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re PR tree-optimization/19224 (Endless loop compiling simple file: Bug in tree-scalar-evolution.c (instantiate_parameters_1)?)

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PR tree-optimization/19224
	* tree-scalar-evolution.c (get_instantiated_value,
	set_instantiated_value): New functions.
	(instantiate_parameters_1): Cache the results.
	(instantiate_parameters, resolve_mixers): Initialize and free
	the cache.

From-SVN: r93106
This commit is contained in:
Zdenek Dvorak 2005-01-09 09:22:10 +01:00 committed by Zdenek Dvorak
parent d1c9ce9fcd
commit eb0bc7afa5
2 changed files with 98 additions and 36 deletions
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9
gcc/ChangeLog
View File

@ -1,3 +1,12 @@
2005-01-09 Zdenek Dvorak <dvorakz@suse.cz>
PR tree-optimization/19224
* tree-scalar-evolution.c (get_instantiated_value,
set_instantiated_value): New functions.
(instantiate_parameters_1): Cache the results.
(instantiate_parameters, resolve_mixers): Initialize and free
the cache.
2005-01-08 David Edelsohn <edelsohn@gnu.org>
* config/i386/i386.md (addhi_4): Correct reference in comment.

125
gcc/tree-scalar-evolution.c
View File

@ -1888,19 +1888,55 @@ analyze_scalar_evolution_in_loop (struct loop *wrto_loop, struct loop *use_loop,
}
}
/* Returns instantiated value for VERSION in CACHE. */
static tree
get_instantiated_value (htab_t cache, tree version)
{
struct scev_info_str *info, pattern;
pattern.var = version;
info = htab_find (cache, &pattern);
if (info)
return info->chrec;
else
return NULL_TREE;
}
/* Sets instantiated value for VERSION to VAL in CACHE. */
static void
set_instantiated_value (htab_t cache, tree version, tree val)
{
struct scev_info_str *info, pattern;
PTR *slot;
pattern.var = version;
slot = htab_find_slot (cache, &pattern, INSERT);
if (*slot)
info = *slot;
else
info = *slot = new_scev_info_str (version);
info->chrec = val;
}
/* Analyze all the parameters of the chrec that were left under a symbolic form,
with respect to LOOP. CHREC is the chrec to instantiate. If
ALLOW_SUPERLOOP_CHRECS is true, replacing loop invariants with
outer loop chrecs is done. */
outer loop chrecs is done. CACHE is the cache of already instantiated
values. */
static tree
instantiate_parameters_1 (struct loop *loop, tree chrec,
bool allow_superloop_chrecs)
bool allow_superloop_chrecs,
htab_t cache)
{
tree res, op0, op1, op2;
basic_block def_bb;
struct loop *def_loop;
if (chrec == NULL_TREE
|| automatically_generated_chrec_p (chrec))
return chrec;
@ -1920,41 +1956,52 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
&& !flow_bb_inside_loop_p (loop, def_bb)))
return chrec;
/* Don't instantiate the SSA_NAME if it is in a mixer
/* We cache the value of instantiated variable to avoid exponential
time complexity due to reevaluations. We also store the convenient
value in the cache in order to prevent infinite recursion -- we do
not want to instantiate the SSA_NAME if it is in a mixer
structure. This is used for avoiding the instantiation of
recursively defined functions, such as:
| a_2 -> {0, +, 1, +, a_2}_1 */
res = get_instantiated_value (cache, chrec);
if (res)
return res;
/* Store the convenient value for chrec in the structure. If it
is defined outside of the loop, we may just leave it in symbolic
form, otherwise we need to admit that we do not know its behavior
inside the loop. */
res = !flow_bb_inside_loop_p (loop, def_bb) ? chrec : chrec_dont_know;
set_instantiated_value (cache, chrec, res);
/* To make things even more complicated, instantiate_parameters_1
calls analyze_scalar_evolution that may call # of iterations
analysis that may in turn call instantiate_parameters_1 again.
To prevent the infinite recursion, keep also the bitmap of
ssa names that are being instantiated globally. */
if (bitmap_bit_p (already_instantiated, SSA_NAME_VERSION (chrec)))
{
if (!flow_bb_inside_loop_p (loop, def_bb))
{
/* We may keep the loop invariant in symbolic form. */
return chrec;
}
else
