+++ /dev/null
-/* Static Single Assignment conversion routines for the GNU compiler.
- Copyright (C) 2000, 2001, 2002 Free Software Foundation, Inc.
-
-This file is part of GCC.
-
-GCC 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.
-
-GCC 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 GCC; see the file COPYING. If not, write to the Free
-Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-02111-1307, USA. */
-
-/* References:
-
- Building an Optimizing Compiler
- Robert Morgan
- Butterworth-Heinemann, 1998
-
- Static Single Assignment Construction
- Preston Briggs, Tim Harvey, Taylor Simpson
- Technical Report, Rice University, 1995
- ftp://ftp.cs.rice.edu/public/preston/optimizer/SSA.ps.gz. */
-
-#include "config.h"
-#include "system.h"
-
-#include "rtl.h"
-#include "expr.h"
-#include "varray.h"
-#include "partition.h"
-#include "sbitmap.h"
-#include "hashtab.h"
-#include "regs.h"
-#include "hard-reg-set.h"
-#include "flags.h"
-#include "function.h"
-#include "real.h"
-#include "insn-config.h"
-#include "recog.h"
-#include "basic-block.h"
-#include "output.h"
-#include "ssa.h"
-
-/* TODO:
-
- Handle subregs better, maybe. For now, if a reg that's set in a
- subreg expression is duplicated going into SSA form, an extra copy
- is inserted first that copies the entire reg into the duplicate, so
- that the other bits are preserved. This isn't strictly SSA, since
- at least part of the reg is assigned in more than one place (though
- they are adjacent).
-
- ??? What to do about strict_low_part. Probably I'll have to split
- them out of their current instructions first thing.
-
- Actually the best solution may be to have a kind of "mid-level rtl"
- in which the RTL encodes exactly what we want, without exposing a
- lot of niggling processor details. At some later point we lower
- the representation, calling back into optabs to finish any necessary
- expansion. */
-
-/* All pseudo-registers and select hard registers are converted to SSA
- form. When converting out of SSA, these select hard registers are
- guaranteed to be mapped to their original register number. Each
- machine's .h file should define CONVERT_HARD_REGISTER_TO_SSA_P
- indicating which hard registers should be converted.
-
- When converting out of SSA, temporaries for all registers are
- partitioned. The partition is checked to ensure that all uses of
- the same hard register in the same machine mode are in the same
- class. */
-
-/* If conservative_reg_partition is non-zero, use a conservative
- register partitioning algorithm (which leaves more regs after
- emerging from SSA) instead of the coalescing one. This is being
- left in for a limited time only, as a debugging tool until the
- coalescing algorithm is validated. */
-
-static int conservative_reg_partition;
-
-/* This flag is set when the CFG is in SSA form. */
-int in_ssa_form = 0;
-
-/* Element I is the single instruction that sets register I. */
-varray_type ssa_definition;
-
-/* Element I-PSEUDO is the normal register that originated the ssa
- register in question. */
-varray_type ssa_rename_from;
-
-/* Element I is the normal register that originated the ssa
- register in question.
-
- A hash table stores the (register, rtl) pairs. These are each
- xmalloc'ed and deleted when the hash table is destroyed. */
-htab_t ssa_rename_from_ht;
-
-/* The running target ssa register for a given pseudo register.
- (Pseudo registers appear in only one mode.) */
-static rtx *ssa_rename_to_pseudo;
-/* Similar, but for hard registers. A hard register can appear in
- many modes, so we store an equivalent pseudo for each of the
- modes. */
-static rtx ssa_rename_to_hard[FIRST_PSEUDO_REGISTER][NUM_MACHINE_MODES];
-
-/* ssa_rename_from maps pseudo registers to the original corresponding
- RTL. It is implemented as using a hash table. */
-
-typedef struct {
- unsigned int reg;
- rtx original;
-} ssa_rename_from_pair;
-
-struct ssa_rename_from_hash_table_data {
- sbitmap canonical_elements;
- partition reg_partition;
-};
-
-static void ssa_rename_from_initialize
- PARAMS ((void));
-static rtx ssa_rename_from_lookup
- PARAMS ((int reg));
-static unsigned int original_register
- PARAMS ((unsigned int regno));
-static void ssa_rename_from_insert
- PARAMS ((unsigned int reg, rtx r));
-static void ssa_rename_from_free
- PARAMS ((void));
-typedef int (*srf_trav) PARAMS ((int regno, rtx r, sbitmap canonical_elements, partition reg_partition));
-static void ssa_rename_from_traverse
- PARAMS ((htab_trav callback_function, sbitmap canonical_elements, partition reg_partition));
-/*static Avoid warnign message. */ void ssa_rename_from_print
- PARAMS ((void));
-static int ssa_rename_from_print_1
- PARAMS ((void **slot, void *data));
-static hashval_t ssa_rename_from_hash_function
- PARAMS ((const void * srfp));
-static int ssa_rename_from_equal
- PARAMS ((const void *srfp1, const void *srfp2));
-static void ssa_rename_from_delete
- PARAMS ((void *srfp));
-
-static rtx ssa_rename_to_lookup
- PARAMS ((rtx reg));
-static void ssa_rename_to_insert
- PARAMS ((rtx reg, rtx r));
-
-/* The number of registers that were live on entry to the SSA routines. */
-static unsigned int ssa_max_reg_num;
-
-/* Local function prototypes. */
-
-struct rename_context;
-
-static inline rtx * phi_alternative
- PARAMS ((rtx, int));
-static void compute_dominance_frontiers_1
- PARAMS ((sbitmap *frontiers, int *idom, int bb, sbitmap done));
-static void find_evaluations_1
- PARAMS ((rtx dest, rtx set, void *data));
-static void find_evaluations
- PARAMS ((sbitmap *evals, int nregs));
-static void compute_iterated_dominance_frontiers
- PARAMS ((sbitmap *idfs, sbitmap *frontiers, sbitmap *evals, int nregs));
-static void insert_phi_node
- PARAMS ((int regno, int b));
-static void insert_phi_nodes
- PARAMS ((sbitmap *idfs, sbitmap *evals, int nregs));
-static void create_delayed_rename
- PARAMS ((struct rename_context *, rtx *));
-static void apply_delayed_renames
- PARAMS ((struct rename_context *));
-static int rename_insn_1
- PARAMS ((rtx *ptr, void *data));
-static void rename_block
- PARAMS ((int b, int *idom));
-static void rename_registers
- PARAMS ((int nregs, int *idom));
-
-static inline int ephi_add_node
- PARAMS ((rtx reg, rtx *nodes, int *n_nodes));
-static int * ephi_forward
- PARAMS ((int t, sbitmap visited, sbitmap *succ, int *tstack));
-static void ephi_backward
- PARAMS ((int t, sbitmap visited, sbitmap *pred, rtx *nodes));
-static void ephi_create
- PARAMS ((int t, sbitmap visited, sbitmap *pred, sbitmap *succ, rtx *nodes));
-static void eliminate_phi
- PARAMS ((edge e, partition reg_partition));
-static int make_regs_equivalent_over_bad_edges
- PARAMS ((int bb, partition reg_partition));
-
-/* These are used only in the conservative register partitioning
- algorithms. */
-static int make_equivalent_phi_alternatives_equivalent
- PARAMS ((int bb, partition reg_partition));
-static partition compute_conservative_reg_partition
- PARAMS ((void));
-static int record_canonical_element_1
- PARAMS ((void **srfp, void *data));
-static int check_hard_regs_in_partition
- PARAMS ((partition reg_partition));
-static int rename_equivalent_regs_in_insn
- PARAMS ((rtx *ptr, void *data));
-
-/* These are used in the register coalescing algorithm. */
-static int coalesce_if_unconflicting
- PARAMS ((partition p, conflict_graph conflicts, int reg1, int reg2));
-static int coalesce_regs_in_copies
- PARAMS ((basic_block bb, partition p, conflict_graph conflicts));
-static int coalesce_reg_in_phi
- PARAMS ((rtx, int dest_regno, int src_regno, void *data));
-static int coalesce_regs_in_successor_phi_nodes
- PARAMS ((basic_block bb, partition p, conflict_graph conflicts));
-static partition compute_coalesced_reg_partition
- PARAMS ((void));
-static int mark_reg_in_phi
- PARAMS ((rtx *ptr, void *data));
-static void mark_phi_and_copy_regs
- PARAMS ((regset phi_set));
-
-static int rename_equivalent_regs_in_insn
- PARAMS ((rtx *ptr, void *data));
-static void rename_equivalent_regs
- PARAMS ((partition reg_partition));
-
-/* Deal with hard registers. */
-static int conflicting_hard_regs_p
- PARAMS ((int reg1, int reg2));
-
-/* ssa_rename_to maps registers and machine modes to SSA pseudo registers. */
-
-/* Find the register associated with REG in the indicated mode. */
-
-static rtx
-ssa_rename_to_lookup (reg)
- rtx reg;
-{
- if (!HARD_REGISTER_P (reg))
- return ssa_rename_to_pseudo[REGNO (reg) - FIRST_PSEUDO_REGISTER];
- else
- return ssa_rename_to_hard[REGNO (reg)][GET_MODE (reg)];
-}
-
-/* Store a new value mapping REG to R in ssa_rename_to. */
-
-static void
-ssa_rename_to_insert(reg, r)
- rtx reg;
- rtx r;
-{
- if (!HARD_REGISTER_P (reg))
- ssa_rename_to_pseudo[REGNO (reg) - FIRST_PSEUDO_REGISTER] = r;
- else
- ssa_rename_to_hard[REGNO (reg)][GET_MODE (reg)] = r;
-}
-
-/* Prepare ssa_rename_from for use. */
-
-static void
-ssa_rename_from_initialize ()
-{
- /* We use an arbitrary initial hash table size of 64. */
- ssa_rename_from_ht = htab_create (64,
- &ssa_rename_from_hash_function,
- &ssa_rename_from_equal,
- &ssa_rename_from_delete);
-}
-
-/* Find the REG entry in ssa_rename_from. Return NULL_RTX if no entry is
- found. */
-
-static rtx
-ssa_rename_from_lookup (reg)
- int reg;
-{
- ssa_rename_from_pair srfp;
- ssa_rename_from_pair *answer;
- srfp.reg = reg;
- srfp.original = NULL_RTX;
- answer = (ssa_rename_from_pair *)
- htab_find_with_hash (ssa_rename_from_ht, (void *) &srfp, reg);
- return (answer == 0 ? NULL_RTX : answer->original);
-}
-
-/* Find the number of the original register specified by REGNO. If
- the register is a pseudo, return the original register's number.
