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* web.c: Fix various comments.
From-SVN: r72743
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Eric Botcazou
Eric Botcazou
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@ -1,3 +1,7 @@
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2003-10-21 Eric Botcazou <ebotcazou@libertysurf.fr>
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* web.c: Fix various comments.
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2003-10-20 Nicolas Pitre <nico@cam.org>
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* config/arm/arm.c (arm_override_options): Set arm_constant_limit
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72
gcc/web.c
72
gcc/web.c
@ -1,5 +1,5 @@
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/* Web construction code for GNU compiler.
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Contributed by Jan Hubicka
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Contributed by Jan Hubicka.
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Copyright (C) 2001, 2002 Free Software Foundation, Inc.
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This file is part of GCC.
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@ -19,28 +19,28 @@ along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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/* Simple optimization pass that splits indepdendent uses of each pseudo
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/* Simple optimization pass that splits independent uses of each pseudo,
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increasing effectivity of other optimizations. The optimization can
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serve as an example of the use of dataflow module.
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serve as an example of use for the dataflow module.
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We don't split registers with REG_USERVAR set unless -fmessy-debugging is
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used, because debug information about such split variables is almost
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useless.
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We don't split registers with REG_USERVAR set unless -fmessy-debugging
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is specified, because debugging information about such split variables
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is almost unusable.
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TODO
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- Add code to keep debugging up-to-date after splitting of user variable
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pseudos. This can be done by remembering all the pseudos used for the
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variable and use life analysis information before reload to determing
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wich one of the possible choices is alive and in case more are live,
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choose one with latest definition.
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- Add code to keep debugging up-to-date after splitting user variable
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pseudos. This can be done by keeping track of all the pseudos used
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for the variable and using life analysis information before reload
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to determine which one is live and, in case more than one are live,
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choose the one with the latest definition.
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Some other optimization passes will benefit from the infrastructure
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too.
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Other optimization passes can benefit from the infrastructure too.
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- We may use profile information and ignore infrequent use for purposes
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of web unifying inserting the compensation code later to implement full
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induction variable expansion for loops (currently we expand only if
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induction is dead afterwards, that is often the case anyway). */
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- We may use profile information and ignore infrequent use for the
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purpose of web unifying, inserting the compensation code later to
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implement full induction variable expansion for loops (currently
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we expand only if the induction variable is dead afterward, which
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is often the case). */
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#include "config.h"
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#include "system.h"
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@ -60,9 +60,9 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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/* This entry is allocated for each reference in the insn stream. */
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struct web_entry
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{
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/* pointer to the parent in the union/find tree. */
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/* Pointer to the parent in the union/find tree. */
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struct web_entry *pred;
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/* Newly assigned register to the entry. Set only for roots. */
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/* Newly assigned register to the entry. Set only for roots. */
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rtx reg;
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};
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@ -77,7 +77,7 @@ static rtx entry_register PARAMS ((struct web_entry *,
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static void replace_ref PARAMS ((struct ref *, rtx));
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static int mark_addressof PARAMS ((rtx *, void *));
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/* Find the root of unionfind tree (the representatnt of set). */
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/* Find the root of unionfind tree (the representative of set). */
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static struct web_entry *
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unionfind_root (element)
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@ -109,8 +109,8 @@ unionfind_union (first, second)
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second->pred = first;
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}
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/* For each use, all possible defs reaching it must come in same register,
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union them. */
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/* For each use, all possible defs reaching it must come in the same
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register, union them. */
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static void
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union_defs (df, use, def_entry, use_entry)
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@ -125,9 +125,9 @@ union_defs (df, use, def_entry, use_entry)
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struct df_link *def_link = DF_INSN_DEFS (df, insn);
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rtx set = single_set (insn);
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/* Some instructions may use match_dup for it's operands. In case the
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operands are dead, we will assign them different pseudos creating
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invalid instruction, so union all uses of the same operands for each
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/* Some instructions may use match_dup for their operands. In case the
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operands are dead, we will assign them different pseudos, creating
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invalid instructions, so union all uses of the same operand for each
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insn. */
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while (use_link)
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@ -139,9 +139,9 @@ union_defs (df, use, def_entry, use_entry)
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use_link = use_link->next;
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}
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/* Recognize trivial noop moves and attempt to keep them noop.
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While most of noop moves should be removed we still keep some at
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libcall boundaries and such. */
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/* Recognize trivial noop moves and attempt to keep them as noop.
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While most of noop moves should be removed, we still keep some
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of them at libcall boundaries and such. */
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if (set
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&& SET_SRC (set) == DF_REF_REG (use)
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@ -162,7 +162,7 @@ union_defs (df, use, def_entry, use_entry)
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link = link->next;
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}
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/* An READ_WRITE use require the corresponding def to be in the same
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/* A READ_WRITE use requires the corresponding def to be in the same
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register. Find it and union. */
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if (use->flags & DF_REF_READ_WRITE)
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{
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@ -176,7 +176,7 @@ union_defs (df, use, def_entry, use_entry)
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}
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}
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/* Find corresponding register for given entry. */
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/* Find the corresponding register for the given entry. */
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static rtx
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entry_register (entry, ref, used, use_addressof)
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@ -188,14 +188,12 @@ entry_register (entry, ref, used, use_addressof)
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struct web_entry *root;
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rtx reg, newreg;
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/* Find corresponding web and see if it has been visited. */
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/* Find the corresponding web and see if it has been visited. */
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root = unionfind_root (entry);
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if (root->reg)
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return root->reg;
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/* We are seeing this web first time, do the assignment. */
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/* We are seeing this web for the first time, do the assignment. */
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reg = DF_REF_REAL_REG (ref);
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/* In case the original register is already assigned, generate new one. */
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@ -252,7 +250,7 @@ replace_ref (ref, reg)
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*loc = reg;
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}
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/* Mark each pseudo, whose address is taken. */
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/* Mark each pseudo whose address is taken. */
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static int
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mark_addressof (rtl, data)
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@ -312,8 +310,8 @@ web_main ()
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replace_ref (df->defs[i], entry_register (def_entry + i, df->defs[i],
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used, use_addressof));
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/* Dataflow information is corrupt here, but it can be easy to update it
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by creating new entries for new registers and update or calilng
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/* Dataflow information is corrupt here, but it can be easily updated
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by creating new entries for new registers and updates or calling
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df_insns_modify. */
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free (def_entry);
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free (use_entry);
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