{
/* Something with unknown behavior in LOOP. */
return chrec_dont_know;
}
}
return res;
def_loop = find_common_loop (loop, def_bb->loop_father);
/* If the analysis yields a parametric chrec, instantiate the
result again. Avoid the cyclic instantiation in mixers. */
result again. */
bitmap_set_bit (already_instantiated, SSA_NAME_VERSION (chrec));
res = analyze_scalar_evolution (def_loop, chrec);
res = instantiate_parameters_1 (loop, res, allow_superloop_chrecs);
res = instantiate_parameters_1 (loop, res, allow_superloop_chrecs, cache);
bitmap_clear_bit (already_instantiated, SSA_NAME_VERSION (chrec));
/* Store the correct value to the cache. */
set_instantiated_value (cache, chrec, res);
return res;
case POLYNOMIAL_CHREC:
op0 = instantiate_parameters_1 (loop, CHREC_LEFT (chrec),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
op1 = instantiate_parameters_1 (loop, CHREC_RIGHT (chrec),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
if (CHREC_LEFT (chrec) != op0
|| CHREC_RIGHT (chrec) != op1)
chrec = build_polynomial_chrec (CHREC_VARIABLE (chrec), op0, op1);
@ -1962,9 +2009,9 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
case PLUS_EXPR:
op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
if (TREE_OPERAND (chrec, 0) != op0
|| TREE_OPERAND (chrec, 1) != op1)
chrec = chrec_fold_plus (TREE_TYPE (chrec), op0, op1);
@ -1972,9 +2019,9 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
case MINUS_EXPR:
op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
if (TREE_OPERAND (chrec, 0) != op0
|| TREE_OPERAND (chrec, 1) != op1)
chrec = chrec_fold_minus (TREE_TYPE (chrec), op0, op1);
@ -1982,9 +2029,9 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
case MULT_EXPR:
op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
if (TREE_OPERAND (chrec, 0) != op0
|| TREE_OPERAND (chrec, 1) != op1)
chrec = chrec_fold_multiply (TREE_TYPE (chrec), op0, op1);
@ -1994,7 +2041,7 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
case CONVERT_EXPR:
case NON_LVALUE_EXPR:
op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
if (op0 == chrec_dont_know)
return chrec_dont_know;
@ -2017,11 +2064,11 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
{
case 3:
op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
op2 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 2),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
if (op0 == chrec_dont_know
|| op1 == chrec_dont_know
|| op2 == chrec_dont_know)
@ -2037,9 +2084,9 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
case 2:
op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
if (op0 == chrec_dont_know
|| op1 == chrec_dont_know)
return chrec_dont_know;
@ -2051,7 +2098,7 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
case 1:
op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
allow_superloop_chrecs);
allow_superloop_chrecs, cache);
if (op0 == chrec_dont_know)
return chrec_dont_know;
if (op0 == TREE_OPERAND (chrec, 0))
@ -2078,6 +2125,7 @@ instantiate_parameters (struct loop *loop,
tree chrec)
{
tree res;
htab_t cache = htab_create (10, hash_scev_info, eq_scev_info, del_scev_info);
if (dump_file && (dump_flags & TDF_DETAILS))
{
@ -2088,7 +2136,7 @@ instantiate_parameters (struct loop *loop,
fprintf (dump_file, ")\n");
}
res = instantiate_parameters_1 (loop, chrec, true);
res = instantiate_parameters_1 (loop, chrec, true, cache);
if (dump_file && (dump_flags & TDF_DETAILS))
{
@ -2096,6 +2144,8 @@ instantiate_parameters (struct loop *loop,
print_generic_expr (dump_file, res, 0);
fprintf (dump_file, "))\n");
}
htab_delete (cache);
return res;
}
@ -2106,7 +2156,10 @@ instantiate_parameters (struct loop *loop,
static tree
resolve_mixers (struct loop *loop, tree chrec)
{
return instantiate_parameters_1 (loop, chrec, false);
htab_t cache = htab_create (10, hash_scev_info, eq_scev_info, del_scev_info);
tree ret = instantiate_parameters_1 (loop, chrec, false, cache);
htab_delete (cache);
return ret;
}
/* Entry point for the analysis of the number of iterations pass.