- /* Fields set up by the caller to struct_equiv_block_eq */
-
- basic_block x_block, y_block; /* The two blocks being matched. */
-
- /* MODE carries the mode bits from cleanup_cfg if we are called from
- try_crossjump_to_edge, and additionally it carries the
- STRUCT_EQUIV_* bits described above. */
- int mode;
-
- /* INPUT_COST is the cost that adding an extra input to the matched blocks
- is supposed to have, and is taken into account when considering if the
- matched sequence should be extended backwards. input_cost < 0 means
- don't accept any inputs at all. */
- int input_cost;
-
-
- /* Fields to track state inside of struct_equiv_block_eq. Some of these
- are also outputs. */
-
- /* X_INPUT and Y_INPUT are used by struct_equiv to record a register that
- is used as an input parameter, i.e. where different registers are used
- as sources. This is only used for a register that is live at the end
- of the blocks, or in some identical code at the end of the blocks;
- Inputs that are dead at the end go into X_LOCAL / Y_LOCAL. */
- rtx x_input, y_input;
- /* When a previous pass has identified a valid input, INPUT_REG is set
- by struct_equiv_block_eq, and it is henceforth replaced in X_BLOCK
- for the input. */
- rtx input_reg;
-
- /* COMMON_LIVE keeps track of the registers which are currently live
- (as we scan backwards from the end) and have the same numbers in both
- blocks. N.B. a register that is in common_live is unsuitable to become
- a local reg. */
- regset common_live;
- /* Likewise, X_LOCAL_LIVE / Y_LOCAL_LIVE keep track of registers that are
- local to one of the blocks; these registers must not be accepted as
- identical when encountered in both blocks. */
- regset x_local_live, y_local_live;
-
- /* EQUIV_USED indicates for which insns a REG_EQUAL or REG_EQUIV note is
- being used, to avoid having to backtrack in the next pass, so that we
- get accurate life info for this insn then. For each such insn,
- the bit with the number corresponding to the CUR.NINSNS value at the
- time of scanning is set. */
- bitmap equiv_used;
-
- /* Current state that can be saved & restored easily. */
- struct struct_equiv_checkpoint cur;
- /* BEST_MATCH is used to store the best match so far, weighing the
- cost of matched insns COSTS_N_INSNS (CUR.NINSNS) against the cost
- CUR.INPUT_COUNT * INPUT_COST of setting up the inputs. */
- struct struct_equiv_checkpoint best_match;
- /* If a checkpoint restore failed, or an input conflict newly arises,
- NEED_RERUN is set. This has to be tested by the caller to re-run
- the comparison if the match appears otherwise sound. The state kept in
- x_start, y_start, equiv_used and check_input_conflict ensures that
- we won't loop indefinitely. */
- bool need_rerun;
- /* If there is indication of an input conflict at the end,
- CHECK_INPUT_CONFLICT is set so that we'll check for input conflicts
- for each insn in the next pass. This is needed so that we won't discard
- a partial match if there is a longer match that has to be abandoned due
- to an input conflict. */
- bool check_input_conflict;
- /* HAD_INPUT_CONFLICT is set if CHECK_INPUT_CONFLICT was already set and we
- have passed a point where there were multiple dying inputs. This helps
- us decide if we should set check_input_conflict for the next pass. */
- bool had_input_conflict;
-
- /* LIVE_UPDATE controls if we want to change any life info at all. We
- set it to false during REG_EQUAL / REG_EUQIV note comparison of the final
- pass so that we don't introduce new registers just for the note; if we
- can't match the notes without the current register information, we drop
- them. */
- bool live_update;
-
- /* X_LOCAL and Y_LOCAL are used to gather register numbers of register pairs
- that are local to X_BLOCK and Y_BLOCK, with CUR.LOCAL_COUNT being the index
- to the next free entry. */
- rtx x_local[STRUCT_EQUIV_MAX_LOCAL], y_local[STRUCT_EQUIV_MAX_LOCAL];
- /* LOCAL_RVALUE is nonzero if the corresponding X_LOCAL / Y_LOCAL entry
- was a source operand (including STRICT_LOW_PART) for the last invocation
- of struct_equiv mentioning it, zero if it was a destination-only operand.
- Since we are scanning backwards, this means the register is input/local
- for the (partial) block scanned so far. */
- bool local_rvalue[STRUCT_EQUIV_MAX_LOCAL];
-
-
- /* Additional fields that are computed for the convenience of the caller. */
-
- /* DYING_INPUTS is set to the number of local registers that turn out
- to be inputs to the (possibly partial) block. */
- int dying_inputs;
- /* X_END and Y_END are the last insns in X_BLOCK and Y_BLOCK, respectively,
- that are being compared. A final jump insn will not be included. */
- rtx x_end, y_end;
-
- /* If we are matching tablejumps, X_LABEL in X_BLOCK corresponds to
- Y_LABEL in Y_BLOCK. */
- rtx x_label, y_label;
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