* Make die_mem_offset() be able to handle DW_AT_data_member_location
attributes generated by Clang 3.4. * Document how different compilers generate DW_AT_data_member_location attributes differently. * Document the quirks about DW_FORM_data[48].
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parent
bc5fce8d8f
commit
e3fa6e64ee
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/projects/elftoolchain/; revision=260880
@ -492,23 +492,71 @@ die_mem_offset(dwarf_t *dw, Dwarf_Die die, Dwarf_Half name,
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Dwarf_Locdesc *loc = NULL;
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Dwarf_Signed locnum = 0;
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Dwarf_Attribute at;
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Dwarf_Half form;
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if (name != DW_AT_data_member_location)
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terminate("die %llu: can only process attribute "
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"DW_AT_data_member_location\n", die_off(dw, die));
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if ((at = die_attr(dw, die, name, 0)) == NULL)
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return (0);
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if (dwarf_loclist(at, &loc, &locnum, &dw->dw_err) != DW_DLV_OK)
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if (dwarf_whatform(at, &form, &dw->dw_err) != DW_DLV_OK)
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return (0);
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if (locnum != 1 || loc->ld_s->lr_atom != DW_OP_plus_uconst) {
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terminate("die %llu: cannot parse member offset\n",
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die_off(dw, die));
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}
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switch (form) {
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case DW_FORM_sec_offset:
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case DW_FORM_block:
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case DW_FORM_block1:
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case DW_FORM_block2:
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case DW_FORM_block4:
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/*
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* GCC in base and Clang (3.3 or below) generates
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* DW_AT_data_member_location attribute with DW_FORM_block*
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* form. The attribute contains one DW_OP_plus_uconst
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* operator. The member offset stores in the operand.
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*/
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if (dwarf_loclist(at, &loc, &locnum, &dw->dw_err) != DW_DLV_OK)
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return (0);
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if (locnum != 1 || loc->ld_s->lr_atom != DW_OP_plus_uconst) {
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terminate("die %llu: cannot parse member offset with "
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"operator other than DW_OP_plus_uconst\n",
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die_off(dw, die));
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}
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*valp = loc->ld_s->lr_number;
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if (loc != NULL) {
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dwarf_dealloc(dw->dw_dw, loc->ld_s, DW_DLA_LOC_BLOCK);
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dwarf_dealloc(dw->dw_dw, loc, DW_DLA_LOCDESC);
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}
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break;
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*valp = loc->ld_s->lr_number;
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case DW_FORM_data1:
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case DW_FORM_data2:
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case DW_FORM_data4:
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case DW_FORM_data8:
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case DW_FORM_udata:
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/*
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* Clang 3.4 generates DW_AT_data_member_location attribute
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* with DW_FORM_data* form (constant class). The attribute
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* stores a contant value which is the member offset.
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*
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* However, note that DW_FORM_data[48] in DWARF version 2 or 3
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* could be used as a section offset (offset into .debug_loc in
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* this case). Here we assume the attribute always stores a
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* constant because we know Clang 3.4 does this and GCC in
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* base won't emit DW_FORM_data[48] for this attribute. This
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* code will remain correct if future vesrions of Clang and
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* GCC conform to DWARF4 standard and only use the form
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* DW_FORM_sec_offset for section offset.
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*/
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if (dwarf_attrval_unsigned(die, name, valp, &dw->dw_err) !=
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DW_DLV_OK)
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return (0);
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break;
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if (loc != NULL) {
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dwarf_dealloc(dw->dw_dw, loc->ld_s, DW_DLA_LOC_BLOCK);
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dwarf_dealloc(dw->dw_dw, loc, DW_DLA_LOCDESC);
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default:
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terminate("die %llu: cannot parse member offset with form "
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"%u\n", die_off(dw, die), form);
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}
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return (1);
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