Re: Stop Gas from generating line info or address ranges
* doc/as.texi (.nop): Document optional size arg. * dwarf2dbg.c (dwarf2_gen_line_info_1): Only check SEC_ALLOC when ELF. Warn whenever dwarf line number information is ignored. * frags.c (frag_offset_ignore_align_p): New function. * frags.h (frag_offset_ignore_align_p): Declare. * read.c (s_nop): Extend to support optional size arg. * testsuite/gas/elf/dwarf2-20.d: Expect warnings, and exact range. * testsuite/gas/elf/dwarf2-20.s: Emit 16 bytes worth of nops. * testsuite/gas/m68hc11/indexed12.d: Expect warnings.
This commit is contained in:
Alan Modra
parent
99fabbc973
commit
058430b4a1
9 changed files with 121 additions and 31 deletions
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@ -1,3 +1,15 @@
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2020-11-18 Alan Modra <amodra@gmail.com>
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* doc/as.texi (.nop): Document optional size arg.
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* dwarf2dbg.c (dwarf2_gen_line_info_1): Only check SEC_ALLOC
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when ELF. Warn whenever dwarf line number information is ignored.
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* frags.c (frag_offset_ignore_align_p): New function.
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* frags.h (frag_offset_ignore_align_p): Declare.
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* read.c (s_nop): Extend to support optional size arg.
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* testsuite/gas/elf/dwarf2-20.d: Expect warnings, and exact range.
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* testsuite/gas/elf/dwarf2-20.s: Emit 16 bytes worth of nops.
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* testsuite/gas/m68hc11/indexed12.d: Expect warnings.
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2020-11-18 Jozef Lawrynowicz <jozef.l@mittosystems.com>
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H.J. Lu <hongjiu.lu@intel.com>
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@ -6169,14 +6169,18 @@ counter, and @code{.nolist} decrements it. Assembly listings are
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generated whenever the counter is greater than zero.
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@node Nop
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@section @code{.nop}
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@section @code{.nop [@var{size}]}
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@cindex @code{nop} directive
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@cindex filling memory with no-op instructions
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This directive emits a single no-op instruction. It is provided on all
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architectures, allowing the creation of architecture neutral tests involving
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actual code. The size of the generated instruction is target specific. The
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instruction does affect the generation of DWARF debug line information.
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This directive emits no-op instructions. It is provided on all architectures,
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allowing the creation of architecture neutral tests involving actual code. The
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size of the generated instruction is target specific, but if the optional
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@var{size} argument is given and resolves to an absolute positive value at that
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point in assembly (no forward expressions allowed) then the fewest no-op
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instructions are emitted that equal or exceed a total @var{size} in bytes.
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@code{.nop} does affect the generation of DWARF debug line information.
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Some targets do not support using @code{.nop} with @var{size}.
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@node Nops
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@section @code{.nops @var{size}[, @var{control}]}
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@ -504,16 +504,18 @@ dwarf2_gen_line_info_1 (symbolS *label, struct dwarf2_line_info *loc)
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{
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struct line_subseg *lss;
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struct line_entry *e;
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flagword need_flags = SEC_ALLOC | SEC_LOAD | SEC_CODE;
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flagword need_flags = SEC_LOAD | SEC_CODE;
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/* PR 26850: Do not record LOCs in non-executable, non-allocated,
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or non-loaded sections. */
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/* PR 26850: Do not record LOCs in non-executable or non-loaded
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sections. SEC_ALLOC isn't tested for non-ELF because obj-coff.c
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obj_coff_section is careless in setting SEC_ALLOC. */
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if (IS_ELF)
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need_flags |= SEC_ALLOC;
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if ((now_seg->flags & need_flags) != need_flags)
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{
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if (! SEG_NORMAL (now_seg))
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/* FIXME: Add code to suppress multiple warnings ? */
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as_warn ("dwarf line number information for %s ignored",
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segment_name (now_seg));
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/* FIXME: Add code to suppress multiple warnings ? */
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as_warn ("dwarf line number information for %s ignored",
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segment_name (now_seg));
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return;
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}
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42
gas/frags.c
42
gas/frags.c
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@ -468,6 +468,48 @@ frag_offset_fixed_p (const fragS *frag1, const fragS *frag2, offsetT *offset)
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return FALSE;
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}
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/* Return TRUE if FRAG2 follows FRAG1 with a fixed relationship
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between the two assuming alignment frags do nothing. Set OFFSET to
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the difference in address not already accounted for in the frag
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FR_ADDRESS. */
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bfd_boolean
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frag_offset_ignore_align_p (const fragS *frag1, const fragS *frag2,
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offsetT *offset)
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{
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const fragS *frag;
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offsetT off;
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/* Start with offset initialised to difference between the two frags.
