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Diffstat (limited to 'gnu/gcc2/lib/stupid.c')
| -rw-r--r-- | gnu/gcc2/lib/stupid.c | 544 |
1 files changed, 0 insertions, 544 deletions
diff --git a/gnu/gcc2/lib/stupid.c b/gnu/gcc2/lib/stupid.c deleted file mode 100644 index 47d7740fb64f..000000000000 --- a/gnu/gcc2/lib/stupid.c +++ /dev/null @@ -1,544 +0,0 @@ -/* Dummy data flow analysis for GNU compiler in nonoptimizing mode. - Copyright (C) 1987, 1991 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 2, 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. */ - - -/* This file performs stupid register allocation, which is used - when cc1 gets the -noreg switch (which is when cc does not get -O). - - Stupid register allocation goes in place of the the flow_analysis, - local_alloc and global_alloc passes. combine_instructions cannot - be done with stupid allocation because the data flow info that it needs - is not computed here. - - In stupid allocation, the only user-defined variables that can - go in registers are those declared "register". They are assumed - to have a life span equal to their scope. Other user variables - are given stack slots in the rtl-generation pass and are not - represented as pseudo regs. A compiler-generated temporary - is assumed to live from its first mention to its last mention. - - Since each pseudo-reg's life span is just an interval, it can be - represented as a pair of numbers, each of which identifies an insn by - its position in the function (number of insns before it). The first - thing done for stupid allocation is to compute such a number for each - insn. It is called the suid. Then the life-interval of each - pseudo reg is computed. Then the pseudo regs are ordered by priority - and assigned hard regs in priority order. */ - -#include <stdio.h> -#include "config.h" -#include "rtl.h" -#include "hard-reg-set.h" -#include "regs.h" -#include "flags.h" - -/* Vector mapping INSN_UIDs to suids. - The suids are like uids but increase monotonically always. - We use them to see whether a subroutine call came - between a variable's birth and its death. */ - -static int *uid_suid; - -/* Get the suid of an insn. */ - -#define INSN_SUID(INSN) (uid_suid[INSN_UID (INSN)]) - -/* Record the suid of the last CALL_INSN - so we can tell whether a pseudo reg crosses any calls. */ - -static int last_call_suid; - -/* Record the suid of the last JUMP_INSN - so we can tell whether a pseudo reg crosses any jumps. */ - -static int last_jump_suid; - -/* Record the suid of the last CODE_LABEL - so we can tell whether a pseudo reg crosses any labels. */ - -static int last_label_suid; - -/* Element N is suid of insn where life span of pseudo reg N ends. - Element is 0 if register N has not been seen yet on backward scan. */ - -static int *reg_where_dead; - -/* Element N is suid of insn where life span of pseudo reg N begins. */ - -static int *reg_where_born; - -/* Element N is 1 if pseudo reg N lives across labels or jumps. */ - -static char *reg_crosses_blocks; - -/* Numbers of pseudo-regs to be allocated, highest priority first. */ - -static int *reg_order; - -/* Indexed by reg number (hard or pseudo), nonzero if register is live - at the current point in the instruction stream. */ - -static char *regs_live; - -/* Indexed by insn's suid, the set of hard regs live after that insn. */ - -static HARD_REG_SET *after_insn_hard_regs; - -/* Record that hard reg REGNO is live after insn INSN. */ - -#define MARK_LIVE_AFTER(INSN,REGNO) \ - SET_HARD_REG_BIT (after_insn_hard_regs[INSN_SUID (INSN)], (REGNO)) - -static void stupid_mark_refs (); -static int stupid_reg_compare (); -static int stupid_find_reg (); - -/* Stupid life analysis is for the case where only variables declared - `register' go in registers. For this case, we mark all - pseudo-registers that belong to register variables as - dying in the last instruction of the function, and all other - pseudo registers as dying