return var;
}
-/* Fold a call to the str{n}{case}cmp builtin pointed by GSI iterator.
- FCODE is the name of the builtin. */
+/* Fold a call to the str{n}{case}cmp builtin pointed by GSI iterator. */
static bool
gimple_fold_builtin_string_compare (gimple_stmt_iterator *gsi)
tree str1 = gimple_call_arg (stmt, 0);
tree str2 = gimple_call_arg (stmt, 1);
tree lhs = gimple_call_lhs (stmt);
- HOST_WIDE_INT length = -1;
+ tree len = NULL_TREE;
+ unsigned HOST_WIDE_INT bound = HOST_WIDE_INT_M1U;
/* Handle strncmp and strncasecmp functions. */
if (gimple_call_num_args (stmt) == 3)
{
- tree len = gimple_call_arg (stmt, 2);
+ len = gimple_call_arg (stmt, 2);
if (tree_fits_uhwi_p (len))
- length = tree_to_uhwi (len);
+ bound = tree_to_uhwi (len);
}
/* If the LEN parameter is zero, return zero. */
- if (length == 0)
+ if (bound == 0)
{
replace_call_with_value (gsi, integer_zero_node);
return true;
return true;
}
- const char *p1 = c_getstr (str1);
- const char *p2 = c_getstr (str2);
+ /* Initially set to the number of characters, including the terminating
+ nul if each array has one. LENx == strnlen (Sx, LENx) implies that
+ the array Sx is not terminated by a nul.
+ For nul-terminated strings then adjusted to their length so that
+ LENx == NULPOSx holds. */
+ unsigned HOST_WIDE_INT len1 = HOST_WIDE_INT_MAX, len2 = len1;
+ const char *p1 = c_getstr (str1, &len1);
+ const char *p2 = c_getstr (str2, &len2);
+
+ /* The position of the terminating nul character if one exists, otherwise
+ a value greater than LENx. */
+ unsigned HOST_WIDE_INT nulpos1 = HOST_WIDE_INT_MAX, nulpos2 = nulpos1;
+
+ if (p1)
+ {
+ size_t n = strnlen (p1, len1);
+ if (n < len1)
+ len1 = nulpos1 = n;
+ }
+
+ if (p2)
+ {
+ size_t n = strnlen (p2, len2);
+ if (n < len2)
+ len2 = nulpos2 = n;
+ }
/* For known strings, return an immediate value. */
if (p1 && p2)
{
case BUILT_IN_STRCMP:
case BUILT_IN_STRCMP_EQ:
- {
- r = strcmp (p1, p2);
- known_result = true;
+ if (len1 != nulpos1 || len2 != nulpos2)
break;
- }
+
+ r = strcmp (p1, p2);
+ known_result = true;
+ break;
+
case BUILT_IN_STRNCMP:
case BUILT_IN_STRNCMP_EQ:
{
- if (length == -1)
+ /* Reduce the bound to be no more than the length
+ of the shorter of the two strings, or the sizes
+ of the unterminated arrays. */
+ unsigned HOST_WIDE_INT n = bound;
+
+ if (len1 == nulpos1 && len1 < n)
+ n = len1 + 1;
+ if (len2 == nulpos2 && len2 < n)
+ n = len2 + 1;
+
+ if (MIN (nulpos1, nulpos2) + 1 < n)
break;
- r = strncmp (p1, p2, length);
+
+ r = strncmp (p1, p2, n);
known_result = true;
break;
}
break;
case BUILT_IN_STRNCASECMP:
{
- if (length == -1)
+ if (bound == HOST_WIDE_INT_M1U)
break;
- r = strncmp (p1, p2, length);
+ r = strncmp (p1, p2, bound);
if (r == 0)
known_result = true;
break;
}
}
- bool nonzero_length = length >= 1
+ bool nonzero_bound = (bound >= 1 && bound < HOST_WIDE_INT_M1U)
|| fcode == BUILT_IN_STRCMP
|| fcode == BUILT_IN_STRCMP_EQ
|| fcode == BUILT_IN_STRCASECMP;
location_t loc = gimple_location (stmt);
/* If the second arg is "", return *(const unsigned char*)arg1. */
- if (p2 && *p2 == '\0' && nonzero_length)
+ if (p2 && *p2 == '\0' && nonzero_bound)
{
gimple_seq stmts = NULL;
tree var = gimple_load_first_char (loc, str1, &stmts);
}
/* If the first arg is "", return -*(const unsigned char*)arg2. */
- if (p1 && *p1 == '\0' && nonzero_length)
+ if (p1 && *p1 == '\0' && nonzero_bound)
{
gimple_seq stmts = NULL;
tree var = gimple_load_first_char (loc, str2, &stmts);
