/* Common subexpression elimination for GNU compiler.
Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998
- 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+ 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
+ Free Software Foundation, Inc.
This file is part of GCC.
table since its use is guaranteed to be the insn immediately following
its definition and any other insn is presumed to invalidate it.
- Instead, we store below the value last assigned to CC0. If it should
- happen to be a constant, it is stored in preference to the actual
- assigned value. In case it is a constant, we store the mode in which
- the constant should be interpreted. */
+ Instead, we store below the current and last value assigned to CC0.
+ If it should happen to be a constant, it is stored in preference
+ to the actual assigned value. In case it is a constant, we store
+ the mode in which the constant should be interpreted. */
-static rtx prev_insn_cc0;
-static enum machine_mode prev_insn_cc0_mode;
-
-/* Previous actual insn. 0 if at first insn of basic block. */
-
-static rtx prev_insn;
+static rtx this_insn_cc0, prev_insn_cc0;
+static enum machine_mode this_insn_cc0_mode, prev_insn_cc0_mode;
#endif
/* Insn being scanned. */
static unsigned int cse_reg_info_table_first_uninitialized;
/* The timestamp at the beginning of the current run of
- cse_basic_block. We increment this variable at the beginning of
- the current run of cse_basic_block. The timestamp field of a
+ cse_extended_basic_block. We increment this variable at the beginning of
+ the current run of cse_extended_basic_block. The timestamp field of a
cse_reg_info entry matches the value of this variable if and only
if the entry has been initialized during the current run of
- cse_basic_block. */
+ cse_extended_basic_block. */
static unsigned int cse_reg_info_timestamp;
/* A HARD_REG_SET containing all the hard registers for which there is
#define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
-/* Nonzero if this pass has made changes, and therefore it's
- worthwhile to run the garbage collector. */
-
-static int cse_altered;
-
/* Nonzero if cse has altered conditional jump insns
in such a way that jump optimization should be redone. */
static int constant_pool_entries_cost;
static int constant_pool_entries_regcost;
-/* This data describes a block that will be processed by cse_basic_block. */
+/* This data describes a block that will be processed by
+ cse_extended_basic_block. */
struct cse_basic_block_data
{
int high_cuid;
/* Total number of SETs in block. */
int nsets;
- /* Last insn in the block. */
- rtx last;
/* Size of current branch path, if any. */
int path_size;
- /* Current branch path, indicating which branches will be taken. */
+ /* Current path, indicating which basic_blocks will be processed. */
struct branch_path
{
- /* The branch insn. */
- rtx branch;
- /* Whether it should be taken or not. AROUND is the same as taken
- except that it is used when the destination label is not preceded
- by a BARRIER. */
- enum taken {PATH_TAKEN, PATH_NOT_TAKEN, PATH_AROUND} status;
+ /* The basic block for this path entry. */
+ basic_block bb;
} *path;
};
+/* A simple bitmap to track which basic blocks have been visited
+ already as part of an already processed extended basic block. */
+static sbitmap cse_visited_basic_blocks;
+
static bool fixed_base_plus_p (rtx x);
static int notreg_cost (rtx, enum rtx_code);
static int approx_reg_cost_1 (rtx *, void *);
static unsigned hash_rtx_string (const char *);
static rtx canon_reg (rtx, rtx);
-static void find_best_addr (rtx, rtx *, enum machine_mode);
static enum rtx_code find_comparison_args (enum rtx_code, rtx *, rtx *,
enum machine_mode *,
enum machine_mode *);
static rtx fold_rtx (rtx, rtx);
static rtx equiv_constant (rtx);
-static void record_jump_equiv (rtx, int);
+static void record_jump_equiv (rtx, bool);
static void record_jump_cond (enum rtx_code, enum machine_mode, rtx, rtx,
int);
static void cse_insn (rtx, rtx);
-static void cse_end_of_basic_block (rtx, struct cse_basic_block_data *,
- int, int);
-static int addr_affects_sp_p (rtx);
+static void cse_prescan_path (struct cse_basic_block_data *);
static void invalidate_from_clobbers (rtx);
static rtx cse_process_notes (rtx, rtx);
-static void invalidate_skipped_set (rtx, rtx, void *);
-static void invalidate_skipped_block (rtx);
-static rtx cse_basic_block (rtx, rtx, struct branch_path *);
+static void cse_extended_basic_block (struct cse_basic_block_data *);
static void count_reg_usage (rtx, int *, rtx, int);
static int check_for_label_ref (rtx *, void *);
extern void dump_class (struct table_elt*);
return cost;
}
-/* Returns a canonical version of X for the address, from the point of view,
- that all multiplications are represented as MULT instead of the multiply
- by a power of 2 being represented as ASHIFT. */
-
-static rtx
-canon_for_address (rtx x)
-{
- enum rtx_code code;
- enum machine_mode mode;
- rtx new = 0;
- int i;
- const char *fmt;
-
- if (!x)
- return x;
-
- code = GET_CODE (x);
- mode = GET_MODE (x);
-
- switch (code)
- {
- case ASHIFT:
- if (GET_CODE (XEXP (x, 1)) == CONST_INT
- && INTVAL (XEXP (x, 1)) < GET_MODE_BITSIZE (mode)
- && INTVAL (XEXP (x, 1)) >= 0)
- {
- new = canon_for_address (XEXP (x, 0));
- new = gen_rtx_MULT (mode, new,
- gen_int_mode ((HOST_WIDE_INT) 1
- << INTVAL (XEXP (x, 1)),
- mode));
- }
- break;
- default:
- break;
-
- }
- if (new)
- return new;
-
- /* Now recursively process each operand of this operation. */
- fmt = GET_RTX_FORMAT (code);
- for (i = 0; i < GET_RTX_LENGTH (code); i++)
- if (fmt[i] == 'e')
- {
- new = canon_for_address (XEXP (x, i));
- XEXP (x, i) = new;
- }
- return x;
-}
-
/* Return a negative value if an rtx A, whose costs are given by COST_A
and REGCOST_A, is more desirable than an rtx B.
Return a positive value if A is less desirable, or 0 if the two are
}
#ifdef HAVE_cc0
- prev_insn = 0;
prev_insn_cc0 = 0;
#endif
}
return x;
}
\f
-/* LOC is a location within INSN that is an operand address (the contents of
- a MEM). Find the best equivalent address to use that is valid for this
- insn.
-
- On most CISC machines, complicated address modes are costly, and rtx_cost
- is a good approximation for that cost. However, most RISC machines have
- only a few (usually only one) memory reference formats. If an address is
- valid at all, it is often just as cheap as any other address. Hence, for
- RISC machines, we use `address_cost' to compare the costs of various
- addresses. For two addresses of equal cost, choose the one with the
- highest `rtx_cost' value as that has the potential of eliminating the
- most insns. For equal costs, we choose the first in the equivalence
- class. Note that we ignore the fact that pseudo registers are cheaper than
- hard registers here because we would also prefer the pseudo registers. */
-
-static void
-find_best_addr (rtx insn, rtx *loc, enum machine_mode mode)
-{
- struct table_elt *elt;
- rtx addr = *loc;
- struct table_elt *p;
- int found_better = 1;
- int save_do_not_record = do_not_record;
- int save_hash_arg_in_memory = hash_arg_in_memory;
- int addr_volatile;
- int regno;
- unsigned hash;
-
- /* Do not try to replace constant addresses or addresses of local and
- argument slots. These MEM expressions are made only once and inserted
- in many instructions, as well as being used to control symbol table
- output. It is not safe to clobber them.
-
- There are some uncommon cases where the address is already in a register
- for some reason, but we cannot take advantage of that because we have
- no easy way to unshare the MEM. In addition, looking up all stack
- addresses is costly. */
- if ((GET_CODE (addr) == PLUS
- && REG_P (XEXP (addr, 0))
- && GET_CODE (XEXP (addr, 1)) == CONST_INT
- && (regno = REGNO (XEXP (addr, 0)),
- regno == FRAME_POINTER_REGNUM || regno == HARD_FRAME_POINTER_REGNUM
- || regno == ARG_POINTER_REGNUM))
- || (REG_P (addr)
- && (regno = REGNO (addr), regno == FRAME_POINTER_REGNUM
- || regno == HARD_FRAME_POINTER_REGNUM
- || regno == ARG_POINTER_REGNUM))
- || CONSTANT_ADDRESS_P (addr))
- return;
-
- /* If this address is not simply a register, try to fold it. This will
- sometimes simplify the expression. Many simplifications
- will not be valid, but some, usually applying the associative rule, will
- be valid and produce better code. */
- if (!REG_P (addr))
- {
- rtx folded = canon_for_address (fold_rtx (addr, NULL_RTX));
-
- if (folded != addr)
- {
