->getOption().matches(options::OPT_gN_Group)) {
         DebugInfoKind = DebugLevelToInfoKind(*A);
         // If you say "-gsplit-dwarf -gline-tables-only", -gsplit-dwarf loses.
@@ -3168,22 +3170,12 @@
         // 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 (DwarfFission != DwarfFissionKind::None) {
-          if (A->getIndex() > SplitDWARFArg->getIndex()) {
-            if (DebugInfoKind == codegenoptions::NoDebugInfo ||
-                DebugInfoKind == codegenoptions::DebugDirectivesOnly ||
-                (DebugInfoKind == codegenoptions::DebugLineTablesOnly &&
-                 SplitDWARFInlining))
-              DwarfFission = DwarfFissionKind::None;
-          } else if (SplitDWARFInlining)
-            DebugInfoKind = codegenoptions::NoDebugInfo;
-        }
-      } else {
-        // For any other 'g' option, use Limited.
-        DebugInfoKind = codegenoptions::LimitedDebugInfo;
+        if (DebugInfoKind == codegenoptions::NoDebugInfo ||
+            DebugInfoKind == codegenoptions::DebugDirectivesOnly ||
+            (DebugInfoKind == codegenoptions::DebugLineTablesOnly &&
+             SplitDWARFInlining))
+          DwarfFission = DwarfFissionKind::None;
       }
-    } else {
-      DebugInfoKind = codegenoptions::LimitedDebugInfo;
     }
   }
 
@@ -3265,9 +3257,6 @@
       CmdArgs.push_back("-fno-split-dwarf-inlining");
 
     if (DwarfFission != DwarfFissionKind::None) {
-      if (DebugInfoKind == codegenoptions::NoDebugInfo)
-        DebugInfoKind = codegenoptions::LimitedDebugInfo;
-
       if (DwarfFission == DwarfFissionKind::Single)
         CmdArgs.push_back("-enable-split-dwarf=single");
       else


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