- Otherwise, return this register number REGNO. */
-
-static unsigned int
-original_register (regno)
- unsigned int regno;
-{
- rtx original_rtx = ssa_rename_from_lookup (regno);
- return original_rtx != NULL_RTX ? REGNO (original_rtx) : regno;
-}
-
-/* Add mapping from R to REG to ssa_rename_from even if already present. */
-
-static void
-ssa_rename_from_insert (reg, r)
- unsigned int reg;
- rtx r;
-{
- void **slot;
- ssa_rename_from_pair *srfp = xmalloc (sizeof (ssa_rename_from_pair));
- srfp->reg = reg;
- srfp->original = r;
- slot = htab_find_slot_with_hash (ssa_rename_from_ht, (const void *) srfp,
- reg, INSERT);
- if (*slot != 0)
- free ((void *) *slot);
- *slot = srfp;
-}
-
-/* Apply the CALLBACK_FUNCTION to each element in ssa_rename_from.
- CANONICAL_ELEMENTS and REG_PARTITION pass data needed by the only
- current use of this function. */
-
-static void
-ssa_rename_from_traverse (callback_function,
- canonical_elements, reg_partition)
- htab_trav callback_function;
- sbitmap canonical_elements;
- partition reg_partition;
-{
- struct ssa_rename_from_hash_table_data srfhd;
- srfhd.canonical_elements = canonical_elements;
- srfhd.reg_partition = reg_partition;
- htab_traverse (ssa_rename_from_ht, callback_function, (void *) &srfhd);
-}
-
-/* Destroy ssa_rename_from. */
-
-static void
-ssa_rename_from_free ()
-{
- htab_delete (ssa_rename_from_ht);
-}
-
-/* Print the contents of ssa_rename_from. */
-
-/* static Avoid erroneous error message. */
-void
-ssa_rename_from_print ()
-{
- printf ("ssa_rename_from's hash table contents:\n");
- htab_traverse (ssa_rename_from_ht, &ssa_rename_from_print_1, NULL);
-}
-
-/* Print the contents of the hash table entry SLOT, passing the unused
- sttribute DATA. Used as a callback function with htab_traverse (). */
-
-static int
-ssa_rename_from_print_1 (slot, data)
- void **slot;
- void *data ATTRIBUTE_UNUSED;
-{
- ssa_rename_from_pair * p = *slot;
- printf ("ssa_rename_from maps pseudo %i to original %i.\n",
- p->reg, REGNO (p->original));
- return 1;
-}
-
-/* Given a hash entry SRFP, yield a hash value. */
-
-static hashval_t
-ssa_rename_from_hash_function (srfp)
- const void *srfp;
-{
- return ((const ssa_rename_from_pair *) srfp)->reg;
-}
-
-/* Test whether two hash table entries SRFP1 and SRFP2 are equal. */
-
-static int
-ssa_rename_from_equal (srfp1, srfp2)
- const void *srfp1;
- const void *srfp2;
-{
- return ssa_rename_from_hash_function (srfp1) ==
- ssa_rename_from_hash_function (srfp2);
-}
-
-/* Delete the hash table entry SRFP. */
-
-static void
-ssa_rename_from_delete (srfp)
- void *srfp;
-{
- free (srfp);
-}
-
-/* Given the SET of a PHI node, return the address of the alternative
- for predecessor block C. */
-
-static inline rtx *
-phi_alternative (set, c)
- rtx set;
- int c;
-{
- rtvec phi_vec = XVEC (SET_SRC (set), 0);
- int v;
-
- for (v = GET_NUM_ELEM (phi_vec) - 2; v >= 0; v -= 2)
- if (INTVAL (RTVEC_ELT (phi_vec, v + 1)) == c)
- return &RTVEC_ELT (phi_vec, v);
-
- return NULL;
-}
-
-/* Given the SET of a phi node, remove the alternative for predecessor
- block C. Return non-zero on success, or zero if no alternative is
- found for C. */
-
-int
-remove_phi_alternative (set, block)
- rtx set;
- basic_block block;
-{
- rtvec phi_vec = XVEC (SET_SRC (set), 0);
- int num_elem = GET_NUM_ELEM (phi_vec);
- int v, c;
-
- c = block->index;
- for (v = num_elem - 2; v >= 0; v -= 2)
- if (INTVAL (RTVEC_ELT (phi_vec, v + 1)) == c)
- {
- if (v < num_elem - 2)
- {
- RTVEC_ELT (phi_vec, v) = RTVEC_ELT (phi_vec, num_elem - 2);
- RTVEC_ELT (phi_vec, v + 1) = RTVEC_ELT (phi_vec, num_elem - 1);
- }
- PUT_NUM_ELEM (phi_vec, num_elem - 2);
- return 1;
- }
-
- return 0;
-}
-
-/* For all registers, find all blocks in which they are set.
-
- This is the transform of what would be local kill information that
- we ought to be getting from flow. */
-
-static sbitmap *fe_evals;
-static int fe_current_bb;
-
-static void
-find_evaluations_1 (dest, set, data)
- rtx dest;
- rtx set ATTRIBUTE_UNUSED;
- void *data ATTRIBUTE_UNUSED;
-{
- if (GET_CODE (dest) == REG
- && CONVERT_REGISTER_TO_SSA_P (REGNO (dest)))
- SET_BIT (fe_evals[REGNO (dest)], fe_current_bb);
-}
-
-static void
-find_evaluations (evals, nregs)
- sbitmap *evals;
- int nregs;
-{
- int bb;
-
- sbitmap_vector_zero (evals, nregs);
- fe_evals = evals;
-
- for (bb = n_basic_blocks; --bb >= 0; )
- {
- rtx p, last;
-
- fe_current_bb = bb;
- p = BLOCK_HEAD (bb);
- last = BLOCK_END (bb);
- while (1)
- {
- if (INSN_P (p))
- note_stores (PATTERN (p), find_evaluations_1, NULL);
-
- if (p == last)
- break;
- p = NEXT_INSN (p);
- }
- }
-}
-
-/* Computing the Dominance Frontier:
-
- As decribed in Morgan, section 3.5, this may be done simply by
- walking the dominator tree bottom-up, computing the frontier for
- the children before the parent. When considering a block B,
- there are two cases:
-
- (1) A flow graph edge leaving B that does not lead to a child
- of B in the dominator tree must be a block that is either equal
- to B or not dominated by B. Such blocks belong in the frontier
- of B.
-
- (2) Consider a block X in the frontier of one of the children C
- of B. If X is not equal to B and is not dominated by B, it
- is in the frontier of B.
-*/
-
-static void
-compute_dominance_frontiers_1 (frontiers, idom, bb, done)
- sbitmap *frontiers;
- int *idom;
- int bb;
- sbitmap done;
-{
- basic_block b = BASIC_BLOCK (bb);
- edge e;
- int c;
-
- SET_BIT (done, bb);
- sbitmap_zero (frontiers[bb]);
-
- /* Do the frontier of the children first. Not all children in the
- dominator tree (blocks dominated by this one) are children in the
- CFG, so check all blocks. */
- for (c = 0; c < n_basic_blocks; ++c)
- if (idom[c] == bb && ! TEST_BIT (done, c))
- compute_dominance_frontiers_1 (frontiers, idom, c, done);
-
- /* Find blocks conforming to rule (1) above. */
- for (e = b->succ; e; e = e->succ_next)
- {
- if (e->dest == EXIT_BLOCK_PTR)
- continue;
- if (idom[e->dest->index] != bb)
- SET_BIT (frontiers[bb], e->dest->index);
- }
-
- /* Find blocks conforming to rule (2). */
- for (c = 0; c < n_basic_blocks; ++c)
- if (idom[c] == bb)
- {
- int x;
- EXECUTE_IF_SET_IN_SBITMAP (frontiers[c], 0, x,
- {
- if (idom[x] != bb)
- SET_BIT (frontiers[bb], x);
- });
- }
-}
-
-void
-compute_dominance_frontiers (frontiers, idom)
- sbitmap *frontiers;
- int *idom;
-{
- sbitmap done = sbitmap_alloc (n_basic_blocks);
- sbitmap_zero (done);
-
- compute_dominance_frontiers_1 (frontiers, idom, 0, done);
-
- sbitmap_free (done);
-}
-
-/* Computing the Iterated Dominance Frontier:
-
- This is the set of merge points for a given register.
