diff options
Diffstat (limited to 'gas/doc')
| -rw-r--r-- | gas/doc/internals.texi | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/gas/doc/internals.texi b/gas/doc/internals.texi index fa99bc6..a42bc0f 100644 --- a/gas/doc/internals.texi +++ b/gas/doc/internals.texi @@ -1601,6 +1601,16 @@ called to convert the frag to an @code{rs_fill} frag with no variant part. Sometimes changing addressing modes may also require rewriting the instruction. It can be accessed via @code{fr_opcode} or @code{fr_fix}. +If you generate frags separately for the basic insn opcode and any relaxable +operands, do not call @code{fix_new} thinking you can emit fixups for the +opcode field from the relaxable frag. It is not garanteed to be the same frag. +If you need to emit fixups for the opcode field from inspection of the +relaxable frag, then you need to generate a common frag for both the basic +opcode and relaxable fields, or you need to provide the frag for the opcode to +pass to @code{fix_new}. The latter can be done for example by defining +@code{TC_FRAG_TYPE} to include a pointer to it and defining @code{TC_FRAG_INIT} +to set the pointer. + Sometimes @code{fr_var} is increased instead, and @code{frag_wane} is not called. I'm not sure, but I think this is to keep @code{fr_fix} referring to an earlier byte, and @code{fr_subtype} set to @code{rs_machine_dependent} so |