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[PATCH] fwprop, updated patch and SPEC results
- From: Paolo Bonzini <paolo dot bonzini at lu dot unisi dot ch>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Cc: Roger Sayle <roger at eyesopen dot com>, Steven Bosscher <stevenb dot gcc at gmail dot com>
- Date: Fri, 03 Nov 2006 20:00:50 +0100
- Subject: [PATCH] fwprop, updated patch and SPEC results
This is a reissue of the fwprop patch from the 4.2 timeframe. The new
pass is unchanged from that code. I did fix the FSF mailing address in
fwprop.c. :-)
Given that Steven decided to deal himself with path following rather
than getting rid of it, there are some differences in the opts.c hunks,
and we don't need an additional GCSE pass as was in last May's patches.
SPEC2000 results are as follows, for i686-pc-linux-gnu with 3 runs:
164.gzip 1400 159 879* 1400 160 875*
175.vpr 1400 165 847* 1400 167 840*
176.gcc 1100 72.1 1526* 1100 72.6 1514*
181.mcf 1800 177 1019* 1800 176 1024*
186.crafty 1000 98.8 1012* 1000 98.5 1015*
197.parser 1800 204 881* 1800 205 879*
252.eon X X
253.perlbmk 1800 123 1469* 1800 123 1469*
254.gap 1100 77.2 1425* 1100 79.9 1378*
255.vortex 1900 137 1386* 1900 139 1365*
256.bzip2 1500 158 949* 1500 156 963*
300.twolf 3000 246 1218* 3000 233 1285*
Est. SPECint_base2000 1120
Est. SPECint2000 1120
168.wupwise 1600 118 1359* 1600 118 1360*
171.swim 3100 172 1803* 3100 168 1844*
172.mgrid 1800 286 630* 1800 286 630*
173.applu 2100 190 1103* 2100 190 1106*
177.mesa 1400 175 799* 1400 180 777*
178.galgel 2900 146 1992* 2900 145 2000*
179.art 2600 432 602* 2600 429 605*
183.equake 1300 77.9 1669* 1300 76.0 1710*
187.facerec 1900 194 981* 1900 193 985*
188.ammp 2200 311 708* 2200 312 705*
189.lucas 2000 232 862* 2000 235 853*
191.fma3d 2100 226 927* 2100 225 934*
200.sixtrack 1100 193 569* 1100 193 570*
301.apsi 2600 277 939* 2600 259 1005*
Est. SPECfp_base2000 985
Est. SPECfp2000 992
Mostly neutral or in the +/- 1% noise, some loss on gap (3.5%) and mesa
(2.8%) apparently, but wins on twolf (5.5%), equake (2.5%), apsi (7%).
Regtested on i686-pc-linux-gnu. Ok for mainline?
Paolo
2006-11-03 Paolo Bonzini <bonzini@gnu.org>
Steven Bosscher <stevenb.gcc@gmail.com>
* fwprop.c: New file.
* Makefile.in: Add fwprop.o.
* tree-pass.h (pass_rtl_fwprop, pass_rtl_fwprop_with_addr): New.
* passes.c (init_optimization_passes): Schedule forward propagation.
* rtlanal.c (loc_mentioned_in_p): Support NULL value of the second
parameter.
* timevar.def (TV_FWPROP): New.
* common.opt (-fforward-propagate): New.
* opts.c (decode_options): Enable forward propagation at -O2.
* gcse.c (one_cprop_pass): Do not run local cprop unless touching jumps.
* cse.c (fold_rtx_subreg, fold_rtx_mem, fold_rtx_mem_1, find_best_addr,
canon_for_address, table_size): Remove.
(new_basic_block, insert, remove_from_table): Remove references to
table_size.
(fold_rtx): Process SUBREGs and MEMs with equiv_constant, make
simplification loop more straightforward by not calling fold_rtx
recursively.
(equiv_constant): Move here a small part of fold_rtx_subreg,
do not call fold_rtx. Call avoid_constant_pool_reference
to process MEMs.
* recog.c (canonicalize_change_group): New.
* recog.h (canonicalize_change_group): New.
* doc/invoke.texi (Optimization Options): Document fwprop.
Index: doc/invoke.texi
===================================================================
--- doc/invoke.texi (revision 118411)
+++ doc/invoke.texi (working copy)
@@ -310,7 +310,7 @@ Objective-C and Objective-C++ Dialects}.
-fcse-skip-blocks -fcx-limited-range -fdata-sections @gol
-fdelayed-branch -fdelete-null-pointer-checks -fearly-inlining @gol
-fexpensive-optimizations -ffast-math -ffloat-store @gol
--fforce-addr -ffunction-sections @gol
+-fforce-addr -fforward-propagate -ffunction-sections @gol
-fgcse -fgcse-lm -fgcse-sm -fgcse-las -fgcse-after-reload @gol
-fcrossjumping -fif-conversion -fif-conversion2 @gol
-finline-functions -finline-functions-called-once @gol
@@ -4621,6 +4621,16 @@ register-load. This option is now a nop
Force memory address constants to be copied into registers before
doing arithmetic on them.
+@item -fforward-propagate
+@opindex fforward-propagate
+Perform a forward propagation pass on RTL. The pass tries to combine two
+instructions and checks if the result can be simplified. If loop unrolling
+is active, two passes are performed and the second is scheduled after
+loop unrolling.
+
+This option is enabled by default at optimization levels @option{-O2},
+@option{-O3}, @option{-Os}.
