[clang] Add cc1 option for dumping layout for all complete types

[daltenty]

Summary

This change adds an option which, in addition to dumping the record
layout as is done by -fdump-record-layouts, causes us to compute the
layout for all complete record types (rather than the as-needed basis
which is usually done by clang), so that we will dump them as well.
This is useful if we are looking for layout differences across large
code bases without needing to instantiate every type we are interested in.

[dexonsmith]

clang/lib/AST/Decl.cpp

4585

Nit: please add whitespace around =. (Have you run git-clang-format? That should fix this.)

4586

Probably this deserves a comment, explaining that computing the record layout has a side effect of dumping it.

Nit: I think we usually skip braces for one-line if statements.

4587

Might be reasonable to cast to (void) rather than assigning to an ignored variable.

[daltenty]

• clang-format
• Address comments

[dexonsmith]

LGTM.

[thakis]

This breaks check-clang: http://45.33.8.238/linux/49502/step_7.txt

Please take a look and revert for now if it takes a while to fix. It's been a pretty rough day for the tree.

[thakis]

Probably the "need to bump AST serialization Version after adding a langopt" thing again?

[thakis]

a8bf33ad36837b398d3dabfd5fff1142660a1dca fixed this.

clang/include/clang/Basic/LangOptions.def

 LANGOPT(AlignedAllocationUnavailable, 1, 0, "aligned allocation functions are unavailable")
 LANGOPT(NewAlignOverride  , 32, 0, "maximum alignment guaranteed by '::operator new(size_t)'")
 LANGOPT(ConceptSatisfactionCaching , 1, 1, "enable satisfaction caching for C++20 Concepts")
 BENIGN_LANGOPT(ModulesCodegen , 1, 0, "Modules code generation")
 BENIGN_LANGOPT(ModulesDebugInfo , 1, 0, "Modules debug info")
 BENIGN_LANGOPT(ElideConstructors , 1, 1, "C++ copy constructor elision")
 BENIGN_LANGOPT(DumpRecordLayouts , 1, 0, "dumping the layout of IRgen'd records")
 BENIGN_LANGOPT(DumpRecordLayoutsSimple , 1, 0, "dumping the layout of IRgen'd records in a simple form")
+BENIGN_LANGOPT(DumpRecordLayoutsComplete , 1, 0, "dumping the AST layout of all complete records")
 BENIGN_LANGOPT(DumpVTableLayouts , 1, 0, "dumping the layouts of emitted vtables")
 LANGOPT(NoConstantCFStrings , 1, 0, "no constant CoreFoundation strings")
 BENIGN_LANGOPT(InlineVisibilityHidden , 1, 0, "hidden visibility for inline C++ methods")
 BENIGN_LANGOPT(IgnoreXCOFFVisibility, 1, 0, "All the visibility attributes that are specified in the source code are ignored in aix XCOFF.")
 BENIGN_LANGOPT(VisibilityInlinesHiddenStaticLocalVar, 1, 0,
                "hidden visibility for static local variables in inline C++ "
                "methods when -fvisibility-inlines hidden is enabled")
 LANGOPT(GlobalAllocationFunctionVisibilityHidden , 1, 0, "hidden visibility for global operator new and delete declaration")

clang/include/clang/Driver/Options.td

def print_stats : Flag<["-"], "print-stats">,
   HelpText<"Print performance metrics and statistics">,
   MarshallingInfoFlag<FrontendOpts<"ShowStats">>;
 def stats_file : Joined<["-"], "stats-file=">,
   HelpText<"Filename to write statistics to">,
   MarshallingInfoString<FrontendOpts<"StatsFile">>;
 def fdump_record_layouts_simple : Flag<["-"], "fdump-record-layouts-simple">,
   HelpText<"Dump record layout information in a simple form used for testing">,
   MarshallingInfoFlag<LangOpts<"DumpRecordLayoutsSimple">>;
+def fdump_record_layouts_complete : Flag<["-"], "fdump-record-layouts-complete">,
+  HelpText<"Dump record layout information for all complete types">,
+  MarshallingInfoFlag<LangOpts<"DumpRecordLayoutsComplete">>;
 def fdump_record_layouts : Flag<["-"], "fdump-record-layouts">,
   HelpText<"Dump record layout information">,
   MarshallingInfoFlag<LangOpts<"DumpRecordLayouts">>,
-  ImpliedByAnyOf<[fdump_record_layouts_simple.KeyPath]>;
+  ImpliedByAnyOf<[fdump_record_layouts_simple.KeyPath, fdump_record_layouts_complete.KeyPath]>;
 def fix_what_you_can : Flag<["-"], "fix-what-you-can">,
   HelpText<"Apply fix-it advice even in the presence of unfixable errors">,
   MarshallingInfoFlag<FrontendOpts<"FixWhatYouCan">>;
 def fix_only_warnings : Flag<["-"], "fix-only-warnings">,
   HelpText<"Apply fix-it advice only for warnings, not errors">,
   MarshallingInfoFlag<FrontendOpts<"FixOnlyWarnings">>;
 def fixit_recompile : Flag<["-"], "fixit-recompile">,
   HelpText<"Apply fix-it changes and recompile">,

clang/lib/AST/Decl.cpp

RecordDecl::field_iterator RecordDecl::field_begin() const {
   return field_iterator(decl_iterator(FirstDecl));
 }
 
 /// completeDefinition - Notes that the definition of this type is now
 /// complete.
 void RecordDecl::completeDefinition() {
   assert(!isCompleteDefinition() && "Cannot redefine record!");
   TagDecl::completeDefinition();
+
+  ASTContext &Ctx=getASTContext();
+  if (Ctx.getLangOpts().DumpRecordLayoutsComplete) {
+    const ASTRecordLayout &RL = Ctx.getASTRecordLayout(this);
+  }
 }
 
 /// isMsStruct - Get whether or not this record uses ms_struct layout.
 /// This which can be turned on with an attribute, pragma, or the
 /// -mms-bitfields command-line option.
 bool RecordDecl::isMsStruct(const ASTContext &C) const {
   return hasAttr<MSStructAttr>() || C.getLangOpts().MSBitfields == 1;
 }

clang/test/Layout/dump-complete.cpp

+// RUN: %clang_cc1 -emit-llvm-only -fdump-record-layouts-complete %s | FileCheck %s
+
+struct a {
+  int x;
+};
+
+struct b {
+  char y;
+} foo;
+
+class c {};
+
+class d;
+
+// CHECK:          0 | struct a
+// CHECK:          0 | struct b
+// CHECK:          0 | class c
+// CHECK-NOT:      0 | class d