diff options
Diffstat (limited to 'bfd/elf32-msp430.c')
| -rw-r--r-- | bfd/elf32-msp430.c | 70 |
1 files changed, 59 insertions, 11 deletions
diff --git a/bfd/elf32-msp430.c b/bfd/elf32-msp430.c index 67ad958..4d68d40 100644 --- a/bfd/elf32-msp430.c +++ b/bfd/elf32-msp430.c @@ -2362,11 +2362,11 @@ msp430_elf_relax_section (bfd * abfd, asection * sec, able to relax. */ if ((long) value < 1016 && (long) value > -1016) { - int code2; + int code1, code2, opcode; /* Get the opcode. */ code2 = bfd_get_16 (abfd, contents + irel->r_offset - 2); - if (code2 != 0x4030) + if (code2 != 0x4030) /* BR -> JMP */ continue; /* FIXME: check r4 and r3 ? */ /* FIXME: Handle 0x4010 as well ? */ @@ -2391,17 +2391,65 @@ msp430_elf_relax_section (bfd * abfd, asection * sec, if (debug_relocs) printf (" R_MSP430_16 -> R_MSP430_10_PCREL "); } + /* If we're trying to shrink a BR[A] after previously having + grown a JMP for this reloc, then we have a sequence like + this: + J<cond> 1f + BR[A] + 1: + The opcode for J<cond> has the target hard-coded as 2 words + ahead of the insn, instead of using a reloc. + This means we cannot rely on any of the helper functions to + update this hard-coded jump destination if we remove the + BR[A] insn, so we must explicitly update it here. + This does mean that we can remove the entire branch + instruction, and invert the conditional jump, saving us 4 + bytes rather than only 2 if we detected this in the normal + way. */ + code1 = bfd_get_16 (abfd, contents + irel->r_offset - 4); + switch (code1) + { + case 0x3802: opcode = 0x3401; break; /* Jl +2 -> Jge +1 */ + case 0x3402: opcode = 0x3801; break; /* Jge +2 -> Jl +1 */ + case 0x2c02: opcode = 0x2801; break; /* Jhs +2 -> Jlo +1 */ + case 0x2802: opcode = 0x2c01; break; /* Jlo +2 -> Jhs +1 */ + case 0x2402: opcode = 0x2001; break; /* Jeq +2 -> Jne +1 */ + case 0x2002: opcode = 0x2401; break; /* jne +2 -> Jeq +1 */ + case 0x3002: /* jn +2 */ + /* FIXME: There is no direct inverse of the Jn insn. */ + continue; + default: + /* The previous opcode does not have a hard-coded jump + that we added when previously relaxing, so relax the + current branch as normal. */ + opcode = 0x3c00; + break; + } if (debug_relocs) - printf ("(shrinking with new opcode 0x3c00)\n"); - - /* Fix the opcode right way. */ - bfd_put_16 (abfd, 0x3c00, contents + irel->r_offset - 2); - irel->r_offset -= 2; + printf ("(shrinking with new opcode 0x%x)\n", opcode); - /* Delete bytes. */ - if (!msp430_elf_relax_delete_bytes (abfd, sec, - irel->r_offset + 2, 2)) - goto error_return; + if (opcode != 0x3c00) + { + /* Invert the opcode of the conditional jump. */ + bfd_put_16 (abfd, opcode, contents + irel->r_offset - 4); + irel->r_offset -= 4; + + /* Delete 4 bytes - the full BR insn. */ + if (!msp430_elf_relax_delete_bytes (abfd, sec, + irel->r_offset + 2, 4)) + goto error_return; + } + else + { + /* Fix the opcode right way. */ + bfd_put_16 (abfd, opcode, contents + irel->r_offset - 2); + irel->r_offset -= 2; + + /* Delete bytes. */ + if (!msp430_elf_relax_delete_bytes (abfd, sec, + irel->r_offset + 2, 2)) + goto error_return; + } /* That will change things, so, we should relax again. Note that this is not required, and it may be slow. */ |