[llvm-dwarfdump] Display DW_AT_high_pc as absolute value

[JDevlieghere]

Summary

DWARF4 relative DW_AT_high_pc values are now displayed as their absolute
address. The relative value is only shown when displayed with
-show-form (-F).

DW_AT_low_pc	(0x0000000000000049)
DW_AT_high_pc	(0x00000019)

becomes

DW_AT_low_pc	(0x0000000000000049)
DW_AT_high_pc	(0x0000000000000062)

[probinson]

I'm not seeing a test that -show-form actually affects how DW_AT_high_pc is displayed.

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

13 ↗

(On Diff #123822)

So, the DIE that has the error gets printed with forms, but not in -show-form mode? Is that why high_pc is still displayed as 8 bytes instead of 4?

[JDevlieghere]

• Don't print address with -verbose

[JDevlieghere]

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

13 ↗

(On Diff #123822)

I didn't account for the fact that the form encoding was also printed in -verbose mode. I've updated the diff and test to make this consistent with -show-form mode, so that if the form is printed we get the 4-byte offset rather than the 8-byte address.

[probinson]

Still needs a test demonstrating that -F affects the display of the high_pc value. This is probably the only case where -F does more than display the form.

[JDevlieghere]

• Update form.test to check we don't print the address in verbose and show-form mode.

[dblaikie]

Happy to hear from Adrian and Paul if this doesn't seem like the right direction - but can be handled post-commit too.

Just the change from getHighAndLow to getHigh, I think.

lib/DebugInfo/DWARF/DWARFDie.cpp

241

It seems unfortunate that this searches for the low pc when we already have the form/attribute in formValue.

What happens if a buggy DIE has two LowPCs? This might erroneously print the same one twice? (I assume DWARF supports, in general, multiple instances of the same attribute in a DIE? or is that buggy enough to have been detected earlier?)

[dblaikie]

In D40317#935075, @dblaikie wrote:

Happy to hear from Adrian and Paul if this doesn't seem like the right direction - but can be handled post-commit too.

Just the change from getHighAndLow to getHigh, I think.

My comments here were a bit out of date, wrote them before this had been reviewed/signed off by others.

Also before I thought about it and realized getHigh needs the low first, etc...

[probinson]

lib/DebugInfo/DWARF/DWARFDie.cpp

241

You can't repeat the same attribute in the same DIE, that's invalid DWARF. I don't know whether the verifier checks for that.

lib/DebugInfo/DWARF/DWARFDie.cpp

if (const auto *LT = U->getContext().getLineTableForUnit(U))
       }
   } 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 if (Attr == DW_AT_location || Attr == DW_AT_frame_base ||
+  else if (Attr == DW_AT_high_pc && !DumpOpts.ShowForm && !DumpOpts.Verbose &&
+           formValue.getAsUnsignedConstant()) {
+    // Print the actual address rather than the offset.
+    uint64_t LowPC, HighPC, Index;
+    if (Die.getLowAndHighPC(LowPC, HighPC, Index))
+      OS << format("0x%016" PRIx64, HighPC);
+    else
+      formValue.dump(OS, DumpOpts);
+  } else if (Attr == DW_AT_location || Attr == DW_AT_frame_base ||
              Attr == DW_AT_data_member_location ||
              Attr == DW_AT_GNU_call_site_value)
     dumpLocation(OS, formValue, U, sizeof(BaseIndent) + Indent + 4, DumpOpts);
   else
     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) {

test/tools/dsymutil/X86/basic-lto-dw4-linking-x86.test

 RUN: llvm-dsymutil -f -o - -oso-prepend-path=%p/.. %p/../Inputs/basic-lto-dw4.macho.x86_64 | llvm-dwarfdump -a - | FileCheck %s
 