-
- This is not particularly intuitive. See section 7.1 of Morgan, in
- particular figures 7.3 and 7.4 and the immediately surrounding text.
-*/
-
-static void
-compute_iterated_dominance_frontiers (idfs, frontiers, evals, nregs)
- sbitmap *idfs;
- sbitmap *frontiers;
- sbitmap *evals;
- int nregs;
-{
- sbitmap worklist;
- int reg, passes = 0;
-
- worklist = sbitmap_alloc (n_basic_blocks);
-
- for (reg = 0; reg < nregs; ++reg)
- {
- sbitmap idf = idfs[reg];
- int b, changed;
-
- /* Start the iterative process by considering those blocks that
- evaluate REG. We'll add their dominance frontiers to the
- IDF, and then consider the blocks we just added. */
- sbitmap_copy (worklist, evals[reg]);
-
- /* Morgan's algorithm is incorrect here. Blocks that evaluate
- REG aren't necessarily in REG's IDF. Start with an empty IDF. */
- sbitmap_zero (idf);
-
- /* Iterate until the worklist is empty. */
- do
- {
- changed = 0;
- passes++;
- EXECUTE_IF_SET_IN_SBITMAP (worklist, 0, b,
- {
- RESET_BIT (worklist, b);
- /* For each block on the worklist, add to the IDF all
- blocks on its dominance frontier that aren't already
- on the IDF. Every block that's added is also added
- to the worklist. */
- sbitmap_union_of_diff (worklist, worklist, frontiers[b], idf);
- sbitmap_a_or_b (idf, idf, frontiers[b]);
- changed = 1;
- });
- }
- while (changed);
- }
-
- sbitmap_free (worklist);
-
- if (rtl_dump_file)
- {
- fprintf (rtl_dump_file,
- "Iterated dominance frontier: %d passes on %d regs.\n",
- passes, nregs);
- }
-}
-
-/* Insert the phi nodes. */
-
-static void
-insert_phi_node (regno, bb)
- int regno, bb;
-{
- basic_block b = BASIC_BLOCK (bb);
- edge e;
- int npred, i;
- rtvec vec;
- rtx phi, reg;
- rtx insn;
- int end_p;
-
- /* Find out how many predecessors there are. */
- for (e = b->pred, npred = 0; e; e = e->pred_next)
- if (e->src != ENTRY_BLOCK_PTR)
- npred++;
-
- /* If this block has no "interesting" preds, then there is nothing to
- do. Consider a block that only has the entry block as a pred. */
- if (npred == 0)
- return;
-
- /* This is the register to which the phi function will be assigned. */
- reg = regno_reg_rtx[regno];
-
- /* Construct the arguments to the PHI node. The use of pc_rtx is just
- a placeholder; we'll insert the proper value in rename_registers. */
- vec = rtvec_alloc (npred * 2);
- for (e = b->pred, i = 0; e ; e = e->pred_next, i += 2)
- if (e->src != ENTRY_BLOCK_PTR)
- {
- RTVEC_ELT (vec, i + 0) = pc_rtx;
- RTVEC_ELT (vec, i + 1) = GEN_INT (e->src->index);
- }
-
- phi = gen_rtx_PHI (VOIDmode, vec);
- phi = gen_rtx_SET (VOIDmode, reg, phi);
-
- insn = first_insn_after_basic_block_note (b);
- end_p = PREV_INSN (insn) == b->end;
- emit_insn_before (phi, insn);
- if (end_p)
- b->end = PREV_INSN (insn);
-}
-
-static void
-insert_phi_nodes (idfs, evals, nregs)
- sbitmap *idfs;
- sbitmap *evals ATTRIBUTE_UNUSED;
- int nregs;
-{
- int reg;
-
- for (reg = 0; reg < nregs; ++reg)
- if (CONVERT_REGISTER_TO_SSA_P (reg))
- {
- int b;
- EXECUTE_IF_SET_IN_SBITMAP (idfs[reg], 0, b,
- {
- if (REGNO_REG_SET_P (BASIC_BLOCK (b)->global_live_at_start, reg))
- insert_phi_node (reg, b);
- });
- }
-}
-
-/* Rename the registers to conform to SSA.
-
- This is essentially the algorithm presented in Figure 7.8 of Morgan,
- with a few changes to reduce pattern search time in favour of a bit
- more memory usage. */
-
-/* One of these is created for each set. It will live in a list local
- to its basic block for the duration of that block's processing. */
-struct rename_set_data
-{
- struct rename_set_data *next;
- /* This is the SET_DEST of the (first) SET that sets the REG. */
- rtx *reg_loc;
- /* This is what used to be at *REG_LOC. */
- rtx old_reg;
- /* This is the REG that will replace OLD_REG. It's set only
- when the rename data is moved onto the DONE_RENAMES queue. */
- rtx new_reg;
- /* This is what to restore ssa_rename_to_lookup (old_reg) to. It is
- usually the previous contents of ssa_rename_to_lookup (old_reg). */
- rtx prev_reg;
- /* This is the insn that contains all the SETs of the REG. */
- rtx set_insn;
-};
-
-/* This struct is used to pass information to callback functions while
- renaming registers. */
-struct rename_context
-{
- struct rename_set_data *new_renames;
- struct rename_set_data *done_renames;
- rtx current_insn;
-};
-
-/* Queue the rename of *REG_LOC. */
-static void
-create_delayed_rename (c, reg_loc)
- struct rename_context *c;
- rtx *reg_loc;
-{
- struct rename_set_data *r;
- r = (struct rename_set_data *) xmalloc (sizeof(*r));
-
- if (GET_CODE (*reg_loc) != REG
- || !CONVERT_REGISTER_TO_SSA_P (REGNO (*reg_loc)))
- abort ();
-
- r->reg_loc = reg_loc;
- r->old_reg = *reg_loc;
- r->prev_reg = ssa_rename_to_lookup(r->old_reg);
- r->set_insn = c->current_insn;
- r->next = c->new_renames;
- c->new_renames = r;
-}
-
-/* This is part of a rather ugly hack to allow the pre-ssa regno to be
- reused. If, during processing, a register has not yet been touched,
- ssa_rename_to[regno][machno] will be NULL. Now, in the course of pushing
- and popping values from ssa_rename_to, when we would ordinarily
- pop NULL back in, we pop RENAME_NO_RTX. We treat this exactly the
- same as NULL, except that it signals that the original regno has
- already been reused. */
-#define RENAME_NO_RTX pc_rtx
-
-/* Move all the entries from NEW_RENAMES onto DONE_RENAMES by
- applying all the renames on NEW_RENAMES. */
-
-static void
-apply_delayed_renames (c)
- struct rename_context *c;
-{
- struct rename_set_data *r;
- struct rename_set_data *last_r = NULL;
-
- for (r = c->new_renames; r != NULL; r = r->next)
- {
- int new_regno;
-
- /* Failure here means that someone has a PARALLEL that sets
- a register twice (bad!). */
- if (ssa_rename_to_lookup (r->old_reg) != r->prev_reg)
- abort ();
- /* Failure here means we have changed REG_LOC before applying
- the rename. */
- /* For the first set we come across, reuse the original regno. */
- if (r->prev_reg == NULL_RTX && !HARD_REGISTER_P (r->old_reg))
- {
- r->new_reg = r->old_reg;
- /* We want to restore RENAME_NO_RTX rather than NULL_RTX. */
- r->prev_reg = RENAME_NO_RTX;
- }
- else
- r->new_reg = gen_reg_rtx (GET_MODE (r->old_reg));
- new_regno = REGNO (r->new_reg);
- ssa_rename_to_insert (r->old_reg, r->new_reg);
-
- if (new_regno >= (int) ssa_definition->num_elements)
- {
- int new_limit = new_regno * 5 / 4;
- VARRAY_GROW (ssa_definition, new_limit);
- }
-
- VARRAY_RTX (ssa_definition, new_regno) = r->set_insn;
- ssa_rename_from_insert (new_regno, r->old_reg);
- last_r = r;
- }
- if (last_r != NULL)
- {
- last_r->next = c->done_renames;
- c->done_renames = c->new_renames;
- c->new_renames = NULL;
- }
-}
-
-/* Part one of the first step of rename_block, called through for_each_rtx.
