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Link-time relaxations of branches are common for MSP430, given that GCC
can generate pessimal branch instructions, and the
-mcode-region=either/-mdata-region=either options to shuffle sections
can further change the type of branch instruction required.
These relaxations can result in invalid code when .uleb128
directives, used in the .gcc_except_table section, are used to calculate
the distance between two labels. A value for the .uleb128 directive is
calculated at assembly-time, and can't be updated at link-time, even if
relaxation causes the distance between the labels to change.
This patch adds relocations for subtract expressions in .uleb128
directives, to allow the linker to re-calculate the value of these
expressions after relaxation has been performed.
bfd/ChangeLog:
* bfd-in2.h (bfd_reloc_code_real): Add
BFD_RELOC_MSP430_{SET,SUB}_ULEB128.
* elf32-msp430.c (msp430_elf_ignore_reloc): New.
(elf_msp430_howto_table): Add R_MSP430{,X}_GNU_{SET,SUB}_ULEB128.
(msp430_reloc_map): Add R_MSP430_GNU_{SET,SUB}_ULEB128.
(msp430x_reloc_map): Add R_MSP430X_GNU_{SET,SUB}_ULEB128.
(write_uleb128): New.
(msp430_final_link_relocate): Handle R_MSP430{,X}_GNU_{SET,SUB}_ULEB128.
* libbfd.c (_bfd_write_unsigned_leb128): New.
* libbfd.h (_bfd_write_unsigned_leb128): New prototype.
Add BFD_RELOC_MSP430_{SET,SUB}_ULEB128.
* reloc.c: Document BFD_RELOC_MSP430_{SET,SUB}_ULEB128.
binutils/ChangeLog:
* readelf.c (target_specific_reloc_handling): Handle
R_MSP430{,X}_GNU_{SET,SUB}_ULEB128.
gas/ChangeLog:
* config/tc-msp430.c (msp430_insert_uleb128_fixes): New.
(msp430_md_end): Call msp430_insert_uleb128_fixes.
include/ChangeLog:
* elf/msp430.h (elf_msp430_reloc_type): Add
R_MSP430_GNU_{SET,SUB}_ULEB128.
(elf_msp430x_reloc_type): Add R_MSP430X_GNU_{SET,SUB}_ULEB128.
ld/ChangeLog:
* testsuite/ld-msp430-elf/msp430-elf.exp: Run new tests.
* testsuite/ld-msp430-elf/uleb128.s: New test.
* testsuite/ld-msp430-elf/uleb128_430.d: New test.
* testsuite/ld-msp430-elf/uleb128_430x.d: New test.
11 lines
150 B
Makefile
11 lines
150 B
Makefile
#source: uleb128.s
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#as: -mcpu=msp430
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#ld:
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#objdump: -sj.text
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.*:[ ]+file format .*
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Contents of section .text:
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[0-9a-f]+ 04000401 04840200.*
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#pass
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