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[LLD] [COFF] Add /debug: options nodwarf and nosymtab #75180

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merged 1 commit into from
Dec 15, 2023

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mstorsjo
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These allow tweaking what gets implied by /debug and /debug:dwarf.

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llvmbot commented Dec 12, 2023

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@llvm/pr-subscribers-lld-coff

Author: Martin Storsjö (mstorsjo)

Changes

These allow tweaking what gets implied by /debug and /debug:dwarf.


Full diff: https://github.com/llvm/llvm-project/pull/75180.diff

7 Files Affected:

  • (modified) lld/COFF/Config.h (+2-2)
  • (modified) lld/COFF/Driver.cpp (+57-57)
  • (modified) lld/COFF/InputFiles.cpp (+2-2)
  • (modified) lld/COFF/Writer.cpp (+1-1)
  • (modified) lld/test/COFF/debug-dwarf.test (+13)
  • (modified) lld/test/COFF/sort-debug.test (+4)
  • (modified) lld/test/COFF/symtab.test (+4)
diff --git a/lld/COFF/Config.h b/lld/COFF/Config.h
index 24126f635a06f2..48c48cefe91d8e 100644
--- a/lld/COFF/Config.h
+++ b/lld/COFF/Config.h
@@ -130,9 +130,9 @@ struct Configuration {
   bool forceMultipleRes = false;
   bool forceUnresolved = false;
   bool debug = false;
-  bool debugDwarf = false;
+  bool includeDwarfChunks = false;
   bool debugGHashes = false;
-  bool debugSymtab = false;
+  bool writeSymtab = false;
   bool driver = false;
   bool driverUponly = false;
   bool driverWdm = false;
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 99c1a60735adc5..826022e7450292 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -858,46 +858,6 @@ static std::string createResponseFile(const opt::InputArgList &args,
   return std::string(data.str());
 }
 
-enum class DebugKind {
-  Unknown,
-  None,
-  Full,
-  FastLink,
-  GHash,
-  NoGHash,
-  Dwarf,
-  Symtab
-};
-
-static DebugKind parseDebugKind(const opt::InputArgList &args) {
-  auto *a = args.getLastArg(OPT_debug, OPT_debug_opt);
-  if (!a)
-    return DebugKind::None;
-  if (a->getNumValues() == 0)
-    return DebugKind::Full;
-
-  DebugKind debug = StringSwitch<DebugKind>(a->getValue())
-                        .CaseLower("none", DebugKind::None)
-                        .CaseLower("full", DebugKind::Full)
-                        .CaseLower("fastlink", DebugKind::FastLink)
-                        // LLD extensions
-                        .CaseLower("ghash", DebugKind::GHash)
-                        .CaseLower("noghash", DebugKind::NoGHash)
-                        .CaseLower("dwarf", DebugKind::Dwarf)
-                        .CaseLower("symtab", DebugKind::Symtab)
-                        .Default(DebugKind::Unknown);
-
-  if (debug == DebugKind::FastLink) {
-    warn("/debug:fastlink unsupported; using /debug:full");
-    return DebugKind::Full;
-  }
-  if (debug == DebugKind::Unknown) {
-    error("/debug: unknown option: " + Twine(a->getValue()));
-    return DebugKind::None;
-  }
-  return debug;
-}
-
 static unsigned parseDebugTypes(const opt::InputArgList &args) {
   unsigned debugTypes = static_cast<unsigned>(DebugType::None);
 
@@ -1647,12 +1607,62 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   if (args.hasArg(OPT_force, OPT_force_multipleres))
     config->forceMultipleRes = true;
 
+  // Don't warn about long section names, such as .debug_info, for mingw (or
+  // when -debug:dwarf is requested, handled below).
+  if (config->mingw)
+    config->warnLongSectionNames = false;
+
+  bool doGC = true;
+
   // Handle /debug
-  DebugKind debug = parseDebugKind(args);
-  if (debug == DebugKind::Full || debug == DebugKind::Dwarf ||
-      debug == DebugKind::GHash || debug == DebugKind::NoGHash) {
-    config->debug = true;
-    config->incremental = true;
+  bool shouldCreatePDB = false;
+  for (auto *arg : args.filtered(OPT_debug, OPT_debug_opt)) {
+    std::string str;
+    if (arg->getOption().getID() == OPT_debug)
+      str = "full";
+    else
+      str = StringRef(arg->getValue()).lower();
+    SmallVector<StringRef, 1> vec;
+    StringRef(str).split(vec, ',');
+    for (StringRef s : vec) {
+      if (s == "fastlink") {
+        warn("/debug:fastlink unsupported; using /debug:full");
+        s = "full";
+      }
+      if (s == "none") {
+        config->debug = false;
+        config->incremental = false;
+        config->includeDwarfChunks = false;
+        config->debugGHashes = false;
+        config->writeSymtab = false;
+        shouldCreatePDB = false;
+        doGC = true;
+      } else if (s == "full" || s == "ghash" || s == "noghash") {
+        config->debug = true;
+        config->incremental = true;
+        config->includeDwarfChunks = true;
+        if (s == "full" || s == "ghash")
+          config->debugGHashes = true;
+        shouldCreatePDB = true;
+        doGC = false;
+      } else if (s == "dwarf") {
+        config->debug = true;
+        config->incremental = true;
+        config->includeDwarfChunks = true;
+        config->writeSymtab = true;
+        config->warnLongSectionNames = false;
+        doGC = false;
+      } else if (s == "nodwarf") {
+        config->includeDwarfChunks = false;
+      } else if (s == "symtab") {
+        config->writeSymtab = true;
+        doGC = false;
+      } else if (s == "nosymtab") {
+        config->writeSymtab = false;
+      } else {
+        error("/debug: unknown option: " + s);
+      }
+    }
   }
 
