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tree-ssa-forwprop.c (simplify_gimple_switch): Enhance check for which sign-changes we allow when...

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2014-04-14  Richard Biener  <rguenther@suse.de>

	* tree-ssa-forwprop.c (simplify_gimple_switch): Enhance
	check for which sign-changes we allow when forwarding
	a converted value into a switch.

	* g++.dg/tree-ssa/forwprop-switch.C: New testcase.

From-SVN: r209372
This commit is contained in:
Richard Biener 2014-04-14 13:53:35 +00:00 committed by Richard Biener
parent 4116e7d0e0
commit 7b4cae1b53
4 changed files with 59 additions and 30 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2014-04-14 Richard Biener <rguenther@suse.de>
* tree-ssa-forwprop.c (simplify_gimple_switch): Enhance
check for which sign-changes we allow when forwarding
a converted value into a switch.
2014-04-14 Eric Botcazou <ebotcazou@adacore.com>
* stor-layout.c (place_field): Finalize non-constant offset for the

4
gcc/testsuite/ChangeLog
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@ -1,3 +1,7 @@
2014-04-14 Richard Biener <rguenther@suse.de>
* g++.dg/tree-ssa/forwprop-switch.C: New testcase.
2014-04-14 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
* gcc.dg/lto/pr55113_0.c: Skip on i?86-*-solaris2.1[0-1]*.

24
gcc/testsuite/g++.dg/tree-ssa/forwprop-switch.C Normal file
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@ -0,0 +1,24 @@
// { dg-do compile }
// { dg-options "-O -fdump-tree-cddce1" }
enum Scale { E1, E2, E3, E4, E5, E6, E7, E8 };
int Test(Scale s)
{
switch(s)
{
case E1: return 12;
case E2: return 17;
case E3: return 22;
case E4: return 42;
default: break;
}
return 0;
}
// tree forwprop should have eliminated the (int) s cast for the
// switch value and directly switch on the 's' parameter
// { dg-final { scan-tree-dump-not "\\\(int\\\)" "cddce1" } }
// { dg-final { scan-tree-dump "switch \\\(s_.\\\(D\\\)\\\)" "cddce1" } }
// { dg-final { cleanup-tree-dump "cddce1" } }

55
gcc/tree-ssa-forwprop.c
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@ -1356,43 +1356,38 @@ simplify_gimple_switch_label_vec (gimple stmt, tree index_type)
static bool
simplify_gimple_switch (gimple stmt)
{
tree cond = gimple_switch_index (stmt);
tree def, to, ti;
gimple def_stmt;
/* The optimization that we really care about is removing unnecessary
casts. That will let us do much better in propagating the inferred
constant at the switch target. */
tree cond = gimple_switch_index (stmt);
if (TREE_CODE (cond) == SSA_NAME)
{
def_stmt = SSA_NAME_DEF_STMT (cond);
if (is_gimple_assign (def_stmt))
gimple def_stmt = SSA_NAME_DEF_STMT (cond);
if (gimple_assign_cast_p (def_stmt))
{
if (gimple_assign_rhs_code (def_stmt) == NOP_EXPR)
tree def = gimple_assign_rhs1 (def_stmt);
if (TREE_CODE (def) != SSA_NAME)
return false;
/* If we have an extension or sign-change that preserves the
values we check against then we can copy the source value into
the switch. */
tree ti = TREE_TYPE (def);
if (INTEGRAL_TYPE_P (ti)
&& TYPE_PRECISION (ti) <= TYPE_PRECISION (TREE_TYPE (cond)))
{
int need_precision;
bool fail;
def = gimple_assign_rhs1 (def_stmt);
to = TREE_TYPE (cond);
ti = TREE_TYPE (def);
/* If we have an extension that preserves value, then we
can copy the source value into the switch. */
need_precision = TYPE_PRECISION (ti);
fail = false;
if (! INTEGRAL_TYPE_P (ti))
fail = true;
else if (TYPE_UNSIGNED (to) && !TYPE_UNSIGNED (ti))
fail = true;
else if (!TYPE_UNSIGNED (to) && TYPE_UNSIGNED (ti))
need_precision += 1;
if (TYPE_PRECISION (to) < need_precision)
fail = true;
if (!fail)
size_t n = gimple_switch_num_labels (stmt);
tree min = NULL_TREE, max = NULL_TREE;
if (n > 1)
{
min = CASE_LOW (gimple_switch_label (stmt, 1));
if (CASE_HIGH (gimple_switch_label (stmt, n - 1)))
max = CASE_HIGH (gimple_switch_label (stmt, n - 1));
else
max = CASE_LOW (gimple_switch_label (stmt, n - 1));
}
if ((!min || int_fits_type_p (min, ti))
&& (!max || int_fits_type_p (max, ti)))
{
gimple_switch_set_index (stmt, def);
simplify_gimple_switch_label_vec (stmt, ti);