- int addr_folded_cost = address_cost (folded, mode);
- int addr_cost = address_cost (addr, mode);
-
- if ((addr_folded_cost < addr_cost
- || (addr_folded_cost == addr_cost
- /* ??? The rtx_cost comparison is left over from an older
- version of this code. It is probably no longer helpful.*/
- && (rtx_cost (folded, MEM) > rtx_cost (addr, MEM)
- || approx_reg_cost (folded) < approx_reg_cost (addr))))
- && validate_change (insn, loc, folded, 0))
- addr = folded;
- }
- }
-
- /* If this address is not in the hash table, we can't look for equivalences
- of the whole address. Also, ignore if volatile. */
-
- do_not_record = 0;
- hash = HASH (addr, Pmode);
- addr_volatile = do_not_record;
- do_not_record = save_do_not_record;
- hash_arg_in_memory = save_hash_arg_in_memory;
-
- if (addr_volatile)
- return;
-
- elt = lookup (addr, hash, Pmode);
-
- if (elt)
- {
- /* We need to find the best (under the criteria documented above) entry
- in the class that is valid. We use the `flag' field to indicate
- choices that were invalid and iterate until we can't find a better
- one that hasn't already been tried. */
-
- for (p = elt->first_same_value; p; p = p->next_same_value)
- p->flag = 0;
-
- while (found_better)
- {
- int best_addr_cost = address_cost (*loc, mode);
- int best_rtx_cost = (elt->cost + 1) >> 1;
- int exp_cost;
- struct table_elt *best_elt = elt;
-
- found_better = 0;
- for (p = elt->first_same_value; p; p = p->next_same_value)
- if (! p->flag)
- {
- if ((REG_P (p->exp)
- || exp_equiv_p (p->exp, p->exp, 1, false))
- && ((exp_cost = address_cost (p->exp, mode)) < best_addr_cost
- || (exp_cost == best_addr_cost
- && ((p->cost + 1) >> 1) > best_rtx_cost)))
- {
- found_better = 1;
- best_addr_cost = exp_cost;
- best_rtx_cost = (p->cost + 1) >> 1;
- best_elt = p;
- }
- }
-
- if (found_better)
- {
- if (validate_change (insn, loc,
- canon_reg (copy_rtx (best_elt->exp),
- NULL_RTX), 0))
- return;
- else
- best_elt->flag = 1;
- }
- }
- }
-
- /* If the address is a binary operation with the first operand a register
- and the second a constant, do the same as above, but looking for
- equivalences of the register. Then try to simplify before checking for
- the best address to use. This catches a few cases: First is when we
- have REG+const and the register is another REG+const. We can often merge
- the constants and eliminate one insn and one register. It may also be
- that a machine has a cheap REG+REG+const. Finally, this improves the
- code on the Alpha for unaligned byte stores. */
-
- if (flag_expensive_optimizations
- && ARITHMETIC_P (*loc)
- && REG_P (XEXP (*loc, 0)))
- {
- rtx op1 = XEXP (*loc, 1);
-
- do_not_record = 0;
- hash = HASH (XEXP (*loc, 0), Pmode);
- do_not_record = save_do_not_record;
- hash_arg_in_memory = save_hash_arg_in_memory;
-
- elt = lookup (XEXP (*loc, 0), hash, Pmode);
- if (elt == 0)
- return;
-
- /* We need to find the best (under the criteria documented above) entry
- in the class that is valid. We use the `flag' field to indicate
- choices that were invalid and iterate until we can't find a better
- one that hasn't already been tried. */
-
- for (p = elt->first_same_value; p; p = p->next_same_value)
- p->flag = 0;
-
- while (found_better)
- {
- int best_addr_cost = address_cost (*loc, mode);
- int best_rtx_cost = (COST (*loc) + 1) >> 1;
- struct table_elt *best_elt = elt;
- rtx best_rtx = *loc;
- int count;
-
- /* This is at worst case an O(n^2) algorithm, so limit our search
- to the first 32 elements on the list. This avoids trouble
- compiling code with very long basic blocks that can easily
- call simplify_gen_binary so many times that we run out of
- memory. */
-
- found_better = 0;
- for (p = elt->first_same_value, count = 0;
- p && count < 32;
- p = p->next_same_value, count++)
- if (! p->flag
- && (REG_P (p->exp)
- || (GET_CODE (p->exp) != EXPR_LIST
- && exp_equiv_p (p->exp, p->exp, 1, false))))
-
- {
- rtx new = simplify_gen_binary (GET_CODE (*loc), Pmode,
- p->exp, op1);
- int new_cost;
-
- /* Get the canonical version of the address so we can accept
- more. */
- new = canon_for_address (new);
-
- new_cost = address_cost (new, mode);
-
- if (new_cost < best_addr_cost
- || (new_cost == best_addr_cost
- && (COST (new) + 1) >> 1 > best_rtx_cost))
- {
- found_better = 1;
- best_addr_cost = new_cost;
- best_rtx_cost = (COST (new) + 1) >> 1;
- best_elt = p;
- best_rtx = new;
- }
- }
-
- if (found_better)
- {
- if (validate_change (insn, loc,
- canon_reg (copy_rtx (best_rtx),
- NULL_RTX), 0))
- return;
- else
- best_elt->flag = 1;
- }
- }
- }
-}
-\f
/* Given an operation (CODE, *PARG1, *PARG2), where code is a comparison
operation (EQ, NE, GT, etc.), follow it back through the hash table and
what values are being compared.
return code;
}
\f
-/* Fold SUBREG. */
-
-static rtx
-fold_rtx_subreg (rtx x, rtx insn)
-{
- enum machine_mode mode = GET_MODE (x);
- rtx folded_arg0;
- rtx const_arg0;
- rtx new;
-
- /* See if we previously assigned a constant value to this SUBREG. */
- if ((new = lookup_as_function (x, CONST_INT)) != 0
- || (new = lookup_as_function (x, CONST_DOUBLE)) != 0)
- return new;
-
- /* If this is a paradoxical SUBREG, we have no idea what value the
- extra bits would have. However, if the operand is equivalent to
- a SUBREG whose operand is the same as our mode, and all the modes
- are within a word, we can just use the inner operand because
- these SUBREGs just say how to treat the register.
-
- Similarly if we find an integer constant. */
-
- if (GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
- {
- enum machine_mode imode = GET_MODE (SUBREG_REG (x));
- struct table_elt *elt;
-
- if (GET_MODE_SIZE (mode) <= UNITS_PER_WORD
- && GET_MODE_SIZE (imode) <= UNITS_PER_WORD
- && (elt = lookup (SUBREG_REG (x), HASH (SUBREG_REG (x), imode),
- imode)) != 0)
- for (elt = elt->first_same_value; elt; elt = elt->next_same_value)
- {
- if (CONSTANT_P (elt->exp)
- && GET_MODE (elt->exp) == VOIDmode)
- return elt->exp;
-
- if (GET_CODE (elt->exp) == SUBREG
- && GET_MODE (SUBREG_REG (elt->exp)) == mode
- && exp_equiv_p (elt->exp, elt->exp, 1, false))
- return copy_rtx (SUBREG_REG (elt->exp));
- }
-
- return x;
- }
-
- /* Fold SUBREG_REG. If it changed, see if we can simplify the
- SUBREG. We might be able to if the SUBREG is extracting a single
- word in an integral mode or extracting the low part. */
-
- folded_arg0 = fold_rtx (SUBREG_REG (x), insn);
- const_arg0 = equiv_constant (folded_arg0);
- if (const_arg0)
- folded_arg0 = const_arg0;
-
- if (folded_arg0 != SUBREG_REG (x))
- {
- new = simplify_subreg (mode, folded_arg0,
- GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x));
- if (new)
- return new;
- }
-
- if (REG_P (folded_arg0)
- && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (folded_arg0)))
- {
- struct table_elt *elt;
-
- elt = lookup (folded_arg0,
- HASH (folded_arg0, GET_MODE (folded_arg0)),
- GET_MODE (folded_arg0));
-
- if (elt)
- elt = elt->first_same_value;
-
- if (subreg_lowpart_p (x))
- /* If this is a narrowing SUBREG and our operand is a REG, see
- if we can find an equivalence for REG that is an arithmetic
- operation in a wider mode where both operands are
- paradoxical SUBREGs from objects of our result mode. In
- that case, we couldn-t report an equivalent value for that
- operation, since we don't know what the extra bits will be.
- But we can find an equivalence for this SUBREG by folding
- that operation in the narrow mode. This allows us to fold
- arithmetic in narrow modes when the machine only supports
- word-sized arithmetic.
-
- Also look for a case where we have a SUBREG whose operand
- is the same as our result. If both modes are smaller than
- a word, we are simply interpreting a register in different
- modes and we can use the inner value. */
-
- for (; elt; elt = elt->next_same_value)
- {
- enum rtx_code eltcode = GET_CODE (elt->exp);
-
- /* Just check for unary and binary operations. */
- if (UNARY_P (elt->exp)
- && eltcode != SIGN_EXTEND
- && eltcode != ZERO_EXTEND
- && GET_CODE (XEXP (elt->exp, 0)) == SUBREG
- && GET_MODE (SUBREG_REG (XEXP (elt->exp, 0))) == mode
- && (GET_MODE_CLASS (mode)
- == GET_MODE_CLASS (GET_MODE (XEXP (elt->exp, 0)))))
- {
- rtx op0 = SUBREG_REG (XEXP (elt->exp, 0));
+/* If X is a nontrivial arithmetic operation on an argument for which
+ a constant value can be determined, return the result of operating
+ on that value, as a constant. Otherwise, return X, possibly with
+ one or more operands changed to a forward-propagated constant.