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Prior to assigning frag addresses this will be zero. */
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off = frag1->fr_address - frag2->fr_address;
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if (frag1 == frag2)
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{
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*offset = off;
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return TRUE;
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}
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frag = frag1;
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while (frag->fr_type == rs_fill
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|| frag->fr_type == rs_align
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|| frag->fr_type == rs_align_code
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|| frag->fr_type == rs_align_test)
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{
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if (frag->fr_type == rs_fill)
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off += frag->fr_fix + frag->fr_offset * frag->fr_var;
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frag = frag->fr_next;
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if (frag == NULL)
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break;
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if (frag == frag2)
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{
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*offset = off;
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return TRUE;
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}
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}
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return FALSE;
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}
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/* Return TRUE if we can determine whether FRAG2 OFF2 appears after
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(strict >, not >=) FRAG1 OFF1, assuming it is not before. Set
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*OFFSET so that resolve_expression will resolve an O_gt operation
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@ -154,6 +154,8 @@ char *frag_var (relax_stateT type,
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char *opcode);
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bfd_boolean frag_offset_fixed_p (const fragS *, const fragS *, offsetT *);
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bfd_boolean frag_offset_ignore_align_p (const fragS *, const fragS *,
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offsetT *);
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bfd_boolean frag_gtoffset_p (valueT, const fragS *, valueT, const fragS *,
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offsetT *);
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44
gas/read.c
44
gas/read.c
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@ -3506,6 +3506,11 @@ s_space (int mult)
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void
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s_nop (int ignore ATTRIBUTE_UNUSED)
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{
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expressionS exp;
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fragS *start;
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addressT start_off;
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offsetT frag_off;
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#ifdef md_flush_pending_output
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md_flush_pending_output ();
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#endif
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@ -3515,29 +3520,42 @@ s_nop (int ignore ATTRIBUTE_UNUSED)
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#endif
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SKIP_WHITESPACE ();
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expression (&exp);
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demand_empty_rest_of_line ();
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start = frag_now;
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start_off = frag_now_fix ();
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do
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{
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#ifdef md_emit_single_noop
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md_emit_single_noop;
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md_emit_single_noop;
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#else
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char * nop;
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char *nop;
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#ifndef md_single_noop_insn
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#define md_single_noop_insn "nop"
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#endif
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/* md_assemble might modify its argument, so
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we must pass it a string that is writeable. */
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if (asprintf (&nop, "%s", md_single_noop_insn) < 0)
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as_fatal ("%s", xstrerror (errno));
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/* md_assemble might modify its argument, so
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we must pass it a string that is writable. */
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if (asprintf (&nop, "%s", md_single_noop_insn) < 0)
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as_fatal ("%s", xstrerror (errno));
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/* Some targets assume that they can update input_line_pointer inside
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md_assemble, and, worse, that they can leave it assigned to the string
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pointer that was provided as an argument. So preserve ilp here. */
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char * saved_ilp = input_line_pointer;
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md_assemble (nop);
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input_line_pointer = saved_ilp;
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free (nop);
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/* Some targets assume that they can update input_line_pointer
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inside md_assemble, and, worse, that they can leave it
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assigned to the string pointer that was provided as an
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argument. So preserve ilp here. */
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char *saved_ilp = input_line_pointer;
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md_assemble (nop);
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input_line_pointer = saved_ilp;
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free (nop);
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#endif
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#ifdef md_flush_pending_output
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md_flush_pending_output ();
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#endif
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} while (exp.X_op == O_constant
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&& exp.X_add_number > 0
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&& frag_offset_ignore_align_p (start, frag_now, &frag_off)
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&& frag_off + frag_now_fix () < start_off + exp.X_add_number);
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}
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void
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@ -3,6 +3,12 @@
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#name: DWARF2_20: debug ranges ignore non-code sections
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# The mn10200 target has a pointer size of 3, but it does not use segment selectors. This confuses DWARF and readelf will complain.
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#xfail: mn102*-*
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# score-elf, tic6x-elf and xtensa-elf need special handling to support .nop 16
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#xfail: score-* tic6x-* xtensa-*
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#warning: .* \.alloc0 ignored
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#warning: .* \.alloc1 ignored
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#warning: .* \.nonalloc ignored
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#warning: .* \.nonallocexec ignored
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Contents of the .debug_aranges section:
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@ -13,6 +19,6 @@ Contents of the .debug_aranges section:
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[ ]+Segment Size:[ ]+0
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[ ]+Address[ ]+Length
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[ ]+0+000 0+00.
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[ ]+0+000 0+010
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[ ]+0+000 0+000
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#pass
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@ -1,10 +1,10 @@
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.section .alloc0,"a"
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.nop
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.nop 16
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.section .alloc1,"a"
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.nop
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.nop 16
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.section .nonalloc,""
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.nop
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.nop 16
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.section .allocexec,"ax"
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.nop
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.nop 16
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.section .nonallocexec,"x"
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.nop
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.nop 16
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@ -2,6 +2,10 @@
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#as: -m68hc12 -gdwarf2
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#name: 68HC12 indexed addressing mode with 5, 9 and 16-bit offsets (indexed12)
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#source: indexed12.s
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#warning: .* line number information for \.data ignored
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#warning: .* line number information for \.data ignored
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#warning: .* line number information for \.data ignored
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#warning: .* line number information for \.data ignored
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.*: +file format elf32\-m68hc12
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