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Commit 2426d8dd by Eric Botcazou Committed by Eric Botcazou
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* web.c: Fix various comments. 

From-SVN: r72743
parent de696511
Showing with 39 additions and 37 deletions
gcc/ChangeLog
2003-10-21 Eric Botcazou <ebotcazou@libertysurf.fr>
* web.c: Fix various comments.
2003-10-20 Nicolas Pitre <nico@cam.org>
* config/arm/arm.c (arm_override_options): Set arm_constant_limit
......
gcc/web.c
/* Web construction code for GNU compiler.
Contributed by Jan Hubicka
Contributed by Jan Hubicka.
Copyright (C) 2001, 2002 Free Software Foundation, Inc.
This file is part of GCC.
......@@ -19,28 +19,28 @@ along with GCC; see the file COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
/* Simple optimization pass that splits indepdendent uses of each pseudo
/* Simple optimization pass that splits independent uses of each pseudo,
increasing effectivity of other optimizations. The optimization can
serve as an example of the use of dataflow module.
serve as an example of use for the dataflow module.
We don't split registers with REG_USERVAR set unless -fmessy-debugging is
used, because debug information about such split variables is almost
useless.
We don't split registers with REG_USERVAR set unless -fmessy-debugging
is specified, because debugging information about such split variables
is almost unusable.
TODO
- Add code to keep debugging up-to-date after splitting of user variable
pseudos. This can be done by remembering all the pseudos used for the
variable and use life analysis information before reload to determing
wich one of the possible choices is alive and in case more are live,
choose one with latest definition.
- Add code to keep debugging up-to-date after splitting user variable
pseudos. This can be done by keeping track of all the pseudos used
for the variable and using life analysis information before reload
to determine which one is live and, in case more than one are live,
choose the one with the latest definition.
Some other optimization passes will benefit from the infrastructure
too.
Other optimization passes can benefit from the infrastructure too.
- We may use profile information and ignore infrequent use for purposes
of web unifying inserting the compensation code later to implement full
induction variable expansion for loops (currently we expand only if
induction is dead afterwards, that is often the case anyway). */
- We may use profile information and ignore infrequent use for the
purpose of web unifying, inserting the compensation code later to
implement full induction variable expansion for loops (currently
we expand only if the induction variable is dead afterward, which
is often the case). */
#include "config.h"
#include "system.h"
......@@ -60,9 +60,9 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
/* This entry is allocated for each reference in the insn stream. */
struct web_entry
{
/* pointer to the parent in the union/find tree. */
/* Pointer to the parent in the union/find tree. */
struct web_entry *pred;
/* Newly assigned register to the entry. Set only for roots. */
/* Newly assigned register to the entry. Set only for roots. */
rtx reg;
};
......@@ -77,7 +77,7 @@ static rtx entry_register PARAMS ((struct web_entry *,
static void replace_ref PARAMS ((struct ref *, rtx));
static int mark_addressof PARAMS ((rtx *, void *));
/* Find the root of unionfind tree (the representatnt of set). */
/* Find the root of unionfind tree (the representative of set). */
static struct web_entry *
unionfind_root (element)
......@@ -109,8 +109,8 @@ unionfind_union (first, second)
second->pred = first;
}
/* For each use, all possible defs reaching it must come in same register,
union them. */
/* For each use, all possible defs reaching it must come in the same
register, union them. */
static void
union_defs (df, use, def_entry, use_entry)
......@@ -125,9 +125,9 @@ union_defs (df, use, def_entry, use_entry)
struct df_link *def_link = DF_INSN_DEFS (df, insn);
rtx set = single_set (insn);
/* Some instructions may use match_dup for it's operands. In case the
operands are dead, we will assign them different pseudos creating
invalid instruction, so union all uses of the same operands for each
/* Some instructions may use match_dup for their operands. In case the
operands are dead, we will assign them different pseudos, creating
invalid instructions, so union all uses of the same operand for each
insn. */
while (use_link)
......@@ -139,9 +139,9 @@ union_defs (df, use, def_entry, use_entry)
use_link = use_link->next;
}
/* Recognize trivial noop moves and attempt to keep them noop.
While most of noop moves should be removed we still keep some at
libcall boundaries and such. */
/* Recognize trivial noop moves and attempt to keep them as noop.
While most of noop moves should be removed, we still keep some
of them at libcall boundaries and such. */
if (set
&& SET_SRC (set) == DF_REF_REG (use)
......@@ -162,7 +162,7 @@ union_defs (df, use, def_entry, use_entry)
link = link->next;
}
/* An READ_WRITE use require the corresponding def to be in the same
/* A READ_WRITE use requires the corresponding def to be in the same
register. Find it and union. */
if (use->flags & DF_REF_READ_WRITE)
{
......@@ -176,7 +176,7 @@ union_defs (df, use, def_entry, use_entry)
}
}
/* Find corresponding register for given entry. */
/* Find the corresponding register for the given entry. */
static rtx
entry_register (entry, ref, used, use_addressof)
......@@ -188,14 +188,12 @@ entry_register (entry, ref, used, use_addressof)
struct web_entry *root;
rtx reg, newreg;
/* Find corresponding web and see if it has been visited. */
/* Find the corresponding web and see if it has been visited. */
root = unionfind_root (entry);
if (root->reg)
return root->reg;
/* We are seeing this web first time, do the assignment. */
/* We are seeing this web for the first time, do the assignment. */
reg = DF_REF_REAL_REG (ref);
/* In case the original register is already assigned, generate new one. */
......@@ -252,7 +250,7 @@ replace_ref (ref, reg)
*loc = reg;
}
/* Mark each pseudo, whose address is taken. */
/* Mark each pseudo whose address is taken. */
static int
mark_addressof (rtl, data)
......@@ -312,8 +310,8 @@ web_main ()
replace_ref (df->defs[i], entry_register (def_entry + i, df->defs[i],
used, use_addressof));
/* Dataflow information is corrupt here, but it can be easy to update it
by creating new entries for new registers and update or calilng
/* Dataflow information is corrupt here, but it can be easily updated
by creating new entries for new registers and updates or calling
df_insns_modify. */
free (def_entry);
free (use_entry);
......
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