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Diffstat (limited to 'gcc-1.40/rtlanal.c')
| -rw-r--r-- | gcc-1.40/rtlanal.c | 681 |
1 files changed, 681 insertions, 0 deletions
diff --git a/gcc-1.40/rtlanal.c b/gcc-1.40/rtlanal.c new file mode 100644 index 0000000..17ee75e --- /dev/null +++ b/gcc-1.40/rtlanal.c @@ -0,0 +1,681 @@ +/* Analyze RTL for C-Compiler + Copyright (C) 1987, 1988 Free Software Foundation, Inc. + +This file is part of GNU CC. + +GNU CC is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 1, or (at your option) +any later version. + +GNU CC is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU CC; see the file COPYING. If not, write to +the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ + + +#include "config.h" +#include "rtl.h" + +extern void note_stores (); +static int reg_set_p (); + +/* Return 1 if the value of X is unstable + (would be different at a different point in the program). + The frame pointer, arg pointer, etc. are considered stable + (within one function) and so is anything marked `unchanging'. */ + +int +rtx_unstable_p (x) + rtx x; +{ + register RTX_CODE code = GET_CODE (x); + register int i; + register char *fmt; + + if (code == MEM) + return ! RTX_UNCHANGING_P (x); + + if (code == QUEUED) + return 1; + + if (code == CONST || code == CONST_INT) + return 0; + + if (code == REG) + return ! (REGNO (x) == FRAME_POINTER_REGNUM + || REGNO (x) == ARG_POINTER_REGNUM + || RTX_UNCHANGING_P (x)); + + fmt = GET_RTX_FORMAT (code); + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + if (fmt[i] == 'e') + if (rtx_unstable_p (XEXP (x, i))) + return 1; + return 0; +} + +/* Return 1 if X has a value that can vary even between two + executions of the program. 0 means X can be compared reliably + against certain constants or near-constants. + The frame pointer and the arg pointer are considered constant. */ + +int +rtx_varies_p (x) + rtx x; +{ + register RTX_CODE code = GET_CODE (x); + register int i; + register char *fmt; + + if (code == MEM) + return 1; + + if (code == QUEUED) + return 1; + + if (code == CONST || code == CONST_INT) + return 0; + + if (code == REG) + return ! (REGNO (x) == FRAME_POINTER_REGNUM + || REGNO (x) == ARG_POINTER_REGNUM); + + fmt = GET_RTX_FORMAT (code); + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + if (fmt[i] == 'e') + if (rtx_varies_p (XEXP (x, i))) + return 1; + return 0; +} + +/* Return 1 if X refers to a memory location whose address + cannot be compared reliably with constant addresses, + or if X refers to a BLKmode memory object. */ + +int +rtx_addr_varies_p (x) + rtx x; +{ + register enum rtx_code code; + register int i; + register char *fmt; + + if (x == 0) + return 0; + + code = GET_CODE (x); + if (code == MEM) + return GET_MODE (x) == BLKmode || rtx_varies_p (XEXP (x, 0)); + + fmt = GET_RTX_FORMAT (code); + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + if (fmt[i] == 'e') + if (rtx_addr_varies_p (XEXP (x, i))) + return 1; + return 0; +} + +/* Nonzero if register REG appears somewhere within IN. + Also works if REG is not a register; in this case it checks + for a subexpression of IN that is Lisp "equal" to REG. */ + +int +reg_mentioned_p (reg, in) + register rtx reg, in; +{ + register char *fmt; + register int i; + register enum rtx_code code; + + if (in == 0) + return 0; + + if (reg == in) + return 1; + + code = GET_CODE (in); + + switch (code) + { + /* Compare registers by number. */ + case REG: + return GET_CODE (reg) == REG && REGNO (in) == REGNO (reg); + + /* These codes have no constituent expressions + and are unique. */ + case CC0: + case PC: + return 0; + + case CONST_INT: + return GET_CODE (reg) == CONST_INT && INTVAL (in) == INTVAL (reg); + } + + if (GET_CODE (reg) == code && rtx_equal_p (reg, in)) + return 1; + + fmt = GET_RTX_FORMAT (code); + + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + { + if (fmt[i] == 'E') + { + register int j; + for (j = XVECLEN (in, i) - 1; j >= 0; j--) + if (reg_mentioned_p (reg, XVECEXP (in, i, j))) + return 1; + } + else if (fmt[i] == 'e' + && reg_mentioned_p (reg, XEXP (in, i))) + return 1; + } + return 0; +} + +/* Nonzero if register REG is used in an insn between + FROM_INSN and TO_INSN (exclusive of those two). */ + +int +reg_used_between_p (reg, from_insn, to_insn) + rtx reg, from_insn, to_insn; +{ + register rtx insn; + register RTX_CODE code; + for (insn = NEXT_INSN (from_insn); insn != to_insn; insn = NEXT_INSN (insn)) + if (((code = GET_CODE (insn)) == INSN + || code == JUMP_INSN || code == CALL_INSN) + && reg_mentioned_p (reg, PATTERN (insn))) + return 1; + return 0; +} + +/* Nonzero if register REG is set or clobbered in an insn between + FROM_INSN and TO_INSN (exclusive of those two). + Does not notice increments, only SET and CLOBBER. */ + +int +reg_set_between_p (reg, from_insn, to_insn) + rtx reg, from_insn, to_insn; +{ + register rtx insn; + register RTX_CODE code; + for (insn = NEXT_INSN (from_insn); insn != to_insn; insn = NEXT_INSN (insn)) + if (((code = GET_CODE (insn)) == INSN + || code == JUMP_INSN || code == CALL_INSN) + && reg_set_p (reg, PATTERN (insn))) + return 1; + return 0; +} + +/* Internals of reg_set_between_p. */ + +static rtx reg_set_reg; +static int reg_set_flag; + +static void +reg_set_p_1 (x) + rtx x; +{ + if (reg_overlap_mentioned_p (reg_set_reg, x)) + reg_set_flag = 1; +} + +static int +reg_set_p (reg, insn) + rtx reg, insn; +{ + reg_set_reg = reg; + reg_set_flag = 0; + note_stores (insn, reg_set_p_1); + return reg_set_flag; +} + +/* Return nonzero if hard register in range [REGNO, ENDREGNO) + appears either explicitly or implicitly in X + other than being stored into. + + References contained within the substructure at LOC do not count. + LOC may be zero, meaning don't ignore anything. */ + +int +refers_to_regno_p (regno, endregno, x, loc) + int regno, endregno; + rtx x; + rtx *loc; +{ + register int i; + register RTX_CODE code; + register char *fmt; + + repeat: + code = GET_CODE (x); + if (code == REG) + { + i = REGNO (x); + return (endregno > i && regno < i + HARD_REGNO_NREGS (i, GET_MODE (x))); + } + + if (code == SET) + { + /* Note setting a SUBREG counts as referring to the REG it is in! */ + if (GET_CODE (SET_DEST (x)) != REG + && refers_to_regno_p (regno, endregno, SET_DEST (x), loc)) + return 1; + if (loc == &SET_SRC (x)) + return 0; + x = SET_SRC (x); + goto repeat; + } + + if (code == CLOBBER) + { + if (GET_CODE (SET_DEST (x)) != REG + && refers_to_regno_p (regno, endregno, SET_DEST (x), loc)) + return 1; + return 0; + } + + /* X does not match, so try its subexpressions. */ + + fmt = GET_RTX_FORMAT (code); + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + { + if (fmt[i] == 'e' && loc != &XEXP (x, i)) + { + if (i == 0) + { + x = XEXP (x, 0); + goto repeat; + } + else + if (refers_to_regno_p (regno, endregno, XEXP (x, i), loc)) + return 1; + } + else if (fmt[i] == 'E') + { + register int j; + for (j = XVECLEN (x, i) - 1; j >=0; j--) + if (loc != &XVECEXP (x, i, j) + && refers_to_regno_p (regno, endregno, XVECEXP (x, i, j), loc)) + return 1; + } + } + return 0; +} + +/* Nonzero if X contains any reg that overlaps hard register REG. */ + +int +reg_overlap_mentioned_p (reg, x) + rtx reg, x; +{ + int regno = REGNO (reg); + int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg)); + return refers_to_regno_p (regno, endregno, x, 0); +} + +/* This is 1 until after reload pass. */ +int rtx_equal_function_value_matters; + +/* Return 1 if X and Y are identical-looking rtx's. + This is the Lisp function EQUAL for rtx arguments. */ + +int +rtx_equal_p (x, y) + rtx x, y; +{ + register int i; + register int j; + register enum rtx_code code; + register char *fmt; + + if (x == y) + return 1; + if (x == 0 || y == 0) + return 0; + + code = GET_CODE (x); + /* Rtx's of different codes cannot be equal. */ + if (code != GET_CODE (y)) + return 0; + + /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. + (REG:SI x) and (REG:HI x) are NOT equivalent. */ + + if (GET_MODE (x) != GET_MODE (y)) + return 0; + + /* These three types of rtx's can be compared nonrecursively. */ + /* Until the end of reload, + don't consider the a reference to the return register of the current + function the same as the return from a called function. This eases + the job of function integration. Once the distinction no longer + matters, the insn will be deleted. */ + if (code == REG) + return (REGNO (x) == REGNO (y) + && (! rtx_equal_function_value_matters + || REG_FUNCTION_VALUE_P (x) == REG_FUNCTION_VALUE_P (y))); + if (code == LABEL_REF) + return XEXP (x, 0) == XEXP (y, 0); + if (code == SYMBOL_REF) + return XSTR (x, 0) == XSTR (y, 0); + + /* Compare the elements. If any pair of corresponding elements + fail to match, return 0 for the whole things. */ + + fmt = GET_RTX_FORMAT (code); + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + { + switch (fmt[i]) + { + case 'i': + if (XINT (x, i) != XINT (y, i)) + return 0; + break; + + case 'E': + /* Two vectors must have the same length. */ + if (XVECLEN (x, i) != XVECLEN (y, i)) + return 0; + + /* And the corresponding elements must match. */ + for (j = 0; j < XVECLEN (x, i); j++) + if (rtx_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)) == 0) + return 0; + break; + + case 'e': + if (rtx_equal_p (XEXP (x, i), XEXP (y, i)) == 0) + return 0; + break; + + case 's': + if (strcmp (XSTR (x, i), XSTR (y, i))) + return 0; + break; + + case 'u': + /* These are just backpointers, so they don't matter. */ + break; + + case '0': + break; + + /* It is believed that rtx's at this level will never + contain anything but integers and other rtx's, + except for within LABEL_REFs and SYMBOL_REFs. */ + default: + abort (); + } + } + return 1; +} + +/* Call FUN on each register or MEM that is stored into or clobbered by X. + (X would be the pattern of an insn). + FUN receives two arguments: + the REG, MEM, CC0 or PC being stored in or clobbered, + the SET or CLOBBER rtx that does the store. */ + +void +note_stores (x, fun) + register rtx x; + void (*fun) (); +{ + if ((GET_CODE (x) == SET || GET_CODE (x) == CLOBBER)) + { + register rtx dest = SET_DEST (x); + while (GET_CODE (dest) == SUBREG + || GET_CODE (dest) == ZERO_EXTRACT + || GET_CODE (dest) == SIGN_EXTRACT + || GET_CODE (dest) == STRICT_LOW_PART) + dest = XEXP (dest, 0); + (*fun) (dest, x); + } + else if (GET_CODE (x) == PARALLEL) + { + register int i; + for (i = XVECLEN (x, 0) - 1; i >= 0; i--) + { + register rtx y = XVECEXP (x, 0, i); + if (GET_CODE (y) == SET || GET_CODE (y) == CLOBBER) + { + register rtx dest = SET_DEST (y); + while (GET_CODE (dest) == SUBREG + || GET_CODE (dest) == ZERO_EXTRACT + || GET_CODE (dest) == SIGN_EXTRACT + || GET_CODE (dest) == STRICT_LOW_PART) + dest = XEXP (dest, 0); + (*fun) (dest, XVECEXP (x, 0, i)); + } + } + } +} + +/* Return nonzero if register REG's old contents don't survive after INSN. + This can be because REG dies in INSN or because INSN entirely sets REG. + + "Entirely set" means set directly and not through a SUBREG, + ZERO_EXTRACT or SIGN_EXTRACT, so no trace of the old contents remains. + + REG may be a hard or pseudo reg. Renumbering is not taken into account, + but for this use that makes no difference, since regs don't overlap + during their lifetimes. Therefore, this function may be used + at any time after deaths have been computed (in flow.c). */ + +int +dead_or_set_p (insn, reg) + rtx insn; + rtx reg; +{ + register rtx link; + register int regno = REGNO (reg); + + for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) + if ((REG_NOTE_KIND (link) == REG_DEAD + || REG_NOTE_KIND (link) == REG_INC) + && REGNO (XEXP (link, 0)) == regno) + return 1; + + if (GET_CODE (PATTERN (insn)) == SET) + return (GET_CODE (SET_DEST (PATTERN (insn))) == REG + && REGNO (SET_DEST (PATTERN (insn))) == regno); + else if (GET_CODE (PATTERN (insn)) == PARALLEL) + { + register int i; + for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--) + { + if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == SET + && GET_CODE (SET_DEST (XVECEXP (PATTERN (insn), 0, i))) == REG + && REGNO (SET_DEST (XVECEXP (PATTERN (insn), 0, i))) == regno) + return 1; + } + } + return 0; +} + +/* Return the reg-note of kind KIND in insn INSN, if there is one. + If DATUM is nonzero, look for one whose datum is DATUM. */ + +rtx +find_reg_note (insn, kind, datum) + rtx insn; + enum reg_note kind; + rtx datum; +{ + register rtx link; + + for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) + if (REG_NOTE_KIND (link) == kind + && (datum == 0 || datum == XEXP (link, 0))) + return link; + return 0; +} + +/* Return the reg-note of kind KIND in insn INSN which applies to register + number REGNO, if any. Return 0 if there is no such reg-note. */ + +rtx +find_regno_note (insn, kind, regno) + rtx insn; + enum reg_note kind; + int regno; +{ + register rtx link; + + for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) + if (REG_NOTE_KIND (link) == kind + && REGNO (XEXP (link, 0)) == regno) + return link; + return 0; +} + +/* Nonzero if FROM precedes TO with no intervening labels. */ + +int +no_labels_between (from, to) + register rtx from, to; +{ + register rtx p = to; + + while (1) + { + p = PREV_INSN (p); + if (p == 0) + return 0; + if (p == from) + return 1; + if (GET_CODE (p) == CODE_LABEL) + return 0; + } +} + +/* Nonzero if X contains any volatile memory references + or volatile ASM_OPERANDS expressions. */ + +int +volatile_refs_p (x) + rtx x; +{ + register RTX_CODE code; + + code = GET_CODE (x); + switch (code) + { + case LABEL_REF: + case SYMBOL_REF: + case CONST_INT: + case CONST: + case CONST_DOUBLE: + case CC0: + case PC: + case REG: + case CLOBBER: + case ASM_INPUT: + case ADDR_VEC: + case ADDR_DIFF_VEC: + return 0; + + case CALL: + return 1; + + case MEM: + case ASM_OPERANDS: + if (MEM_VOLATILE_P (x)) + return 1; + } + + /* Recursively scan the operands of this expression. */ + + { + register char *fmt = GET_RTX_FORMAT (code); + register int i; + + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + { + if (fmt[i] == 'e') + { + if (volatile_refs_p (XEXP (x, i))) + return 1; + } + if (fmt[i] == 'E') + { + register int j; + for (j = 0; j < XVECLEN (x, i); j++) + if (volatile_refs_p (XVECEXP (x, i, j))) + return 1; + } + } + } + return 0; +} + +/* Return nonzero if evaluating rtx X might cause a trap. */ + +int +may_trap_p (x) + rtx x; +{ + int i; + enum rtx_code code; + char *fmt; + + if (x == 0) + return 0; + code = GET_CODE (x); + switch (code) + { + /* Handle these cases fast. */ + case CONST_INT: + case CONST_DOUBLE: + case SYMBOL_REF: + case LABEL_REF: + case CONST: + case PC: + case CC0: + case REG: + return 0; + + /* Memory ref can trap unless it's a static var or a stack slot. */ + case MEM: + return rtx_varies_p (XEXP (x, 0)); + + /* Division by a non-constant might trap. */ + case DIV: + case MOD: + case UDIV: + case UMOD: + if (! CONSTANT_P (XEXP (x, 1)) + && GET_CODE (XEXP (x, 1)) != CONST_DOUBLE) + return 1; + if (XEXP (x, 1) == const0_rtx) + return 1; + default: + /* Any floating arithmetic may trap. */ + if (GET_MODE_CLASS (GET_MODE (x)) == MODE_FLOAT) + return 1; + } + + fmt = GET_RTX_FORMAT (code); + for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) + { + if (fmt[i] == 'e') + { + if (may_trap_p (XEXP (x, i))) + return 1; + } + else if (fmt[i] == 'E') + { + register int j; + for (j = 0; j < XVECLEN (x, i); j++) + if (may_trap_p (XVECEXP (x, i, j))) + return 1; + } + } + return 0; +} |