- if (!REG_P (op0) && ! CONSTANT_P (op0))
- op0 = fold_rtx (op0, NULL_RTX);
-
- op0 = equiv_constant (op0);
- if (op0)
- new = simplify_unary_operation (GET_CODE (elt->exp), mode,
- op0, mode);
- }
- else if (ARITHMETIC_P (elt->exp)
- && eltcode != DIV && eltcode != MOD
- && eltcode != UDIV && eltcode != UMOD
- && eltcode != ASHIFTRT && eltcode != LSHIFTRT
- && eltcode != ROTATE && eltcode != ROTATERT
- && ((GET_CODE (XEXP (elt->exp, 0)) == SUBREG
- && (GET_MODE (SUBREG_REG (XEXP (elt->exp, 0)))
- == mode))
- || CONSTANT_P (XEXP (elt->exp, 0)))
- && ((GET_CODE (XEXP (elt->exp, 1)) == SUBREG
- && (GET_MODE (SUBREG_REG (XEXP (elt->exp, 1)))
- == mode))
- || CONSTANT_P (XEXP (elt->exp, 1))))
- {
- rtx op0 = gen_lowpart_common (mode, XEXP (elt->exp, 0));
- rtx op1 = gen_lowpart_common (mode, XEXP (elt->exp, 1));
-
- if (op0 && !REG_P (op0) && ! CONSTANT_P (op0))
- op0 = fold_rtx (op0, NULL_RTX);
-
- if (op0)
- op0 = equiv_constant (op0);
-
- if (op1 && !REG_P (op1) && ! CONSTANT_P (op1))
- op1 = fold_rtx (op1, NULL_RTX);
-
- if (op1)
- op1 = equiv_constant (op1);
-
- /* If we are looking for the low SImode part of
- (ashift:DI c (const_int 32)), it doesn't work to
- compute that in SImode, because a 32-bit shift in
- SImode is unpredictable. We know the value is
- 0. */
- if (op0 && op1
- && GET_CODE (elt->exp) == ASHIFT
- && GET_CODE (op1) == CONST_INT
- && INTVAL (op1) >= GET_MODE_BITSIZE (mode))
- {
- if (INTVAL (op1)
- < GET_MODE_BITSIZE (GET_MODE (elt->exp)))
- /* If the count fits in the inner mode's width,
- but exceeds the outer mode's width, the value
- will get truncated to 0 by the subreg. */
- new = CONST0_RTX (mode);
- else
- /* If the count exceeds even the inner mode's width,
- don't fold this expression. */
- new = 0;
- }
- else if (op0 && op1)
- new = simplify_binary_operation (GET_CODE (elt->exp),
- mode, op0, op1);
- }
-
- else if (GET_CODE (elt->exp) == SUBREG
- && GET_MODE (SUBREG_REG (elt->exp)) == mode
- && (GET_MODE_SIZE (GET_MODE (folded_arg0))
- <= UNITS_PER_WORD)
- && exp_equiv_p (elt->exp, elt->exp, 1, false))
- new = copy_rtx (SUBREG_REG (elt->exp));
-
- if (new)
- return new;
- }
- else
- /* A SUBREG resulting from a zero extension may fold to zero
- if it extracts higher bits than the ZERO_EXTEND's source
- bits. FIXME: if combine tried to, er, combine these
- instructions, this transformation may be moved to
- simplify_subreg. */
- for (; elt; elt = elt->next_same_value)
- {
- if (GET_CODE (elt->exp) == ZERO_EXTEND
- && subreg_lsb (x)
- >= GET_MODE_BITSIZE (GET_MODE (XEXP (elt->exp, 0))))
- return CONST0_RTX (mode);
- }
- }
-
- return x;
-}
-
-/* Fold MEM. */
-
-static rtx
-fold_rtx_mem (rtx x, rtx insn)
-{
- enum machine_mode mode = GET_MODE (x);
- rtx new;
-
- /* If we are not actually processing an insn, don't try to find the
- best address. Not only don't we care, but we could modify the
- MEM in an invalid way since we have no insn to validate
- against. */
- if (insn != 0)
- find_best_addr (insn, &XEXP (x, 0), mode);
-
- {
- /* Even if we don't fold in the insn itself, we can safely do so
- here, in hopes of getting a constant. */
- rtx addr = fold_rtx (XEXP (x, 0), NULL_RTX);
- rtx base = 0;
- HOST_WIDE_INT offset = 0;
-
- if (REG_P (addr)
- && REGNO_QTY_VALID_P (REGNO (addr)))
- {
- int addr_q = REG_QTY (REGNO (addr));
- struct qty_table_elem *addr_ent = &qty_table[addr_q];
-
- if (GET_MODE (addr) == addr_ent->mode
- && addr_ent->const_rtx != NULL_RTX)
- addr = addr_ent->const_rtx;
- }
-
- /* Call target hook to avoid the effects of -fpic etc.... */
- addr = targetm.delegitimize_address (addr);
-
- /* If address is constant, split it into a base and integer
- offset. */
- if (GET_CODE (addr) == SYMBOL_REF || GET_CODE (addr) == LABEL_REF)
- base = addr;
- else if (GET_CODE (addr) == CONST && GET_CODE (XEXP (addr, 0)) == PLUS
- && GET_CODE (XEXP (XEXP (addr, 0), 1)) == CONST_INT)
- {
- base = XEXP (XEXP (addr, 0), 0);
- offset = INTVAL (XEXP (XEXP (addr, 0), 1));
- }
- else if (GET_CODE (addr) == LO_SUM
- && GET_CODE (XEXP (addr, 1)) == SYMBOL_REF)
- base = XEXP (addr, 1);
-
- /* If this is a constant pool reference, we can fold it into its
- constant to allow better value tracking. */
- if (base && GET_CODE (base) == SYMBOL_REF
- && CONSTANT_POOL_ADDRESS_P (base))
- {
- rtx constant = get_pool_constant (base);
- enum machine_mode const_mode = get_pool_mode (base);
- rtx new;
-
- if (CONSTANT_P (constant) && GET_CODE (constant) != CONST_INT)
- {
- constant_pool_entries_cost = COST (constant);
- constant_pool_entries_regcost = approx_reg_cost (constant);
- }
-
- /* If we are loading the full constant, we have an
- equivalence. */
- if (offset == 0 && mode == const_mode)
- return constant;
-
- /* If this actually isn't a constant (weird!), we can't do
- anything. Otherwise, handle the two most common cases:
- extracting a word from a multi-word constant, and
- extracting the low-order bits. Other cases don't seem
- common enough to worry about. */
- if (! CONSTANT_P (constant))
- return x;
-
- if (GET_MODE_CLASS (mode) == MODE_INT
- && GET_MODE_SIZE (mode) == UNITS_PER_WORD
- && offset % UNITS_PER_WORD == 0
- && (new = operand_subword (constant,
- offset / UNITS_PER_WORD,
- 0, const_mode)) != 0)
- return new;
-
- if (((BYTES_BIG_ENDIAN
- && offset == GET_MODE_SIZE (GET_MODE (constant)) - 1)
- || (! BYTES_BIG_ENDIAN && offset == 0))
- && (new = gen_lowpart (mode, constant)) != 0)
- return new;
- }
-
- /* If this is a reference to a label at a known position in a jump
- table, we also know its value. */
- if (base && GET_CODE (base) == LABEL_REF)
- {
- rtx label = XEXP (base, 0);
- rtx table_insn = NEXT_INSN (label);
-
- if (table_insn && JUMP_P (table_insn)
- && GET_CODE (PATTERN (table_insn)) == ADDR_VEC)
- {
- rtx table = PATTERN (table_insn);
-
- if (offset >= 0
- && (offset / GET_MODE_SIZE (GET_MODE (table))
- < XVECLEN (table, 0)))
- {
- rtx label = XVECEXP
- (table, 0, offset / GET_MODE_SIZE (GET_MODE (table)));
- rtx set;
-
- /* If we have an insn that loads the label from the
- jumptable into a reg, we don't want to set the reg
- to the label, because this may cause a reference to
- the label to remain after the label is removed in
- some very obscure cases (PR middle-end/18628). */
- if (!insn)
- return label;
-
- set = single_set (insn);
-
- if (! set || SET_SRC (set) != x)
- return x;
-
- /* If it's a jump, it's safe to reference the label. */
- if (SET_DEST (set) == pc_rtx)
- return label;
-
- return x;
- }
- }
- if (table_insn && JUMP_P (table_insn)
- && GET_CODE (PATTERN (table_insn)) == ADDR_DIFF_VEC)
- {
- rtx table = PATTERN (table_insn);
-
- if (offset >= 0
- && (offset / GET_MODE_SIZE (GET_MODE (table))
- < XVECLEN (table, 1)))
- {
- offset /= GET_MODE_SIZE (GET_MODE (table));
- new = gen_rtx_MINUS (Pmode, XVECEXP (table, 1, offset),
- XEXP (table, 0));
-
- if (GET_MODE (table) != Pmode)
- new = gen_rtx_TRUNCATE (GET_MODE (table), new);
-
- /* Indicate this is a constant. This isn't a valid
- form of CONST, but it will only be used to fold the
- next insns and then discarded, so it should be
- safe.
-
- Note this expression must be explicitly discarded,
- by cse_insn, else it may end up in a REG_EQUAL note
- and "escape" to cause problems elsewhere. */
- return gen_rtx_CONST (GET_MODE (new), new);
- }
- }
- }
-
- return x;
- }
-}
-
-/* If X is a nontrivial arithmetic operation on an argument
- for which a constant value can be determined, return
- the result of operating on that value, as a constant.
- Otherwise, return X, possibly with one or more operands
- modified by recursive calls to this function.
-
- If X is a register whose contents are known, we do NOT
- return those contents here. equiv_constant is called to
- perform that task.
+ If X is a register whose contents are known, we do NOT return
+ those contents here; equiv_constant is called to perform that task.
+ For SUBREGs and MEMs, we do that both here and in equiv_constant.
INSN is the insn that we may be modifying. If it is 0, make a copy
of X before modifying it. */
const char *fmt;
int i;
rtx new = 0;
- int copied = 0;
- int must_swap = 0;
+ int changed = 0;
- /* Folded equivalents of first two operands of X. */
+ /* Operands of X. */
rtx folded_arg0;
rtx folded_arg1;
if (x == 0)
return x;
- mode = GET_MODE (x);
+ /* Try to perform some initial simplifications on X. */
code = GET_CODE (x);
switch (code)
{
+ case MEM:
+ case SUBREG:
+ if ((new = equiv_constant (x)) != NULL_RTX)
+ return new;
+ return x;
+
case CONST:
case CONST_INT:
case CONST_DOUBLE:
return prev_insn_cc0;
#endif
- case SUBREG:
- return fold_rtx_subreg (x, insn);
-
- case NOT:
- case NEG:
- /* If we have (NOT Y), see if Y is known to be (NOT Z).
- If so, (NOT Y) simplifies to Z. Similarly for NEG. */
- new = lookup_as_function (XEXP (x, 0), code);
- if (new)
- return fold_rtx (copy_rtx (XEXP (new, 0)), insn);
- break;
-
- case MEM:
- return fold_rtx_mem (x, insn);
-
-#ifdef NO_FUNCTION_CSE
- case CALL:
- if (CONSTANT_P (XEXP (XEXP (x, 0), 0)))
- return x;
- break;
-#endif
-
case ASM_OPERANDS:
if (insn)
{
validate_change (insn, &ASM_OPERANDS_INPUT (x, i),
fold_rtx (ASM_OPERANDS_INPUT (x, i), insn), 0);
}
+ return x;
+
+#ifdef NO_FUNCTION_CSE
+ case CALL:
+ if (CONSTANT_P (XEXP (XEXP (x, 0), 0)))
+ return x;
break;
+#endif
+ /* Anything else goes through the loop below. */
default:
break;
}
+ mode = GET_MODE (x);
const_arg0 = 0;
const_arg1 = 0;
const_arg2 = 0;
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
if (fmt[i] == 'e')
{
- rtx arg = XEXP (x, i);
- rtx folded_arg = arg, const_arg = 0;
- enum machine_mode mode_arg = GET_MODE (arg);
- rtx cheap_arg, expensive_arg;
- rtx replacements[2];
- int j;
- int old_cost = COST_IN (XEXP (x, i), code);
-
- /* Most arguments are cheap, so handle them specially. */
- switch (GET_CODE (arg))
+ rtx folded_arg = XEXP (x, i), const_arg;
+ enum machine_mode mode_arg = GET_MODE (folded_arg);
+
+ switch (GET_CODE (folded_arg))
{
+ case MEM:
case REG:
- /* This is the same as calling equiv_constant; it is duplicated
- here for speed. */
- if (REGNO_QTY_VALID_P (REGNO (arg)))
- {
- int arg_q = REG_QTY (REGNO (arg));
- struct qty_table_elem *arg_ent = &qty_table[arg_q];
-
- if (arg_ent->const_rtx != NULL_RTX
- && !REG_P (arg_ent->const_rtx)
- && GET_CODE (arg_ent->const_rtx) != PLUS)
- const_arg
- = gen_lowpart (GET_MODE (arg),
- arg_ent->const_rtx);
- }
+ case SUBREG:
+ const_arg = equiv_constant (folded_arg);
break;
case CONST:
case LABEL_REF:
case CONST_DOUBLE:
case CONST_VECTOR:
- const_arg = arg;
+ const_arg = folded_arg;
break;
#ifdef HAVE_cc0
#endif
default:
- folded_arg = fold_rtx (arg, insn);
+ folded_arg = fold_rtx (folded_arg, insn);
const_arg = equiv_constant (folded_arg);
+ break;
}
/* For the first three operands, see if the operand
break;
}
- /* Pick the least expensive of the folded argument and an
- equivalent constant argument. */
- if (const_arg == 0 || const_arg == folded_arg
- || COST_IN (const_arg, code) > COST_IN (folded_arg, code))
- cheap_arg = folded_arg, expensive_arg = const_arg;
- else
- cheap_arg = const_arg, expensive_arg = folded_arg;
-
- /* Try to replace the operand with the cheapest of the two
- possibilities. If it doesn't work and this is either of the first
- two operands of a commutative operation, try swapping them.