- Mark pseudos that are set for later update. Transform uses of pseudos. */
-
-static int
-rename_insn_1 (ptr, data)
- rtx *ptr;
- void *data;
-{
- rtx x = *ptr;
- struct rename_context *context = data;
-
- if (x == NULL_RTX)
- return 0;
-
- switch (GET_CODE (x))
- {
- case SET:
- {
- rtx *destp = &SET_DEST (x);
- rtx dest = SET_DEST (x);
-
- /* An assignment to a paradoxical SUBREG does not read from
- the destination operand, and thus does not need to be
- wrapped into a SEQUENCE when translating into SSA form.
- We merely strip off the SUBREG and proceed normally for
- this case. */
- if (GET_CODE (dest) == SUBREG
- && (GET_MODE_SIZE (GET_MODE (dest))
- > GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest))))
- && GET_CODE (SUBREG_REG (dest)) == REG
- && CONVERT_REGISTER_TO_SSA_P (REGNO (SUBREG_REG (dest))))
- {
- destp = &XEXP (dest, 0);
- dest = XEXP (dest, 0);
- }
-
- /* Some SETs also use the REG specified in their LHS.
- These can be detected by the presence of
- STRICT_LOW_PART, SUBREG, SIGN_EXTRACT, and ZERO_EXTRACT
- in the LHS. Handle these by changing
- (set (subreg (reg foo)) ...)
- into
- (sequence [(set (reg foo_1) (reg foo))
- (set (subreg (reg foo_1)) ...)])
-
- FIXME: Much of the time this is too much. For some constructs
- we know that the output register is strictly an output
- (paradoxical SUBREGs and some libcalls for example).
-
- For those cases we are better off not making the false
- dependency. */
- if (GET_CODE (dest) == STRICT_LOW_PART
- || GET_CODE (dest) == SUBREG
- || GET_CODE (dest) == SIGN_EXTRACT
- || GET_CODE (dest) == ZERO_EXTRACT)
- {
- rtx i, reg;
- reg = dest;
-
- while (GET_CODE (reg) == STRICT_LOW_PART
- || GET_CODE (reg) == SUBREG
- || GET_CODE (reg) == SIGN_EXTRACT
- || GET_CODE (reg) == ZERO_EXTRACT)
- reg = XEXP (reg, 0);
-
- if (GET_CODE (reg) == REG
- && CONVERT_REGISTER_TO_SSA_P (REGNO (reg)))
- {
- /* Generate (set reg reg), and do renaming on it so
- that it becomes (set reg_1 reg_0), and we will
- replace reg with reg_1 in the SUBREG. */
-
- struct rename_set_data *saved_new_renames;
- saved_new_renames = context->new_renames;
- context->new_renames = NULL;
- i = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
- for_each_rtx (&i, rename_insn_1, data);
- apply_delayed_renames (context);
- context->new_renames = saved_new_renames;
- }
- }
- else if (GET_CODE (dest) == REG
- && CONVERT_REGISTER_TO_SSA_P (REGNO (dest)))
- {
- /* We found a genuine set of an interesting register. Tag
- it so that we can create a new name for it after we finish
- processing this insn. */
-
- create_delayed_rename (context, destp);
-
- /* Since we do not wish to (directly) traverse the
- SET_DEST, recurse through for_each_rtx for the SET_SRC
- and return. */
- if (GET_CODE (x) == SET)
- for_each_rtx (&SET_SRC (x), rename_insn_1, data);
- return -1;
- }
-
- /* Otherwise, this was not an interesting destination. Continue
- on, marking uses as normal. */
- return 0;
- }
-
- case REG:
- if (CONVERT_REGISTER_TO_SSA_P (REGNO (x)) &&
- REGNO (x) < ssa_max_reg_num)
- {
- rtx new_reg = ssa_rename_to_lookup (x);
-
- if (new_reg != NULL_RTX && new_reg != RENAME_NO_RTX)
- {
- if (GET_MODE (x) != GET_MODE (new_reg))
- abort ();
- *ptr = new_reg;
- }
- /* Else this is a use before a set. Warn? */
- }
- return -1;
-
- case CLOBBER:
- /* There is considerable debate on how CLOBBERs ought to be
- handled in SSA. For now, we're keeping the CLOBBERs, which
- means that we don't really have SSA form. There are a couple
- of proposals for how to fix this problem, but neither is
- implemented yet. */
- {
- rtx dest = XCEXP (x, 0, CLOBBER);
- if (REG_P (dest))
- {
- if (CONVERT_REGISTER_TO_SSA_P (REGNO (dest))
- && REGNO (dest) < ssa_max_reg_num)
- {
- rtx new_reg = ssa_rename_to_lookup (dest);
- if (new_reg != NULL_RTX && new_reg != RENAME_NO_RTX)
- XCEXP (x, 0, CLOBBER) = new_reg;
- }
- /* Stop traversing. */
- return -1;
- }
- else
- /* Continue traversing. */
- return 0;
- }
-
- case PHI:
- /* Never muck with the phi. We do that elsewhere, special-like. */
- return -1;
-
- default:
- /* Anything else, continue traversing. */
- return 0;
- }
-}
-
-static void
-rename_block (bb, idom)
- int bb;
- int *idom;
-{
- basic_block b = BASIC_BLOCK (bb);
- edge e;
- rtx insn, next, last;
- struct rename_set_data *set_data = NULL;
- int c;
-
- /* Step One: Walk the basic block, adding new names for sets and
- replacing uses. */
-
- next = b->head;
- last = b->end;
- do
- {
- insn = next;
- if (INSN_P (insn))
- {
- struct rename_context context;
- context.done_renames = set_data;
- context.new_renames = NULL;
- context.current_insn = insn;
-
- start_sequence ();
- for_each_rtx (&PATTERN (insn), rename_insn_1, &context);
- for_each_rtx (®_NOTES (insn), rename_insn_1, &context);
-
- /* Sometimes, we end up with a sequence of insns that
- SSA needs to treat as a single insn. Wrap these in a
- SEQUENCE. (Any notes now get attached to the SEQUENCE,
- not to the old version inner insn.) */
- if (get_insns () != NULL_RTX)
- {
- rtx seq;
- int i;
-
- emit (PATTERN (insn));
- seq = gen_sequence ();
- /* We really want a SEQUENCE of SETs, not a SEQUENCE
- of INSNs. */
- for (i = 0; i < XVECLEN (seq, 0); i++)
- XVECEXP (seq, 0, i) = PATTERN (XVECEXP (seq, 0, i));
- PATTERN (insn) = seq;
- }
- end_sequence ();
-
- apply_delayed_renames (&context);
- set_data = context.done_renames;
- }
-
- next = NEXT_INSN (insn);
- }
- while (insn != last);
-
- /* Step Two: Update the phi nodes of this block's successors. */
-
- for (e = b->succ; e; e = e->succ_next)
- {
- if (e->dest == EXIT_BLOCK_PTR)
- continue;
-
- insn = first_insn_after_basic_block_note (e->dest);
-
- while (PHI_NODE_P (insn))
- {
- rtx phi = PATTERN (insn);
- rtx reg;
-
- /* Find out which of our outgoing registers this node is
- intended to replace. Note that if this is not the first PHI
- node to have been created for this register, we have to
- jump through rename links to figure out which register
- we're talking about. This can easily be recognized by
- noting that the regno is new to this pass. */
- reg = SET_DEST (phi);
- if (REGNO (reg) >= ssa_max_reg_num)
- reg = ssa_rename_from_lookup (REGNO (reg));
- if (reg == NULL_RTX)
- abort ();
- reg = ssa_rename_to_lookup (reg);
-
- /* It is possible for the variable to be uninitialized on
- edges in. Reduce the arity of the PHI so that we don't
- consider those edges. */
- if (reg == NULL || reg == RENAME_NO_RTX)
- {
- if (! remove_phi_alternative (phi, b))
- abort ();
- }
- else
- {
- /* When we created the PHI nodes, we did not know what mode
- the register should be. Now that we've found an original,
- we can fill that in. */
- if (GET_MODE (SET_DEST (phi)) == VOIDmode)
- PUT_MODE (SET_DEST (phi), GET_MODE (reg));
- else if (GET_MODE (SET_DEST (phi)) != GET_MODE (reg))
- abort ();
-
- *phi_alternative (phi, bb) = reg;
- }
-
- insn = NEXT_INSN (insn);
- }
- }
-
- /* Step Three: Do the same to the children of this block in
- dominator order. */
-
- for (c = 0; c < n_basic_blocks; ++c)
- if (idom[c] == bb)
- rename_block (c, idom);
-
- /* Step Four: Update the sets to refer to their new register,
- and restore ssa_rename_to to its previous state. */
