diff options
Diffstat (limited to 'gas/config/tc-bpf.c')
| -rw-r--r-- | gas/config/tc-bpf.c | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/gas/config/tc-bpf.c b/gas/config/tc-bpf.c index fd4144a..3122f80 100644 --- a/gas/config/tc-bpf.c +++ b/gas/config/tc-bpf.c @@ -1223,6 +1223,7 @@ add_relaxed_insn (struct bpf_insn *insn, expressionS *exp) See md_operand below to see how exp_parse_failed is used. */ static int exp_parse_failed = 0; +static bool parsing_insn_operands = false; static char * parse_expression (char *s, expressionS *exp) @@ -1230,6 +1231,9 @@ parse_expression (char *s, expressionS *exp) char *saved_input_line_pointer = input_line_pointer; char *saved_s = s; + /* Wake up bpf_parse_name before the call to expression (). */ + parsing_insn_operands = true; + exp_parse_failed = 0; input_line_pointer = s; expression (exp); @@ -1251,6 +1255,71 @@ parse_expression (char *s, expressionS *exp) return s; } +/* Symbols created by this parse, but not yet committed to the real + symbol table. */ +static symbolS *deferred_sym_rootP; +static symbolS *deferred_sym_lastP; + +/* Symbols discarded by a previous parse. Symbols cannot easily be freed + after creation, so try to recycle. */ +static symbolS *orphan_sym_rootP; +static symbolS *orphan_sym_lastP; + +/* Implement md_parse_name hook. Handles any symbol found in an expression. + This allows us to tentatively create symbols, before we know for sure + whether the parser is using the correct template for an instruction. + If we end up keeping the instruction, the deferred symbols are committed + to the real symbol table. This approach is modeled after the riscv port. */ + +bool +bpf_parse_name (const char *name, expressionS *exp, enum expr_mode mode) +{ + symbolS *sym; + + /* If we aren't currently parsing an instruction, don't do anything. + This prevents tampering with operands to directives. */ + if (!parsing_insn_operands) + return false; + + gas_assert (mode == expr_normal); + + if (symbol_find (name) != NULL) + return false; + + for (sym = deferred_sym_rootP; sym; sym = symbol_next (sym)) + if (strcmp (name, S_GET_NAME (sym)) == 0) + break; + + /* Tentatively create a symbol. */ + if (!sym) + { + /* See if we can reuse a symbol discarded by a previous parse. + This may be quite common, for example when trying multiple templates + for an instruction with the first reference to a valid symbol. */ + for (sym = orphan_sym_rootP; sym; sym = symbol_next (sym)) + if (strcmp (name, S_GET_NAME (sym)) == 0) + { + symbol_remove (sym, &orphan_sym_rootP, &orphan_sym_lastP); + break; + } + + if (!sym) + sym = symbol_create (name, undefined_section, &zero_address_frag, 0); + + /* Add symbol to the deferred list. If we commit to the isntruction, + then the symbol will be inserted into to the real symbol table at + that point (in md_assemble). */ + symbol_append (sym, deferred_sym_lastP, &deferred_sym_rootP, + &deferred_sym_lastP); + } + + exp->X_op = O_symbol; + exp->X_add_symbol = sym; + exp->X_add_number = 0; + + return true; +} + /* Parse a BPF register name and return the corresponding register number. Return NULL in case of parse error, or a pointer to the first character in S that is not part of the register name. */ @@ -1317,6 +1386,16 @@ parse_error (int length, const char *fmt, ...) va_end (args); partial_match_length = length; } + + /* Discard deferred symbols from the failed parse. They may potentially + be reused in the future from the orphan list. */ + while (deferred_sym_rootP) + { + symbolS *sym = deferred_sym_rootP; + symbol_remove (sym, &deferred_sym_rootP, &deferred_sym_lastP); + symbol_append (sym, orphan_sym_lastP, &orphan_sym_rootP, + &orphan_sym_lastP); + } } /* Assemble a machine instruction in STR and emit the frags/bytes it @@ -1606,6 +1685,10 @@ md_assemble (char *str ATTRIBUTE_UNUSED) } } + /* Mark that we are no longer parsing an instruction, bpf_parse_name does + not interfere with symbols in e.g. assembler directives. */ + parsing_insn_operands = false; + if (opcode == NULL) { as_bad (_("unrecognized instruction `%s'"), str); @@ -1622,6 +1705,15 @@ md_assemble (char *str ATTRIBUTE_UNUSED) #undef PARSE_ERROR + /* Commit any symbols created while parsing the instruction. */ + while (deferred_sym_rootP) + { + symbolS *sym = deferred_sym_rootP; + symbol_remove (sym, &deferred_sym_rootP, &deferred_sym_lastP); + symbol_append (sym, symbol_lastP, &symbol_rootP, &symbol_lastP); + symbol_table_insert (sym); + } + /* Generate the frags and fixups for the parsed instruction. */ if (do_relax && isa_spec >= BPF_V4 && insn.is_relaxable) { |