- If THAT fails, try the more expensive, provided it is cheaper
- than what is already there. */
-
- if (cheap_arg == XEXP (x, i))
- continue;
-
- if (insn == 0 && ! copied)
- {
- x = copy_rtx (x);
- copied = 1;
- }
-
- /* Order the replacements from cheapest to most expensive. */
- replacements[0] = cheap_arg;
- replacements[1] = expensive_arg;
-
- for (j = 0; j < 2 && replacements[j]; j++)
- {
- int new_cost = COST_IN (replacements[j], code);
-
- /* Stop if what existed before was cheaper. Prefer constants
- in the case of a tie. */
- if (new_cost > old_cost
- || (new_cost == old_cost && CONSTANT_P (XEXP (x, i))))
- break;
+ /* Pick the least expensive of the argument and an equivalent constant
+ argument. */
+ if (const_arg != 0
+ && const_arg != folded_arg
+ && COST_IN (const_arg, code) <= COST_IN (folded_arg, code)
/* It's not safe to substitute the operand of a conversion
operator with a constant, as the conversion's identity
depends upon the mode of its operand. This optimization
is handled by the call to simplify_unary_operation. */
- if (GET_RTX_CLASS (code) == RTX_UNARY
- && GET_MODE (replacements[j]) != mode_arg0
- && (code == ZERO_EXTEND
- || code == SIGN_EXTEND
- || code == TRUNCATE
- || code == FLOAT_TRUNCATE
- || code == FLOAT_EXTEND
- || code == FLOAT
- || code == FIX
- || code == UNSIGNED_FLOAT
- || code == UNSIGNED_FIX))
- continue;
-
- if (validate_change (insn, &XEXP (x, i), replacements[j], 0))
- break;
-
- if (GET_RTX_CLASS (code) == RTX_COMM_COMPARE
- || GET_RTX_CLASS (code) == RTX_COMM_ARITH)
- {
- validate_change (insn, &XEXP (x, i), XEXP (x, 1 - i), 1);
- validate_change (insn, &XEXP (x, 1 - i), replacements[j], 1);
-
- if (apply_change_group ())
- {
- /* Swap them back to be invalid so that this loop can
- continue and flag them to be swapped back later. */
- rtx tem;
-
- tem = XEXP (x, 0); XEXP (x, 0) = XEXP (x, 1);
- XEXP (x, 1) = tem;
- must_swap = 1;
- break;
- }
- }
- }
- }
+ && (GET_RTX_CLASS (code) != RTX_UNARY
+ || GET_MODE (const_arg) == mode_arg0
+ || (code != ZERO_EXTEND
+ && code != SIGN_EXTEND
+ && code != TRUNCATE
+ && code != FLOAT_TRUNCATE
+ && code != FLOAT_EXTEND
+ && code != FLOAT
+ && code != FIX
+ && code != UNSIGNED_FLOAT
+ && code != UNSIGNED_FIX)))
+ folded_arg = const_arg;
+
+ if (folded_arg == XEXP (x, i))
+ continue;
- else
- {
- if (fmt[i] == 'E')
- /* Don't try to fold inside of a vector of expressions.
- Doing nothing is harmless. */
- {;}
+ if (insn == NULL_RTX && !changed)
+ x = copy_rtx (x);
+ changed = 1;
+ validate_change (insn, &XEXP (x, i), folded_arg, 1);
}
- /* If a commutative operation, place a constant integer as the second
- operand unless the first operand is also a constant integer. Otherwise,
- place any constant second unless the first operand is also a constant. */
-
- if (COMMUTATIVE_P (x))
+ if (changed)
{
- if (must_swap
- || swap_commutative_operands_p (const_arg0 ? const_arg0
- : XEXP (x, 0),
- const_arg1 ? const_arg1
- : XEXP (x, 1)))
+ /* Canonicalize X if necessary, and keep const_argN and folded_argN
+ consistent with the order in X. */
+ if (canonicalize_change_group (insn, x))
{
- rtx tem = XEXP (x, 0);
+ rtx tem;
+ tem = const_arg0, const_arg0 = const_arg1, const_arg1 = tem;
+ tem = folded_arg0, folded_arg0 = folded_arg1, folded_arg1 = tem;
+ }
- if (insn == 0 && ! copied)
- {
- x = copy_rtx (x);
- copied = 1;
- }
-
- validate_change (insn, &XEXP (x, 0), XEXP (x, 1), 1);
- validate_change (insn, &XEXP (x, 1), tem, 1);
- if (apply_change_group ())
- {
- tem = const_arg0, const_arg0 = const_arg1, const_arg1 = tem;
- tem = folded_arg0, folded_arg0 = folded_arg1, folded_arg1 = tem;
- }
- }
- }
+ apply_change_group ();
+ }
/* If X is an arithmetic operation, see if we can simplify it. */
{
int is_shift
= (code == ASHIFT || code == ASHIFTRT || code == LSHIFTRT);
- rtx y = lookup_as_function (folded_arg0, code);
- rtx inner_const;
+ rtx y, inner_const, new_const;
enum rtx_code associate_code;
- rtx new_const;
-
- if (y == 0
- || 0 == (inner_const
- = equiv_constant (fold_rtx (XEXP (y, 1), 0)))
- || GET_CODE (inner_const) != CONST_INT
- /* If we have compiled a statement like
- "if (x == (x & mask1))", and now are looking at
- "x & mask2", we will have a case where the first operand
- of Y is the same as our first operand. Unless we detect
- this case, an infinite loop will result. */
- || XEXP (y, 0) == folded_arg0)
+
+ if (is_shift
+ && (INTVAL (const_arg1) >= GET_MODE_BITSIZE (mode)
+ || INTVAL (const_arg1) < 0))
+ {
+ if (SHIFT_COUNT_TRUNCATED)
+ const_arg1 = GEN_INT (INTVAL (const_arg1)
+ & (GET_MODE_BITSIZE (mode) - 1));
+ else
+ break;
+ }
+
+ y = lookup_as_function (folded_arg0, code);
+ if (y == 0)
+ break;
+
+ /* If we have compiled a statement like
+ "if (x == (x & mask1))", and now are looking at
+ "x & mask2", we will have a case where the first operand
+ of Y is the same as our first operand. Unless we detect
+ this case, an infinite loop will result. */
+ if (XEXP (y, 0) == folded_arg0)
+ break;
+
+ inner_const = equiv_constant (fold_rtx (XEXP (y, 1), 0));
+ if (!inner_const || GET_CODE (inner_const) != CONST_INT)
break;
/* Don't associate these operations if they are a PLUS with the
&& exact_log2 (- INTVAL (const_arg1)) >= 0)))
break;
+ if (is_shift
+ && (INTVAL (inner_const) >= GET_MODE_BITSIZE (mode)
+ || INTVAL (inner_const) < 0))
+ {
+ if (SHIFT_COUNT_TRUNCATED)
+ inner_const = GEN_INT (INTVAL (inner_const)
+ & (GET_MODE_BITSIZE (mode) - 1));
+ else
+ break;
+ }
+
/* Compute the code used to compose the constants. For example,
A-C1-C2 is A-(C1 + C2), so if CODE == MINUS, we want PLUS. */
shift on a machine that does a sign-extend as a pair
of shifts. */
- if (is_shift && GET_CODE (new_const) == CONST_INT
+ if (is_shift
+ && GET_CODE (new_const) == CONST_INT
&& INTVAL (new_const) >= GET_MODE_BITSIZE (mode))
{
/* As an exception, we can turn an ASHIFTRT of this
form into a shift of the number of bits - 1. */
if (code == ASHIFTRT)
new_const = GEN_INT (GET_MODE_BITSIZE (mode) - 1);
+ else if (!side_effects_p (XEXP (y, 0)))
+ return CONST0_RTX (mode);
else
break;
}
if (x == 0 || CONSTANT_P (x))
return x;
- /* If X is a MEM, try to fold it outside the context of any insn to see if
- it might be equivalent to a constant. That handles the case where it
- is a constant-pool reference. Then try to look it up in the hash table
- in case it is something whose value we have seen before. */
+ if (GET_CODE (x) == SUBREG)
+ {
+ rtx new;
+
+ /* See if we previously assigned a constant value to this SUBREG. */
+ if ((new = lookup_as_function (x, CONST_INT)) != 0
+ || (new = lookup_as_function (x, CONST_DOUBLE)) != 0)
+ return new;
+
+ if (REG_P (SUBREG_REG (x))
+ && (new = equiv_constant (SUBREG_REG (x))) != 0)
+ return simplify_subreg (GET_MODE (x), SUBREG_REG (x),
+ GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x));
+
+ return 0;
+ }
+
+ /* If X is a MEM, see if it is a constant-pool reference, or look it up in
+ the hash table in case its value was seen before. */
if (MEM_P (x))
{
struct table_elt *elt;
- x = fold_rtx (x, NULL_RTX);
+ x = avoid_constant_pool_reference (x);
if (CONSTANT_P (x))
return x;
return 0;
}
\f
-/* Given INSN, a jump insn, PATH_TAKEN indicates if we are following the "taken"
- branch. It will be zero if not.
+/* Given INSN, a jump insn, TAKEN indicates if we are following the
+ "taken" branch.
In certain cases, this can cause us to add an equivalence. For example,
if we are following the taken case of
comparison is seen later, we will know its value. */
static void
-record_jump_equiv (rtx insn, int taken)
+record_jump_equiv (rtx insn, bool taken)
{
int cond_known_true;
rtx op0, op1;
enum rtx_code code;
/* Ensure this is the right kind of insn. */
- if (! any_condjump_p (insn))
- return;
+ gcc_assert (any_condjump_p (insn));
+
set = pc_set (insn);
/* See if this jump condition is known true or false. */
rtx tem;
int n_sets = 0;
-#ifdef HAVE_cc0
- /* Records what this insn does to set CC0. */
- rtx this_insn_cc0 = 0;
- enum machine_mode this_insn_cc0_mode = VOIDmode;
-#endif
-
rtx src_eqv = 0;
struct table_elt *src_eqv_elt = 0;
int src_eqv_volatile = 0;
struct set *sets = (struct set *) 0;
this_insn = insn;
+#ifdef HAVE_cc0
+ /* Records what this insn does to set CC0. */
+ this_insn_cc0 = 0;
+ this_insn_cc0_mode = VOIDmode;
+#endif
/* Find all the SETs and CLOBBERs in this instruction.
