[PATCH/PE-COFF] Encode required alignment into IMAGE_SCN_ALIGN bits of object s_flags - Take 3

[Danny Smith]

This is a revised version of the patch I submitted earlier.
http://sourceware.org/ml/binutils/2007-10/msg00294.html

The prior patch failed to check if the alignment power fell within valid
range for PE-COFF target,

To recap the earlier message:

Given an alignment >16-bytes, eg

	.file	"foo.c"
	.data
.globl _x
	.align 32
_x:
	.long	1065353216
	.space 28

gas for PE-COFF targets fails to set section alignment flags correctly,
but always uses default.  So

 as foo.s | objdump -x  gives

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         00000000  00000000  00000000  00000000  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  1 .data         00000020  00000000  00000000  0000008c  2**4
                  ALLOC, LOAD, DATA
  2 .bss          00000000  00000000  00000000  00000000  2**4
                  ALLOC

See also the thread
Re: Fwd: ALIGNOF fails on cygwin at:
http://sourceware.org/ml/binutils/2007-07/msg00014.html

The attached fixs by encoding the section alignment_power into the
appropriate bits of the IMAGE_SCN_ALIGN s_flags using the macro
COFF_ENCODE_ALIGNMENT, defined in coff/pe.h.

Since, now we can pad only as needed, the hardcoded
COFF_SECTION_ALIGNMENT_ENTRIES bfd/pe[i]-i386.c can revert back to the
default.

After this patch  we get
Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         00000000  00000000  00000000  00000000  2**2
                  ALLOC, LOAD, READONLY, CODE
  1 .data         00000020  00000000  00000000  0000008c  2**5
                  CONTENTS, ALLOC, LOAD, DATA
  2 .bss          00000000  00000000  00000000  00000000  2**2
                  ALLOC




In addition, it modifies gas/read.c to enable non-default alignment
limits to be checked. The appropriate p2align limit for i386-pe is
defined for TE_PE in config/tc-i386.h as 13, corresponding to the
largest documented PE section alignment flag,IMAGE_SCN_ALIGN_8192BYTE.

No regressions after in-tree combined build of mingw-targeted
binutils/gcc.

The two testcases in ld-scripts/align.exp and alignof.exp now pass


include/ChangeLog

2007-10-24  Danny Smith  <dannysmith@users.sourceforge.net>

	* coff/pe.h (COFF_ENCODE_ALIGNMENT) Define.

gas/ChangeLog

	* read.c (ALIGN_LIMIT): Rename to ...
	(TC_ALIGN_LIMIT): Guard against prior definition.
	* config/tc-i386.h (TC_ALIGN_LIMIT)[TE_PE]: Define.

bfd/ChangeLog

	* pe-i386.c (COFF_SECTION_ALIGNMENT_ENTRIES): Let .data, .text
	 and .bss section use the default.
	* pei-i386.c (COFF_SECTION_ALIGNMENT_ENTRIES): Likewise.

ld/testsuite/ChangeLog

	* ld-scripts/align.exp: Enable for PECOFF.
	* ld-scripts/alignof.exp: Likewise.
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