clang-cl 18 generates DWARF debug info section with -Z7 when compiling a .s file.

[glandium]

STR:

• Create foo.s with the following content:

.global foo
.section .rodata
.balign 16
foo:

• Compile with clang-cl -o foo.obj -Z7 -c foo.s.
• llvm-readobj --sections foo.obj will show a .debug_line section:

  Section {
    Number: 5
    Name: .debug_line (2F 34 00 00 00 00 00 00)
    VirtualSize: 0x0
    VirtualAddress: 0x0
    RawDataSize: 39
    PointerToRawData: 0xDC
    PointerToRelocations: 0x0
    PointerToLineNumbers: 0x0
    RelocationCount: 0
    LineNumberCount: 0
    Characteristics [ (0x42100040)
      IMAGE_SCN_ALIGN_1BYTES (0x100000)
      IMAGE_SCN_CNT_INITIALIZED_DATA (0x40)
      IMAGE_SCN_MEM_DISCARDABLE (0x2000000)
      IMAGE_SCN_MEM_READ (0x40000000)
    ]
  }

Such a section wasn't created with clang-cl 17.

This is a regression from f58330c.

It is worth noting that the compilation command line emitted the following warning before that change:

clang-cl: warning: argument unused during compilation: '-Z7' [-Wunused-command-line-argument]

which doesn't happen anymore. However, when renaming foo.s to foo.S, the warning is not shown anymore (and the behavior is the same as with foo.s: no .debug_line section before, and one now)

Cc: @bogner

[llvmbot]

@llvm/issue-subscribers-debuginfo

Author: Mike Hommey (glandium)

STR: - Create `foo.s` with the following content: ``` .global foo .section .rodata .balign 16 foo: ``` - Compile with `clang-cl -o foo.obj -Z7 -c foo.s`. - `llvm-readobj --sections foo.obj` will show a `.debug_line` section: ``` Section { Number: 5 Name: .debug_line (2F 34 00 00 00 00 00 00) VirtualSize: 0x0 VirtualAddress: 0x0 RawDataSize: 39 PointerToRawData: 0xDC PointerToRelocations: 0x0 PointerToLineNumbers: 0x0 RelocationCount: 0 LineNumberCount: 0 Characteristics [ (0x42100040) IMAGE_SCN_ALIGN_1BYTES (0x100000) IMAGE_SCN_CNT_INITIALIZED_DATA (0x40) IMAGE_SCN_MEM_DISCARDABLE (0x2000000) IMAGE_SCN_MEM_READ (0x40000000) ] } ```

Such a section wasn't created with clang-cl 17.

This is a regression from f58330c.

It is worth noting that the compilation command line emitted the following warning before that change:

clang-cl: warning: argument unused during compilation: '-Z7' [-Wunused-command-line-argument]

which doesn't happen anymore. However, when renaming foo.s to foo.S, the warning is not shown anymore (and the behavior is the same as with foo.s: no .debug_line section before, and one now)

Cc: @bogner