Record all the SETs in the array `set' and count them.
const_elt; const_elt = const_elt->next_same_value)
if (REG_P (const_elt->exp))
{
- src_related = gen_lowpart (mode,
- const_elt->exp);
+ src_related = gen_lowpart (mode, const_elt->exp);
break;
}
}
larger_elt; larger_elt = larger_elt->next_same_value)
if (REG_P (larger_elt->exp))
{
- src_related = gen_lowpart (mode,
- larger_elt->exp);
+ src_related = gen_lowpart (mode, larger_elt->exp);
break;
}
validate_change (insn, &SET_SRC (sets[i].rtl), new, 1);
apply_change_group ();
+
break;
}
/* If we made a change, recompute SRC values. */
if (src != sets[i].src)
{
- cse_altered = 1;
do_not_record = 0;
hash_arg_in_memory = 0;
sets[i].src = src;
else if (n_sets == 1 && dest == pc_rtx && src == pc_rtx)
{
/* One less use of the label this insn used to jump to. */
- delete_insn (insn);
+ delete_insn_and_edges (insn);
cse_jumps_altered = 1;
/* No more processing for this set. */
sets[i].rtl = 0;
{
rtx new, note;
- new = emit_jump_insn_after (gen_jump (XEXP (src, 0)), insn);
+ new = emit_jump_insn_before (gen_jump (XEXP (src, 0)), insn);
JUMP_LABEL (new) = XEXP (src, 0);
LABEL_NUSES (XEXP (src, 0))++;
REG_NOTES (new) = note;
}
- delete_insn (insn);
+ delete_insn_and_edges (insn);
insn = new;
/* Now emit a BARRIER after the unconditional jump. */
{
if (insert_regs (x, NULL, 0))
{
+ rtx dest = SET_DEST (sets[i].rtl);
+
rehash_using_reg (x);
hash = HASH (x, mode);
+ sets[i].dest_hash = HASH (dest, GET_MODE (dest));
}
elt = insert (x, NULL, hash, mode);
}
&& MEM_VOLATILE_P (PATTERN (insn)))
flush_hash_table ();
+ /* Don't cse over a call to setjmp; on some machines (eg VAX)
+ the regs restored by the longjmp come from a later time
+ than the setjmp. */
+ if (CALL_P (insn) && find_reg_note (insn, REG_SETJMP, NULL))
+ {
+ flush_hash_table ();
+ goto done;
+ }
+
/* Make sure registers mentioned in destinations
are safe for use in an expression to be inserted.
This removes from the hash table
if ((src_ent->first_reg == REGNO (SET_DEST (sets[0].rtl)))
&& ! find_reg_note (insn, REG_RETVAL, NULL_RTX))
{
- rtx prev = insn;
/* Scan for the previous nonnote insn, but stop at a basic
block boundary. */
+ rtx prev = insn;
+ rtx bb_head = BB_HEAD (BLOCK_FOR_INSN (insn));
do
{
prev = PREV_INSN (prev);
}
- while (prev && NOTE_P (prev)
- && NOTE_LINE_NUMBER (prev) != NOTE_INSN_BASIC_BLOCK);
+ while (prev != bb_head && NOTE_P (prev));
/* Do not swap the registers around if the previous instruction
attaches a REG_EQUIV note to REG1.
This section previously turned the REG_EQUIV into a REG_EQUAL
note. We cannot do that because REG_EQUIV may provide an
uninitialized stack slot when REG_PARM_STACK_SPACE is used. */
-
- if (prev != 0 && NONJUMP_INSN_P (prev)
+ if (NONJUMP_INSN_P (prev)
&& GET_CODE (PATTERN (prev)) == SET
&& SET_DEST (PATTERN (prev)) == SET_SRC (sets[0].rtl)
&& ! find_reg_note (prev, REG_EQUIV, NULL_RTX))
}
}
- /* If this is a conditional jump insn, record any known equivalences due to
- the condition being tested. */
-
- if (JUMP_P (insn)
- && n_sets == 1 && GET_CODE (x) == SET
- && GET_CODE (SET_SRC (x)) == IF_THEN_ELSE)
- record_jump_equiv (insn, 0);
-
-#ifdef HAVE_cc0
- /* If the previous insn set CC0 and this insn no longer references CC0,
- delete the previous insn. Here we use the fact that nothing expects CC0
- to be valid over an insn, which is true until the final pass. */
- if (prev_insn && NONJUMP_INSN_P (prev_insn)
- && (tem = single_set (prev_insn)) != 0
- && SET_DEST (tem) == cc0_rtx
- && ! reg_mentioned_p (cc0_rtx, x))
- delete_insn (prev_insn);
-
- prev_insn_cc0 = this_insn_cc0;
- prev_insn_cc0_mode = this_insn_cc0_mode;
- prev_insn = insn;
-#endif
+done:;
}
\f
/* Remove from the hash table all expressions that reference memory. */
}
}
-/* If ADDR is an address that implicitly affects the stack pointer, return
- 1 and update the register tables to show the effect. Else, return 0. */
-
-static int
-addr_affects_sp_p (rtx addr)
-{
- if (GET_RTX_CLASS (GET_CODE (addr)) == RTX_AUTOINC
- && REG_P (XEXP (addr, 0))
- && REGNO (XEXP (addr, 0)) == STACK_POINTER_REGNUM)
- {
- if (REG_TICK (STACK_POINTER_REGNUM) >= 0)
- {
- REG_TICK (STACK_POINTER_REGNUM)++;
- /* Is it possible to use a subreg of SP? */
- SUBREG_TICKED (STACK_POINTER_REGNUM) = -1;
- }
-
- /* This should be *very* rare. */
- if (TEST_HARD_REG_BIT (hard_regs_in_table, STACK_POINTER_REGNUM))
- invalidate (stack_pointer_rtx, VOIDmode);
-
- return 1;
- }
-
- return 0;
-}
-
/* Perform invalidation on the basis of everything about an insn
except for invalidating the actual places that are SET in it.
This includes the places CLOBBERed, and anything that might
{
rtx new = gen_lowpart (GET_MODE (x), ent->const_rtx);
if (new)
- return new;
+ return copy_rtx (new);
}
}
return x;
}
\f
-/* Process one SET of an insn that was skipped. We ignore CLOBBERs
- since they are done elsewhere. This function is called via note_stores. */
+/* Find a path in the CFG, starting with FIRST_BB to perform CSE on.
-static void
-invalidate_skipped_set (rtx dest, rtx set, void *data ATTRIBUTE_UNUSED)
+ DATA is a pointer to a struct cse_basic_block_data, that is used to
+ describe the path.
+ It is filled with a queue of basic blocks, starting with FIRST_BB
+ and following a trace through the CFG.
+
+ If all paths starting at FIRST_BB have been followed, or no new path
+ starting at FIRST_BB can be constructed, this function returns FALSE.
+ Otherwise, DATA->path is filled and the function returns TRUE indicating
+ that a path to follow was found.
+
+ If FOLLOW_JUMPS is false, the maximum path length is 1 and the only
+ block in the path will be FIRST_BB. */
+
+static bool
+cse_find_path (basic_block first_bb, struct cse_basic_block_data *data,
+ int follow_jumps)
{
- enum rtx_code code = GET_CODE (dest);
-
- if (code == MEM
- && ! addr_affects_sp_p (dest) /* If this is not a stack push ... */
- /* There are times when an address can appear varying and be a PLUS
- during this scan when it would be a fixed address were we to know
- the proper equivalences. So invalidate all memory if there is
- a BLKmode or nonscalar memory reference or a reference to a
- variable address. */
- && (MEM_IN_STRUCT_P (dest) || GET_MODE (dest) == BLKmode
- || cse_rtx_varies_p (XEXP (dest, 0), 0)))
+ basic_block bb;
+ edge e;
+ int path_size;
+
+ SET_BIT (cse_visited_basic_blocks, first_bb->index);
+
+ /* See if there is a previous path. */
+ path_size = data->path_size;
+
+ /* There is a previous path. Make sure it started with FIRST_BB. */
+ if (path_size)
+ gcc_assert (data->path[0].bb == first_bb);
+
+ /* There was only one basic block in the last path. Clear the path and
+ return, so that paths starting at another basic block can be tried. */
+ if (path_size == 1)
{
- invalidate_memory ();
- return;
+ path_size = 0;
+ goto done;
}
- if (GET_CODE (set) == CLOBBER
- || CC0_P (dest)
- || dest == pc_rtx)
- return;
+ /* If the path was empty from the beginning, construct a new path. */
+ if (path_size == 0)
+ data->path[path_size++].bb = first_bb;
+ else
+ {
+ /* Otherwise, path_size must be equal to or greater than 2, because
+ a previous path exists that is at least two basic blocks long.
- if (code == STRICT_LOW_PART || code == ZERO_EXTRACT)
- invalidate (XEXP (dest, 0), GET_MODE (dest));
- else if (code == REG || code == SUBREG || code == MEM)
- invalidate (dest, VOIDmode);
-}
+ Update the previous branch path, if any. If the last branch was
+ previously along the branch edge, take the fallthrough edge now. */
+ while (path_size >= 2)
+ {
+ basic_block last_bb_in_path, previous_bb_in_path;
+ edge e;
+
+ --path_size;
+ last_bb_in_path = data->path[path_size].bb;
+ previous_bb_in_path = data->path[path_size - 1].bb;
+
+ /* If we previously followed a path along the branch edge, try
+ the fallthru edge now. */
+ if (EDGE_COUNT (previous_bb_in_path->succs) == 2
+ && any_condjump_p (BB_END (previous_bb_in_path))
+ && (e = find_edge (previous_bb_in_path, last_bb_in_path))
+ && e == BRANCH_EDGE (previous_bb_in_path))
+ {
+ bb = FALLTHRU_EDGE (previous_bb_in_path)->dest;
+ if (bb != EXIT_BLOCK_PTR
+ && single_pred_p (bb)
+ /* We used to assert here that we would only see blocks
+ that we have not visited yet. But we may end up
+ visiting basic blocks twice if the CFG has changed
+ in this run of cse_main, because when the CFG changes
+ the topological sort of the CFG also changes. A basic
+ blocks that previously had more than two predecessors
+ may now have a single predecessor, and become part of
+ a path that starts at another basic block.
