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tree-ssa-dom.c (simple_iv_increment_p): New function. 

* tree-ssa-dom.c (simple_iv_increment_p): New function.
	(simplify_rhs_and_lookup_avail_expr, eliminate_redundant_computations):
	Do not propagate value of iv before increment over the increment.

From-SVN: r95571
This commit is contained in:
Zdenek Dvorak 2005-02-26 08:55:28 +01:00 committed by Zdenek Dvorak
parent e0fa00d1f4
commit f67e783f49
2 changed files with 55 additions and 7 deletions
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12
gcc/ChangeLog
View File

@ -1,3 +1,9 @@
2005-02-26 Zdenek Dvorak <dvorakz@suse.cz>
* tree-ssa-dom.c (simple_iv_increment_p): New function.
(simplify_rhs_and_lookup_avail_expr, eliminate_redundant_computations):
Do not propagate value of iv before increment over the increment.
2005-02-25 Joseph S. Myers <joseph@codesourcery.com>
* c-parser.c: New file.
@ -66,12 +72,6 @@
* doc/extend.texi (5.24 Declaring Attributes of Functions)<noreturn>:
Clarify that the alternative way doesn't work in GNU C++.
2005-02-25 Zdenek Dvorak <dvorakz@suse.cz>
* tree-ssa-dom.c (simple_iv_increment_p): New function.
(simplify_rhs_and_lookup_avail_expr, eliminate_redundant_computations):
Do not propagate value of iv before increment over the increment.
2005-02-25 Zdenek Dvorak <dvorakz@suse.cz>
PR tree-optimization/19937

50
gcc/tree-ssa-dom.c
View File

@ -1635,6 +1635,46 @@ unsafe_associative_fp_binop (tree exp)
&& FLOAT_TYPE_P (TREE_TYPE (exp)));
}
/* Returns true when STMT is a simple iv increment. It detects the
following situation:
i_1 = phi (..., i_2)
i_2 = i_1 +/- ... */
static bool
simple_iv_increment_p (tree stmt)
{
tree lhs, rhs, preinc, phi;
unsigned i;
if (TREE_CODE (stmt) != MODIFY_EXPR)
return false;
lhs = TREE_OPERAND (stmt, 0);
if (TREE_CODE (lhs) != SSA_NAME)
return false;
rhs = TREE_OPERAND (stmt, 1);
if (TREE_CODE (rhs) != PLUS_EXPR
&& TREE_CODE (rhs) != MINUS_EXPR)
return false;
preinc = TREE_OPERAND (rhs, 0);
if (TREE_CODE (preinc) != SSA_NAME)
return false;
phi = SSA_NAME_DEF_STMT (preinc);
if (TREE_CODE (phi) != PHI_NODE)
return false;
for (i = 0; i < (unsigned) PHI_NUM_ARGS (phi); i++)
if (PHI_ARG_DEF (phi, i) == lhs)
return true;
return false;
}
/* STMT is a MODIFY_EXPR for which we were unable to find RHS in the
hash tables. Try to simplify the RHS using whatever equivalences
we may have recorded.
@ -1688,6 +1728,11 @@ simplify_rhs_and_lookup_avail_expr (struct dom_walk_data *walk_data,
{
tree rhs_def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0));
/* If the statement defines an induction variable, do not propagate
its value, so that we do not create overlapping life ranges. */
if (simple_iv_increment_p (rhs_def_stmt))
goto dont_fold_assoc;
/* See if the RHS_DEF_STMT has the same form as our statement. */
if (TREE_CODE (rhs_def_stmt) == MODIFY_EXPR)
{
@ -2551,7 +2596,10 @@ eliminate_redundant_computations (struct dom_walk_data *walk_data,
|| ! def
|| TREE_CODE (def) != SSA_NAME
|| SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def)
|| NUM_V_MAY_DEFS (v_may_defs) != 0)
|| NUM_V_MAY_DEFS (v_may_defs) != 0
/* Do not record equivalences for increments of ivs. This would create
overlapping live ranges for a very questionable gain. */
|| simple_iv_increment_p (stmt))
insert = false;
/* Check if the expression has been computed before. */