-
- while (set_data)
- {
- struct rename_set_data *next;
- rtx old_reg = *set_data->reg_loc;
-
- if (*set_data->reg_loc != set_data->old_reg)
- abort ();
- *set_data->reg_loc = set_data->new_reg;
-
- ssa_rename_to_insert (old_reg, set_data->prev_reg);
-
- next = set_data->next;
- free (set_data);
- set_data = next;
- }
-}
-
-static void
-rename_registers (nregs, idom)
- int nregs;
- int *idom;
-{
- VARRAY_RTX_INIT (ssa_definition, nregs * 3, "ssa_definition");
- ssa_rename_from_initialize ();
-
- ssa_rename_to_pseudo = (rtx *) alloca (nregs * sizeof(rtx));
- memset ((char *) ssa_rename_to_pseudo, 0, nregs * sizeof(rtx));
- memset ((char *) ssa_rename_to_hard, 0,
- FIRST_PSEUDO_REGISTER * NUM_MACHINE_MODES * sizeof (rtx));
-
- rename_block (0, idom);
-
- /* ??? Update basic_block_live_at_start, and other flow info
- as needed. */
-
- ssa_rename_to_pseudo = NULL;
-}
-
-/* The main entry point for moving to SSA. */
-
-void
-convert_to_ssa ()
-{
- /* Element I is the set of blocks that set register I. */
- sbitmap *evals;
-
- /* Dominator bitmaps. */
- sbitmap *dfs;
- sbitmap *idfs;
-
- /* Element I is the immediate dominator of block I. */
- int *idom;
-
- int nregs;
-
- /* Don't do it twice. */
- if (in_ssa_form)
- abort ();
-
- /* Need global_live_at_{start,end} up to date. Do not remove any
- dead code. We'll let the SSA optimizers do that. */
- life_analysis (get_insns (), NULL, 0);
-
- idom = (int *) alloca (n_basic_blocks * sizeof (int));
- memset ((void *) idom, -1, (size_t) n_basic_blocks * sizeof (int));
- calculate_dominance_info (idom, NULL, CDI_DOMINATORS);
-
- if (rtl_dump_file)
- {
- int i;
- fputs (";; Immediate Dominators:\n", rtl_dump_file);
- for (i = 0; i < n_basic_blocks; ++i)
- fprintf (rtl_dump_file, ";\t%3d = %3d\n", i, idom[i]);
- fflush (rtl_dump_file);
- }
-
- /* Compute dominance frontiers. */
-
- dfs = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
- compute_dominance_frontiers (dfs, idom);
-
- if (rtl_dump_file)
- {
- dump_sbitmap_vector (rtl_dump_file, ";; Dominance Frontiers:",
- "; Basic Block", dfs, n_basic_blocks);
- fflush (rtl_dump_file);
- }
-
- /* Compute register evaluations. */
-
- ssa_max_reg_num = max_reg_num ();
- nregs = ssa_max_reg_num;
- evals = sbitmap_vector_alloc (nregs, n_basic_blocks);
- find_evaluations (evals, nregs);
-
- /* Compute the iterated dominance frontier for each register. */
-
- idfs = sbitmap_vector_alloc (nregs, n_basic_blocks);
- compute_iterated_dominance_frontiers (idfs, dfs, evals, nregs);
-
- if (rtl_dump_file)
- {
- dump_sbitmap_vector (rtl_dump_file, ";; Iterated Dominance Frontiers:",
- "; Register", idfs, nregs);
- fflush (rtl_dump_file);
- }
-
- /* Insert the phi nodes. */
-
- insert_phi_nodes (idfs, evals, nregs);
-
- /* Rename the registers to satisfy SSA. */
-
- rename_registers (nregs, idom);
-
- /* All done! Clean up and go home. */
-
- sbitmap_vector_free (dfs);
- sbitmap_vector_free (evals);
- sbitmap_vector_free (idfs);
- in_ssa_form = 1;
-
- reg_scan (get_insns (), max_reg_num (), 1);
-}
-
-/* REG is the representative temporary of its partition. Add it to the
- set of nodes to be processed, if it hasn't been already. Return the
- index of this register in the node set. */
-
-static inline int
-ephi_add_node (reg, nodes, n_nodes)
- rtx reg, *nodes;
- int *n_nodes;
-{
- int i;
- for (i = *n_nodes - 1; i >= 0; --i)
- if (REGNO (reg) == REGNO (nodes[i]))
- return i;
-
- nodes[i = (*n_nodes)++] = reg;
- return i;
-}
-
-/* Part one of the topological sort. This is a forward (downward) search
- through the graph collecting a stack of nodes to process. Assuming no
- cycles, the nodes at top of the stack when we are finished will have
- no other dependencies. */
-
-static int *
-ephi_forward (t, visited, succ, tstack)
- int t;
- sbitmap visited;
- sbitmap *succ;
- int *tstack;
-{
- int s;
-
- SET_BIT (visited, t);
-
- EXECUTE_IF_SET_IN_SBITMAP (succ[t], 0, s,
- {
- if (! TEST_BIT (visited, s))
- tstack = ephi_forward (s, visited, succ, tstack);
- });
-
- *tstack++ = t;
- return tstack;
-}
-
-/* Part two of the topological sort. The is a backward search through
- a cycle in the graph, copying the data forward as we go. */
-
-static void
-ephi_backward (t, visited, pred, nodes)
- int t;
- sbitmap visited, *pred;
- rtx *nodes;
-{
- int p;
-
- SET_BIT (visited, t);
-
- EXECUTE_IF_SET_IN_SBITMAP (pred[t], 0, p,
- {
- if (! TEST_BIT (visited, p))
- {
- ephi_backward (p, visited, pred, nodes);
- emit_move_insn (nodes[p], nodes[t]);
- }
- });
-}
-
-/* Part two of the topological sort. Create the copy for a register
- and any cycle of which it is a member. */
-
-static void
-ephi_create (t, visited, pred, succ, nodes)
- int t;
- sbitmap visited, *pred, *succ;
- rtx *nodes;
-{
- rtx reg_u = NULL_RTX;
- int unvisited_predecessors = 0;
- int p;
-
- /* Iterate through the predecessor list looking for unvisited nodes.
- If there are any, we have a cycle, and must deal with that. At
- the same time, look for a visited predecessor. If there is one,
- we won't need to create a temporary. */
-
- EXECUTE_IF_SET_IN_SBITMAP (pred[t], 0, p,
- {
- if (! TEST_BIT (visited, p))
- unvisited_predecessors = 1;
- else if (!reg_u)
- reg_u = nodes[p];
- });
-
- if (unvisited_predecessors)
- {
- /* We found a cycle. Copy out one element of the ring (if necessary),
- then traverse the ring copying as we go. */
-
- if (!reg_u)
- {
- reg_u = gen_reg_rtx (GET_MODE (nodes[t]));
- emit_move_insn (reg_u, nodes[t]);
- }
-
- EXECUTE_IF_SET_IN_SBITMAP (pred[t], 0, p,
- {
- if (! TEST_BIT (visited, p))
- {
- ephi_backward (p, visited, pred, nodes);
- emit_move_insn (nodes[p], reg_u);
- }
- });
- }
- else
- {
- /* No cycle. Just copy the value from a successor. */
-
- int s;
- EXECUTE_IF_SET_IN_SBITMAP (succ[t], 0, s,
- {
- SET_BIT (visited, t);
- emit_move_insn (nodes[t], nodes[s]);
- return;
- });
- }
-}
-
-/* Convert the edge to normal form. */
-
-static void
-eliminate_phi (e, reg_partition)
- edge e;
- partition reg_partition;
-{
- int n_nodes;
- sbitmap *pred, *succ;
- sbitmap visited;
- rtx *nodes;
- int *stack, *tstack;
- rtx insn;
- int i;
-
- /* Collect an upper bound on the number of registers needing processing. */
-
- insn = first_insn_after_basic_block_note (e->dest);
-
- n_nodes = 0;
- while (PHI_NODE_P (insn))
- {
- insn = next_nonnote_insn (insn);
- n_nodes += 2;
- }
-
- if (n_nodes == 0)
- return;
-
- /* Build the auxiliary graph R(B).
-
- The nodes of the graph are the members of the register partition
- present in Phi(B). There is an edge from FIND(T0)->FIND(T1) for
- each T0 = PHI(...,T1,...), where T1 is for the edge from block C. */
-
- nodes = (rtx *) alloca (n_nodes * sizeof(rtx));
- pred = sbitmap_vector_alloc (n_nodes, n_nodes);
- succ = sbitmap_vector_alloc (n_nodes, n_nodes);
- sbitmap_vector_zero (pred, n_nodes);
- sbitmap_vector_zero (succ, n_nodes);
-
- insn = first_insn_after_basic_block_note (e->dest);
-
- n_nodes = 0;
- for (; PHI_NODE_P (insn); insn = next_nonnote_insn (insn))
- {
- rtx* preg = phi_alternative (PATTERN (insn), e->src->index);
- rtx tgt = SET_DEST (PATTERN (insn));
- rtx reg;
-
- /* There may be no phi alternative corresponding to this edge.