 CHECK: file format Mach-O 64-bit x86-64
 
 CHECK: debug_info contents
 
 CHECK:  Compile Unit: {{.*}} version = 0x0004
 CHECK:  DW_TAG_compile_unit
 CHECK:    DW_AT_producer ("clang version 3.7.0 ")
 CHECK:    DW_AT_language (DW_LANG_C99)
 CHECK:    DW_AT_name ("basic1.c")
 CHECK:    DW_AT_stmt_list (0x00000000)
 CHECK:    DW_AT_comp_dir ("/Inputs")
 CHECK:    DW_AT_low_pc (0x0000000100000f40)
-CHECK:    DW_AT_high_pc (0x0000000b)
+CHECK:    DW_AT_high_pc (0x0000000100000f4b)
 CHECK:    DW_TAG_subprogram
 CHECK:      DW_AT_low_pc (0x0000000100000f40)
-CHECK:      DW_AT_high_pc (0x0000000b)
+CHECK:      DW_AT_high_pc (0x0000000100000f4b)
 CHECK:      DW_AT_frame_base (DW_OP_reg6 RBP)
 CHECK:      DW_AT_name ("main")
 CHECK:      DW_AT_decl_file ("/Inputs{{[/\\]}}basic1.c")
 CHECK:      DW_AT_prototyped (true)
 CHECK:      DW_AT_type (0x00000000000000a1
 CHECK:      DW_AT_external (true)
 CHECK:      DW_TAG_formal_parameter
 CHECK:        DW_AT_location (DW_OP_reg5 RDI, DW_OP_piece 0x4)

 CHECK:  Compile Unit:{{.*}} version = 0x0004
 
 CHECK:  DW_TAG_compile_unit
 CHECK:    DW_AT_producer ("clang version 3.7.0 ")
 CHECK:    DW_AT_language (DW_LANG_C99)
 CHECK:    DW_AT_name ("basic2.c")
 CHECK:    DW_AT_stmt_list (0x00000044)
 CHECK:    DW_AT_low_pc (0x0000000100000f50)
-CHECK:    DW_AT_high_pc (0x00000037)
+CHECK:    DW_AT_high_pc (0x0000000100000f87)
 CHECK:    DW_TAG_base_type
 CHECK:      DW_AT_name ("int")
 CHECK:    DW_TAG_variable
 CHECK:      DW_AT_name ("baz")
 CHECK:      DW_AT_location (DW_OP_addr 0x100001000)
 CHECK:    DW_TAG_variable
 CHECK:      DW_AT_name ("private_int")
 CHECK:      DW_AT_decl_file ("/Inputs{{[/\\]}}basic2.c")
 CHECK:      DW_AT_location (DW_OP_addr 0x100001008)
 CHECK:    DW_TAG_subprogram
 CHECK:      DW_AT_name ("inc")
 CHECK:      DW_AT_type (cu + 0x002a
 CHECK:      DW_AT_inline (DW_INL_inlined)
 CHECK:    DW_TAG_subprogram
 CHECK:      DW_AT_low_pc (0x0000000100000f50)
-CHECK:      DW_AT_high_pc (0x00000037)
+CHECK:      DW_AT_high_pc (0x0000000100000f87)
 CHECK:      DW_AT_frame_base (DW_OP_reg6 RBP)
 CHECK:      DW_AT_name ("foo")
 CHECK:      DW_AT_decl_file ("/Inputs{{[/\\]}}basic2.c")
 CHECK:      DW_AT_prototyped (true)
 CHECK:      DW_AT_type (cu + 0x002a
 CHECK:      DW_TAG_formal_parameter
 CHECK:        DW_AT_location (0x00000000
 CHECK:          0x0000000000000000 - 0x000000000000000c: DW_OP_reg5 RDI, DW_OP_piece 0x4)
 CHECK:        DW_AT_name ("arg")
 CHECK:        DW_AT_type (cu + 0x002a
 CHECK:      DW_TAG_inlined_subroutine
 CHECK:        DW_AT_abstract_origin (cu + 0x005b "inc")
 CHECK:        DW_AT_low_pc (0x0000000100000f61)
-CHECK:        DW_AT_high_pc (0x0000000f)
+CHECK:        DW_AT_high_pc (0x0000000100000f70)
 CHECK:      NULL
 CHECK:    NULL
 