in the last place they are referenced. - Hard registers are marked as dying in the last reference before - the end or before each store into them. */ - -void -stupid_life_analysis (f, nregs, file) - rtx f; - int nregs; - FILE *file; -{ - register int i; - register rtx last, insn; - int max_uid; - - bzero (regs_ever_live, sizeof regs_ever_live); - - regs_live = (char *) alloca (nregs); - - /* First find the last real insn, and count the number of insns, - and assign insns their suids. */ - - for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) - if (INSN_UID (insn) > i) - i = INSN_UID (insn); - - max_uid = i + 1; - uid_suid = (int *) alloca ((i + 1) * sizeof (int)); - - /* Compute the mapping from uids to suids. - Suids are numbers assigned to insns, like uids, - except that suids increase monotonically through the code. */ - - last = 0; /* In case of empty function body */ - for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) - { - if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN - || GET_CODE (insn) == JUMP_INSN) - last = insn; - INSN_SUID (insn) = ++i; - } - - last_call_suid = i + 1; - last_jump_suid = i + 1; - last_label_suid = i + 1; - - max_regno = nregs; - - /* Allocate tables to record info about regs. */ - - reg_where_dead = (int *) alloca (nregs * sizeof (int)); - bzero (reg_where_dead, nregs * sizeof (int)); - - reg_where_born = (int *) alloca (nregs * sizeof (int)); - bzero (reg_where_born, nregs * sizeof (int)); - - reg_crosses_blocks = (char *) alloca (nregs); - bzero (reg_crosses_blocks, nregs); - - reg_order = (int *) alloca (nregs * sizeof (int)); - bzero (reg_order, nregs * sizeof (int)); - - reg_renumber = (short *) oballoc (nregs * sizeof (short)); - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - reg_renumber[i] = i; - - for (i = FIRST_VIRTUAL_REGISTER; i <= LAST_VIRTUAL_REGISTER; i++) - reg_renumber[i] = -1; - - after_insn_hard_regs = (HARD_REG_SET *) alloca (max_uid * sizeof (HARD_REG_SET)); - bzero (after_insn_hard_regs, max_uid * sizeof (HARD_REG_SET)); - - /* Allocate and zero out many data structures - that will record the data from lifetime analysis. */ - - allocate_for_life_analysis (); - - for (i = 0; i < max_regno; i++) - { - reg_n_deaths[i] = 1; - } - - bzero (regs_live, nregs); - - /* Find where each pseudo register is born and dies, - by scanning all insns from the end to the start - and noting all mentions of the registers. - - Also find where each hard register is live - and record that info in after_insn_hard_regs. - regs_live[I] is 1 if hard reg I is live - at the current point in the scan. */ - - for (insn = last; insn; insn = PREV_INSN (insn)) - { - register HARD_REG_SET *p = after_insn_hard_regs + INSN_SUID (insn); - - /* Copy the info in regs_live - into the element of after_insn_hard_regs - for the current position in the rtl code. */ - - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - if (regs_live[i]) - SET_HARD_REG_BIT (*p, i); - - /* Mark all call-clobbered regs as live after each call insn - so that a pseudo whose life span includes this insn - will not go in one of them. - Then mark those regs as all dead for the continuing scan - of the insns before the call. */ - - if (GET_CODE (insn) == CALL_INSN) - { - last_call_suid = INSN_SUID (insn); - IOR_HARD_REG_SET (after_insn_hard_regs[last_call_suid], - call_used_reg_set); - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - if (call_used_regs[i]) - regs_live[i] = 0; - } - - if (GET_CODE (insn) == JUMP_INSN) - last_jump_suid = INSN_SUID (insn); - - if (GET_CODE (insn) == CODE_LABEL) - last_label_suid = INSN_SUID (insn); - - /* Update which hard regs are currently live - and also the birth and death suids of pseudo regs - based on the pattern of this insn. */ - - if (GET_CODE (insn) == INSN - || GET_CODE (insn) == CALL_INSN - || GET_CODE (insn) == JUMP_INSN) - { - stupid_mark_refs (PATTERN (insn), insn); - } - } - - /* Now decide the order in which to allocate