[PATCH] D103131: support debug info for alias variable

[kamlesh kumar via Phabricator via cfe-commits]

kamleshbhalui added a comment.

$cat test.h
int oldname;

$cat test.c

#include "test.h"
int oldname;
__asm__  (

  "movq oldname, %rsp\n\t"

);

extern int newname __attribute__((alias("oldname")));

debug info from gcc:

test.o: file format elf64-x86-64

.debug_info contents:
0x00000000: Compile Unit: length = 0x00000044, format = DWARF32, version = 0x0005, unit_type = DW_UT_compile, abbr_offset = 0x0000, addr_size = 0x08 (next unit at 0x00000048)

0x0000000c: DW_TAG_compile_unit

  DW_AT_producer    ("GNU C17 12.0.0 20210529 (experimental) -g")
  DW_AT_language    (DW_LANG_C11)
  DW_AT_name        ("test.c")
  DW_AT_comp_dir    ("/folk/kkumar/tcgcc/build/")
  DW_AT_stmt_list   (0x00000000)

0x0000001e:   DW_TAG_variable

  DW_AT_name      ("oldname")
  DW_AT_decl_file ("test.h")
  DW_AT_decl_line (1)
  DW_AT_decl_column       (0x05)
  DW_AT_type      (0x00000034 "int")
  DW_AT_external  (true)
  DW_AT_location  (DW_OP_addr 0x0)

0x00000034:   DW_TAG_base_type

  DW_AT_byte_size (0x04)
  DW_AT_encoding  (DW_ATE_signed)
  DW_AT_name      ("int")

0x0000003b:   DW_TAG_variable

  DW_AT_name      ("newname")
  DW_AT_decl_file ("test.c")
  DW_AT_decl_line (7)
  DW_AT_decl_column       (0x0c)
  DW_AT_type      (0x00000034 "int")
  DW_AT_external  (true)

0x00000047:   NULL

debug info from clang:

test1.o:        file format elf64-x86-64

.debug_info contents:
0x00000000: Compile Unit: length = 0x00000042, format = DWARF32, version = 0x0004, abbr_offset = 0x0000, addr_size = 0x08 (next unit at 0x00000046)

0x0000000b: DW_TAG_compile_unit

  DW_AT_producer    ("clang version 13.0.0 (git at github.com:llvm/llvm-project.git b22ff948a94edc7573d226fe404a77b9a7380398)")
  DW_AT_language    (DW_LANG_C99)
  DW_AT_name        ("test.c")
  DW_AT_stmt_list   (0x00000000)
  DW_AT_comp_dir    ("/folk/kkumar/tcgcc/build")

0x0000001e:   DW_TAG_variable

  DW_AT_name      ("newname")
  DW_AT_type      (0x00000029 "int")
  DW_AT_external  (true)
  DW_AT_decl_file ("test.c")
  DW_AT_decl_line (7)

0x00000029:   DW_TAG_base_type

  DW_AT_name      ("int")
  DW_AT_encoding  (DW_ATE_signed)
  DW_AT_byte_size (0x04)

0x00000030:   DW_TAG_variable

  DW_AT_name      ("oldname")
  DW_AT_type      (0x00000029 "int")
  DW_AT_external  (true)
  DW_AT_decl_file ("test.c")
  DW_AT_decl_line (2)
  DW_AT_location  (DW_OP_addr 0x0)

0x00000045:   NULL

so debug info looks same to me in gcc and clang .


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103131/new/

https://reviews.llvm.org/D103131