+
@item -fomit-frame-pointer
@opindex fomit-frame-pointer
Don't keep the frame pointer in a register for functions that
Index: tree-pass.h
===================================================================
--- tree-pass.h (revision 118411)
+++ tree-pass.h (working copy)
@@ -330,6 +330,8 @@ extern struct tree_opt_pass pass_rtl_eh;
extern struct tree_opt_pass pass_initial_value_sets;
extern struct tree_opt_pass pass_unshare_all_rtl;
extern struct tree_opt_pass pass_instantiate_virtual_regs;
+extern struct tree_opt_pass pass_rtl_fwprop;
+extern struct tree_opt_pass pass_rtl_fwprop_addr;
extern struct tree_opt_pass pass_jump2;
extern struct tree_opt_pass pass_cse;
extern struct tree_opt_pass pass_gcse;
Index: rtlanal.c
===================================================================
--- rtlanal.c (revision 118411)
+++ rtlanal.c (working copy)
@@ -2837,10 +2837,15 @@ auto_inc_p (rtx x)
int
loc_mentioned_in_p (rtx *loc, rtx in)
{
- enum rtx_code code = GET_CODE (in);
- const char *fmt = GET_RTX_FORMAT (code);
+ enum rtx_code code;
+ const char *fmt;
int i, j;
+ if (!in)
+ return 0;
+
+ code = GET_CODE (in);
+ fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
if (loc == &in->u.fld[i].rt_rtx)
Index: cse.c
===================================================================
--- cse.c (revision 118411)
+++ cse.c (working copy)
@@ -528,10 +528,6 @@ struct table_elt
static struct table_elt *table[HASH_SIZE];
-/* Number of elements in the hash table. */
-
-static unsigned int table_size;
-
/* Chain of `struct table_elt's made so far for this function
but currently removed from the table. */
@@ -604,7 +600,6 @@ static inline unsigned safe_hash (rtx, e
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 *);
@@ -735,57 +730,6 @@ approx_reg_cost (rtx x)
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
@@ -965,8 +909,6 @@ new_basic_block (void)
}
}
- table_size = 0;
-
#ifdef HAVE_cc0
prev_insn = 0;
prev_insn_cc0 = 0;
@@ -1377,8 +1319,6 @@ remove_from_table (struct table_elt *elt
/* Now add it to the free element chain. */
elt->next_same_hash = free_element_chain;
free_element_chain = elt;
-
- table_size--;
}
/* Look up X in the hash table and return its table element,
@@ -1656,8 +1596,6 @@ insert (rtx x, struct table_elt *classp,
}
}
- table_size++;
-
return elt;
}
@@ -2824,231 +2762,6 @@ canon_reg (rtx x, rtx insn)
return x;
}
-/* 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;
- }
- }
- }
-}
-
/* 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.
@@ -3243,425 +2956,14 @@ find_comparison_args (enum rtx_code code
return code;
}
-/* 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 (!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. Not to be called directly, see fold_rtx_mem instead. */
-
-static rtx
-fold_rtx_mem_1 (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;
- }
-}
-
-/* Fold MEM. */
-
-static rtx
-fold_rtx_mem (rtx x, rtx insn)
-{
- /* To avoid infinite oscillations between fold_rtx and fold_rtx_mem,
- refuse to allow recursion of the latter past n levels. This can
- happen because fold_rtx_mem will try to fold the address of the
- memory reference it is passed, i.e. conceptually throwing away
- the MEM and reinjecting the bare address into fold_rtx. As a
- result, patterns like
-
- set (reg1)
- (plus (reg)
- (mem (plus (reg2) (const_int))))
-
- set (reg2)
- (plus (reg)
- (mem (plus (reg1) (const_int))))
-
- will defeat any "first-order" short-circuit put in either
- function to prevent these infinite oscillations.
-
- The heuristics for determining n is as follows: since each time
- it is invoked fold_rtx_mem throws away a MEM, and since MEMs
- are generically not nested, we assume that each invocation of
- fold_rtx_mem corresponds to a new "top-level" operand, i.e.
- the source or the destination of a SET. So fold_rtx_mem is
- bound to stop or cycle before n recursions, n being the number
- of expressions recorded in the hash table. We also leave some
- play to account for the initial steps. */
-
- static unsigned int depth;
- rtx ret;
-
- if (depth > 3 + table_size)
- return x;
-
- depth++;
- ret = fold_rtx_mem_1 (x, insn);
- depth--;
-
- return ret;
-}
-
-/* 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 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 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. */
@@ -3674,10 +2976,9 @@ fold_rtx (rtx x, rtx insn)
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;
@@ -3694,10 +2995,16 @@ fold_rtx (rtx x, rtx insn)
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:
@@ -3717,28 +3024,6 @@ fold_rtx (rtx x, rtx insn)
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)
{
@@ -3746,12 +3031,21 @@ fold_rtx (rtx x, rtx 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;
@@ -3764,55 +3058,13 @@ fold_rtx (rtx x, rtx insn)
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))
- {
- 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);
- }
- break;
-
- case CONST:
- case CONST_INT:
- case SYMBOL_REF:
- case LABEL_REF:
- case CONST_DOUBLE:
- case CONST_VECTOR:
- const_arg = arg;
- break;
-
+ rtx folded_arg = XEXP (x, i), const_arg;
+ enum machine_mode mode_arg = GET_MODE (folded_arg);
#ifdef HAVE_cc0
- case CC0:
- folded_arg = prev_insn_cc0;
- mode_arg = prev_insn_cc0_mode;
- const_arg = equiv_constant (folded_arg);
- break;
+ if (CC0_P (folded_arg))
+ folded_arg = prev_insn_cc0, mode_arg = prev_insn_cc0_mode;
#endif
-
- default:
- folded_arg = fold_rtx (arg, insn);
- const_arg = equiv_constant (folded_arg);
- }
+ const_arg = equiv_constant (folded_arg);
/* For the first three operands, see if the operand
is constant or equivalent to a constant. */
@@ -3832,120 +3084,50 @@ fold_rtx (rtx x, rtx insn)
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;
+ && (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 (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;
- }
- }
- }
- }
+ 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)))
- {
- rtx tem = XEXP (x, 0);
-
- 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;
- }
+ /* 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;
+ 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. */
@@ -4477,16 +3659,31 @@ equiv_constant (rtx x)
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;
Index: opts.c
===================================================================
--- opts.c (revision 118411)
+++ opts.c (working copy)
@@ -474,6 +474,7 @@ decode_options (unsigned int argc, const
flag_thread_jumps = 1;
flag_crossjumping = 1;
flag_optimize_sibling_calls = 1;
+ flag_forward_propagate = 1;
flag_cse_follow_jumps = 1;
flag_gcse = 1;
flag_expensive_optimizations = 1;
Index: timevar.def
===================================================================
--- timevar.def (revision 118411)
+++ timevar.def (working copy)
@@ -128,6 +128,7 @@ DEFTIMEVAR (TV_TEMPLATE_INSTANTIATION, "
DEFTIMEVAR (TV_EXPAND , "expand")
DEFTIMEVAR (TV_VARCONST , "varconst")
DEFTIMEVAR (TV_JUMP , "jump")
+DEFTIMEVAR (TV_FWPROP , "forward prop")
DEFTIMEVAR (TV_CSE , "CSE")
DEFTIMEVAR (TV_LOOP , "loop analysis")
DEFTIMEVAR (TV_GCSE , "global CSE")
Index: recog.c
===================================================================
--- recog.c (revision 118411)
+++ recog.c (working copy)
@@ -238,6 +238,28 @@ validate_change (rtx object, rtx *loc, r
return apply_change_group ();
}
+/* Keep X canonicalized if some changes have made it non-canonical; only
+ modifies the operands of X, not (for example) its code. Simplifications
+ are not the job of this routine.