+
+ We still want to visit each basic block only once, so
+ halt the path here if we have already visited BB. */
+ && !TEST_BIT (cse_visited_basic_blocks, bb->index))
+ {
+ SET_BIT (cse_visited_basic_blocks, bb->index);
+ data->path[path_size++].bb = bb;
+ break;
+ }
+ }
-/* Invalidate all insns from START up to the end of the function or the
- next label. This called when we wish to CSE around a block that is
- conditionally executed. */
+ data->path[path_size].bb = NULL;
+ }
-static void
-invalidate_skipped_block (rtx start)
-{
- rtx insn;
+ /* If only one block remains in the path, bail. */
+ if (path_size == 1)
+ {
+ path_size = 0;
+ goto done;
+ }
+ }
- for (insn = start; insn && !LABEL_P (insn);
- insn = NEXT_INSN (insn))
+ /* Extend the path if possible. */
+ if (follow_jumps)
{
- if (! INSN_P (insn))
- continue;
-
- if (CALL_P (insn))
+ bb = data->path[path_size - 1].bb;
+ while (bb && path_size < PARAM_VALUE (PARAM_MAX_CSE_PATH_LENGTH))
{
- if (! CONST_OR_PURE_CALL_P (insn))
- invalidate_memory ();
- invalidate_for_call ();
- }
+ if (single_succ_p (bb))
+ e = single_succ_edge (bb);
+ else if (EDGE_COUNT (bb->succs) == 2
+ && any_condjump_p (BB_END (bb)))
+ {
+ /* First try to follow the branch. If that doesn't lead
+ to a useful path, follow the fallthru edge. */
+ e = BRANCH_EDGE (bb);
+ if (!single_pred_p (e->dest))
+ e = FALLTHRU_EDGE (bb);
+ }
+ else
+ e = NULL;
- invalidate_from_clobbers (PATTERN (insn));
- note_stores (PATTERN (insn), invalidate_skipped_set, NULL);
+ if (e && e->dest != EXIT_BLOCK_PTR
+ && single_pred_p (e->dest)
+ /* Avoid visiting basic blocks twice. The large comment
+ above explains why this can happen. */
+ && !TEST_BIT (cse_visited_basic_blocks, e->dest->index))
+ {
+ basic_block bb2 = e->dest;
+ SET_BIT (cse_visited_basic_blocks, bb2->index);
+ data->path[path_size++].bb = bb2;
+ bb = bb2;
+ }
+ else
+ bb = NULL;
+ }
}
+
+done:
+ data->path_size = path_size;
+ return path_size != 0;
}
\f
-/* Find the end of INSN's basic block and return its range,
- the total number of SETs in all the insns of the block, the last insn of the
- block, and the branch path.
+/* Dump the path in DATA to file F. NSETS is the number of sets
+ in the path. */
- The branch path indicates which branches should be followed. If a nonzero
- path size is specified, the block should be rescanned and a different set
- of branches will be taken. The branch path is only used if
- FLAG_CSE_FOLLOW_JUMPS or FLAG_CSE_SKIP_BLOCKS is nonzero.
+static void
+cse_dump_path (struct cse_basic_block_data *data, int nsets, FILE *f)
+{
+ int path_entry;
- DATA is a pointer to a struct cse_basic_block_data, defined below, that is
- used to describe the block. It is filled in with the information about
- the current block. The incoming structure's branch path, if any, is used
- to construct the output branch path. */
+ fprintf (f, ";; Following path with %d sets: ", nsets);
+ for (path_entry = 0; path_entry < data->path_size; path_entry++)
+ fprintf (f, "%d ", (data->path[path_entry].bb)->index);
+ fputc ('\n', dump_file);
+ fflush (f);
+}
+
+\f
+/* Return true if BB has exception handling successor edges. */
+
+static bool
+have_eh_succ_edges (basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ if (e->flags & EDGE_EH)
+ return true;
+
+ return false;
+}
+
+\f
+/* Scan to the end of the path described by DATA. Return an estimate of
+ the total number of SETs, and the lowest and highest insn CUID, of all
+ insns in the path. */
static void
-cse_end_of_basic_block (rtx insn, struct cse_basic_block_data *data,
- int follow_jumps, int skip_blocks)
+cse_prescan_path (struct cse_basic_block_data *data)
{
- rtx p = insn, q;
int nsets = 0;
- int low_cuid = INSN_CUID (insn), high_cuid = INSN_CUID (insn);
- rtx next = INSN_P (insn) ? insn : next_real_insn (insn);
+ int low_cuid = -1, high_cuid = -1; /* FIXME low_cuid not computed correctly */
int path_size = data->path_size;
- int path_entry = 0;
- int i;
+ int path_entry;
- /* Update the previous branch path, if any. If the last branch was
- previously PATH_TAKEN, mark it PATH_NOT_TAKEN.
- If it was previously PATH_NOT_TAKEN,
- shorten the path by one and look at the previous branch. We know that
- at least one branch must have been taken if PATH_SIZE is nonzero. */
- while (path_size > 0)
+ /* Scan to end of each basic block in the path. */
+ for (path_entry = 0; path_entry < path_size; path_entry++)
{
- if (data->path[path_size - 1].status != PATH_NOT_TAKEN)
+ basic_block bb;
+ rtx insn;
+
+ bb = data->path[path_entry].bb;
+
+ FOR_BB_INSNS (bb, insn)
{
- data->path[path_size - 1].status = PATH_NOT_TAKEN;
- break;
+ if (!INSN_P (insn))
+ continue;
+
+ /* A PARALLEL can have lots of SETs in it,
+ especially if it is really an ASM_OPERANDS. */
+ if (GET_CODE (PATTERN (insn)) == PARALLEL)
+ nsets += XVECLEN (PATTERN (insn), 0);
+ else
+ nsets += 1;
+
+ /* Ignore insns made by CSE in a previous traversal of this
+ basic block. They cannot affect the boundaries of the
+ basic block.
+ FIXME: When we only visit each basic block at most once,
+ this can go away. */
+ if (INSN_UID (insn) <= max_uid && INSN_CUID (insn) > high_cuid)
+ high_cuid = INSN_CUID (insn);
+ if (INSN_UID (insn) <= max_uid && INSN_CUID (insn) < low_cuid)
+ low_cuid = INSN_CUID (insn);
}
- else
- path_size--;
}
- /* If the first instruction is marked with QImode, that means we've
- already processed this block. Our caller will look at DATA->LAST
- to figure out where to go next. We want to return the next block
- in the instruction stream, not some branched-to block somewhere
- else. We accomplish this by pretending our called forbid us to
- follow jumps, or skip blocks. */
- if (GET_MODE (insn) == QImode)
- follow_jumps = skip_blocks = 0;
-
- /* Scan to end of this basic block. */
- while (p && !LABEL_P (p))
- {
- /* Don't cse over a call to setjmp; on some machines (eg VAX)
- the regs restored by the longjmp come from
- a later time than the setjmp. */
- if (PREV_INSN (p) && CALL_P (PREV_INSN (p))
- && find_reg_note (PREV_INSN (p), REG_SETJMP, NULL))
- break;
-
- /* A PARALLEL can have lots of SETs in it,
- especially if it is really an ASM_OPERANDS. */
- if (INSN_P (p) && GET_CODE (PATTERN (p)) == PARALLEL)
- nsets += XVECLEN (PATTERN (p), 0);
- else if (!NOTE_P (p))
- nsets += 1;
-
- /* Ignore insns made by CSE; they cannot affect the boundaries of
- the basic block. */
+ data->low_cuid = low_cuid;
+ data->high_cuid = high_cuid;
+ data->nsets = nsets;
+}
+\f
+/* Process a single extended basic block described by EBB_DATA. */
- if (INSN_UID (p) <= max_uid && INSN_CUID (p) > high_cuid)
- high_cuid = INSN_CUID (p);
- if (INSN_UID (p) <= max_uid && INSN_CUID (p) < low_cuid)
- low_cuid = INSN_CUID (p);
+static void
+cse_extended_basic_block (struct cse_basic_block_data *ebb_data)
+{
+ int path_size = ebb_data->path_size;
+ int path_entry;
+ int num_insns = 0;
- /* See if this insn is in our branch path. If it is and we are to
- take it, do so. */
- if (path_entry < path_size && data->path[path_entry].branch == p)
- {
- if (data->path[path_entry].status != PATH_NOT_TAKEN)
- p = JUMP_LABEL (p);
+ /* Allocate the space needed by qty_table. */
+ qty_table = XNEWVEC (struct qty_table_elem, max_qty);
- /* Point to next entry in path, if any. */
- path_entry++;
- }
+ new_basic_block ();
+ for (path_entry = 0; path_entry < path_size; path_entry++)
+ {
+ basic_block bb;
+ rtx insn;
+ rtx libcall_insn = NULL_RTX;
+ int no_conflict = 0;
- /* If this is a conditional jump, we can follow it if -fcse-follow-jumps
- was specified, we haven't reached our maximum path length, there are
- insns following the target of the jump, this is the only use of the
- jump label, and the target label is preceded by a BARRIER.
-
- Alternatively, we can follow the jump if it branches around a
- block of code and there are no other branches into the block.
- In this case invalidate_skipped_block will be called to invalidate any
- registers set in the block when following the jump. */
-
- else if ((follow_jumps || skip_blocks) && path_size < PARAM_VALUE (PARAM_MAX_CSE_PATH_LENGTH) - 1
- && JUMP_P (p)
- && GET_CODE (PATTERN (p)) == SET
- && GET_CODE (SET_SRC (PATTERN (p))) == IF_THEN_ELSE
- && JUMP_LABEL (p) != 0
- && LABEL_NUSES (JUMP_LABEL (p)) == 1
- && NEXT_INSN (JUMP_LABEL (p)) != 0)
+ bb = ebb_data->path[path_entry].bb;
+ FOR_BB_INSNS (bb, insn)
{
- for (q = PREV_INSN (JUMP_LABEL (p)); q; q = PREV_INSN (q))
- if ((!NOTE_P (q)
- || (PREV_INSN (q) && CALL_P (PREV_INSN (q))
- && find_reg_note (PREV_INSN (q), REG_SETJMP, NULL)))
- && (!LABEL_P (q) || LABEL_NUSES (q) != 0))
- break;
+ /* If we have processed 1,000 insns, flush the hash table to
+ avoid extreme quadratic behavior. We must not include NOTEs
+ in the count since there may be more of them when generating
+ debugging information. If we clear the table at different
+ times, code generated with -g -O might be different than code
+ generated with -O but not -g.
