[llvm-dwarfdump] Hide .debug_str and die reference offsets in brief mode

[JDevlieghere]

Summary

• Hide .debug_str offset
• Hide offset into the CU of a die reference

Before:

0x0000002a:   DW_TAG_subprogram
                DW_AT_low_pc    (0x0000000100000fb0)
                DW_AT_high_pc   (0x00000008)
                DW_AT_frame_base        (<0x1> 56 )
                DW_AT_name      ( .debug_str[0x00000056] = "main")
                DW_AT_decl_file ("/Users/jonas/llvm/brief/a.c")
                DW_AT_decl_line (1)
                DW_AT_type      (cu + 0x0043 => {0x00000043})
                DW_AT_external  (true)

After:

0x0000002a:   DW_TAG_subprogram
                DW_AT_low_pc    (0x0000000100000fb0)
                DW_AT_high_pc   (0x00000008)
                DW_AT_frame_base        (<0x1> 56 )
                DW_AT_name      ( .debug_str = "main")
                DW_AT_decl_file ("/Users/jonas/llvm/brief/a.c")
                DW_AT_decl_line (1)
                DW_AT_type      (cu + 0x0043)
                DW_AT_external  (true)

[aprantl]

llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp

487 ↗

(On Diff #111524)

I think we might even want to drop the .debug_str = part. What does Darwin's dwarfdump do in comparison?

[aprantl]

Also, could you please add a testcase? You can probably reuse the input from one of the existing testcases.

[JDevlieghere]

• Hide .debug_str = part as well
• Update test case

I had to generate new assembly because the current test didn't have a DIE reference. I hope this is alright?

[dblaikie]

llvm/trunk/test/tools/llvm-dwarfdump/X86/brief.s

7–10 ↗

(On Diff #111748)

It's probably worth having a positive test for what the string printing looks like in brief mode? I know it was mentioned in the patch description, but it was revised before committing & I was curious to see how it actually prints out now.

FWIW, I'd think we might want to drive towards printing something as simple as:

compile_unit
  name: "foo"

(ie: dropping as much of the ()[]{} sort of stuff as possible, and dropping the DW_*_ prefixes too - since they're unambiguous as to what's a DW_TAG, DW_AT, DW_OP, etc, based on context)

[dblaikie]

ping

[JDevlieghere]

Hi Dave,

The positive tests have been committed as part of D37334 because I had to change the test anyway. Let me know if you think something is still missing!

With regards to dropping the prefixes, I talked to Adrian and he makes a pretty good argument in favor of keeping them. Maybe this is something to discuss on the mailing list as an NFC? I've had a look and implementing this should be relatively straightforward so it really boils down to whether we want to do this or not.

include/llvm/DebugInfo/DWARF/DWARFFormValue.h

 //===- DWARFFormValue.h -----------------------------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_DEBUGINFO_DWARFFORMVALUE_H
 #define LLVM_DEBUGINFO_DWARFFORMVALUE_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/DebugInfo/DIContext.h"
 #include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
 #include <cstdint>
 
 namespace llvm {
 
 class DWARFUnit;
 class raw_ostream;
 
public:
 
   void setBlockValue(const ArrayRef<uint8_t> &Data) {
     Value.data = Data.data();
     setUValue(Data.size());
   }
 
   bool isFormClass(FormClass FC) const;
   const DWARFUnit *getUnit() const { return U; }
-  void dump(raw_ostream &OS) const;
+  void dump(raw_ostream &OS, DIDumpOptions DumpOpts = DIDumpOptions()) const;
 
   /// Extracts a value in \p Data at offset \p *OffsetPtr.
   ///
   /// The passed DWARFUnit is allowed to be nullptr, in which case some
   /// kind of forms that depend on Unit information are disallowed.
   /// \param Data The DWARFDataExtractor to use.
   /// \param OffsetPtr The offset within \p Data where the data starts.
   /// \param U The optional DWARFUnit supplying information for some forms.