+
+ Return true if anything was changed. */
+bool
+canonicalize_change_group (rtx insn, rtx x)
+{
+ if (COMMUTATIVE_P (x)
+ && swap_commutative_operands_p (XEXP (x, 0), XEXP (x, 1)))
+ {
+ /* Oops, the caller has made X no longer canonical.
+ Let's redo the changes in the correct order. */
+ rtx tem = XEXP (x, 0);
+ validate_change (insn, &XEXP (x, 0), XEXP (x, 1), 1);
+ validate_change (insn, &XEXP (x, 1), tem, 1);
+ return true;
+ }
+ else
+ return false;
+}
+
/* This subroutine of apply_change_group verifies whether the changes to INSN
were valid; i.e. whether INSN can still be recognized. */
Index: recog.h
===================================================================
--- recog.h (revision 118411)
+++ recog.h (working copy)
@@ -74,6 +74,7 @@ extern void init_recog_no_volatile (void
extern int check_asm_operands (rtx);
extern int asm_operand_ok (rtx, const char *);
extern int validate_change (rtx, rtx *, rtx, int);
+extern bool canonicalize_change_group (rtx insn, rtx x);
extern int insn_invalid_p (rtx);
extern int verify_changes (int);
extern void confirm_change_group (void);
Index: gcse.c
===================================================================
--- gcse.c (revision 118411)
+++ gcse.c (working copy)
@@ -3396,7 +3396,8 @@ one_cprop_pass (int pass, bool cprop_jum
global_const_prop_count = local_const_prop_count = 0;
global_copy_prop_count = local_copy_prop_count = 0;
- local_cprop_pass (cprop_jumps);
+ if (cprop_jumps)
+ local_cprop_pass (cprop_jumps);
/* Determine implicit sets. */
implicit_sets = XCNEWVEC (rtx, last_basic_block);
Index: common.opt
===================================================================
--- common.opt (revision 118411)
+++ common.opt (working copy)
@@ -444,6 +444,10 @@ fforce-mem
Common Report Var(flag_force_mem)
Copy memory operands into registers before use
+fforward-propagate
+Common Report Var(flag_forward_propagate)
+Perform a forward propagation pass on RTL
+
; Nonzero means don't put addresses of constant functions in registers.
; Used for compiling the Unix kernel, where strange substitutions are
; done on the assembly output.
Index: Makefile.in
===================================================================
--- Makefile.in (revision 118411)
+++ Makefile.in (working copy)
@@ -997,7 +997,7 @@ OBJS-common = \
debug.o df-core.o df-problems.o df-scan.o dfp.o diagnostic.o dojump.o \
dominance.o loop-doloop.o \
dwarf2asm.o dwarf2out.o emit-rtl.o except.o explow.o loop-iv.o \
- expmed.o expr.o final.o flow.o fold-const.o function.o gcse.o \
+ expmed.o expr.o final.o flow.o fold-const.o function.o fwprop.o gcse.o \
genrtl.o ggc-common.o global.o graph.o gtype-desc.o \
haifa-sched.o hooks.o ifcvt.o insn-attrtab.o insn-emit.o insn-modes.o \
insn-extract.o insn-opinit.o insn-output.o insn-peep.o insn-recog.o \
@@ -2336,6 +2336,9 @@ cse.o : cse.c $(CONFIG_H) $(SYSTEM_H) co
hard-reg-set.h $(FLAGS_H) insn-config.h $(RECOG_H) $(EXPR_H) toplev.h \
output.h $(FUNCTION_H) $(BASIC_BLOCK_H) $(GGC_H) $(TM_P_H) $(TIMEVAR_H) \
except.h $(TARGET_H) $(PARAMS_H) rtlhooks-def.h tree-pass.h $(REAL_H)
+fwprop.o : fwprop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
+ toplev.h insn-config.h $(RECOG_H) $(FLAGS_H) $(OBSTACK_H) $(BASIC_BLOCK_H) \
+ output.h $(DF_H) alloc-pool.h $(TIMEVAR_H) tree-pass.h
web.o : web.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
hard-reg-set.h $(FLAGS_H) $(BASIC_BLOCK_H) $(FUNCTION_H) output.h toplev.h \
$(DF_H) $(OBSTACK_H) $(TIMEVAR_H) tree-pass.h
Index: passes.c
===================================================================
--- passes.c (revision 118411)
+++ passes.c (working copy)
@@ -635,6 +635,7 @@ init_optimization_passes (void)
NEXT_PASS (pass_instantiate_virtual_regs);
NEXT_PASS (pass_jump2);
NEXT_PASS (pass_cse);
+ NEXT_PASS (pass_rtl_fwprop);
NEXT_PASS (pass_gcse);
NEXT_PASS (pass_jump_bypass);
NEXT_PASS (pass_rtl_ifcvt);
@@ -645,6 +646,7 @@ init_optimization_passes (void)
NEXT_PASS (pass_loop2);
NEXT_PASS (pass_web);
NEXT_PASS (pass_cse2);
+ NEXT_PASS (pass_rtl_fwprop_addr);
NEXT_PASS (pass_life);
NEXT_PASS (pass_combine);
NEXT_PASS (pass_if_after_combine);
Index: fwprop.c
===================================================================
--- fwprop.c (revision 0)
+++ fwprop.c (revision 0)
@@ -0,0 +1,1034 @@
+/* RTL-based forward propagation pass for GNU compiler.
+ Copyright (C) 2005, 2006 Free Software Foundation, Inc.
+ Contributed by Paolo Bonzini and Steven Bosscher.
+
+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, 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA. */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "toplev.h"
+
+#include "timevar.h"
+#include "rtl.h"
+#include "tm_p.h"
+#include "emit-rtl.h"
+#include "insn-config.h"
+#include "recog.h"
+#include "flags.h"
+#include "obstack.h"
+#include "basic-block.h"
+#include "output.h"
+#include "df.h"
+#include "target.h"
+#include "cfgloop.h"
+#include "tree-pass.h"
+
+
+/* This pass does simple forward propagation and simplification when an
+ operand of an insn can only come from a single def. This pass uses
+ df.c, so it is global. However, we only do limited analysis of
+ available expressions.
+
+ 1) The pass tries to propagate the source of the def into the use,
+ and checks if the result is independent of the substituted value.
+ For example, the high word of a (zero_extend:DI (reg:SI M)) is always
+ zero, independent of the source register.