- This indicates that the phi variable is undefined along this
- edge. */
- if (preg == NULL)
- continue;
- reg = *preg;
-
- if (GET_CODE (reg) != REG || GET_CODE (tgt) != REG)
- abort ();
-
- reg = regno_reg_rtx[partition_find (reg_partition, REGNO (reg))];
- tgt = regno_reg_rtx[partition_find (reg_partition, REGNO (tgt))];
- /* If the two registers are already in the same partition,
- nothing will need to be done. */
- if (reg != tgt)
- {
- int ireg, itgt;
-
- ireg = ephi_add_node (reg, nodes, &n_nodes);
- itgt = ephi_add_node (tgt, nodes, &n_nodes);
-
- SET_BIT (pred[ireg], itgt);
- SET_BIT (succ[itgt], ireg);
- }
- }
-
- if (n_nodes == 0)
- goto out;
-
- /* Begin a topological sort of the graph. */
-
- visited = sbitmap_alloc (n_nodes);
- sbitmap_zero (visited);
-
- tstack = stack = (int *) alloca (n_nodes * sizeof (int));
-
- for (i = 0; i < n_nodes; ++i)
- if (! TEST_BIT (visited, i))
- tstack = ephi_forward (i, visited, succ, tstack);
-
- sbitmap_zero (visited);
-
- /* As we find a solution to the tsort, collect the implementation
- insns in a sequence. */
- start_sequence ();
-
- while (tstack != stack)
- {
- i = *--tstack;
- if (! TEST_BIT (visited, i))
- ephi_create (i, visited, pred, succ, nodes);
- }
-
- insn = gen_sequence ();
- end_sequence ();
- insert_insn_on_edge (insn, e);
- if (rtl_dump_file)
- fprintf (rtl_dump_file, "Emitting copy on edge (%d,%d)\n",
- e->src->index, e->dest->index);
-
- sbitmap_free (visited);
-out:
- sbitmap_vector_free (pred);
- sbitmap_vector_free (succ);
-}
-
-/* For basic block B, consider all phi insns which provide an
- alternative corresponding to an incoming abnormal critical edge.
- Place the phi alternative corresponding to that abnormal critical
- edge in the same register class as the destination of the set.
-
- From Morgan, p. 178:
-
- For each abnormal critical edge (C, B),
- if T0 = phi (T1, ..., Ti, ..., Tm) is a phi node in B,
- and C is the ith predecessor of B,
- then T0 and Ti must be equivalent.
-
- Return non-zero iff any such cases were found for which the two
- regs were not already in the same class. */
-
-static int
-make_regs_equivalent_over_bad_edges (bb, reg_partition)
- int bb;
- partition reg_partition;
-{
- int changed = 0;
- basic_block b = BASIC_BLOCK (bb);
- rtx phi;
-
- /* Advance to the first phi node. */
- phi = first_insn_after_basic_block_note (b);
-
- /* Scan all the phi nodes. */
- for (;
- PHI_NODE_P (phi);
- phi = next_nonnote_insn (phi))
- {
- edge e;
- int tgt_regno;
- rtx set = PATTERN (phi);
- rtx tgt = SET_DEST (set);
-
- /* The set target is expected to be an SSA register. */
- if (GET_CODE (tgt) != REG
- || !CONVERT_REGISTER_TO_SSA_P (REGNO (tgt)))
- abort ();
- tgt_regno = REGNO (tgt);
-
- /* Scan incoming abnormal critical edges. */
- for (e = b->pred; e; e = e->pred_next)
- if ((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e))
- {
- rtx *alt = phi_alternative (set, e->src->index);
- int alt_regno;
-
- /* If there is no alternative corresponding to this edge,
- the value is undefined along the edge, so just go on. */
- if (alt == 0)
- continue;
-
- /* The phi alternative is expected to be an SSA register. */
- if (GET_CODE (*alt) != REG
- || !CONVERT_REGISTER_TO_SSA_P (REGNO (*alt)))
- abort ();
- alt_regno = REGNO (*alt);
-
- /* If the set destination and the phi alternative aren't
- already in the same class... */
- if (partition_find (reg_partition, tgt_regno)
- != partition_find (reg_partition, alt_regno))
- {
- /* ... make them such. */
- if (conflicting_hard_regs_p (tgt_regno, alt_regno))
- /* It is illegal to unify a hard register with a
- different register. */
- abort ();
-
- partition_union (reg_partition,
- tgt_regno, alt_regno);
- ++changed;
- }
- }
- }
-
- return changed;
-}
-
-/* Consider phi insns in basic block BB pairwise. If the set target
- of both isns are equivalent pseudos, make the corresponding phi
- alternatives in each phi corresponding equivalent.
-
- Return nonzero if any new register classes were unioned. */
-
-static int
-make_equivalent_phi_alternatives_equivalent (bb, reg_partition)
- int bb;
- partition reg_partition;
-{
- int changed = 0;
- basic_block b = BASIC_BLOCK (bb);
- rtx phi;
-
- /* Advance to the first phi node. */
- phi = first_insn_after_basic_block_note (b);
-
- /* Scan all the phi nodes. */
- for (;
- PHI_NODE_P (phi);
- phi = next_nonnote_insn (phi))
- {
- rtx set = PATTERN (phi);
- /* The regno of the destination of the set. */
- int tgt_regno = REGNO (SET_DEST (PATTERN (phi)));
-
- rtx phi2 = next_nonnote_insn (phi);
-
- /* Scan all phi nodes following this one. */
- for (;
- PHI_NODE_P (phi2);
- phi2 = next_nonnote_insn (phi2))
- {
- rtx set2 = PATTERN (phi2);
- /* The regno of the destination of the set. */
- int tgt2_regno = REGNO (SET_DEST (set2));
-
- /* Are the set destinations equivalent regs? */
- if (partition_find (reg_partition, tgt_regno) ==
- partition_find (reg_partition, tgt2_regno))
- {
- edge e;
- /* Scan over edges. */
- for (e = b->pred; e; e = e->pred_next)
- {
- int pred_block = e->src->index;
- /* Identify the phi alternatives from both phi
- nodes corresponding to this edge. */
- rtx *alt = phi_alternative (set, pred_block);
- rtx *alt2 = phi_alternative (set2, pred_block);
-
- /* If one of the phi nodes doesn't have a
- corresponding alternative, just skip it. */
- if (alt == 0 || alt2 == 0)
- continue;
-
- /* Both alternatives should be SSA registers. */
- if (GET_CODE (*alt) != REG
- || !CONVERT_REGISTER_TO_SSA_P (REGNO (*alt)))
- abort ();
- if (GET_CODE (*alt2) != REG
- || !CONVERT_REGISTER_TO_SSA_P (REGNO (*alt2)))
- abort ();
-
- /* If the alternatives aren't already in the same
- class ... */
- if (partition_find (reg_partition, REGNO (*alt))
- != partition_find (reg_partition, REGNO (*alt2)))
- {
- /* ... make them so. */
- if (conflicting_hard_regs_p (REGNO (*alt), REGNO (*alt2)))
- /* It is illegal to unify a hard register with
- a different register. */
- abort ();
-
- partition_union (reg_partition,
- REGNO (*alt), REGNO (*alt2));
- ++changed;
- }
- }
- }
- }
- }
-
- return changed;
-}
-
-/* Compute a conservative partition of outstanding pseudo registers.
- See Morgan 7.3.1. */
-
-static partition
-compute_conservative_reg_partition ()
-{
- int bb;
- int changed = 0;
-
- /* We don't actually work with hard registers, but it's easier to
- carry them around anyway rather than constantly doing register
- number arithmetic. */
- partition p =
- partition_new (ssa_definition->num_elements);
-
- /* The first priority is to make sure registers that might have to
- be copied on abnormal critical edges are placed in the same
- partition. This saves us from having to split abnormal critical
- edges. */
- for (bb = n_basic_blocks; --bb >= 0; )
- changed += make_regs_equivalent_over_bad_edges (bb, p);
-
- /* Now we have to insure that corresponding arguments of phi nodes
- assigning to corresponding regs are equivalent. Iterate until
- nothing changes. */
- while (changed > 0)
- {
- changed = 0;
- for (bb = n_basic_blocks; --bb >= 0; )
- changed += make_equivalent_phi_alternatives_equivalent (bb, p);
- }
-
- return p;
-}
-
-/* The following functions compute a register partition that attempts
- to eliminate as many reg copies and phi node copies as possible by
- coalescing registers. This is the strategy:
-
- 1. As in the conservative case, the top priority is to coalesce
- registers that otherwise would cause copies to be placed on
- abnormal critical edges (which isn't possible).
-
- 2. Figure out which regs are involved (in the LHS or RHS) of
- copies and phi nodes. Compute conflicts among these regs.
-
- 3. Walk around the instruction stream, placing two regs in the
- same class of the partition if one appears on the LHS and the
- other on the RHS of a copy or phi node and the two regs don't
- conflict. The conflict information of course needs to be
- updated.
-
- 4. If anything has changed, there may be new opportunities to
- coalesce regs, so go back to 2.
-*/
-
-/* If REG1 and REG2 don't conflict in CONFLICTS, place them in the
- same class of partition P, if they aren't already. Update
- CONFLICTS appropriately.
-
- Returns one if REG1 and REG2 were placed in the same class but were
- not previously; zero otherwise.