lib/DebugInfo/DWARF/DWARFDie.cpp

if (!DumpOpts.Brief) {
     if (!formString.empty())
       OS << " [" << formString << ']';
     else
       OS << format(" [DW_FORM_Unknown_%x]", Form);
   }
 
   DWARFUnit *U = Die.getDwarfUnit();
   DWARFFormValue formValue(Form);
-  
   if (!formValue.extractValue(U->getDebugInfoExtractor(), OffsetPtr, U))
     return;
-  
   OS << "\t(";
-  
   StringRef Name;
   std::string File;
   auto Color = syntax::Enumerator;
   if (Attr == DW_AT_decl_file || Attr == DW_AT_call_file) {
     Color = syntax::String;
     if (const auto *LT = U->getContext().getLineTableForUnit(U))
       if (LT->getFileNameByIndex(formValue.getAsUnsignedConstant().getValue(), U->getCompilationDir(), DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, File)) {
         File = '"' + File + '"';
         Name = File;
       }
   } else if (Optional<uint64_t> Val = formValue.getAsUnsignedConstant())
     Name = AttributeValueString(Attr, *Val);
-  
   if (!Name.empty())
     WithColor(OS, Color) << Name;
   else if (Attr == DW_AT_decl_line || Attr == DW_AT_call_line)
     OS << *formValue.getAsUnsignedConstant();
   else
-    formValue.dump(OS);
-  
+    formValue.dump(OS, DumpOpts);
   // We have dumped the attribute raw value. For some attributes
   // having both the raw value and the pretty-printed value is
   // interesting. These attributes are handled below.
   if (Attr == DW_AT_specification || Attr == DW_AT_abstract_origin) {
     if (const char *Name = Die.getAttributeValueAsReferencedDie(Attr).getName(DINameKind::LinkageName))
         OS << " \"" << Name << '\"';
   } else if (Attr == DW_AT_APPLE_property_attribute) {
     if (Optional<uint64_t> OptVal = formValue.getAsUnsignedConstant())

 
 void DWARFDie::dump(raw_ostream &OS, unsigned RecurseDepth, unsigned Indent,
                     DIDumpOptions DumpOpts) const {
   if (!isValid())
     return;
   DWARFDataExtractor debug_info_data = U->getDebugInfoExtractor();
   const uint32_t Offset = getOffset();
   uint32_t offset = Offset;
-  
   if (debug_info_data.isValidOffset(offset)) {
     uint32_t abbrCode = debug_info_data.getULEB128(&offset);
     WithColor(OS, syntax::Address).get() << format("\n0x%8.8x: ", Offset);
-    
     if (abbrCode) {
       auto AbbrevDecl = getAbbreviationDeclarationPtr();
       if (AbbrevDecl) {
         auto tagString = TagString(getTag());
         if (!tagString.empty())
           WithColor(OS, syntax::Tag).get().indent(Indent) << tagString;
         else
           WithColor(OS, syntax::Tag).get().indent(Indent)
if (abbrCode) {
             // We are dumping .debug_info section ,
             // implicit_const attribute values are not really stored here,
             // but in .debug_abbrev section. So we just skip such attrs.
             continue;
           }
           dumpAttribute(OS, *this, &offset, AttrSpec.Attr, AttrSpec.Form,
                         Indent, DumpOpts);
         }
-        
         DWARFDie child = getFirstChild();
         if (RecurseDepth > 0 && child) {
           while (child) {
             child.dump(OS, RecurseDepth-1, Indent+2, DumpOpts);
             child = child.getSibling();
           }
         }
       } else {

lib/DebugInfo/DWARF/DWARFFormValue.cpp

if (!Str.empty()) {
       Value.data = reinterpret_cast<const uint8_t *>(Str.data());
       *OffsetPtr += Value.uval;
     }
   }
 
   return true;
 }
 
-void DWARFFormValue::dump(raw_ostream &OS) const {
+void DWARFFormValue::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {
   uint64_t UValue = Value.uval;
   bool CURelativeOffset = false;
 
   switch (Form) {
   case DW_FORM_addr:
     OS << format("0x%016" PRIx64, UValue);
     break;
   case DW_FORM_GNU_addr_index: {
void DWARFFormValue::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {
 