+
+ In particular, we propagate constants into the use site. Sometimes
+ RTL expansion did not put the constant in the same insn on purpose,
+ to satisfy a predicate, and the result will fail to be recognized;
+ but this happens rarely and in this case we can still create a
+ REG_EQUAL note. For multi-word operations, this
+
+ (set (subreg:SI (reg:DI 120) 0) (const_int 0))
+ (set (subreg:SI (reg:DI 120) 4) (const_int -1))
+ (set (subreg:SI (reg:DI 122) 0)
+ (ior:SI (subreg:SI (reg:DI 119) 0) (subreg:SI (reg:DI 120) 0)))
+ (set (subreg:SI (reg:DI 122) 4)
+ (ior:SI (subreg:SI (reg:DI 119) 4) (subreg:SI (reg:DI 120) 4)))
+
+ can be simplified to the much simpler
+
+ (set (subreg:SI (reg:DI 122) 0) (subreg:SI (reg:DI 119)))
+ (set (subreg:SI (reg:DI 122) 4) (const_int -1))
+
+ This particular propagation is also effective at putting together
+ complex addressing modes. We are more aggressive inside MEMs, in
+ that all definitions are propagated if the use is in a MEM; if the
+ result is a valid memory address we check address_cost to decide
+ whether the substitution is worthwhile.
+
+ 2) The pass propagates register copies. This is not as effective as
+ the copy propagation done by CSE's canon_reg, which works by walking
+ the instruction chain, but it can help the other transformations.
+
+ We should consider removing this optimization, and instead extract
+ the relevant parts of CSE into separate passes. With some luck,
+ the CSE pass at the end of rest_of_handle_gcse could also go away.
+
+ 3) The pass looks for paradoxical subregs that are actually unnecessary.
+ Things like this:
+
+ (set (reg:QI 120) (subreg:QI (reg:SI 118) 0))
+ (set (reg:QI 121) (subreg:QI (reg:SI 119) 0))
+ (set (reg:SI 122) (plus:SI (subreg:SI (reg:QI 120) 0)
+ (subreg:SI (reg:QI 121) 0)))
+
+ are very common on machines that can only do word-sized operations.
+ For each use of a paradoxical subreg (subreg:WIDER (reg:NARROW N) 0),
+ if it has a single def and it is (subreg:NARROW (reg:WIDE M) 0),
+ we can replace the paradoxical subreg with simply (reg:WIDE M). The
+ above will simplify this to
+
+ (set (reg:QI 120) (subreg:QI (reg:SI 118) 0))
+ (set (reg:QI 121) (subreg:QI (reg:SI 119) 0))
+ (set (reg:SI 122) (plus:SI (reg:SI 118) (reg:SI 119)))
+
+ where the first two insns are now dead. */
+
+
+static struct loops loops;
+static struct df *df;
+static int num_changes;
+
+
+/* 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. */
+
+static bool
+can_simplify_addr (rtx addr)
+{
+ rtx reg;
+
+ if (CONSTANT_ADDRESS_P (addr))
+ return false;
+
+ if (GET_CODE (addr) == PLUS)
+ reg = XEXP (addr, 0);
+ else
+ reg = addr;
+
+ return (!REG_P (reg)
+ || (REGNO (reg) != FRAME_POINTER_REGNUM
+ && REGNO (reg) != HARD_FRAME_POINTER_REGNUM
+ && REGNO (reg) != ARG_POINTER_REGNUM));
+}
+
+/* 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.
+
+ Every ASHIFT we find has been made by simplify_gen_binary and was not
+ there before, so it is not shared. So we can do this in place. */
+
+static void
+canonicalize_address (rtx x)
+{
+ for (;;)
+ switch (GET_CODE (x))
+ {
+ case ASHIFT:
+ if (GET_CODE (XEXP (x, 1)) == CONST_INT
+ && INTVAL (XEXP (x, 1)) < GET_MODE_BITSIZE (GET_MODE (x))
+ && INTVAL (XEXP (x, 1)) >= 0)
+ {
+ HOST_WIDE_INT shift = INTVAL (XEXP (x, 1));
+ PUT_CODE (x, MULT);
+ XEXP (x, 1) = gen_int_mode ((HOST_WIDE_INT) 1 << shift,
+ GET_MODE (x));
+ }
+
+ x = XEXP (x, 0);
+ break;
+
+ case PLUS:
+ if (GET_CODE (XEXP (x, 0)) == PLUS
+ || GET_CODE (XEXP (x, 0)) == ASHIFT
+ || GET_CODE (XEXP (x, 0)) == CONST)
+ canonicalize_address (XEXP (x, 0));
+
+ x = XEXP (x, 1);
+ break;
+
+ case CONST:
+ x = XEXP (x, 0);
+ break;
+
+ default:
+ return;
+ }
+}
+
+/* OLD is a memory address. Return whether it is good to use NEW instead,
+ for a memory access in the given MODE. */
+
+static bool
+should_replace_address (rtx old, rtx new, enum machine_mode mode)
+{
+ int gain;
+
+ if (rtx_equal_p (old, new) || !memory_address_p (mode, new))
+ return false;
+
+ /* Copy propagation is always ok. */
+ if (REG_P (old) && REG_P (new))
+ return true;
+
+ /* Prefer the new address if it is less expensive. */
+ gain = address_cost (old, mode) - address_cost (new, mode);
+
+ /* If the addresses have equivalent cost, prefer the new address
+ if it has the highest `rtx_cost'. That has the potential of
+ eliminating the most insns without additional costs, and it
+ is the same that cse.c used to do. */
+ if (gain == 0)
+ gain = rtx_cost (new, SET) - rtx_cost (old, SET);
+
+ return (gain > 0);
+}
+
+/* Replace all occurrences of OLD in *PX with NEW and try to simplify the
+ resulting expression. Replace *PX with a new RTL expression if an
+ occurrence of OLD was found.
+
+ If CAN_APPEAR is true, we always return true; if it is false, we
+ can return false if, for at least one occurrence OLD, we failed to
+ collapse the result to a constant. For example, (mult:M (reg:M A)
+ (minus:M (reg:M B) (reg:M A))) may collapse to zero if replacing
+ (reg:M B) with (reg:M A).
+
+ CAN_APPEAR is disregarded inside MEMs: in that case, we always return
+ true if the simplification is a cheaper and valid memory address.
