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* reloc.c (_bfd_relocate_contents): Adjust handling of overflow to

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avoid depending upon right shifts of signed numbers, and to
	correct handling of src_mask with lower bits zero.
This commit is contained in:
Ian Lance Taylor 1994-02-26 18:24:10 +00:00
parent a2961423ae
commit 3d51f02f4c
1 changed files with 33 additions and 9 deletions
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42
bfd/reloc.c
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@ -616,7 +616,8 @@ bfd_perform_relocation (abfd, reloc_entry, data, input_section, output_bfd,
reloc_entry->address += input_section->output_offset;
/* WTF?? */
if (abfd->xvec->flavour == bfd_target_coff_flavour)
if (abfd->xvec->flavour == bfd_target_coff_flavour
&& strcmp (abfd->xvec->name, "aixcoff-rs6000") != 0)
{
#if 1
/* For m68k-coff, the addend was being subtracted twice during
@ -1054,13 +1055,23 @@ _bfd_relocate_contents (howto, input_bfd, relocation, location)
&~ ((bfd_vma) -1 >> howto->rightshift)));
}
/* Add in the value from the object file, shifted down so that
it is a straight number. */
/* Get the value from the object file. */
add = x & howto->src_mask;
if ((add & (((~ howto->src_mask) >> 1) & howto->src_mask)) == 0)
signed_add = add;
else
signed_add = add | ((bfd_vma) -1 &~ howto->src_mask);
/* Get the value from the object file with an appropriate sign.
The expression involving howto->src_mask isolates the upper
bit of src_mask. If that bit is set in the value we are
adding, it is negative, and we subtract out that number times
two. If src_mask includes the highest possible bit, then we
can not get the upper bit, but that does not matter since
signed_add needs no adjustment to become negative in that
case. */
signed_add = add;
if ((add & (((~ howto->src_mask) >> 1) & howto->src_mask)) != 0)
signed_add -= (((~ howto->src_mask) >> 1) & howto->src_mask) << 1;
/* Add the value from the object file, shifted so that it is a
straight number. */
if (howto->bitpos == 0)
{
check += add;
@ -1069,10 +1080,14 @@ _bfd_relocate_contents (howto, input_bfd, relocation, location)
else
{
check += add >> howto->bitpos;
/* For the signed case we use ADD, rather than SIGNED_ADD,
to avoid warnings from SVR4 cc. This is OK since we
explictly handle the sign bits. */
if (signed_add >= 0)
signed_check += signed_add >> howto->bitpos;
signed_check += add >> howto->bitpos;
else
signed_check += ((signed_add >> howto->bitpos)
signed_check += ((add >> howto->bitpos)
| ((bfd_vma) -1
&~ ((bfd_vma) -1 >> howto->bitpos)));
}
@ -1447,6 +1462,15 @@ CODE_FRAGMENT
. BFD_RELOC_386_GOTOFF,
. BFD_RELOC_386_GOTPC,
.
. {* PowerPC/POWER (RS/6000) relocs. *}
. {* 26 bit relative branch. Low two bits must be zero. High 24
. bits installed in bits 6 through 29 of instruction. *}
. BFD_RELOC_PPC_B26,
. {* 26 bit absolute branch, like BFD_RELOC_PPC_B26 but absolute. *}
. BFD_RELOC_PPC_BA26,
. {* 16 bit TOC relative reference. *}
. BFD_RELOC_PPC_TOC16,
.
. {* this must be the highest numeric value *}
. BFD_RELOC_UNUSED
. } bfd_reloc_code_real_type;