Commit 2edb36e7 authored by Nick Clifton's avatar Nick Clifton
Browse files

Add command line option to stop the assembler from padding the end of sections...

Add command line option to stop the assembler from padding the end of sections to their alignment boundary.

	PR gas/20247
	* as.h (do_not_pad_sections_to_alignment): New global variable.
	* as.c (show_usage): Add --no-pad-sections.
	(parse_args): Likewise.
	* write.c (size_seg): Skip padding the end of the section if
	requested from the command line.
	* doc/as.texinfo: Document the new option.
	* NEWS: Mention the new feature.
	* testsuite/gas/elf/section11.s: New test.
	* testsuite/gas/elf/section11.d: New test driver.
	* testsuite/gas/elf/elf.exp: Run the new test.
parent c9301e31
-*- text -*-
* Add --no-pad-sections to stop the assembler from padding the end of output
sections up to their alignment boundary.
* Support for the ARMv8-M architecture has been added to the ARM port. Support
for the ARMv8-M Security and DSP Extensions has also been added to the ARM
......@@ -342,6 +342,8 @@ Options:\n\
fprintf (stream, _("\
-nocpp ignored\n"));
fprintf (stream, _("\
-no-pad-sections do not pad the end of sections to alignment boundaries\n"));
fprintf (stream, _("\
-o OBJFILE name the object-file output OBJFILE (default a.out)\n"));
fprintf (stream, _("\
-R fold data section into text section\n"));
......@@ -479,7 +481,8 @@ parse_args (int * pargc, char *** pargv)
/* When you add options here, check that they do
not collide with OPTION_MD_BASE. See as.h. */
......@@ -542,6 +545,7 @@ parse_args (int * pargc, char *** pargv)
,{"MD", required_argument, NULL, OPTION_DEPFILE}
,{"mri", no_argument, NULL, 'M'}
,{"nocpp", no_argument, NULL, OPTION_NOCPP}
,{"no-pad-sections", no_argument, NULL, OPTION_NO_PAD_SECTIONS}
,{"no-warn", no_argument, NULL, 'W'}
,{"reduce-memory-overheads", no_argument, NULL, OPTION_REDUCE_MEMORY_OVERHEADS}
,{"statistics", no_argument, NULL, OPTION_STATISTICS}
......@@ -637,6 +641,10 @@ parse_args (int * pargc, char *** pargv)
do_not_pad_sections_to_alignment = 1;
flag_print_statistics = 1;
......@@ -76,8 +76,8 @@
150 isn't special; it's just an arbitrary non-ASCII char value. */
#define OPTION_STD_BASE 150
/* The first getopt value for machine-dependent long options.
190 gives the standard options room to grow. */
#define OPTION_MD_BASE 190
290 gives the standard options room to grow. */
#define OPTION_MD_BASE 290
#ifdef DEBUG
#undef NDEBUG
......@@ -377,6 +377,8 @@ COMMON int need_pass_2;
leave lots of padding. */
COMMON int linkrelax;
COMMON int do_not_pad_sections_to_alignment;
/* TRUE if we should produce a listing. */
extern int listing;
......@@ -235,6 +235,7 @@ gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
[@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}]
[@b{--listing-lhs-width2}=@var{NUM}] [@b{--listing-rhs-width}=@var{NUM}]
[@b{--listing-cont-lines}=@var{NUM}] [@b{--keep-locals}]
[@b{-o} @var{objfile}] [@b{-R}]
[@b{--hash-size}=@var{NUM}] [@b{--reduce-memory-overheads}]
......@@ -773,6 +774,11 @@ Set the maximum width of an input source line, as displayed in a listing, to
Set the maximum number of lines printed in a listing for a single line of input
to @var{number} + 1.
@item --no-pad-sections
Stop the assembler for padding the ends of output sections to the alignment
of that section. The default is to pad the sections, but this can waste space
which might be needed on targets which have tight memory constraints.
@item -o @var{objfile}
Name the object-file output from @command{@value{AS}} @var{objfile}.
......@@ -2158,6 +2164,7 @@ assembler.)
* listing:: --listing-XXX to configure listing output
* M:: -M or --mri to assemble in MRI compatibility mode
* MD:: --MD for dependency tracking
* no-pad-sections:: --no-pad-sections to stop section padding
* o:: -o to name the object file
* R:: -R to join data and text sections
* statistics:: --statistics to see statistics about assembly
......@@ -2494,6 +2501,15 @@ The rule is written to the file named in its argument.
This feature is used in the automatic updating of makefiles.
@node no-pad-sections
@section Output Section Padding
@kindex --no-pad-sections
@cindex output section padding
Normally the assembler will pad the end of each output section up to its
alignment boundary. But this can waste space, which can be significant on
memory constrained targets. So the @option{--no-pad-sections} option will
disable this behaviour.
@node o
@section Name the Object File: @option{-o}
......@@ -2680,7 +2696,7 @@ do include file processing with the @code{.include} directive
(@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
to get other ``CPP'' style preprocessing by giving the input file a
@samp{.S} suffix. @xref{Overall Options, ,Options Controlling the Kind of
Output,, Using GNU CC} .
Output, gcc info, Using GNU CC}.
Excess whitespace, comments, and character constants
cannot be used in the portions of the input text that are not
......@@ -205,6 +205,7 @@ if { [is_elf_format] } then {
run_dump_test "section8"
run_dump_test "section9"
run_dump_test "section10"
run_dump_test "section11"
run_dump_test "dwarf2-1"
run_dump_test "dwarf2-2"
run_dump_test "dwarf2-3"
#as: --no-pad-sections
#readelf: -S --wide
#name: Disabling section padding
# The RX port uses non standard section names.
#skip: rx-*-*
\[ .\] .text[ ]+PROGBITS[ ]+0+00 0+[0-9a-f]+ 0+0(1|4|5) 00 AX 0 0 16
\[ .\] .data[ ]+PROGBITS[ ]+0+00 0+[0-9a-f]+ 0+01 00 WA 0 0 16
\[ .\] .bss[ ]+NOBITS[ ]+0+00 0+[0-9a-f]+ 0+01 00 WA 0 0 16
.section .bss
.balign 16
.skip 1
.balign 16
.skip 1
.balign 16
.skip 1
......@@ -579,7 +579,12 @@ size_seg (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
x = bfd_set_section_flags (abfd, sec, flags);
gas_assert (x);
newsize = md_section_align (sec, size);
/* If permitted, allow the backend to pad out the section
to some alignment boundary. */
if (do_not_pad_sections_to_alignment)
newsize = size;
newsize = md_section_align (sec, size);
x = bfd_set_section_size (abfd, sec, newsize);
gas_assert (x);
......@@ -1696,7 +1701,7 @@ set_symtab (void)
/* Finish the subsegments. After every sub-segment, we fake an
".align ...". This conforms to BSD4.2 brane-damage. We then fake
".align ...". This conforms to BSD4.2 brain-damage. We then fake
".fill 0" because that is the kind of frag that requires least
thought. ".align" frags like to have a following frag since that
makes calculating their intended length trivial. */
......@@ -1708,6 +1713,7 @@ set_symtab (void)
code-bearing sections. */
(!(FRCHAIN)->frch_next && subseg_text_p (SEG) \
&& !do_not_pad_sections_to_alignment \
? get_recorded_alignment (SEG) \
: 0)
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