+
+ This is only a wrapper around simplify-rtx.c: do not add any pattern
+ matching code here. (The sole exception is the handling of LO_SUM, but
+ that is because there is no simplify_gen_* function for LO_SUM). */
+
+static bool
+propagate_rtx_1 (rtx *px, rtx old, rtx new, bool can_appear)
+{
+ rtx x = *px, tem = NULL_RTX, op0, op1, op2;
+ enum rtx_code code = GET_CODE (x);
+ enum machine_mode mode = GET_MODE (x);
+ enum machine_mode op_mode;
+ bool valid_ops = true;
+
+ /* If X is OLD_RTX, return NEW_RTX. Otherwise, if this is an expression,
+ try to build a new expression from recursive substitution. */
+
+ if (x == old)
+ {
+ *px = new;
+ return can_appear;
+ }
+
+ switch (GET_RTX_CLASS (code))
+ {
+ case RTX_UNARY:
+ op0 = XEXP (x, 0);
+ op_mode = GET_MODE (op0);
+ valid_ops &= propagate_rtx_1 (&op0, old, new, can_appear);
+ if (op0 == XEXP (x, 0))
+ return true;
+ tem = simplify_gen_unary (code, mode, op0, op_mode);
+ break;
+
+ case RTX_BIN_ARITH:
+ case RTX_COMM_ARITH:
+ op0 = XEXP (x, 0);
+ op1 = XEXP (x, 1);
+ valid_ops &= propagate_rtx_1 (&op0, old, new, can_appear);
+ valid_ops &= propagate_rtx_1 (&op1, old, new, can_appear);
+ if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
+ return true;
+ tem = simplify_gen_binary (code, mode, op0, op1);
+ break;
+
+ case RTX_COMPARE:
+ case RTX_COMM_COMPARE:
+ op0 = XEXP (x, 0);
+ op1 = XEXP (x, 1);
+ op_mode = GET_MODE (op0) != VOIDmode ? GET_MODE (op0) : GET_MODE (op1);
+ valid_ops &= propagate_rtx_1 (&op0, old, new, can_appear);
+ valid_ops &= propagate_rtx_1 (&op1, old, new, can_appear);
+ if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
+ return true;
+ tem = simplify_gen_relational (code, mode, op_mode, op0, op1);
+ break;
+
+ case RTX_TERNARY:
+ case RTX_BITFIELD_OPS:
+ op0 = XEXP (x, 0);
+ op1 = XEXP (x, 1);
+ op2 = XEXP (x, 2);
+ op_mode = GET_MODE (op0);
+ valid_ops &= propagate_rtx_1 (&op0, old, new, can_appear);
+ valid_ops &= propagate_rtx_1 (&op1, old, new, can_appear);
+ valid_ops &= propagate_rtx_1 (&op2, old, new, can_appear);
+ if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1) && op2 == XEXP (x, 2))
+ return true;
+ if (op_mode == VOIDmode)
+ op_mode = GET_MODE (op0);
+ tem = simplify_gen_ternary (code, mode, op_mode, op0, op1, op2);
+ break;
+
+ case RTX_EXTRA:
+ /* The only case we try to handle is a SUBREG. */
+ if (code == SUBREG)
+ {
+ op0 = XEXP (x, 0);
+ valid_ops &= propagate_rtx_1 (&op0, old, new, can_appear);
+ if (op0 == XEXP (x, 0))
+ return true;
+ tem = simplify_gen_subreg (mode, op0, GET_MODE (SUBREG_REG (x)),
+ SUBREG_BYTE (x));
+ }
+ break;
+
+ case RTX_OBJ:
+ if (code == MEM && x != new)
+ {
+ rtx new_op0;
+ op0 = XEXP (x, 0);
+
+ /* There are some addresses that we cannot work on. */
+ if (!can_simplify_addr (op0))
+ return true;
+
+ op0 = new_op0 = targetm.delegitimize_address (op0);
+ valid_ops &= propagate_rtx_1 (&new_op0, old, new, true);
+
+ /* Dismiss transformation that we do not want to carry on. */
+ if (!valid_ops
+ || new_op0 == op0
+ || GET_MODE (new_op0) != GET_MODE (op0))
+ return true;
+
+ canonicalize_address (new_op0);
+
+ /* Copy propagations are always ok. Otherwise check the costs. */
+ if (!(REG_P (old) && REG_P (new))
+ && !should_replace_address (op0, new_op0, GET_MODE (x)))
+ return true;
+
+ tem = replace_equiv_address_nv (x, new_op0);
+ }
+
+ else if (code == LO_SUM)
+ {
+ op0 = XEXP (x, 0);
+ op1 = XEXP (x, 1);
+
+ /* The only simplification we do attempts to remove references to op0
+ or make it constant -- in both cases, op0's invalidity will not
+ make the result invalid. */
+ propagate_rtx_1 (&op0, old, new, true);
+ valid_ops &= propagate_rtx_1 (&op1, old, new, can_appear);
+ if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
+ return true;
+
+ /* (lo_sum (high x) x) -> x */
+ if (GET_CODE (op0) == HIGH && rtx_equal_p (XEXP (op0, 0), op1))
+ tem = op1;
+ else
+ tem = gen_rtx_LO_SUM (mode, op0, op1);
+
+ /* OP1 is likely not a legitimate address, otherwise there would have
+ been no LO_SUM. We want it to disappear if it is invalid, return
+ false in that case. */
+ return memory_address_p (mode, tem);
+ }
+
+ else if (code == REG)
+ {
+ if (rtx_equal_p (x, old))
+ {
+ *px = new;
+ return can_appear;
+ }
+ }
+ break;
+
+ default:
+ break;
+ }
+
+ /* No change, no trouble. */
+ if (tem == NULL_RTX)
+ return true;
+
+ *px = tem;
+
+ /* The replacement we made so far is valid, if all of the recursive
+ replacements were valid, or we could simplify everything to
+ a constant. */
+ return valid_ops || can_appear || CONSTANT_P (tem);
+}
+
+/* Replace all occurrences of OLD in X with NEW and try to simplify the
+ resulting expression (in mode MODE). Return a new expresion if it is
+ a constant, otherwise X.
+
+ Simplifications where occurrences of NEW collapse to a constant are always
+ accepted. All simplifications are accepted if NEW is a pseudo too.
