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tree-ssa-strlen.c (fold_strstr_to_memcmp): New function.

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2016-12-14  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
	    Jakub Jelinek  <jakub@redhat.com>

	* tree-ssa-strlen.c (fold_strstr_to_memcmp): New function.
	(strlen_optimize_stmt): Call fold_strstr_to_memcmp.

testsuite/
	* gcc.dg/strlenopt-30.c: New test-case.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>

From-SVN: r243633
This commit is contained in:
Prathamesh Kulkarni 2016-12-14 09:10:31 +00:00 committed by Prathamesh Kulkarni
parent 164f063463
commit 3b1970cb3c
4 changed files with 182 additions and 1 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2016-12-14 Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>
Jakub Jelinek <jakub@redhat.com>
* tree-ssa-strlen.c (fold_strstr_to_memcmp): New function.
(strlen_optimize_stmt): Call fold_strstr_to_memcmp.
2016-12-14 Eric Botcazou <ebotcazou@adacore.com>
* lra-constraints.c (process_address_1): Do not attempt to decompose

5
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,8 @@
2016-12-14 Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>
Jakub Jelinek <jakub@redhat.com>
* gcc.dg/strlenopt-30.c: New test-case.
2016-12-14 Richard Biener <rguenther@suse.de>
PR tree-optimization/78788

63
gcc/testsuite/gcc.dg/strlenopt-30.c Normal file
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@ -0,0 +1,63 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-strlen" } */
__attribute__((no_icf))
_Bool f1(char *s)
{
return __builtin_strstr (s, "hello") == s;
}
__attribute__((no_icf))
_Bool f2(char *s)
{
return s == __builtin_strstr (s, "hello");
}
__attribute__((no_icf))
_Bool f3(char *s)
{
return s != __builtin_strstr (s, "hello");
}
__attribute__((no_icf))
_Bool f4()
{
char *foo_f4(void);
char *t1 = foo_f4();
char *t2 = __builtin_strstr (t1, "hello");
_Bool t3 = t2 == t1;
return t3;
}
__attribute__((no_icf))
void f5(char *s)
{
char *t1 = __builtin_strstr (s, "hello");
void foo_f5(void);
if (t1 != s)
foo_f5();
}
/* Do not perform transform, since strlen (t)
is unknown. */
__attribute__((no_icf))
_Bool f6(char *s, char *t)
{
return __builtin_strstr (s, t) == s;
}
/* Do not perform transform in this case, since
t1 doesn't have single use. */
__attribute__((no_icf))
_Bool f7(char *s)
{
void foo_f7(char *);
char *t1 = __builtin_strstr (s, "hello");
foo_f7 (t1);
return (t1 == s);
}
/* { dg-final { scan-tree-dump-times "__builtin_memcmp" 5 "strlen" } } */

109
gcc/tree-ssa-strlen.c
View File

@ -2222,6 +2222,90 @@ handle_char_store (gimple_stmt_iterator *gsi)
return true;
}
/* Try to fold strstr (s, t) eq/ne s to memcmp (s, t, strlen (t)) eq/ne 0. */
static void
fold_strstr_to_memcmp (tree rhs1, tree rhs2, gimple *stmt)
{
if (TREE_CODE (rhs1) != SSA_NAME
|| TREE_CODE (rhs2) != SSA_NAME)
return;
gimple *call_stmt = NULL;
for (int pass = 0; pass < 2; pass++)
{
gimple *g = SSA_NAME_DEF_STMT (rhs1);
if (gimple_call_builtin_p (g, BUILT_IN_STRSTR)
&& has_single_use (rhs1)
&& gimple_call_arg (g, 0) == rhs2)
{
call_stmt = g;
break;
}
std::swap (rhs1, rhs2);
}
if (call_stmt)
{
tree arg0 = gimple_call_arg (call_stmt, 0);
if (arg0 == rhs2)
{
tree arg1 = gimple_call_arg (call_stmt, 1);
tree arg1_len = NULL_TREE;
int idx = get_stridx (arg1);
if (idx)
{
if (idx < 0)
arg1_len = build_int_cst (size_type_node, ~idx);
else
{
strinfo *si = get_strinfo (idx);
if (si)
arg1_len = get_string_length (si);
}
}
if (arg1_len != NULL_TREE)
{
gimple_stmt_iterator gsi = gsi_for_stmt (call_stmt);
tree memcmp_decl = builtin_decl_explicit (BUILT_IN_MEMCMP);
gcall *memcmp_call = gimple_build_call (memcmp_decl, 3,
arg0, arg1, arg1_len);
tree memcmp_lhs = make_ssa_name (integer_type_node);
gimple_set_vuse (memcmp_call, gimple_vuse (call_stmt));
gimple_call_set_lhs (memcmp_call, memcmp_lhs);
gsi_remove (&gsi, true);
gsi_insert_before (&gsi, memcmp_call, GSI_SAME_STMT);
tree zero = build_zero_cst (TREE_TYPE (memcmp_lhs));
if (is_gimple_assign (stmt))
{
if (gimple_assign_rhs_code (stmt) == COND_EXPR)
{
tree cond = gimple_assign_rhs1 (stmt);
TREE_OPERAND (cond, 0) = memcmp_lhs;
TREE_OPERAND (cond, 1) = zero;
}
else
{
gimple_assign_set_rhs1 (stmt, memcmp_lhs);
gimple_assign_set_rhs2 (stmt, zero);
}
}
else
{
gcond *cond = as_a<gcond *> (stmt);
gimple_cond_set_lhs (cond, memcmp_lhs);
gimple_cond_set_rhs (cond, zero);
}
update_stmt (stmt);
}
}
}
}
/* Attempt to optimize a single statement at *GSI using string length
knowledge. */
@ -2302,7 +2386,23 @@ strlen_optimize_stmt (gimple_stmt_iterator *gsi)
else if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
handle_pointer_plus (gsi);
}
else if (TREE_CODE (lhs) != SSA_NAME && !TREE_SIDE_EFFECTS (lhs))
else if (TREE_CODE (lhs) == SSA_NAME && INTEGRAL_TYPE_P (TREE_TYPE (lhs)))
{
enum tree_code code = gimple_assign_rhs_code (stmt);
if (code == COND_EXPR)
{
tree cond = gimple_assign_rhs1 (stmt);
enum tree_code cond_code = TREE_CODE (cond);
if (cond_code == EQ_EXPR || cond_code == NE_EXPR)
fold_strstr_to_memcmp (TREE_OPERAND (cond, 0),
TREE_OPERAND (cond, 1), stmt);
}
else if (code == EQ_EXPR || code == NE_EXPR)
fold_strstr_to_memcmp (gimple_assign_rhs1 (stmt),
gimple_assign_rhs2 (stmt), stmt);
}
else if (TREE_CODE (lhs) != SSA_NAME && !TREE_SIDE_EFFECTS (lhs))
{
tree type = TREE_TYPE (lhs);
if (TREE_CODE (type) == ARRAY_TYPE)
@ -2316,6 +2416,13 @@ strlen_optimize_stmt (gimple_stmt_iterator *gsi)
}
}
}
else if (gcond *cond = dyn_cast<gcond *> (stmt))
{
enum tree_code code = gimple_cond_code (cond);
if (code == EQ_EXPR || code == NE_EXPR)
fold_strstr_to_memcmp (gimple_cond_lhs (stmt),
gimple_cond_rhs (stmt), stmt);
}
if (gimple_vdef (stmt))
maybe_invalidate (stmt);