+
+ FIXME: This is a real kludge and needs to be done some other
+ way. */
+ if (INSN_P (insn)
+ && num_insns++ > PARAM_VALUE (PARAM_MAX_CSE_INSNS))
+ {
+ flush_hash_table ();
+ num_insns = 0;
+ }
- /* If we ran into a BARRIER, this code is an extension of the
- basic block when the branch is taken. */
- if (follow_jumps && q != 0 && BARRIER_P (q))
+ if (INSN_P (insn))
{
- /* Don't allow ourself to keep walking around an
- always-executed loop. */
- if (next_real_insn (q) == next)
+ /* Process notes first so we have all notes in canonical forms
+ when looking for duplicate operations. */
+ if (REG_NOTES (insn))
+ REG_NOTES (insn) = cse_process_notes (REG_NOTES (insn),
+ NULL_RTX);
+
+ /* Track when we are inside in LIBCALL block. Inside such
+ a block we do not want to record destinations. The last
+ insn of a LIBCALL block is not considered to be part of
+ the block, since its destination is the result of the
+ block and hence should be recorded. */
+ if (REG_NOTES (insn) != 0)
{
- p = NEXT_INSN (p);
- continue;
- }
-
- /* Similarly, don't put a branch in our path more than once. */
- for (i = 0; i < path_entry; i++)
- if (data->path[i].branch == p)
- break;
-
- if (i != path_entry)
- break;
+ rtx p;
- data->path[path_entry].branch = p;
- data->path[path_entry++].status = PATH_TAKEN;
+ if ((p = find_reg_note (insn, REG_LIBCALL, NULL_RTX)))
+ libcall_insn = XEXP (p, 0);
+ else if (find_reg_note (insn, REG_RETVAL, NULL_RTX))
+ {
+ /* Keep libcall_insn for the last SET insn of
+ a no-conflict block to prevent changing the
+ destination. */
+ if (!no_conflict)
+ libcall_insn = NULL_RTX;
+ else
+ no_conflict = -1;
+ }
+ else if (find_reg_note (insn, REG_NO_CONFLICT, NULL_RTX))
+ no_conflict = 1;
+ }
- /* This branch now ends our path. It was possible that we
- didn't see this branch the last time around (when the
- insn in front of the target was a JUMP_INSN that was
- turned into a no-op). */
- path_size = path_entry;
+ cse_insn (insn, libcall_insn);
- p = JUMP_LABEL (p);
- /* Mark block so we won't scan it again later. */
- PUT_MODE (NEXT_INSN (p), QImode);
- }
- /* Detect a branch around a block of code. */
- else if (skip_blocks && q != 0 && !LABEL_P (q))
- {
- rtx tmp;
-
- if (next_real_insn (q) == next)
+ /* If we kept libcall_insn for a no-conflict bock,
+ clear it here. */
+ if (no_conflict == -1)
{
- p = NEXT_INSN (p);
- continue;
+ libcall_insn = NULL_RTX;
+ no_conflict = 0;
}
+
+ /* If we haven't already found an insn where we added a LABEL_REF,
+ check this one. */
+ if (NONJUMP_INSN_P (insn) && ! recorded_label_ref
+ && for_each_rtx (&PATTERN (insn), check_for_label_ref,
+ (void *) insn))
+ recorded_label_ref = 1;
- for (i = 0; i < path_entry; i++)
- if (data->path[i].branch == p)
- break;
-
- if (i != path_entry)
- break;
-
- /* This is no_labels_between_p (p, q) with an added check for
- reaching the end of a function (in case Q precedes P). */
- for (tmp = NEXT_INSN (p); tmp && tmp != q; tmp = NEXT_INSN (tmp))
- if (LABEL_P (tmp))
- break;
+#ifdef HAVE_cc0
+ /* If the previous insn set CC0 and this insn no longer
+ references CC0, delete the previous insn. Here we use
+ fact that nothing expects CC0 to be valid over an insn,
+ which is true until the final pass. */
+ {
+ rtx prev_insn, tem;
+
+ prev_insn = PREV_INSN (insn);
+ if (prev_insn && NONJUMP_INSN_P (prev_insn)
+ && (tem = single_set (prev_insn)) != 0
+ && SET_DEST (tem) == cc0_rtx
+ && ! reg_mentioned_p (cc0_rtx, PATTERN (insn)))
+ delete_insn (prev_insn);
+ }
- if (tmp == q)
+ /* If this insn is not the last insn in the basic block,
+ it will be PREV_INSN(insn) in the next iteration. If
+ we recorded any CC0-related information for this insn,
+ remember it. */
+ if (insn != BB_END (bb))
{
- data->path[path_entry].branch = p;
- data->path[path_entry++].status = PATH_AROUND;
-
- path_size = path_entry;
+ prev_insn_cc0 = this_insn_cc0;
+ prev_insn_cc0_mode = this_insn_cc0_mode;
+ }
+#endif
+ }
+ }
- p = JUMP_LABEL (p);
- /* Mark block so we won't scan it again later. */
- PUT_MODE (NEXT_INSN (p), QImode);
+ /* Make sure that libcalls don't span multiple basic blocks. */
+ gcc_assert (libcall_insn == NULL_RTX);
+
+ /* With non-call exceptions, we are not always able to update
+ the CFG properly inside cse_insn. So clean up possibly
+ redundant EH edges here. */
+ if (flag_non_call_exceptions && have_eh_succ_edges (bb))
+ purge_dead_edges (bb);
+
+ /* If we changed a conditional jump, we may have terminated
+ the path we are following. Check that by verifying that
+ the edge we would take still exists. If the edge does
+ not exist anymore, purge the remainder of the path.
+ Note that this will cause us to return to the caller. */
+ if (path_entry < path_size - 1)
+ {
+ basic_block next_bb = ebb_data->path[path_entry + 1].bb;
+ if (!find_edge (bb, next_bb))
+ {
+ do
+ {
+ path_size--;
+
+ /* If we truncate the path, we must also reset the
+ visited bit on the remaining blocks in the path,
+ or we will never visit them at all. */
+ RESET_BIT (cse_visited_basic_blocks,
+ ebb_data->path[path_size].bb->index);
+ ebb_data->path[path_size].bb = NULL;
}
+ while (path_size - 1 != path_entry);
+ ebb_data->path_size = path_size;
}
}
- p = NEXT_INSN (p);
- }
- data->low_cuid = low_cuid;
- data->high_cuid = high_cuid;
- data->nsets = nsets;
- data->last = p;
+ /* If this is a conditional jump insn, record any known
+ equivalences due to the condition being tested. */
+ insn = BB_END (bb);
+ if (path_entry < path_size - 1
+ && JUMP_P (insn)
+ && single_set (insn)
+ && any_condjump_p (insn))
+ {
+ basic_block next_bb = ebb_data->path[path_entry + 1].bb;
+ bool taken = (next_bb == BRANCH_EDGE (bb)->dest);
+ record_jump_equiv (insn, taken);
+ }
- /* If all jumps in the path are not taken, set our path length to zero
- so a rescan won't be done. */
- for (i = path_size - 1; i >= 0; i--)
- if (data->path[i].status != PATH_NOT_TAKEN)
- break;
+#ifdef HAVE_cc0
+ /* Clear the CC0-tracking related insns, they can't provide
+ useful information across basic block boundaries. */
+ prev_insn_cc0 = 0;
+#endif
+ }
- if (i == -1)
- data->path_size = 0;
- else
- data->path_size = path_size;
+ gcc_assert (next_qty <= max_qty);
- /* End the current branch path. */
- data->path[path_size].branch = 0;
+ free (qty_table);
}
\f
/* Perform cse on the instructions of a function.
in conditional jump instructions. */
int
-cse_main (rtx f, int nregs)
+cse_main (rtx f ATTRIBUTE_UNUSED, int nregs)
{
- struct cse_basic_block_data val;
- rtx insn = f;
- int i;
+ struct cse_basic_block_data ebb_data;
+ basic_block bb;
+ int *rc_order = XNEWVEC (int, last_basic_block);
+ int i, n_blocks;
init_cse_reg_info (nregs);
- val.path = XNEWVEC (struct branch_path, PARAM_VALUE (PARAM_MAX_CSE_PATH_LENGTH));
+ ebb_data.path = XNEWVEC (struct branch_path,
+ PARAM_VALUE (PARAM_MAX_CSE_PATH_LENGTH));
cse_jumps_altered = 0;
recorded_label_ref = 0;
constant_pool_entries_cost = 0;
constant_pool_entries_regcost = 0;
- val.path_size = 0;
+ ebb_data.path_size = 0;
+ ebb_data.nsets = 0;
rtl_hooks = cse_rtl_hooks;
init_recog ();
reg_eqv_table = XNEWVEC (struct reg_eqv_elem, nregs);
- /* Find the largest uid. */
+ /* Set up the table of already visited basic blocks. */
+ cse_visited_basic_blocks = sbitmap_alloc (last_basic_block);
+ sbitmap_zero (cse_visited_basic_blocks);
+ /* Compute the mapping from uids to cuids.
+ CUIDs are numbers assigned to insns, like uids, except that
+ that cuids increase monotonically through the code. */
max_uid = get_max_uid ();
uid_cuid = XCNEWVEC (int, max_uid + 1);
-
- /* Compute the mapping from uids to cuids.
- CUIDs are numbers assigned to insns, like uids,
- except that cuids increase monotonically through the code.
- Don't assign cuids to line-number NOTEs, so that the distance in cuids
- between two insns is not affected by -g. */
-
- for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
+ i = 0;
+ FOR_EACH_BB (bb)
{
- if (!NOTE_P (insn)
- || NOTE_LINE_NUMBER (insn) < 0)
+ rtx insn;
+ FOR_BB_INSNS (bb, insn)
INSN_CUID (insn) = ++i;
- else
- /* Give a line number note the same cuid as preceding insn. */
- INSN_CUID (insn) = i;
}
- /* Loop over basic blocks.
- Compute the maximum number of qty's needed for each basic block
- (which is 2 for each SET). */
- insn = f;
- while (insn)
+ /* Loop over basic blocks in reverse completion order (RPO),
+ excluding the ENTRY and EXIT blocks. */
+ n_blocks = pre_and_rev_post_order_compute (NULL, rc_order, false);
+ i = 0;
+ while (i < n_blocks)
{
- cse_altered = 0;
- cse_end_of_basic_block (insn, &val, flag_cse_follow_jumps,
- flag_cse_skip_blocks);
-
- /* If this basic block was already processed or has no sets, skip it. */
- if (val.nsets == 0 || GET_MODE (insn) == QImode)
+ /* Find the first block in the RPO queue that we have not yet
+ processed before. */
+ do
{
- PUT_MODE (insn, VOIDmode);
- insn = (val.last ? NEXT_INSN (val.last) : 0);
- val.path_size = 0;
- continue;
+ bb = BASIC_BLOCK (rc_order[i++]);
}
+ while (TEST_BIT (cse_visited_basic_blocks, bb->index)
+ && i < n_blocks);
- cse_basic_block_start = val.low_cuid;
- cse_basic_block_end = val.high_cuid;
- max_qty = val.nsets * 2;
-
- if (dump_file)
- fprintf (dump_file, ";; Processing block from %d to %d, %d sets.\n",
- INSN_UID (insn), val.last ? INSN_UID (val.last) : 0,
- val.nsets);
-
- /* Make MAX_QTY bigger to give us room to optimize
- past the end of this basic block, if that should prove useful. */
- if (max_qty < 500)
- max_qty = 500;
-
- /* If this basic block is being extended by following certain jumps,
- (see `cse_end_of_basic_block'), we reprocess the code from the start.