+ Otherwise, we accept simplifications that have a lower or equal cost. */
+
+static rtx
+propagate_rtx (rtx x, enum machine_mode mode, rtx old, rtx new)
+{
+ rtx tem;
+ bool collapsed;
+
+ if (REG_P (new) && REGNO (new) < FIRST_PSEUDO_REGISTER)
+ return NULL_RTX;
+
+ new = copy_rtx (new);
+
+ tem = x;
+ collapsed = propagate_rtx_1 (&tem, old, new, REG_P (new) || CONSTANT_P (new));
+ if (tem == x || !collapsed)
+ return NULL_RTX;
+
+ /* gen_lowpart_common will not be able to process VOIDmode entities other
+ than CONST_INTs. */
+ if (GET_MODE (tem) == VOIDmode && GET_CODE (tem) != CONST_INT)
+ return NULL_RTX;
+
+ if (GET_MODE (tem) == VOIDmode)
+ tem = rtl_hooks.gen_lowpart_no_emit (mode, tem);
+ else
+ gcc_assert (GET_MODE (tem) == mode);
+
+ return tem;
+}
+
+
+
+
+/* Return true if the register from reference REF is killed
+ between FROM to (but not including) TO. */
+
+static bool
+local_ref_killed_between_p (struct df_ref * ref, rtx from, rtx to)
+{
+ rtx insn;
+ struct df_ref *def;
+
+ for (insn = from; insn != to; insn = NEXT_INSN (insn))
+ {
+ if (!INSN_P (insn))
+ continue;
+
+ def = DF_INSN_DEFS (df, insn);
+ while (def)
+ {
+ if (DF_REF_REGNO (ref) == DF_REF_REGNO (def))
+ return true;
+ def = def->next_ref;
+ }
+ }
+ return false;
+}
+
+
+/* Check if the given DEF is available in INSN. This would require full
+ computation of available expressions; we check only restricted conditions:
+ - if DEF is the sole definition of its register, go ahead;
+ - in the same basic block, we check for no definitions killing the
+ definition of DEF_INSN;
+ - if USE's basic block has DEF's basic block as the sole predecessor,
+ we check if the definition is killed after DEF_INSN or before
+ TARGET_INSN insn, in their respective basic blocks. */
+static bool
+use_killed_between (struct df_ref *use, rtx def_insn, rtx target_insn)
+{
+ basic_block def_bb, target_bb;
+ int regno;
+ struct df_ref * def;
+
+ /* Check if the reg in USE has only one definition. We already
+ know that this definition reaches use, or we wouldn't be here. */
+ regno = DF_REF_REGNO (use);
+ def = DF_REG_DEF_GET (df, regno)->reg_chain;
+ if (def && (def->next_reg == NULL))
+ return false;
+
+ /* Check if we are in the same basic block. */
+ def_bb = BLOCK_FOR_INSN (def_insn);
+ target_bb = BLOCK_FOR_INSN (target_insn);
+ if (def_bb == target_bb)
+ {
+ /* In some obscure situations we can have a def reaching a use
+ that is _before_ the def. In other words the def does not
+ dominate the use even though the use and def are in the same
+ basic block. This can happen when a register may be used
+ uninitialized in a loop. In such cases, we must assume that
+ DEF is not available. */
+ if (DF_INSN_LUID (df, def_insn) >= DF_INSN_LUID (df, target_insn))
+ return true;
+
+ return local_ref_killed_between_p (use, def_insn, target_insn);
+ }
+
+ /* Finally, if DEF_BB is the sole predecessor of TARGET_BB. */
+ if (single_pred_p (target_bb)
+ && single_pred (target_bb) == def_bb)
+ {
+ struct df_ref *x;
+
+ /* See if USE is killed between DEF_INSN and the last insn in the
+ basic block containing DEF_INSN. */
+ x = df_bb_regno_last_def_find (df, def_bb, regno);
+ if (x && DF_INSN_LUID (df, x->insn) >= DF_INSN_LUID (df, def_insn))
+ return true;
+
+ /* See if USE is killed between TARGET_INSN and the first insn in the
+ basic block containing TARGET_INSN. */
+ x = df_bb_regno_first_def_find (df, target_bb, regno);
+ if (x && DF_INSN_LUID (df, x->insn) < DF_INSN_LUID (df, target_insn))
+ return true;
+
+ return false;
+ }
+
+ /* Otherwise assume the worst case. */
+ return true;
+}
+
+
+/* for_each_rtx traversal function that returns 1 if BODY points to
+ a non-constant mem. */
+
+static int
+varying_mem_p (rtx *body, void *data ATTRIBUTE_UNUSED)
+{
+ rtx x = *body;
+ return MEM_P (x) && !MEM_READONLY_P (x);
+}
+
+/* Check if all uses in DEF_INSN can be used in TARGET_INSN. This
+ would require full computation of available expressions;
+ we check only restricted conditions, see use_killed_between. */
+static bool
+all_uses_available_at (rtx def_insn, rtx target_insn)
+{
+ struct df_ref * use;
+ rtx def_set = single_set (def_insn);
+
+ gcc_assert (def_set);
+
+ /* If target_insn comes right after def_insn, which is very common
+ for addresses, we can use a quicker test. */
+ if (NEXT_INSN (def_insn) == target_insn
+ && REG_P (SET_DEST (def_set)))
+ {
+ rtx def_reg = SET_DEST (def_set);
+
+ /* If the insn uses the reg that it defines, the substitution is
+ invalid. */
+ for (use = DF_INSN_USES (df, def_insn); use; use = use->next_ref)
+ if (rtx_equal_p (use->reg, def_reg))
+ return false;
+ }
+ else
+ {
+ /* Look at all the uses of DEF_INSN, and see if they are not
+ killed between DEF_INSN and TARGET_INSN. */
+ for (use = DF_INSN_USES (df, def_insn); use; use = use->next_ref)
+ if (use_killed_between (use, def_insn, target_insn))
+ return false;
+ }
+
+ /* We don't do any analysis of memories or aliasing. Reject any
+ instruction that involves references to non-constant memory. */
+ return !for_each_rtx (&SET_SRC (def_set), varying_mem_p, NULL);
+}
+
+
+struct find_occurrence_data
+{
+ rtx find;
+ rtx *retval;
+};
+
+/* Callback for for_each_rtx, used in find_occurrence.