   // Handle /demangle
@@ -1672,9 +1682,6 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
       config->driverUponly || config->driverWdm || args.hasArg(OPT_driver);
 
   // Handle /pdb
-  bool shouldCreatePDB =
-      (debug == DebugKind::Full || debug == DebugKind::GHash ||
-       debug == DebugKind::NoGHash);
   if (shouldCreatePDB) {
     if (auto *arg = args.getLastArg(OPT_pdb))
       config->pdbPath = arg->getValue();
@@ -1837,8 +1844,9 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
 
   config->noimplib = args.hasArg(OPT_noimplib);
 
+  if (args.hasArg(OPT_profile))
+    doGC = true;
   // Handle /opt.
-  bool doGC = debug == DebugKind::None || args.hasArg(OPT_profile);
   std::optional<ICFLevel> icfLevel;
   if (args.hasArg(OPT_profile))
     icfLevel = ICFLevel::None;
@@ -2028,9 +2036,6 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
     parseSwaprun(arg->getValue());
   config->terminalServerAware =
       !config->dll && args.hasFlag(OPT_tsaware, OPT_tsaware_no, true);
-  config->debugDwarf = debug == DebugKind::Dwarf;
-  config->debugGHashes = debug == DebugKind::GHash || debug == DebugKind::Full;
-  config->debugSymtab = debug == DebugKind::Symtab;
   config->autoImport =
       args.hasFlag(OPT_auto_import, OPT_auto_import_no, config->mingw);
   config->pseudoRelocs = args.hasFlag(
@@ -2047,11 +2052,6 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   if (args.hasFlag(OPT_inferasanlibs, OPT_inferasanlibs_no, false))
     warn("ignoring '/inferasanlibs', this flag is not supported");
 
-  // Don't warn about long section names, such as .debug_info, for mingw or
-  // when -debug:dwarf is requested.
-  if (config->mingw || config->debugDwarf)
-    config->warnLongSectionNames = false;
-
   if (config->incremental && args.hasArg(OPT_profile)) {
     warn("ignoring '/incremental' due to '/profile' specification");
     config->incremental = false;
diff --git a/lld/COFF/InputFiles.cpp b/lld/COFF/InputFiles.cpp
index dd2e1419bb10a6..cd744800cb0dec 100644
--- a/lld/COFF/InputFiles.cpp
+++ b/lld/COFF/InputFiles.cpp
@@ -236,8 +236,8 @@ SectionChunk *ObjFile::readSection(uint32_t sectionNumber,
   // CodeView needs linker support. We need to interpret debug info,
   // and then write it to a separate .pdb file.
 
-  // Ignore DWARF debug info unless /debug is given.
-  if (!ctx.config.debug && name.starts_with(".debug_"))
+  // Ignore DWARF debug info unless requested to be included.
+  if (!ctx.config.includeDwarfChunks && name.starts_with(".debug_"))
     return nullptr;
 
   if (sec->Characteristics & llvm::COFF::IMAGE_SCN_LNK_REMOVE)
diff --git a/lld/COFF/Writer.cpp b/lld/COFF/Writer.cpp
index 7b1ff8071e2e3d..ec5d10ed990325 100644
--- a/lld/COFF/Writer.cpp
+++ b/lld/COFF/Writer.cpp
@@ -1376,7 +1376,7 @@ void Writer::createSymbolAndStringTable() {
     sec->setStringTableOff(addEntryToStringTable(sec->name));
   }
 