- Otherwise, we start after this basic block. */
- if (val.path_size > 0)
- cse_basic_block (insn, val.last, val.path);
- else
+ /* Find all paths starting with BB, and process them. */
+ while (cse_find_path (bb, &ebb_data, flag_cse_follow_jumps))
{
- int old_cse_jumps_altered = cse_jumps_altered;
- rtx temp;
-
- /* When cse changes a conditional jump to an unconditional
- jump, we want to reprocess the block, since it will give
- us a new branch path to investigate. */
- cse_jumps_altered = 0;
- temp = cse_basic_block (insn, val.last, val.path);
- if (cse_jumps_altered == 0
- || (flag_cse_follow_jumps == 0 && flag_cse_skip_blocks == 0))
- insn = temp;
-
- cse_jumps_altered |= old_cse_jumps_altered;
- }
+ /* Pre-scan the path. */
+ cse_prescan_path (&ebb_data);
- if (cse_altered)
- ggc_collect ();
+ /* If this basic block has no sets, skip it. */
+ if (ebb_data.nsets == 0)
+ continue;
-#ifdef USE_C_ALLOCA
- alloca (0);
-#endif
+ /* Get a reasonable estimate for the maximum number of qty's
+ needed for this path. For this, we take the number of sets
+ and multiply that by MAX_RECOG_OPERANDS. */
+ max_qty = ebb_data.nsets * MAX_RECOG_OPERANDS;
+ cse_basic_block_start = ebb_data.low_cuid;
+ cse_basic_block_end = ebb_data.high_cuid;
+
+ /* Dump the path we're about to process. */
+ if (dump_file)
+ cse_dump_path (&ebb_data, ebb_data.nsets, dump_file);
+
+ cse_extended_basic_block (&ebb_data);
+ }
}
/* Clean up. */
end_alias_analysis ();
free (uid_cuid);
free (reg_eqv_table);
- free (val.path);
+ free (ebb_data.path);
+ sbitmap_free (cse_visited_basic_blocks);
+ free (rc_order);
rtl_hooks = general_rtl_hooks;
return cse_jumps_altered || recorded_label_ref;
}
-
-/* Process a single basic block. FROM and TO and the limits of the basic
- block. NEXT_BRANCH points to the branch path when following jumps or
- a null path when not following jumps. */
-
-static rtx
-cse_basic_block (rtx from, rtx to, struct branch_path *next_branch)
-{
- rtx insn;
- int to_usage = 0;
- rtx libcall_insn = NULL_RTX;
- int num_insns = 0;
- int no_conflict = 0;
-
- /* Allocate the space needed by qty_table. */
- qty_table = XNEWVEC (struct qty_table_elem, max_qty);
-
- new_basic_block ();
-
- /* TO might be a label. If so, protect it from being deleted. */
- if (to != 0 && LABEL_P (to))
- ++LABEL_NUSES (to);
-
- for (insn = from; insn != to; insn = NEXT_INSN (insn))
- {
- enum rtx_code code = GET_CODE (insn);
-
- /* If we have processed 1,000 insns, flush the hash table to
- avoid extreme quadratic behavior. We must not include NOTEs
- in the count since there may be more of them when generating
- debugging information. If we clear the table at different
- times, code generated with -g -O might be different than code
- generated with -O but not -g.
-
- ??? This is a real kludge and needs to be done some other way.
- Perhaps for 2.9. */
- if (code != NOTE && num_insns++ > PARAM_VALUE (PARAM_MAX_CSE_INSNS))
- {
- flush_hash_table ();
- num_insns = 0;
- }
-
- /* See if this is a branch that is part of the path. If so, and it is
- to be taken, do so. */
- if (next_branch->branch == insn)
- {
- enum taken status = next_branch++->status;
- if (status != PATH_NOT_TAKEN)
- {
- if (status == PATH_TAKEN)
- record_jump_equiv (insn, 1);
- else
- invalidate_skipped_block (NEXT_INSN (insn));
-
- /* Set the last insn as the jump insn; it doesn't affect cc0.
- Then follow this branch. */
-#ifdef HAVE_cc0
- prev_insn_cc0 = 0;
- prev_insn = insn;
-#endif
- insn = JUMP_LABEL (insn);
- continue;
- }
- }
-
- if (GET_MODE (insn) == QImode)
- PUT_MODE (insn, VOIDmode);
-
- if (GET_RTX_CLASS (code) == RTX_INSN)
- {
- rtx p;
-
- /* Process notes first so we have all notes in canonical forms when
- looking for duplicate operations. */
-
- if (REG_NOTES (insn))
- REG_NOTES (insn) = cse_process_notes (REG_NOTES (insn), NULL_RTX);
-
- /* Track when we are inside in LIBCALL block. Inside such a block,
- we do not want to record destinations. The last insn of a
- LIBCALL block is not considered to be part of the block, since
- its destination is the result of the block and hence should be
- recorded. */
-
- if (REG_NOTES (insn) != 0)
- {
- if ((p = find_reg_note (insn, REG_LIBCALL, NULL_RTX)))
- libcall_insn = XEXP (p, 0);
- else if (find_reg_note (insn, REG_RETVAL, NULL_RTX))
- {
- /* Keep libcall_insn for the last SET insn of a no-conflict
- block to prevent changing the destination. */
- if (! no_conflict)
- libcall_insn = 0;
- else
- no_conflict = -1;
- }
- else if (find_reg_note (insn, REG_NO_CONFLICT, NULL_RTX))
- no_conflict = 1;
- }
-
- cse_insn (insn, libcall_insn);
-
- if (no_conflict == -1)
- {
- libcall_insn = 0;
- no_conflict = 0;
- }
-
- /* If we haven't already found an insn where we added a LABEL_REF,
- check this one. */
- if (NONJUMP_INSN_P (insn) && ! recorded_label_ref
- && for_each_rtx (&PATTERN (insn), check_for_label_ref,
- (void *) insn))
- recorded_label_ref = 1;
- }
-
- /* If INSN is now an unconditional jump, skip to the end of our
- basic block by pretending that we just did the last insn in the
- basic block. If we are jumping to the end of our block, show
- that we can have one usage of TO. */
-
- if (any_uncondjump_p (insn))
- {
- if (to == 0)
- {
- free (qty_table);
- return 0;
- }
-
- if (JUMP_LABEL (insn) == to)
- to_usage = 1;
-
- /* Maybe TO was deleted because the jump is unconditional.
- If so, there is nothing left in this basic block. */
- /* ??? Perhaps it would be smarter to set TO
- to whatever follows this insn,
- and pretend the basic block had always ended here. */
- if (INSN_DELETED_P (to))
- break;
-
- insn = PREV_INSN (to);
- }
-
- /* See if it is ok to keep on going past the label
- which used to end our basic block. Remember that we incremented
- the count of that label, so we decrement it here. If we made
- a jump unconditional, TO_USAGE will be one; in that case, we don't
- want to count the use in that jump. */
-
- if (to != 0 && NEXT_INSN (insn) == to
- && LABEL_P (to) && --LABEL_NUSES (to) == to_usage)
- {
- struct cse_basic_block_data val;
- rtx prev;
-
- insn = NEXT_INSN (to);
-
- /* If TO was the last insn in the function, we are done. */
- if (insn == 0)
- {
- free (qty_table);
- return 0;
- }
-
- /* If TO was preceded by a BARRIER we are done with this block
- because it has no continuation. */
- prev = prev_nonnote_insn (to);
- if (prev && BARRIER_P (prev))
- {
- free (qty_table);
- return insn;
- }
-
- /* Find the end of the following block. Note that we won't be
- following branches in this case. */
- to_usage = 0;
- val.path_size = 0;
- val.path = XNEWVEC (struct branch_path, PARAM_VALUE (PARAM_MAX_CSE_PATH_LENGTH));
- cse_end_of_basic_block (insn, &val, 0, 0);
- free (val.path);
-
- /* If the tables we allocated have enough space left
- to handle all the SETs in the next basic block,
- continue through it. Otherwise, return,
- and that block will be scanned individually. */
- if (val.nsets * 2 + next_qty > max_qty)
- break;
-
- cse_basic_block_start = val.low_cuid;
- cse_basic_block_end = val.high_cuid;
- to = val.last;
-
- /* Prevent TO from being deleted if it is a label. */
- if (to != 0 && LABEL_P (to))
- ++LABEL_NUSES (to);
-
- /* Back up so we process the first insn in the extension. */
- insn = PREV_INSN (insn);
- }
- }
-
- gcc_assert (next_qty <= max_qty);
-
- free (qty_table);
-
- return to ? NEXT_INSN (to) : 0;
-}
\f
/* Called via for_each_rtx to see if an insn is using a LABEL_REF for which
there isn't a REG_LABEL note. Return one if so. DATA is the insn. */
rest_of_handle_cse (void)
{
int tem;
-
if (dump_file)
dump_flow_info (dump_file, dump_flags);
reg_scan (get_insns (), max_reg_num ());
tem = cse_main (get_insns (), max_reg_num ());
- if (tem)
- rebuild_jump_labels (get_insns ());
- if (purge_all_dead_edges ())
- delete_unreachable_blocks ();
-
- delete_trivially_dead_insns (get_insns (), max_reg_num ());
/* If we are not running more CSE passes, then we are no longer
expecting CSE to be run. But always rerun it in a cheap mode. */
cse_not_expected = !flag_rerun_cse_after_loop && !flag_gcse;
if (tem)
- delete_dead_jumptables ();
+ rebuild_jump_labels (get_insns ());
if (tem || optimize > 1)
cleanup_cfg (CLEANUP_EXPENSIVE);
+
return 0;
}
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func |
- TODO_ggc_collect, /* todo_flags_finish */
+ TODO_ggc_collect |
+ TODO_verify_flow, /* todo_flags_finish */
's' /* letter */
};
bypassed safely. */
cse_condition_code_reg ();
- purge_all_dead_edges ();
delete_trivially_dead_insns (get_insns (), max_reg_num ());
if (tem)
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func |
- TODO_ggc_collect, /* todo_flags_finish */
+ TODO_ggc_collect |
+ TODO_verify_flow, /* todo_flags_finish */
't' /* letter */
};