+ See if PX is the rtx we have to find. Return 1 to stop for_each_rtx
+ if successful, or 0 to continue traversing otherwise. */
+
+static int
+find_occurrence_callback (rtx *px, void *data)
+{
+ struct find_occurrence_data *fod = (struct find_occurrence_data *) data;
+ rtx x = *px;
+ rtx find = fod->find;
+
+ if (x == find)
+ {
+ fod->retval = px;
+ return 1;
+ }
+
+ return 0;
+}
+
+/* Return a pointer to one of the occurrences of register FIND in *PX. */
+
+static rtx *
+find_occurrence (rtx *px, rtx find)
+{
+ struct find_occurrence_data data;
+
+ gcc_assert (REG_P (find)
+ || (GET_CODE (find) == SUBREG
+ && REG_P (SUBREG_REG (find))));
+
+ data.find = find;
+ data.retval = NULL;
+ for_each_rtx (px, find_occurrence_callback, &data);
+ return data.retval;
+}
+
+
+/* Inside INSN, the expression rooted at *LOC has been changed, moving some
+ uses from ORIG_USES. Find those that are present, and create new items
+ in the data flow object of the pass. Mark any new uses as having the
+ given TYPE. */
+static void
+update_df (rtx insn, rtx *loc, struct df_ref *orig_uses, enum df_ref_type type,
+ int new_flags)
+{
+ struct df_ref *use;
+
+ /* Add a use for the registers that were propagated. */
+ for (use = orig_uses; use; use = use->next_ref)
+ {
+ struct df_ref *orig_use = use, *new_use;
+ rtx *new_loc = find_occurrence (loc, DF_REF_REG (orig_use));
+
+ if (!new_loc)
+ continue;
+
+ /* Add a new insn use. Use the original type, because it says if the
+ use was within a MEM. */
+ new_use = df_ref_create (df, DF_REF_REG (orig_use), new_loc,
+ insn, BLOCK_FOR_INSN (insn),
+ type, DF_REF_FLAGS (orig_use) | new_flags);
+
+ /* Set up the use-def chain. */
+ df_chain_copy (df->problems_by_index[DF_CHAIN],
+ new_use, DF_REF_CHAIN (orig_use));
+ }
+}
+
+
+/* Try substituting NEW into LOC, which originated from forward propagation
+ of USE's value from DEF_INSN. SET_REG_EQUAL says whether we are
+ substituting the whole SET_SRC, so we can set a REG_EQUAL note if the
+ new insn is not recognized. Return whether the substitution was
+ performed. */
+
+static bool
+try_fwprop_subst (struct df_ref *use, rtx *loc, rtx new, rtx def_insn, bool set_reg_equal)
+{
+ rtx insn = DF_REF_INSN (use);
+ enum df_ref_type type = DF_REF_TYPE (use);
+ int flags = DF_REF_FLAGS (use);
+
+ if (dump_file)
+ {
+ fprintf (dump_file, "\nIn insn %d, replacing\n ", INSN_UID (insn));
+ print_inline_rtx (dump_file, *loc, 2);
+ fprintf (dump_file, "\n with ");
+ print_inline_rtx (dump_file, new, 2);
+ fprintf (dump_file, "\n");
+ }
+
+ if (validate_change (insn, loc, new, false))
+ {
+ num_changes++;
+ if (dump_file)
+ fprintf (dump_file, "Changed insn %d\n", INSN_UID (insn));
+
+ /* Unlink the use that we changed. */
+ df_ref_remove (df, use);
+ if (!CONSTANT_P (new))
+ update_df (insn, loc, DF_INSN_USES (df, def_insn), type, flags);
+
+ return true;
+ }
+ else
+ {
+ if (dump_file)
+ fprintf (dump_file, "Changes to insn %d not recognized\n",
+ INSN_UID (insn));
+
+ /* Can also record a simplified value in a REG_EQUAL note, making a
+ new one if one does not already exist. */
+ if (set_reg_equal)
+ {
+ if (dump_file)
+ fprintf (dump_file, " Setting REG_EQUAL note\n");
+
+ REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_EQUAL, copy_rtx (new),
+ REG_NOTES (insn));
+
+ if (!CONSTANT_P (new))
+ update_df (insn, loc, DF_INSN_USES (df, def_insn),
+ type, DF_REF_IN_NOTE);
+ }
+
+ return false;
+ }
+}
+
+
+/* If USE is a paradoxical subreg, see if it can be replaced by a pseudo. */
+
+static bool
+forward_propagate_subreg (struct df_ref *use, rtx def_insn, rtx def_set)
+{
+ rtx use_reg = DF_REF_REG (use);
+ rtx use_insn, src;
+
+ /* Only consider paradoxical subregs... */
+ enum machine_mode use_mode = GET_MODE (use_reg);
+ if (GET_CODE (use_reg) != SUBREG
+ || !REG_P (SET_DEST (def_set))
+ || GET_MODE_SIZE (use_mode)
+ <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (use_reg))))
+ return false;
+
+ /* 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. */
+ use_insn = DF_REF_INSN (use);
+ src = SET_SRC (def_set);
+ if (GET_CODE (src) == SUBREG
+ && REG_P (SUBREG_REG (src))
+ && GET_MODE (SUBREG_REG (src)) == use_mode
+ && subreg_lowpart_p (src)
+ && all_uses_available_at (def_insn, use_insn))
+ return try_fwprop_subst (use, DF_REF_LOC (use), SUBREG_REG (src),
+ def_insn, false);
+ else
+ return false;
+}
+
+/* Try to replace USE with SRC (defined in DEF_INSN) and simplify the
+ result. */
+
+static bool
+forward_propagate_and_simplify (struct df_ref *use, rtx def_insn, rtx def_set)
+{
+ rtx use_insn = DF_REF_INSN (use);
+ rtx use_set = single_set (use_insn);
+ rtx src, reg, new, *loc;
+ bool set_reg_equal;
+ enum machine_mode mode;
+
+ if (!use_set)
+ return false;
+
+ /* Do not propagate into PC, CC0, etc. */
+ if (GET_MODE (SET_DEST (use_set)) == VOIDmode)
+ return false;
+
+ /* If def and use are subreg, check if they match. */
+ reg = DF_REF_REG (use);
+ if (GET_CODE (reg) == SUBREG
+ && GET_CODE (SET_DEST (def_set)) == SUBREG
+ && (SUBREG_BYTE (SET_DEST (def_set)) != SUBREG_BYTE (reg)
+ || GET_MODE (SET_DEST (def_set)) != GET_MODE (reg)))
+ return false;
+
+ /* Check if the def had a subreg, but the use has the whole reg. */
+ if (REG_P (reg) && GET_CODE (SET_DEST (def_set)) == SUBREG)
+ return false;
+
+ /* Check if the use has a subreg, but the def had the whole reg. Unlike the
+ previous case, the optimization is possible and often useful indeed. */
+ if (GET_CODE (reg) == SUBREG && REG_P (SET_DEST (def_set)))
+ reg = SUBREG_REG (reg);
+
+ /* Check if the substitution is valid (last, because it's the most
+ expensive check!). */
+ src = SET_SRC (def_set);
+ if (!CONSTANT_P (src) && !all_uses_available_at (def_insn, use_insn))
+ return false;
+
+ /* Check if the def is loading something from the constant pool; in this
+ case we would undo optimization such as compress_float_constant.