-
- See Morgan figure 11.15. */
-
-static int
-coalesce_if_unconflicting (p, conflicts, reg1, reg2)
- partition p;
- conflict_graph conflicts;
- int reg1;
- int reg2;
-{
- int reg;
-
- /* Work only on SSA registers. */
- if (!CONVERT_REGISTER_TO_SSA_P (reg1) || !CONVERT_REGISTER_TO_SSA_P (reg2))
- return 0;
-
- /* Find the canonical regs for the classes containing REG1 and
- REG2. */
- reg1 = partition_find (p, reg1);
- reg2 = partition_find (p, reg2);
-
- /* If they're already in the same class, there's nothing to do. */
- if (reg1 == reg2)
- return 0;
-
- /* If the regs conflict, our hands are tied. */
- if (conflicting_hard_regs_p (reg1, reg2) ||
- conflict_graph_conflict_p (conflicts, reg1, reg2))
- return 0;
-
- /* We're good to go. Put the regs in the same partition. */
- partition_union (p, reg1, reg2);
-
- /* Find the new canonical reg for the merged class. */
- reg = partition_find (p, reg1);
-
- /* Merge conflicts from the two previous classes. */
- conflict_graph_merge_regs (conflicts, reg, reg1);
- conflict_graph_merge_regs (conflicts, reg, reg2);
-
- return 1;
-}
-
-/* For each register copy insn in basic block BB, place the LHS and
- RHS regs in the same class in partition P if they do not conflict
- according to CONFLICTS.
-
- Returns the number of changes that were made to P.
-
- See Morgan figure 11.14. */
-
-static int
-coalesce_regs_in_copies (bb, p, conflicts)
- basic_block bb;
- partition p;
- conflict_graph conflicts;
-{
- int changed = 0;
- rtx insn;
- rtx end = bb->end;
-
- /* Scan the instruction stream of the block. */
- for (insn = bb->head; insn != end; insn = NEXT_INSN (insn))
- {
- rtx pattern;
- rtx src;
- rtx dest;
-
- /* If this isn't a set insn, go to the next insn. */
- if (GET_CODE (insn) != INSN)
- continue;
- pattern = PATTERN (insn);
- if (GET_CODE (pattern) != SET)
- continue;
-
- src = SET_SRC (pattern);
- dest = SET_DEST (pattern);
-
- /* We're only looking for copies. */
- if (GET_CODE (src) != REG || GET_CODE (dest) != REG)
- continue;
-
- /* Coalesce only if the reg modes are the same. As long as
- each reg's rtx is unique, it can have only one mode, so two
- pseudos of different modes can't be coalesced into one.
-
- FIXME: We can probably get around this by inserting SUBREGs
- where appropriate, but for now we don't bother. */
- if (GET_MODE (src) != GET_MODE (dest))
- continue;
-
- /* Found a copy; see if we can use the same reg for both the
- source and destination (and thus eliminate the copy,
- ultimately). */
- changed += coalesce_if_unconflicting (p, conflicts,
- REGNO (src), REGNO (dest));
- }
-
- return changed;
-}
-
-struct phi_coalesce_context
-{
- partition p;
- conflict_graph conflicts;
- int changed;
-};
-
-/* Callback function for for_each_successor_phi. If the set
- destination and the phi alternative regs do not conflict, place
- them in the same paritition class. DATA is a pointer to a
- phi_coalesce_context struct. */
-
-static int
-coalesce_reg_in_phi (insn, dest_regno, src_regno, data)
- rtx insn ATTRIBUTE_UNUSED;
- int dest_regno;
- int src_regno;
- void *data;
-{
- struct phi_coalesce_context *context =
- (struct phi_coalesce_context *) data;
-
- /* Attempt to use the same reg, if they don't conflict. */
- context->changed
- += coalesce_if_unconflicting (context->p, context->conflicts,
- dest_regno, src_regno);
- return 0;
-}
-
-/* For each alternative in a phi function corresponding to basic block
- BB (in phi nodes in successor block to BB), place the reg in the
- phi alternative and the reg to which the phi value is set into the
- same class in partition P, if allowed by CONFLICTS.
-
- Return the number of changes that were made to P.
-
- See Morgan figure 11.14. */
-
-static int
-coalesce_regs_in_successor_phi_nodes (bb, p, conflicts)
- basic_block bb;
- partition p;
- conflict_graph conflicts;
-{
- struct phi_coalesce_context context;
- context.p = p;
- context.conflicts = conflicts;
- context.changed = 0;
-
- for_each_successor_phi (bb, &coalesce_reg_in_phi, &context);
-
- return context.changed;
-}
-
-/* Compute and return a partition of pseudos. Where possible,
- non-conflicting pseudos are placed in the same class.
-
- The caller is responsible for deallocating the returned partition. */
-
-static partition
-compute_coalesced_reg_partition ()
-{
- int bb;
- int changed = 0;
- regset_head phi_set_head;
- regset phi_set = &phi_set_head;
-
- partition p =
- partition_new (ssa_definition->num_elements);
-
- /* The first priority is to make sure registers that might have to
- be copied on abnormal critical edges are placed in the same
- partition. This saves us from having to split abnormal critical
- edges (which can't be done). */
- for (bb = n_basic_blocks; --bb >= 0; )
- make_regs_equivalent_over_bad_edges (bb, p);
-
- INIT_REG_SET (phi_set);
-
- do
- {
- conflict_graph conflicts;
-
- changed = 0;
-
- /* Build the set of registers involved in phi nodes, either as
- arguments to the phi function or as the target of a set. */
- CLEAR_REG_SET (phi_set);
- mark_phi_and_copy_regs (phi_set);
-
- /* Compute conflicts. */
- conflicts = conflict_graph_compute (phi_set, p);
-
- /* FIXME: Better would be to process most frequently executed
- blocks first, so that most frequently executed copies would
- be more likely to be removed by register coalescing. But any
- order will generate correct, if non-optimal, results. */
- for (bb = n_basic_blocks; --bb >= 0; )
- {
- basic_block block = BASIC_BLOCK (bb);
- changed += coalesce_regs_in_copies (block, p, conflicts);
- changed +=
- coalesce_regs_in_successor_phi_nodes (block, p, conflicts);
- }
-
- conflict_graph_delete (conflicts);
- }
- while (changed > 0);
-
- FREE_REG_SET (phi_set);
-
- return p;
-}
-
-/* Mark the regs in a phi node. PTR is a phi expression or one of its
- components (a REG or a CONST_INT). DATA is a reg set in which to
- set all regs. Called from for_each_rtx. */
-
-static int
-mark_reg_in_phi (ptr, data)
- rtx *ptr;
- void *data;
-{
- rtx expr = *ptr;
- regset set = (regset) data;
-
- switch (GET_CODE (expr))
- {
- case REG:
- SET_REGNO_REG_SET (set, REGNO (expr));
- /* Fall through. */
- case CONST_INT:
- case PHI:
- return 0;
- default:
- abort ();
- }
-}
-
-/* Mark in PHI_SET all pseudos that are used in a phi node -- either
- set from a phi expression, or used as an argument in one. Also
- mark regs that are the source or target of a reg copy. Uses
- ssa_definition. */
-
-static void
-mark_phi_and_copy_regs (phi_set)
- regset phi_set;
-{
- unsigned int reg;
-
- /* Scan the definitions of all regs. */
- for (reg = 0; reg < VARRAY_SIZE (ssa_definition); ++reg)
- if (CONVERT_REGISTER_TO_SSA_P (reg))
- {
- rtx insn = VARRAY_RTX (ssa_definition, reg);
- rtx pattern;
- rtx src;
-
- if (insn == NULL
- || (GET_CODE (insn) == NOTE
- && NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED))
- continue;
- pattern = PATTERN (insn);
- /* Sometimes we get PARALLEL insns. These aren't phi nodes or
- copies. */
- if (GET_CODE (pattern) != SET)
- continue;
- src = SET_SRC (pattern);
-
- if (GET_CODE (src) == REG)
- {
- /* It's a reg copy. */
- SET_REGNO_REG_SET (phi_set, reg);
- SET_REGNO_REG_SET (phi_set, REGNO (src));
- }
- else if (GET_CODE (src) == PHI)
- {
- /* It's a phi node. Mark the reg being set. */
- SET_REGNO_REG_SET (phi_set, reg);
- /* Mark the regs used in the phi function. */
- for_each_rtx (&src, mark_reg_in_phi, phi_set);
- }
- /* ... else nothing to do. */
- }
-}
-
-/* Rename regs in insn PTR that are equivalent. DATA is the register
- partition which specifies equivalences. */
-
-static int
-rename_equivalent_regs_in_insn (ptr, data)
- rtx *ptr;
- void* data;
-{
- rtx x = *ptr;
- partition reg_partition = (partition) data;
-
- if (x == NULL_RTX)
- return 0;
-
- switch (GET_CODE (x))
- {
- case REG:
- if (CONVERT_REGISTER_TO_SSA_P (REGNO (x)))
- {
- unsigned int regno = REGNO (x);
- unsigned int new_regno = partition_find (reg_partition, regno);
- rtx canonical_element_rtx = ssa_rename_from_lookup (new_regno);
-
- if (canonical_element_rtx != NULL_RTX &&