   case DW_FORM_sdata:
     OS << Value.sval;
     break;
   case DW_FORM_udata:
     OS << Value.uval;
     break;
   case DW_FORM_strp:
+    if (!DumpOpts.Brief)
       OS << format(" .debug_str[0x%8.8x] = ", (uint32_t)UValue);
     dumpString(OS);
     break;
   case DW_FORM_strx:
   case DW_FORM_strx1:
   case DW_FORM_strx2:
   case DW_FORM_strx3:
   case DW_FORM_strx4:
   case DW_FORM_GNU_str_index:
case DW_FORM_sec_offset:
     OS << format("0x%08x", (uint32_t)UValue);
     break;
 
   default:
     OS << format("DW_FORM(0x%4.4x)", Form);
     break;
   }
 
-  if (CURelativeOffset) {
+  if (CURelativeOffset && !DumpOpts.Brief) {
     OS << " => {";
     WithColor(OS, syntax::Address).get()
         << format("0x%8.8" PRIx64, UValue + (U ? U->getOffset() : 0));
     OS << "}";
   }
 }
 
 void DWARFFormValue::dumpString(raw_ostream &OS) const {

test/tools/llvm-dwarfdump/X86/brief.s

 # RUN: llvm-mc %s -filetype obj -triple x86_64-apple-darwin -o - \
 # RUN: | llvm-dwarfdump -debug-dump=info -brief - \
 # RUN: | FileCheck %s
 
 # CHECK: DW_TAG_compile_unit
 # CHECK-NOT: DW_FORM
 # CHECK: DW_AT
+# CHECK-NOT: debug_str
+# CHECK-NOT: DW_AT_type {{.*}} =>
 
-# This test is meant to verify that --brief hides DW_FORMs
-# and abbreviation codes from .debug_info section.
-
+# This test is meant to verify that -brief hides DW_FORMs and abbreviation
+# codes from .debug_info section. Furthermore it verifies that it also hides
+# .debug_str and die reference offsets into the CU.
 