 CHECK:  Compile Unit: {{.*}} version = 0x0004
 
 CHECK:  DW_TAG_compile_unit
 CHECK:    DW_AT_producer ("clang version 3.7.0 ")
 CHECK:    DW_AT_name ("basic3.c")
 CHECK:    DW_AT_stmt_list (0x0000009a)
 CHECK:    DW_AT_low_pc (0x0000000100000f90)
-CHECK:    DW_AT_high_pc (0x00000024)
+CHECK:    DW_AT_high_pc (0x0000000100000fb4)
 CHECK:    DW_TAG_variable
 CHECK:      DW_AT_name ("val")
 CHECK:      DW_AT_decl_file ("/Inputs{{[/\\]}}basic3.c")
 CHECK:      DW_AT_location (DW_OP_addr 0x100001004)
 CHECK:    DW_TAG_volatile_type
 CHECK:    DW_TAG_subprogram
 CHECK:      DW_AT_name ("inc")
 CHECK:      DW_AT_inline (DW_INL_inlined)
 CHECK:    DW_TAG_subprogram
 CHECK:      DW_AT_low_pc (0x0000000100000f90)
-CHECK:      DW_AT_high_pc (0x00000024)
+CHECK:      DW_AT_high_pc (0x0000000100000fb4)
 CHECK:      DW_AT_frame_base (DW_OP_reg6 RBP)
 CHECK:      DW_AT_name ("bar")
 CHECK:      DW_TAG_formal_parameter
 CHECK:        DW_AT_location (0x00000025
 CHECK:          0x0000000000000000 - 0x000000000000000f: DW_OP_reg5 RDI, DW_OP_piece 0x4
 CHECK:          0x0000000000000019 - 0x000000000000001d: DW_OP_reg5 RDI, DW_OP_piece 0x4)
 CHECK:        DW_AT_name ("arg")
 CHECK:      DW_TAG_inlined_subroutine

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

 # RUN: llvm-mc %s -filetype obj -triple i686-pc-linux -o %t
 # RUN: llvm-dwarfdump %t | FileCheck %s
 
 # CHECK:      DW_TAG_subprogram
 # CHECK-NEXT:   DW_AT_external  (true)
 # CHECK-NEXT:   DW_AT_name      ("fn4")
 # CHECK-NEXT:   DW_AT_linkage_name      ("test")
 # CHECK-NEXT:   DW_AT_low_pc    (0x0000000000000000)
-# CHECK-NEXT:   DW_AT_high_pc   (0x00000000)
+# CHECK-NEXT:   DW_AT_high_pc   (0x0000000000000000)
 # CHECK-NEXT:   DW_AT_frame_base        (DW_OP_call_frame_cfa)
 # CHECK-NEXT:   DW_AT_GNU_all_call_sites        (true)
 
 # CHECK:      DW_TAG_GNU_call_site
 # CHECK-NEXT:   DW_AT_low_pc  (0x0000000000000000)
 # CHECK-NEXT:   DW_AT_abstract_origin (cu + 0x0021 "test")
 
 # CHECK:      DW_TAG_GNU_call_site_parameter

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

 # RUN: FileCheck %s -check-prefixes=CHECK,C
 
 # CHECK: Compile Unit: length = 0x00000060 version = 0x0004 abbr_offset = 0x0000 addr_size = 0x08 (next unit at 0x00000064)
 
 # CHECK: DW_TAG_compile_unit
 # CHECK:   DW_AT_name        ("foo.c")
 # CHECK:   DW_AT_stmt_list   (0x00000000)
 # CHECK:   DW_AT_low_pc      (0x0000000000000000)
-# CHECK:   DW_AT_high_pc     (0x00000016)
+# CHECK:   DW_AT_high_pc     (0x0000000000000016)
 
 # CHECK: DW_TAG_subprogram
 # CHECK:     DW_AT_low_pc    (0x0000000000000000)
-# CHECK:     DW_AT_high_pc   (0x00000016)
+# CHECK:     DW_AT_high_pc   (0x0000000000000016)
 # CHECK:     DW_AT_name      ("foo")
 
 # LEX: DW_TAG_lexical_block
 # LEX:       DW_AT_low_pc  (0x0000000000000004)
-# LEX:       DW_AT_high_pc (0x00000010)
+# LEX:       DW_AT_high_pc (0x0000000000000014)
 
 # A: Line info: file 'foo.c', line 3, column 9, start line 1
 # B: Line info: file 'foo.c', line 4, column 6, start line 1
 # C: Line info: file 'foo.c', line 6, column 1, start line 1
 
   .section  __TEXT,__text,regular,pure_instructions
   .macosx_version_min 10, 13
   .globl  _foo                    ## -- Begin function foo