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| author | Alan Modra <amodra@gmail.com> | 2019-10-29 11:35:05 +1030 |
|---|---|---|
| committer | Alan Modra <amodra@gmail.com> | 2019-10-29 12:20:54 +1030 |
| commit | b9d8f5601bcfbe96ab0476286ae8e249ada10db5 (patch) | |
| tree | 07b6b1daeba6597f6fbd54b823d3524005337509 | |
| parent | d7b510baa8603e37080405e09e907248bee81d35 (diff) | |
| download | gdb-b9d8f5601bcfbe96ab0476286ae8e249ada10db5.zip gdb-b9d8f5601bcfbe96ab0476286ae8e249ada10db5.tar.gz gdb-b9d8f5601bcfbe96ab0476286ae8e249ada10db5.tar.bz2 | |
Re: Optimise away eh_frame advance_loc 0
If we happen to get the fixed and variable parts of the advance_loc
in different frags, bad things happen when subtracting one from a
fr_fix of zero.
PR 25125
* dw2gencfi.c (output_cfi_insn): Don't allow DW_CFA_advance_loc4
to be placed in a different frag to the rs_cfa.
| -rw-r--r-- | gas/ChangeLog | 6 | ||||
| -rw-r--r-- | gas/dw2gencfi.c | 7 |
2 files changed, 12 insertions, 1 deletions
diff --git a/gas/ChangeLog b/gas/ChangeLog index 53c90ea..17f45e3 100644 --- a/gas/ChangeLog +++ b/gas/ChangeLog @@ -1,3 +1,9 @@ +2019-10-29 Alan Modra <amodra@gmail.com> + + PR 25125 + * dw2gencfi.c (output_cfi_insn): Don't allow DW_CFA_advance_loc4 + to be placed in a different frag to the rs_cfa. + 2019-10-26 John David Anglin <danglin@gcc.gnu.org> PR gas/25121 diff --git a/gas/dw2gencfi.c b/gas/dw2gencfi.c index b01e4c4..6c0478a 100644 --- a/gas/dw2gencfi.c +++ b/gas/dw2gencfi.c @@ -1630,7 +1630,12 @@ output_cfi_insn (struct cfi_insn_data *insn) /* The code in ehopt.c expects that one byte of the encoding is already allocated to the frag. This comes from the way that it scans the .eh_frame section looking first for the - .byte DW_CFA_advance_loc4. */ + .byte DW_CFA_advance_loc4. Call frag_grow with the sum of + room needed by frag_more and frag_var to preallocate space + ensuring that the DW_CFA_advance_loc4 is in the fixed part + of the rs_cfa frag, so that the relax machinery can remove + the advance_loc should it advance by zero. */ + frag_grow (5); *frag_more (1) = DW_CFA_advance_loc4; frag_var (rs_cfa, 4, 0, DWARF2_LINE_MIN_INSN_LENGTH << 3, |