   .section  __TEXT,__text,regular,pure_instructions
+  .macosx_version_min 10, 12
+  .globl  _main                   ## -- Begin function main
+  .p2align  4, 0x90
+_main:                                  ## @main
+Lfunc_begin0:
+  .file 1 "brief.c"
+  .loc  1 1 0                   ## brief.c:1:0
+  .cfi_startproc
+## BB#0:                                ## %entry
+  pushq %rbp
+Lcfi0:
+  .cfi_def_cfa_offset 16
+Lcfi1:
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+Lcfi2:
+  .cfi_def_cfa_register %rbp
+  xorl  %eax, %eax
+Ltmp0:
+  .loc  1 1 12 prologue_end     ## brief.c:1:12
+  popq  %rbp
+  retq
+Ltmp1:
+Lfunc_end0:
+  .cfi_endproc
+                                        ## -- End function
   .section  __DWARF,__debug_str,regular,debug
 Linfo_string:
-  .asciz  "basic.c"               ## string offset=42
-  .section  __DWARF,__debug_loc,regular,debug
-Lsection_debug_loc:
+  .asciz  "clang version 6.0.0 (trunk 311115) (llvm/trunk 311188)" ## string offset=0
+  .asciz  "brief.c"               ## string offset=55
+  .asciz  "/private/tmp"          ## string offset=63
+  .asciz  "main"                  ## string offset=76
+  .asciz  "int"                   ## string offset=81
   .section  __DWARF,__debug_abbrev,regular,debug
 Lsection_abbrev:
   .byte 1                       ## Abbreviation Code
   .byte 17                      ## DW_TAG_compile_unit
-  .byte 0                       ## DW_CHILDREN_no
+  .byte 1                       ## DW_CHILDREN_yes
   .byte 37                      ## DW_AT_producer
   .byte 14                      ## DW_FORM_strp
   .byte 19                      ## DW_AT_language
   .byte 5                       ## DW_FORM_data2
   .byte 3                       ## DW_AT_name
   .byte 14                      ## DW_FORM_strp
   .byte 16                      ## DW_AT_stmt_list
   .byte 23                      ## DW_FORM_sec_offset
   .byte 27                      ## DW_AT_comp_dir
   .byte 14                      ## DW_FORM_strp
+  .byte 17                      ## DW_AT_low_pc
+  .byte 1                       ## DW_FORM_addr
+  .byte 18                      ## DW_AT_high_pc
+  .byte 6                       ## DW_FORM_data4
+  .byte 0                       ## EOM(1)
+  .byte 0                       ## EOM(2)
+  .byte 2                       ## Abbreviation Code
+  .byte 46                      ## DW_TAG_subprogram
+  .byte 0                       ## DW_CHILDREN_no
+  .byte 17                      ## DW_AT_low_pc
+  .byte 1                       ## DW_FORM_addr
+  .byte 18                      ## DW_AT_high_pc
+  .byte 6                       ## DW_FORM_data4
+  .byte 64                      ## DW_AT_frame_base
+  .byte 24                      ## DW_FORM_exprloc
+  .byte 3                       ## DW_AT_name
+  .byte 14                      ## DW_FORM_strp
+  .byte 58                      ## DW_AT_decl_file
+  .byte 11                      ## DW_FORM_data1
+  .byte 59                      ## DW_AT_decl_line
+  .byte 11                      ## DW_FORM_data1
+  .byte 73                      ## DW_AT_type
+  .byte 19                      ## DW_FORM_ref4
+  .byte 63                      ## DW_AT_external
+  .byte 25                      ## DW_FORM_flag_present
+  .byte 0                       ## EOM(1)
+  .byte 0                       ## EOM(2)
+  .byte 3                       ## Abbreviation Code
+  .byte 36                      ## DW_TAG_base_type
+  .byte 0                       ## DW_CHILDREN_no
+  .byte 3                       ## DW_AT_name
+  .byte 14                      ## DW_FORM_strp
+  .byte 62                      ## DW_AT_encoding
+  .byte 11                      ## DW_FORM_data1
+  .byte 11                      ## DW_AT_byte_size
+  .byte 11                      ## DW_FORM_data1
   .byte 0                       ## EOM(1)
   .byte 0                       ## EOM(2)
   .byte 0                       ## EOM(3)
   .section  __DWARF,__debug_info,regular,debug
 Lsection_info:
 Lcu_begin0:
-  .long 26                      ## Length of Unit
+  .long 71                      ## Length of Unit
   .short  4                       ## DWARF version number
 Lset0 = Lsection_abbrev-Lsection_abbrev ## Offset Into Abbrev. Section
   .long Lset0
   .byte 8                       ## Address Size (in bytes)
-  .byte 1                       ## Abbrev [1] 0xb:0x13 DW_TAG_compile_unit
+  .byte 1                       ## Abbrev [1] 0xb:0x40 DW_TAG_compile_unit
   .long 0                       ## DW_AT_producer
   .short  12                      ## DW_AT_language
-  .long 42                      ## DW_AT_name
+  .long 55                      ## DW_AT_name
 Lset1 = Lline_table_start0-Lsection_line ## DW_AT_stmt_list
   .long Lset1