-  if (ctx.config.debugDwarf || ctx.config.debugSymtab) {
+  if (ctx.config.writeSymtab) {
     for (ObjFile *file : ctx.objFileInstances) {
       for (Symbol *b : file->getSymbols()) {
         auto *d = dyn_cast_or_null<Defined>(b);
diff --git a/lld/test/COFF/debug-dwarf.test b/lld/test/COFF/debug-dwarf.test
index 156b2f58f64e31..c52e7c6067fa78 100644
--- a/lld/test/COFF/debug-dwarf.test
+++ b/lld/test/COFF/debug-dwarf.test
@@ -17,3 +17,16 @@
 # RUN: rm -f %t.pdb
 # RUN: lld-link /debug:dwarf /pdb:%t.pdb /entry:main /out:%t.exe %p/Inputs/ret42.obj
 # RUN: not ls %t.pdb
+
+# Check that /debug /debug:dwarf or /debug:full,dwarf creates %t.pdb.
+# RUN: rm -f %t.pdb
+# RUN: lld-link /debug /debug:dwarf /entry:main /out:%t.exe %p/Inputs/ret42.obj
+# RUN: ls %t.pdb
+# RUN: rm -f %t.pdb
+# RUN: lld-link /debug:full,dwarf /entry:main /out:%t.exe %p/Inputs/ret42.obj
+# RUN: ls %t.pdb
+
+# Check that /debug /debug:full,nodwarf creates %t.pdb.
+# RUN: rm -f %t.pdb
+# RUN: lld-link /debug:full,nodwarf /entry:main /out:%t.exe %p/Inputs/ret42.obj
+# RUN: ls %t.pdb
diff --git a/lld/test/COFF/sort-debug.test b/lld/test/COFF/sort-debug.test
index bbe2ecd0efd8df..30cad394665489 100644
--- a/lld/test/COFF/sort-debug.test
+++ b/lld/test/COFF/sort-debug.test
@@ -7,6 +7,10 @@
 # RUN: llvm-readobj --sections %t.exe | FileCheck -check-prefix=NODEBUG %s
 # RUN: lld-link /debug:symtab /out:%t.exe /entry:main %t.obj
 # RUN: llvm-readobj --sections %t.exe | FileCheck -check-prefix=NODEBUG %s
+# RUN: lld-link /debug:full,nodwarf /out:%t.exe /entry:main %t.obj
+# RUN: llvm-readobj --sections %t.exe | FileCheck -check-prefix=NODEBUG %s
+# RUN: lld-link /debug:full /debug:nodwarf /out:%t.exe /entry:main %t.obj
+# RUN: llvm-readobj --sections %t.exe | FileCheck -check-prefix=NODEBUG %s
 
 # CHECK: Name: .text
 # CHECK: Name: .reloc
diff --git a/lld/test/COFF/symtab.test b/lld/test/COFF/symtab.test
index 48c749957a422a..45e8ed39737a46 100644
--- a/lld/test/COFF/symtab.test
+++ b/lld/test/COFF/symtab.test
@@ -5,9 +5,13 @@
 # RUN: llvm-readobj --symbols %t.exe | FileCheck %s
 # RUN: lld-link /debug:symtab /opt:noref /out:%t.exe /entry:main %t.obj %p/Inputs/std64.lib
 # RUN: llvm-readobj --symbols %t.exe | FileCheck %s
+# RUN: lld-link /debug:full,symtab /opt:noref /out:%t.exe /entry:main %t.obj %p/Inputs/std64.lib
+# RUN: llvm-readobj --symbols %t.exe | FileCheck %s
 
 # RUN: lld-link /debug /out:%t.exe /entry:main %t.obj %p/Inputs/std64.lib
 # RUN: llvm-readobj --symbols %t.exe | FileCheck -check-prefix=NO %s
+# RUN: lld-link /debug:dwarf,nosymtab /out:%t.exe /entry:main %t.obj %p/Inputs/std64.lib
+# RUN: llvm-readobj --symbols %t.exe | FileCheck -check-prefix=NO %s
 
 # CHECK:      Symbols [
 # CHECK-NEXT:   Symbol {

@mstorsjo
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This goes on top of #75178; only the topmost commit should be reviewed in this PR. The overall direction of the larger patchset that this belongs to, was presented/discussed in #74820.

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For a non-list option, I think it is very uncommon for a second occurrence of an option to override partial effects done by the first occurrence. Actually, I cannot think of an example off my head.

ELF linkers have an example of -z defs, -z undefs, --allow-shlib-undefined, --unresolved-symbols where --unresolved-symbols overrides both diagRegular/diagShlib while other options may override one of diagRegular/diagShlib.

That said, if this /debug: is useful, I think it is fine to be a special case...

@mstorsjo
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For a non-list option, I think it is very uncommon for a second occurrence of an option to override partial effects done by the first occurrence. Actually, I cannot think of an example off my head.

ELF linkers have an example of -z defs, -z undefs, --allow-shlib-undefined, --unresolved-symbols where --unresolved-symbols overrides both diagRegular/diagShlib while other options may override one of diagRegular/diagShlib.

That said, if this /debug: is useful, I think it is fine to be a special case...

Yes, it's a bit of an uncommon case. On the other hand, this is mostly internal api, as the main/only user outside of tests, is the lld mingw interface.

I guess we could make the options more orthogonal by not implicitly enable including DWARF, when enabling the regular PDB /debug or /debug:full. But that's potentially a more user visible change. In any case, it's easy to do that after this change as well, if we want to proceed in such a direction.

These allow tweaking what gets implied by /debug and /debug:dwarf.
@mstorsjo mstorsjo merged commit e36535d into llvm:main Dec 15, 2023
3 of 4 checks passed
@mstorsjo mstorsjo deleted the lld-debug-nodwarf-nosymtab branch December 15, 2023 18:10
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4 participants