- HARD_REGISTER_P (canonical_element_rtx))
- {
- if (REGNO (canonical_element_rtx) != regno)
- *ptr = canonical_element_rtx;
- }
- else if (regno != new_regno)
- {
- rtx new_reg = regno_reg_rtx[new_regno];
- if (GET_MODE (x) != GET_MODE (new_reg))
- abort ();
- *ptr = new_reg;
- }
- }
- return -1;
-
- case PHI:
- /* No need to rename the phi nodes. We'll check equivalence
- when inserting copies. */
- return -1;
-
- default:
- /* Anything else, continue traversing. */
- return 0;
- }
-}
-
-/* Record the register's canonical element stored in SRFP in the
- canonical_elements sbitmap packaged in DATA. This function is used
- as a callback function for traversing ssa_rename_from. */
-
-static int
-record_canonical_element_1 (srfp, data)
- void **srfp;
- void *data;
-{
- unsigned int reg = ((ssa_rename_from_pair *) *srfp)->reg;
- sbitmap canonical_elements =
- ((struct ssa_rename_from_hash_table_data *) data)->canonical_elements;
- partition reg_partition =
- ((struct ssa_rename_from_hash_table_data *) data)->reg_partition;
-
- SET_BIT (canonical_elements, partition_find (reg_partition, reg));
- return 1;
-}
-
-/* For each class in the REG_PARTITION corresponding to a particular
- hard register and machine mode, check that there are no other
- classes with the same hard register and machine mode. Returns
- nonzero if this is the case, i.e., the partition is acceptable. */
-
-static int
-check_hard_regs_in_partition (reg_partition)
- partition reg_partition;
-{
- /* CANONICAL_ELEMENTS has a nonzero bit if a class with the given register
- number and machine mode has already been seen. This is a
- problem with the partition. */
- sbitmap canonical_elements;
- int element_index;
- int already_seen[FIRST_PSEUDO_REGISTER][NUM_MACHINE_MODES];
- int reg;
- int mach_mode;
-
- /* Collect a list of canonical elements. */
- canonical_elements = sbitmap_alloc (max_reg_num ());
- sbitmap_zero (canonical_elements);
- ssa_rename_from_traverse (&record_canonical_element_1,
- canonical_elements, reg_partition);
-
- /* We have not seen any hard register uses. */
- for (reg = 0; reg < FIRST_PSEUDO_REGISTER; ++reg)
- for (mach_mode = 0; mach_mode < NUM_MACHINE_MODES; ++mach_mode)
- already_seen[reg][mach_mode] = 0;
-
- /* Check for classes with the same hard register and machine mode. */
- EXECUTE_IF_SET_IN_SBITMAP (canonical_elements, 0, element_index,
- {
- rtx hard_reg_rtx = ssa_rename_from_lookup (element_index);
- if (hard_reg_rtx != NULL_RTX &&
- HARD_REGISTER_P (hard_reg_rtx) &&
- already_seen[REGNO (hard_reg_rtx)][GET_MODE (hard_reg_rtx)] != 0)
- /* Two distinct partition classes should be mapped to the same
- hard register. */
- return 0;
- });
-
- sbitmap_free (canonical_elements);
-
- return 1;
-}
-
-/* Rename regs that are equivalent in REG_PARTITION. Also collapse
- any SEQUENCE insns. */
-
-static void
-rename_equivalent_regs (reg_partition)
- partition reg_partition;
-{
- int bb;
-
- for (bb = n_basic_blocks; --bb >= 0; )
- {
- basic_block b = BASIC_BLOCK (bb);
- rtx next = b->head;
- rtx last = b->end;
- rtx insn;
-
- do
- {
- insn = next;
- if (INSN_P (insn))
- {
- for_each_rtx (&PATTERN (insn),
- rename_equivalent_regs_in_insn,
- reg_partition);
- for_each_rtx (®_NOTES (insn),
- rename_equivalent_regs_in_insn,
- reg_partition);
-
- if (GET_CODE (PATTERN (insn)) == SEQUENCE)
- {
- rtx s = PATTERN (insn);
- int slen = XVECLEN (s, 0);
- int i;
-
- if (slen <= 1)
- abort ();
-
- PATTERN (insn) = XVECEXP (s, 0, slen-1);
- for (i = 0; i < slen - 1; i++)
- emit_insn_before (XVECEXP (s, 0, i), insn);
- }
- }
-
- next = NEXT_INSN (insn);
- }
- while (insn != last);
- }
-}
-
-/* The main entry point for moving from SSA. */
-
-void
-convert_from_ssa ()
-{
- int bb;
- partition reg_partition;
- rtx insns = get_insns ();
-
- /* Need global_live_at_{start,end} up to date. There should not be
- any significant dead code at this point, except perhaps dead
- stores. So do not take the time to perform dead code elimination.
-
- Register coalescing needs death notes, so generate them. */
- life_analysis (insns, NULL, PROP_DEATH_NOTES);
-
- /* Figure out which regs in copies and phi nodes don't conflict and
- therefore can be coalesced. */
- if (conservative_reg_partition)
- reg_partition = compute_conservative_reg_partition ();
- else
- reg_partition = compute_coalesced_reg_partition ();
-
- if (!check_hard_regs_in_partition (reg_partition))
- /* Two separate partitions should correspond to the same hard
- register but do not. */
- abort ();
-
- rename_equivalent_regs (reg_partition);
-
- /* Eliminate the PHI nodes. */
- for (bb = n_basic_blocks; --bb >= 0; )
- {
- basic_block b = BASIC_BLOCK (bb);
- edge e;
-
- for (e = b->pred; e; e = e->pred_next)
- if (e->src != ENTRY_BLOCK_PTR)
- eliminate_phi (e, reg_partition);
- }
-
- partition_delete (reg_partition);
-
- /* Actually delete the PHI nodes. */
- for (bb = n_basic_blocks; --bb >= 0; )
- {
- rtx insn = BLOCK_HEAD (bb);
-
- while (1)
- {
- /* If this is a PHI node delete it. */
- if (PHI_NODE_P (insn))
- {
- if (insn == BLOCK_END (bb))
- BLOCK_END (bb) = PREV_INSN (insn);
- insn = delete_insn (insn);
- }
- /* Since all the phi nodes come at the beginning of the
- block, if we find an ordinary insn, we can stop looking
- for more phi nodes. */
- else if (INSN_P (insn))
- break;
- /* If we've reached the end of the block, stop. */
- else if (insn == BLOCK_END (bb))
- break;
- else
- insn = NEXT_INSN (insn);
- }
- }
-
- /* Commit all the copy nodes needed to convert out of SSA form. */
- commit_edge_insertions ();
-
- in_ssa_form = 0;
-
- count_or_remove_death_notes (NULL, 1);
-
- /* Deallocate the data structures. */
- VARRAY_FREE (ssa_definition);
- ssa_rename_from_free ();
-}
-
-/* Scan phi nodes in successors to BB. For each such phi node that
- has a phi alternative value corresponding to BB, invoke FN. FN
- is passed the entire phi node insn, the regno of the set
- destination, the regno of the phi argument corresponding to BB,
- and DATA.
-
- If FN ever returns non-zero, stops immediately and returns this
- value. Otherwise, returns zero. */
-
-int
-for_each_successor_phi (bb, fn, data)
- basic_block bb;
- successor_phi_fn fn;
- void *data;
-{
- edge e;
-
- if (bb == EXIT_BLOCK_PTR)
- return 0;
-
- /* Scan outgoing edges. */
- for (e = bb->succ; e != NULL; e = e->succ_next)
- {
- rtx insn;
-
- basic_block successor = e->dest;
- if (successor == ENTRY_BLOCK_PTR
- || successor == EXIT_BLOCK_PTR)
- continue;
-
- /* Advance to the first non-label insn of the successor block. */
- insn = first_insn_after_basic_block_note (successor);
-
- if (insn == NULL)
- continue;
-
- /* Scan phi nodes in the successor. */
- for ( ; PHI_NODE_P (insn); insn = NEXT_INSN (insn))
- {
- int result;
- rtx phi_set = PATTERN (insn);
- rtx *alternative = phi_alternative (phi_set, bb->index);
- rtx phi_src;
-
- /* This phi function may not have an alternative
- corresponding to the incoming edge, indicating the
- assigned variable is not defined along the edge. */
- if (alternative == NULL)
- continue;
- phi_src = *alternative;
-
- /* Invoke the callback. */
- result = (*fn) (insn, REGNO (SET_DEST (phi_set)),
- REGNO (phi_src), data);
-
- /* Terminate if requested. */
- if (result != 0)
- return result;
- }
- }
-
- return 0;
-}
-
-/* Assuming the ssa_rename_from mapping has been established, yields
- nonzero if 1) only one SSA register of REG1 and REG2 comes from a
- hard register or 2) both SSA registers REG1 and REG2 come from
- different hard registers. */
-
-static int
-conflicting_hard_regs_p (reg1, reg2)
- int reg1;
- int reg2;
-{
- int orig_reg1 = original_register (reg1);
- int orig_reg2 = original_register (reg2);
- if (HARD_REGISTER_NUM_P (orig_reg1) && HARD_REGISTER_NUM_P (orig_reg2)
- && orig_reg1 != orig_reg2)
- return 1;
- if (HARD_REGISTER_NUM_P (orig_reg1) && !HARD_REGISTER_NUM_P (orig_reg2))
- return 1;
- if (!HARD_REGISTER_NUM_P (orig_reg1) && HARD_REGISTER_NUM_P (orig_reg2))
- return 1;
-
- return 0;
-}
projects / msp430-gcc.git / blobdiff