+ Still, we can set a REG_EQUAL note. */
+ if (MEM_P (src) && MEM_READONLY_P (src))
+ {
+ rtx x = avoid_constant_pool_reference (src);
+ if (x != src)
+ {
+ rtx note = find_reg_note (use_insn, REG_EQUAL, NULL_RTX);
+ rtx old = note ? XEXP (note, 0) : SET_SRC (use_set);
+ rtx new = simplify_replace_rtx (old, src, x);
+ if (old != new)
+ set_unique_reg_note (use_insn, REG_EQUAL, copy_rtx (new));
+ }
+ return false;
+ }
+
+ /* Else try simplifying. */
+
+ if (DF_REF_TYPE (use) == DF_REF_REG_MEM_STORE)
+ {
+ loc = &SET_DEST (use_set);
+ set_reg_equal = false;
+ }
+ else
+ {
+ rtx note = find_reg_note (use_insn, REG_EQUAL, NULL_RTX);
+ if (DF_REF_FLAGS (use) & DF_REF_IN_NOTE)
+ loc = &XEXP (note, 0);
+ else
+ loc = &SET_SRC (use_set);
+
+ /* Do not replace an existing REG_EQUAL note if the insn is not
+ recognized. Either we're already replacing in the note, or
+ we'll separately try plugging the definition in the note and
+ simplifying. */
+ set_reg_equal = (note == NULL_RTX);
+ }
+
+ if (GET_MODE (*loc) == VOIDmode)
+ mode = GET_MODE (SET_DEST (use_set));
+ else
+ mode = GET_MODE (*loc);
+
+ new = propagate_rtx (*loc, mode, reg, src);
+
+ if (!new)
+ return false;
+
+ return try_fwprop_subst (use, loc, new, def_insn, set_reg_equal);
+}
+
+
+/* Given a use USE of an insn, if it has a single reaching
+ definition, try to forward propagate it into that insn. */
+
+static void
+forward_propagate_into (struct df_ref *use)
+{
+ struct df_link *defs;
+ struct df_ref *def;
+ rtx def_insn, def_set, use_insn;
+ rtx parent;
+
+ if (DF_REF_FLAGS (use) & DF_REF_READ_WRITE)
+ return;
+
+ /* Only consider uses that have a single definition. */
+ defs = DF_REF_CHAIN (use);
+ if (!defs || defs->next)
+ return;
+
+ def = defs->ref;
+ if (DF_REF_FLAGS (def) & DF_REF_READ_WRITE)
+ return;
+
+ /* Do not propagate loop invariant definitions inside the loop if
+ we are going to unroll. */
+ if (loops.num > 0
+ && DF_REF_BB (def)->loop_father != DF_REF_BB (use)->loop_father)
+ return;
+
+ /* Check if the use is still present in the insn! */
+ use_insn = DF_REF_INSN (use);
+ if (DF_REF_FLAGS (use) & DF_REF_IN_NOTE)
+ parent = find_reg_note (use_insn, REG_EQUAL, NULL_RTX);
+ else
+ parent = PATTERN (use_insn);
+
+ if (!loc_mentioned_in_p (DF_REF_LOC (use), parent))
+ return;
+
+ def_insn = DF_REF_INSN (def);
+ def_set = single_set (def_insn);
+ if (!def_set)
+ return;
+
+ /* Only try one kind of propagation. If two are possible, we'll
+ do it on the following iterations. */
+ if (!forward_propagate_and_simplify (use, def_insn, def_set))
+ forward_propagate_subreg (use, def_insn, def_set);
+}
+
+
+static void
+fwprop_init (void)
+{
+ num_changes = 0;
+
+ /* We do not always want to propagate into loops, so we have to find
+ loops and be careful about them. But we have to call flow_loops_find
+ before df_analyze, because flow_loops_find may introduce new jump
+ insns (sadly) if we are not working in cfglayout mode. */
+ if (flag_rerun_cse_after_loop && (flag_unroll_loops || flag_peel_loops))
+ {
+ calculate_dominance_info (CDI_DOMINATORS);
+ flow_loops_find (&loops);
+ }
+
+ /* Now set up the dataflow problem (we only want use-def chains) and
+ put the dataflow solver to work. */
+ df = df_init (DF_SUBREGS | DF_EQUIV_NOTES);
+ df_chain_add_problem (df, DF_UD_CHAIN);
+ df_analyze (df);
+ df_dump (df, dump_file);
+}
+
+static void
+fwprop_done (void)
+{
+ df_finish (df);
+
+ if (flag_rerun_cse_after_loop && (flag_unroll_loops || flag_peel_loops))
+ {
+ flow_loops_free (&loops);
+ free_dominance_info (CDI_DOMINATORS);
+ loops.num = 0;
+ }
+
+ cleanup_cfg (0);
+ delete_trivially_dead_insns (get_insns (), max_reg_num ());
+
+ if (dump_file)
+ fprintf (dump_file,
+ "\nNumber of successful forward propagations: %d\n\n",
+ num_changes);
+}
+
+
+
+/* Main entry point. */
+
+static bool
+gate_fwprop (void)
+{
+ return optimize > 0 && flag_forward_propagate;
+}
+
+static unsigned int
+fwprop (void)
+{
+ unsigned i;
+
+ fwprop_init ();
+
+ /* Go through all the uses. update_df will create new ones at the
+ end, and we'll go through them as well.
+
+ Do not forward propagate addresses into loops until after unrolling.
+ CSE did so because it was able to fix its own mess, but we are not. */
+
+ df_reorganize_refs (&df->use_info);
+ for (i = 0; i < DF_USES_SIZE (df); i++)
+ {
+ struct df_ref *use = DF_USES_GET (df, i);
+ if (use)
+ if (loops.num == 0
+ || DF_REF_TYPE (use) == DF_REF_REG_USE
+ || DF_REF_BB (use)->loop_father == NULL)
+ forward_propagate_into (use);
+ }
+
+ fwprop_done ();
+
+ return 0;
+}
+
+struct tree_opt_pass pass_rtl_fwprop =
+{
+ "fwprop1", /* name */
+ gate_fwprop, /* gate */
+ fwprop, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ TV_FWPROP, /* tv_id */
+ 0, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_dump_func, /* todo_flags_finish */
+ 0 /* letter */
+};
+
+static bool
+gate_fwprop_addr (void)
+{
+ return optimize > 0 && flag_forward_propagate && flag_rerun_cse_after_loop
+ && (flag_unroll_loops || flag_peel_loops);
+}
+
+static unsigned int
+fwprop_addr (void)
+{
+ unsigned i;
+ fwprop_init ();
+
+ /* Go through all the uses. update_df will create new ones at the
+ end, and we'll go through them as well. */
+ df_reorganize_refs (&df->use_info);
+ for (i = 0; i < DF_USES_SIZE (df); i++)
+ {
+ struct df_ref *use = DF_USES_GET (df, i);
+ if (use)
+ if (DF_REF_TYPE (use) != DF_REF_REG_USE
+ && DF_REF_BB (use)->loop_father != NULL)
+ forward_propagate_into (use);
+ }
+
+ fwprop_done ();
+
+ return 0;
+}
+
+struct tree_opt_pass pass_rtl_fwprop_addr =
+{
+ "fwprop2", /* name */
+ gate_fwprop_addr, /* gate */
+ fwprop_addr, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ TV_FWPROP, /* tv_id */
+ 0, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_dump_func, /* todo_flags_finish */
+ 0 /* letter */
+};