[clang] Add -fdump-record-layouts-canonical option

[daltenty]

Summary

This option implies -fdump-record-layouts but dumps record layout information with canonical field types, which can be more useful in certain cases when comparing structure layouts.

[stevewan]

I'm not familiar with getCanonicalType(), can you confirm whether it sees through nested typedef's?

[daltenty]

• Update test case with nested typedef

[daltenty]

In D105112#2850990, @stevewan wrote:

I'm not familiar with getCanonicalType(), can you confirm whether it sees through nested typedef's?

Added a test case that hopefully will cover the case you intend

[stevewan]

LGTM. Thanks.

[thakis]

Hi, you have to bump clang/include/clang/Serialization/ASTBitCodes.h's VERSION_MAJOR after adding a LangOption, else builds with LLVM_APPEND_VC_REV=NO won't invalidate their module cache correctly. See e.g. https://reviews.llvm.org/rGb8b7a9dcdcbc Without that, tests are broken on bots with LLVM_APPEND_VC_REV=NO , eg http://45.33.8.238/linux/50460/step_7.txt

[stevewan]

In D105112#2858702, @thakis wrote:

Hi, you have to bump clang/include/clang/Serialization/ASTBitCodes.h's VERSION_MAJOR after adding a LangOption, else builds with LLVM_APPEND_VC_REV=NO won't invalidate their module cache correctly. See e.g. https://reviews.llvm.org/rGb8b7a9dcdcbc Without that, tests are broken on bots with LLVM_APPEND_VC_REV=NO , eg http://45.33.8.238/linux/50460/step_7.txt

Posted fix rGe2904c8e0fa901adeefe579297cb2ece2757fb18. Sorry for the churn.

[thakis]

Thanks for the fix :)

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(DumpRecordLayoutsCanonical , 1, 0, "dumping the AST layout of records using canonical field types")
 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")

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_canonical : Flag<["-"], "fdump-record-layouts-canonical">,
+  HelpText<"Dump record layout information with canonical field types">,
+  MarshallingInfoFlag<LangOpts<"DumpRecordLayoutsCanonical">>;
 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, fdump_record_layouts_complete.KeyPath]>;
+  ImpliedByAnyOf<[fdump_record_layouts_simple.KeyPath, fdump_record_layouts_complete.KeyPath, fdump_record_layouts_canonical.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/RecordLayoutBuilder.cpp

for (RecordDecl::field_iterator I = RD->field_begin(),
     if (Field.isBitField()) {
       uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
       unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
       unsigned Width = Field.getBitWidthValue(C);
       PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
     } else {
       PrintOffset(OS, FieldOffset, IndentLevel);
     }
-    OS << Field.getType().getAsString() << ' ' << Field << '\n';
+    const QualType &FieldType = C.getLangOpts().DumpRecordLayoutsCanonical
+                                    ? Field.getType().getCanonicalType()
+                                    : Field.getType();
+    OS << FieldType.getAsString() << ' ' << Field << '\n';
   }
 
   // Dump virtual bases.
   if (CXXRD && IncludeVirtualBases) {
     const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
       Layout.getVBaseOffsetsMap();
 
     for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {

clang/test/Layout/dump-canonical.cpp

+// RUN: %clang_cc1 -emit-llvm-only -fdump-record-layouts %s | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm-only -fdump-record-layouts-canonical %s | FileCheck %s -check-prefix CANONICAL
+
+typedef long foo_t;
+
+
+struct a {
+  foo_t x;
+} b;
+
+struct c {
+  typedef foo_t bar_t;
+  bar_t x;
+} d;
+
+// CHECK:          0 | foo_t
+// CHECK:          0 | c::bar_t
+// CANONICAL-NOT:  0 | foo_t
+// CANONICAL-NOT:  0 | c::bar_t
+// CANONICAL:      0 | long