As mentioned in the PR, it should be valid to use strncmp instead of memcmp
because first argument of a strstr can be shorter than a second (known)
argument.
Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.
Ready to be installed?
Martin
>From 4a9dcb24d82ce1793a281710ce1ddab59f9dd7a8 Mon Sep 17 00:00:00 2001
From: marxin <mli...@suse.cz>
Date: Mon, 23 Jan 2017 13:18:37 +0100
Subject: [PATCH] Fix strstr folding (PR tree-optimization/79196).
gcc/ChangeLog:
2017-01-23 Martin Liska <mli...@suse.cz>
* tree-ssa-strlen.c (fold_strstr_to_memcmp): Rename
to fold_strstr_to_strncmp and fold the pattern to strncmp
instead of memcmp.
(strlen_optimize_stmt): Call the renamed function.
gcc/testsuite/ChangeLog:
2017-01-23 Martin Liska <mli...@suse.cz>
* gcc.dg/asan/pr79196.c: New test.
* gcc.dg/strlenopt-30.c: Update scanned pattern.
---
gcc/testsuite/gcc.dg/asan/pr79196.c | 17 +++++++++++++++++
gcc/testsuite/gcc.dg/strlenopt-30.c | 2 +-
gcc/tree-ssa-strlen.c | 36 ++++++++++++++++++------------------
3 files changed, 36 insertions(+), 19 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/asan/pr79196.c
diff --git a/gcc/testsuite/gcc.dg/asan/pr79196.c b/gcc/testsuite/gcc.dg/asan/pr79196.c
new file mode 100644
index 00000000000..66a31b90f30
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/asan/pr79196.c
@@ -0,0 +1,17 @@
+// PR tree-optimization/79196
+// { dg-do run }
+
+int
+__attribute__((noinline))
+test(char *a)
+{
+ if (__builtin_strstr (a, "DROP CONVERSION") == a)
+ return 1;
+
+ return 0;
+}
+
+int main(int argc, char **argv)
+{
+ return test ("x");
+}
diff --git a/gcc/testsuite/gcc.dg/strlenopt-30.c b/gcc/testsuite/gcc.dg/strlenopt-30.c
index 089b3a2341d..a85df686ce2 100644
--- a/gcc/testsuite/gcc.dg/strlenopt-30.c
+++ b/gcc/testsuite/gcc.dg/strlenopt-30.c
@@ -60,4 +60,4 @@ _Bool f7(char *s)
return (t1 == s);
}
-/* { dg-final { scan-tree-dump-times "__builtin_memcmp" 5 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "__builtin_strncmp" 5 "strlen" } } */
diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c
index 2e7ac2c7786..141115ed12b 100644
--- a/gcc/tree-ssa-strlen.c
+++ b/gcc/tree-ssa-strlen.c
@@ -2225,10 +2225,10 @@ 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. */
+/* Try to fold strstr (s, t) eq/ne s to strncmp (s, t, strlen (t)) eq/ne 0. */
static void
-fold_strstr_to_memcmp (tree rhs1, tree rhs2, gimple *stmt)
+fold_strstr_to_strncmp (tree rhs1, tree rhs2, gimple *stmt)
{
if (TREE_CODE (rhs1) != SSA_NAME
|| TREE_CODE (rhs2) != SSA_NAME)
@@ -2273,34 +2273,34 @@ fold_strstr_to_memcmp (tree rhs1, tree rhs2, gimple *stmt)
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,
+ tree strncmp_decl = builtin_decl_explicit (BUILT_IN_STRNCMP);
+ gcall *strncmp_call = gimple_build_call (strncmp_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);
+ tree strncmp_lhs = make_ssa_name (integer_type_node);
+ gimple_set_vuse (strncmp_call, gimple_vuse (call_stmt));
+ gimple_call_set_lhs (strncmp_call, strncmp_lhs);
gsi_remove (&gsi, true);
- gsi_insert_before (&gsi, memcmp_call, GSI_SAME_STMT);
- tree zero = build_zero_cst (TREE_TYPE (memcmp_lhs));
+ gsi_insert_before (&gsi, strncmp_call, GSI_SAME_STMT);
+ tree zero = build_zero_cst (TREE_TYPE (strncmp_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, 0) = strncmp_lhs;
TREE_OPERAND (cond, 1) = zero;
}
else
{
- gimple_assign_set_rhs1 (stmt, memcmp_lhs);
+ gimple_assign_set_rhs1 (stmt, strncmp_lhs);
gimple_assign_set_rhs2 (stmt, zero);
}
}
else
{
gcond *cond = as_a<gcond *> (stmt);
- gimple_cond_set_lhs (cond, memcmp_lhs);
+ gimple_cond_set_lhs (cond, strncmp_lhs);
gimple_cond_set_rhs (cond, zero);
}
update_stmt (stmt);
@@ -2398,12 +2398,12 @@ strlen_optimize_stmt (gimple_stmt_iterator *gsi)
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);
+ fold_strstr_to_strncmp (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);
+ fold_strstr_to_strncmp (gimple_assign_rhs1 (stmt),
+ gimple_assign_rhs2 (stmt), stmt);
}
else if (TREE_CODE (lhs) != SSA_NAME && !TREE_SIDE_EFFECTS (lhs))
{
@@ -2423,8 +2423,8 @@ strlen_optimize_stmt (gimple_stmt_iterator *gsi)
{
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);
+ fold_strstr_to_strncmp (gimple_cond_lhs (stmt),
+ gimple_cond_rhs (stmt), stmt);
}
if (gimple_vdef (stmt))
--
2.11.0