-  .long 50                      ## DW_AT_comp_dir
+  .long 63                      ## DW_AT_comp_dir
+  .quad Lfunc_begin0            ## DW_AT_low_pc
+Lset2 = Lfunc_end0-Lfunc_begin0         ## DW_AT_high_pc
+  .long Lset2
+  .byte 2                       ## Abbrev [2] 0x2a:0x19 DW_TAG_subprogram
+  .quad Lfunc_begin0            ## DW_AT_low_pc
+Lset3 = Lfunc_end0-Lfunc_begin0         ## DW_AT_high_pc
+  .long Lset3
+  .byte 1                       ## DW_AT_frame_base
+  .byte 86
+  .long 76                      ## DW_AT_name
+  .byte 1                       ## DW_AT_decl_file
+  .byte 1                       ## DW_AT_decl_line
+  .long 67                      ## DW_AT_type
+                                        ## DW_AT_external
+  .byte 3                       ## Abbrev [3] 0x43:0x7 DW_TAG_base_type
+  .long 81                      ## DW_AT_name
+  .byte 5                       ## DW_AT_encoding
+  .byte 4                       ## DW_AT_byte_size
+  .byte 0                       ## End Of Children Mark
   .section  __DWARF,__debug_ranges,regular,debug
 Ldebug_range:
   .section  __DWARF,__debug_macinfo,regular,debug
 Ldebug_macinfo:
 Lcu_macro_begin0:
   .byte 0                       ## End Of Macro List Mark
   .section  __DWARF,__apple_names,regular,debug
 Lnames_begin:
   .long 1212240712              ## Header Magic
   .short  1                       ## Header Version
   .short  0                       ## Header Hash Function
   .long 1                       ## Header Bucket Count
-  .long 0                       ## Header Hash Count
+  .long 1                       ## Header Hash Count
   .long 12                      ## Header Data Length
   .long 0                       ## HeaderData Die Offset Base
   .long 1                       ## HeaderData Atom Count
   .short  1                       ## DW_ATOM_die_offset
   .short  6                       ## DW_FORM_data4
-  .long -1                      ## Bucket 0
+  .long 0                       ## Bucket 0
+  .long 2090499946              ## Hash in Bucket 0
+  .long LNames0-Lnames_begin    ## Offset in Bucket 0
+LNames0:
+  .long 76                      ## main
+  .long 1                       ## Num DIEs
+  .long 42
+  .long 0
   .section  __DWARF,__apple_objc,regular,debug
 Lobjc_begin:
   .long 1212240712              ## Header Magic
   .short  1                       ## Header Version
   .short  0                       ## Header Hash Function
   .long 1                       ## Header Bucket Count
   .long 0                       ## Header Hash Count
   .long 12                      ## Header Data Length
Lnamespac_begin:
   .short  6                       ## DW_FORM_data4
   .long -1                      ## Bucket 0
   .section  __DWARF,__apple_types,regular,debug
 Ltypes_begin:
   .long 1212240712              ## Header Magic
   .short  1                       ## Header Version
   .short  0                       ## Header Hash Function
   .long 1                       ## Header Bucket Count
-  .long 0                       ## Header Hash Count
+  .long 1                       ## Header Hash Count
   .long 20                      ## Header Data Length
   .long 0                       ## HeaderData Die Offset Base
   .long 3                       ## HeaderData Atom Count
   .short  1                       ## DW_ATOM_die_offset
   .short  6                       ## DW_FORM_data4
   .short  3                       ## DW_ATOM_die_tag
   .short  5                       ## DW_FORM_data2
   .short  4                       ## DW_ATOM_type_flags
   .short  11                      ## DW_FORM_data1
-  .long -1                      ## Bucket 0
-  .section  __DWARF,__apple_exttypes,regular,debug
-Lexttypes_begin:
-  .long  1212240712              ## Header Magic
-  .short  1                       ## Header Version
-  .short  0                       ## Header Hash Function
-  .long 1                       ## Header Bucket Count
-  .long  0                       ## Header Hash Count
-  .long  12                      ## Header Data Length
-  .long 0                       ## HeaderData Die Offset Base
-  .long 1                       ## HeaderData Atom Count
-  .short  7                       ## DW_ATOM_ext_types
-  .short  6                       ## DW_FORM_data4
-  .long -1                      ## Bucket 0
+  .long 0                       ## Bucket 0
+  .long  193495088               ## Hash in Bucket 0
+  .long  Ltypes0-Ltypes_begin    ## Offset in Bucket 0
+Ltypes0:
+  .long 81                      ## int
+  .long 1                       ## Num DIEs
+  .long 67
+  .short  36
+  .byte 0
+  .long 0
 
 .subsections_via_symbols
   .section  __DWARF,__debug_line,regular,debug
 Lsection_line:
 Lline_table_start0: