[llvm-bugs] [Bug 38824] New: debug_info missing parameters for naked functions

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=38824

            Bug ID: 38824
           Summary: debug_info missing parameters for naked functions
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: DebugInfo
          Assignee: unassignedbugs at nondot.org
          Reporter: dimitry at google.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 20837
  --> https://bugs.llvm.org/attachment.cgi?id=20837&action=edit
source file

Source file:

extern "C" void naked_function(int value, char* name);
extern "C" void regular_function(int value, char* name);

void __attribute__((naked, noinline)) naked_function(int value, char* name) {
}

void regular_function(int value, char* name) {
}


Command line:
clang++ -g --shared -fPIC -o libtest.so src.cc

Result:
$ readelf -wi libtest.so 
Contents of the .debug_info section:

  Compilation Unit @ offset 0x0:
   Length:        0x81 (32-bit)
   Version:       4
   Abbrev Offset: 0x0
   Pointer Size:  8
 <0><b>: Abbrev Number: 1 (DW_TAG_compile_unit)
    <c>   DW_AT_producer    : (indirect string, offset: 0x0): clang version
8.0.0 (https://git.llvm.org/git/clang.git/
1bc73590ad1335313e8f262393547b8af67c9167) (https://git.llvm.org/git/llvm.git/
24a8df2c420ee959f27acae6bac2969cdd0a5388)
    <10>   DW_AT_language    : 4        (C++)
    <12>   DW_AT_name        : (indirect string, offset: 0xb1): src.cc
    <16>   DW_AT_stmt_list   : 0x0
    <1a>   DW_AT_comp_dir    : (indirect string, offset: 0xb8):
/ssd/llvm/test/naked_debug_info
    <1e>   DW_AT_low_pc      : 0x610
    <26>   DW_AT_high_pc     : 0x1d
 <1><2a>: Abbrev Number: 2 (DW_TAG_subprogram)
    <2b>   DW_AT_low_pc      : 0x610
    <33>   DW_AT_high_pc     : 0x7
    <37>   DW_AT_frame_base  : 1 byte block: 56         (DW_OP_reg6 (rbp))
    <39>   DW_AT_name        : (indirect string, offset: 0xd8): naked_function
    <3d>   DW_AT_decl_file   : 1
    <3e>   DW_AT_decl_line   : 4
    <3f>   DW_AT_external    : 1
 <1><3f>: Abbrev Number: 3 (DW_TAG_subprogram)
    <40>   DW_AT_low_pc      : 0x620
    <48>   DW_AT_high_pc     : 0xd
    <4c>   DW_AT_frame_base  : 1 byte block: 56         (DW_OP_reg6 (rbp))
    <4e>   DW_AT_name        : (indirect string, offset: 0xe7):
regular_function
    <52>   DW_AT_decl_file   : 1
    <53>   DW_AT_decl_line   : 7
    <54>   DW_AT_external    : 1
 <2><54>: Abbrev Number: 4 (DW_TAG_formal_parameter)
    <55>   DW_AT_location    : 2 byte block: 91 7c      (DW_OP_fbreg: -4)
    <58>   DW_AT_name        : (indirect string, offset: 0xf8): value
    <5c>   DW_AT_decl_file   : 1
    <5d>   DW_AT_decl_line   : 7
    <5e>   DW_AT_type        : <0x71>
 <2><62>: Abbrev Number: 4 (DW_TAG_formal_parameter)
    <63>   DW_AT_location    : 2 byte block: 91 70      (DW_OP_fbreg: -16)
    <66>   DW_AT_name        : (indirect string, offset: 0x102): name
    <6a>   DW_AT_decl_file   : 1
    <6b>   DW_AT_decl_line   : 7
    <6c>   DW_AT_type        : <0x78>
 <2><70>: Abbrev Number: 0
 <1><71>: Abbrev Number: 5 (DW_TAG_base_type)
    <72>   DW_AT_name        : (indirect string, offset: 0xfe): int
    <76>   DW_AT_encoding    : 5        (signed)
    <77>   DW_AT_byte_size   : 4
 <1><78>: Abbrev Number: 6 (DW_TAG_pointer_type)
    <79>   DW_AT_type        : <0x7d>
 <1><7d>: Abbrev Number: 5 (DW_TAG_base_type)
    <7e>   DW_AT_name        : (indirect string, offset: 0x107): char
    <82>   DW_AT_encoding    : 6        (signed char)
    <83>   DW_AT_byte_size   : 1
 <1><84>: Abbrev Number: 0



Note that while parameters for not naked function are preserved naked function
parameters are lost.

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