the pseudo registers. */ - - for (i = LAST_VIRTUAL_REGISTER + 1; i < max_regno; i++) - reg_order[i] = i; - - qsort (®_order[LAST_VIRTUAL_REGISTER + 1], - max_regno - LAST_VIRTUAL_REGISTER - 1, sizeof (int), - stupid_reg_compare); - - /* Now, in that order, try to find hard registers for those pseudo regs. */ - - for (i = LAST_VIRTUAL_REGISTER + 1; i < max_regno; i++) - { - register int r = reg_order[i]; - enum reg_class class; - - /* Some regnos disappear from the rtl. Ignore them to avoid crash. */ - if (regno_reg_rtx[r] == 0) - continue; - - /* Now find the best hard-register class for this pseudo register */ - if (N_REG_CLASSES > 1) - { - class = reg_preferred_class (r); - - reg_renumber[r] = stupid_find_reg (reg_n_calls_crossed[r], class, - PSEUDO_REGNO_MODE (r), - reg_where_born[r], - reg_where_dead[r], - reg_crosses_blocks[r]); - } - else - reg_renumber[r] = -1; - - /* If no reg available in that class, - try any reg. */ - if (reg_renumber[r] == -1) - reg_renumber[r] = stupid_find_reg (reg_n_calls_crossed[r], - GENERAL_REGS, - PSEUDO_REGNO_MODE (r), - reg_where_born[r], - reg_where_dead[r], - reg_crosses_blocks[r]); - } - - if (file) - dump_flow_info (file); -} - -/* Comparison function for qsort. - Returns -1 (1) if register *R1P is higher priority than *R2P. */ - -static int -stupid_reg_compare (r1p, r2p) - int *r1p, *r2p; -{ - register int r1 = *r1p, r2 = *r2p; - register int len1 = reg_where_dead[r1] - reg_where_born[r1]; - register int len2 = reg_where_dead[r2] - reg_where_born[r2]; - int tem; - - tem = len2 - len1; - if (tem != 0) return tem; - - tem = reg_n_refs[r1] - reg_n_refs[r2]; - if (tem != 0) return tem; - - /* If regs are equally good, sort by regno, - so that the results of qsort leave nothing to chance. */ - return r1 - r2; -} - -/* Find a block of SIZE words of hard registers in reg_class CLASS - that can hold a value of machine-mode MODE - (but actually we test only the first of the block for holding MODE) - currently free from after insn whose suid is BIRTH - through the insn whose suid is DEATH, - and return the number of the first of them. - Return -1 if such a block cannot be found. - - If CALL_PRESERVED is nonzero, insist on registers preserved - over subroutine calls, and return -1 if cannot find such. - If CROSSES_BLOCKS is nonzero, reject registers for which - PRESERVE_DEATH_INFO_REGNO_P is true. */ - -static int -stupid_find_reg (call_preserved, class, mode, - born_insn, dead_insn, crosses_blocks) - int call_preserved; - enum reg_class class; - enum machine_mode mode; - int born_insn, dead_insn; - int crosses_blocks; -{ - register int i, ins; -#ifdef HARD_REG_SET - register /* Declare them register if they are scalars. */ -#endif - HARD_REG_SET used, this_reg; -#ifdef ELIMINABLE_REGS - static struct {int from, to; } eliminables[] = ELIMINABLE_REGS; -#endif - - COPY_HARD_REG_SET (used, - call_preserved ? call_used_reg_set : fixed_reg_set); - -#ifdef ELIMINABLE_REGS - for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++) - SET_HARD_REG_BIT (used, eliminables[i].from); -#else - SET_HARD_REG_BIT (used, FRAME_POINTER_REGNUM); -#endif - - for (ins = born_insn; ins < dead_insn; ins++) - IOR_HARD_REG_SET (used, after_insn_hard_regs[ins]); - - IOR_COMPL_HARD_REG_SET (used, reg_class_contents[(int) class]); - - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - { -#ifdef REG_ALLOC_ORDER - int regno = reg_alloc_order[i]; -#else - int regno = i; -#endif - - /* If we need reasonable death info on this hard reg, - don't use it for anything whose life spans a label or a jump. */ -#ifdef PRESERVE_DEATH_INFO_REGNO_P - if (PRESERVE_DEATH_INFO_REGNO_P (regno) - && crosses_blocks) - continue; -#endif - /* If a register has screwy overlap problems, - don't use it at all if not optimizing. - Actually this is only for the 387 stack register, - and it's because subsequent code won't work. */ -#ifdef OVERLAPPING_REGNO_P - if (OVERLAPPING_REGNO_P (regno)) - continue; -#endif - - if (! TEST_HARD_REG_BIT (used, regno) - && HARD_REGNO_MODE_OK (regno, mode)) - { - register int j; - register int size1 = HARD_REGNO_NREGS (regno, mode); - for (j = 1; j < size1 && ! TEST_HARD_REG_BIT (used, regno + j); j++); - if (j == size1) - { - CLEAR_HARD_REG_SET (this_reg); - while (--j >= 0) - SET_HARD_REG_BIT (this_reg, regno + j); - for (ins = born_insn; ins < dead_insn; ins++) - { - IOR_HARD_REG_SET (after_insn_hard_regs[ins], this_reg); - } - return regno; - } -#ifndef REG_ALLOC_ORDER - i += j; /* Skip starting points we know will lose */ -#endif - } - } - return -1; -} - -/* Walk X, noting all assignments and references to registers - and recording what they imply about life spans. - INSN is the current insn, supplied so we can find its suid. */ - -static void -stupid_mark_refs (x, insn) - rtx x, insn; -{ - register RTX_CODE code = GET_CODE (x); - register char *fmt; - register int regno, i; - - if (code == SET || code == CLOBBER) - { - if (SET_DEST (x) != 0 && GET_CODE (SET_DEST (x)) == REG) - { - /* Register is being assigned. */ - regno = REGNO (SET_DEST (x)); - - /* For hard regs, update the where-live info. */ - if (regno < FIRST_PSEUDO_REGISTER) - { - register int j - = HARD_REGNO_NREGS (regno, GET_MODE (SET_DEST (x))); - while (--j >= 0) - { - regs_ever_live[regno+j] = 1; - regs_live[regno+j] = 0; - /* The following line is for unused outputs; - they do get stored even though never used again. */ - MARK_LIVE_AFTER (insn, regno); - /* When a hard reg is clobbered, mark it in use - just before this insn, so it is live all through. */ - if (code == CLOBBER && INSN_SUID (insn) > 0) - SET_HARD_REG_BIT (after_insn_hard_regs[INSN_SUID (insn) - 1], - regno); - } - } - /* For pseudo regs, record where born, where dead, number of - times used, and whether live across a call. */ - else - { - /* Update the life-interval bounds of this pseudo reg. */ - - /* When a pseudo-reg is CLOBBERed, it is born just before - the clobbering insn. When setting, just after. */ - int where_born = INSN_SUID (insn) - (code == CLOBBER); - - reg_where_born[regno] = where_born; - /* The reg must live at least one insn even - in it is never again used--because it has to go - in SOME hard reg. Mark it as dying after the current - insn so that it will conflict with any other outputs of - this insn. */ - if (reg_where_dead[regno] < where_born + 2) - reg_where_dead[regno] = where_born + 2; - - /* Count the refs of this reg. */ - reg_n_refs[regno]++; - - if (last_call_suid < reg_where_dead[regno]) - reg_n_calls_crossed[regno] += 1; - if (last_jump_suid < reg_where_dead[regno] - || last_label_suid < reg_where_dead[regno]) - reg_crosses_blocks[regno] = 1; - } - } - /* Record references from the value being set, - or from addresses in the place being set if that's not a reg. - If setting a SUBREG, we treat the entire reg as *used*. */ - if (code == SET) - { - stupid_mark_refs (SET_SRC (x), insn); - if (GET_CODE (SET_DEST (x)) != REG) - stupid_mark_refs (SET_DEST (x), insn); - } - return; - } - - /* Register value being used, not set. */ - - if (code == REG) - { - regno = REGNO (x); - if (regno < FIRST_PSEUDO_REGISTER) - { - /* Hard reg: mark it live for continuing scan of previous insns. */ - register int j = HARD_REGNO_NREGS (regno, GET_MODE (x)); - while (--j >= 0) - { - regs_ever_live[regno+j] = 1; - regs_live[regno+j] = 1; - } - } - else - { - /* Pseudo reg: record first use, last use and number of uses. */ - - reg_where_born[regno] = INSN_SUID (insn); - reg_n_refs[regno]++; - if (regs_live[regno] == 0) - { - regs_live[regno] = 1; - reg_where_dead[regno] = INSN_SUID (insn); - } - } - return; - } - - /* Recursive scan of all other rtx's. */ - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - if (fmt[i] == 'e') - stupid_mark_refs (XEXP (x, i), insn); - if (fmt[i] == 'E') - { - register int j; - for (j = XVECLEN (x, i) - 1; j >= 0; j--) - stupid_mark_refs (XVECEXP (x, i, j), insn); - } - } -} |