A more robust way of testing debug_line parser near the end of module

[labath]

Summary

While removing -z separate-code makes lld produce place the code at the
end of a segment right now, it's possible that future changes to the
linker will change that, thereby removing the coverage for the changes
in r367983. This patch adds a linker script to one of the line table
tests, which ensures that the code (and its line table) will be placed
at the very end of a module.

[MaskRay]

lit/SymbolFile/DWARF/Inputs/debug-line-basic.script

6 ↗

(On Diff #213531)

0 (output section address, addrExpr in lld) can be deleted. For non-SHF_ALLOC sections (.shstrtab .debug_info etc), the address expression is just ignored.

// lld/ELF/LinkerScript.cpp#L772

if ((sec->flags & SHF_ALLOC) && sec->addrExpr)
  setDot(sec->addrExpr, sec->location, false);

(I guess it was retrieved from ld --verbose)

[labath]

• remove output section addresses

lldb/trunk/lit/SymbolFile/DWARF/Inputs/debug-line-basic.script

+PHDRS {
+  text PT_LOAD;
+}
+SECTIONS {
+  .shstrtab     : { *(.shstrtab    ) }
+  .debug_info   : { *(.debug_info  ) }
+  .debug_line   : { *(.debug_line  ) }
+  .debug_str    : { *(.debug_str   ) }
+  .debug_abbrev : { *(.debug_abbrev) }
+
+  . = 0x201000;
+  .text : { *(.text .text.f) } :text
+  /DISCARD/ : { *(*) }
+}

lldb/trunk/lit/SymbolFile/DWARF/debug-line-basic.s

+# Test basics of debug_line parsing. This test uses a linker script which
+# ensures the code is placed at the end of a module to test the boundary
+# condition when the final end-of-sequence line table entry points to an address
+# that is outside the range of memory covered by the module.
+
 # REQUIRES: lld, x86
 
 # RUN: llvm-mc -triple x86_64-pc-linux %s -filetype=obj > %t.o
-# RUN: ld.lld %t.o -o %t
+# RUN: ld.lld --script=%S/Inputs/debug-line-basic.script %t.o -o %t
 # RUN: %lldb %t -o "image dump line-table -v a.c" -o exit | FileCheck %s
 
-
   .text
   .globl  _start
 _start:
 # CHECK: Line table for /tmp/a.c
   .file 1 "/tmp/b.c"
   .loc  1 0 0
         nop
 # CHECK-NEXT: 0x0000000000201000: /tmp/b.c, is_start_of_statement = TRUE{{$}}

 # CHECK-NEXT: 0x0000000000201005: /tmp/b.c:2, is_prologue_end = TRUE{{$}}
         .loc   1 2 0 is_stmt 0 epilogue_begin
         nop
 # CHECK-NEXT: 0x0000000000201006: /tmp/b.c:2, is_epilogue_begin = TRUE{{$}}
   .file  2 "/tmp/c.c"
   .loc   2 1 0 is_stmt 0
         nop
 # CHECK-NEXT: 0x0000000000201007: /tmp/c.c:1{{$}}
-
 # CHECK-NEXT: 0x0000000000201008: /tmp/c.c:1, is_terminal_entry = TRUE{{$}}
 
+  .section  .text.f,"ax",@progbits
+f:
+        .loc   1 3 0 is_stmt 0
+        nop
+# CHECK-NEXT: 0x0000000000201008: /tmp/b.c:3{{$}}
+# CHECK-NEXT: 0x0000000000201009: /tmp/b.c:3, is_terminal_entry = TRUE{{$}}
+
+
   .section  .debug_str,"MS",@progbits,1
 .Linfo_string1:
   .asciz  "a.c"
 .Linfo_string2:
   .asciz  "/tmp"
   .section  .debug_abbrev,"",@progbits
   .byte 1                       # Abbreviation Code
   .byte 17                      # DW_TAG_compile_unit