return true;
}
- /* If len parameter is one, return an expression corresponding to
+ /* If BOUND is one, return an expression corresponding to
(*(const unsigned char*)arg2 - *(const unsigned char*)arg1). */
- if (fcode == BUILT_IN_STRNCMP && length == 1)
+ if (fcode == BUILT_IN_STRNCMP && bound == 1)
{
gimple_seq stmts = NULL;
tree temp1 = gimple_load_first_char (loc, str1, &stmts);
return true;
}
- /* If length is larger than the length of one constant string,
- replace strncmp with corresponding strcmp */
- if (fcode == BUILT_IN_STRNCMP
- && length > 0
- && ((p2 && (size_t) length > strlen (p2))
- || (p1 && (size_t) length > strlen (p1))))
+ /* If BOUND is greater than the length of one constant string,
+ and the other argument is also a nul-terminated string, replace
+ strncmp with strcmp. */
+ if (fcode == BUILT_IN_STRNCMP
+ && bound > 0 && bound < HOST_WIDE_INT_M1U
+ && ((p2 && len2 < bound && len2 == nulpos2)
+ || (p1 && len1 < bound && len1 == nulpos1)))
{
tree fn = builtin_decl_implicit (BUILT_IN_STRCMP);
if (!fn)
--- /dev/null
+/* PR tree-optimization/92501 - strncmp with constant unterminated arrays
+ not folded
+ { dg-do compile }
+ { dg-options "-O1 -Wall -fdump-tree-forwprop1" } */
+
+/* Unterminated arrays of the size encoded in name. */
+const char a1[] = { '1' };
+const char a12[] = { '1', '2' };
+const char a112[] = { '1', '1', '2' };
+const char a123[] = { '1', '2', '3' };
+
+/* Nul-terminated strings of the length encoded in name. */
+const char s[] = "";
+const char s1[] = "1";
+const char s12[] = "12";
+const char s112[] = "112";
+const char s123[] = "123";
+
+extern void failure_on_line (int);
+
+/* Verify that the test in 'if (EQL strncmp (S, T, N))' is folded. */
+#define T(eql, s, t, n) do { \
+ if (!(eql __builtin_strncmp (s, t, n))) \
+ failure_on_line (__LINE__); \
+ } while (0)
+
+
+void test (void)
+{
+ /* Mixed array and string. */
+ T (0 ==, a1, "", 0);
+ T (0 ==, a1, s, 0);
+ T (0 !=, a1, "", 1);
+ T (0 !=, a1, s, 1);
+
+ /* The following two are safe to fold because while strncmp compares
+ at most N bytes it doesn't compare any bytes past the first nul. */
+ T (0 !=, a1, "", 9);
+ T (0 !=, a1, s, 9);
+
+ T (0 ==, a1, "1", 0);
+ T (0 ==, a1, s1, 0);
+ T (0 ==, a1, "1", 1);
+ T (0 ==, a1, s1, 1);
+ T (0 ==, a1, "12", 1);
+ T (0 ==, a1, s12, 1);
+
+ /* As above, the following three are also safe to fold. */
+ T (0 !=, a1, s12 + 1, 1);
+ T (0 !=, a1, s12 + 1, 2);
+ T (0 !=, a1, s12 + 1, 9);
+
+ T (0 ==, a12, s, 0);
+ T (0 ==, a12, "", 0);
+ T (0 ==, a12, s1, 0);
+ T (0 ==, a12, "1", 0);
+ T (0 ==, a12, s1, 1);
+ T (0 ==, a12, "1", 1);
+ T (0 !=, a12, s1, 2);
+ T (0 !=, a12, "1", 2);
+ T (0 ==, a12, s12, 0);
+ T (0 ==, a12, "12", 0);
+ T (0 ==, a12, s12, 1);
+ T (0 ==, a12, "12", 1);
+ T (0 ==, a12, s12, 2);
+ T (0 ==, a12, "12", 2);
+ T (0 ==, a12, s123, 2);
+ T (0 ==, a12, "123", 2);
+
+ T (0 ==, a12 + 0, s123 + 1, 0);
+ T (0 !=, a12 + 0, s123 + 1, 1);
+ T (0 !=, a12 + 0, s123 + 1, 2);
+ T (0 ==, a12 + 1, s123 + 0, 0);
+ T (0 !=, a12 + 1, s123 + 0, 1);
+ T (0 !=, a12 + 1, s123 + 0, 2);
+ T (0 ==, a12 + 1, s123 + 1, 1);
+ T (0 !=, a12 + 1, s123 + 2, 1);
+ T (0 !=, a12 + 1, s123 + 3, 1);
+
+ T (0 ==, a12 + 1, "123" + 1, 1);
+ T (0 !=, a12 + 1, "123" + 2, 1);
+ T (0 !=, a12 + 1, "123" + 3, 1);
+ T (0 !=, a12 + 1, "123" + 3, 9);
+
+ /* Both arguments arrays. */
+ T (0 ==, a112 + 0, a1, 1);
+ T (0 ==, a112 + 1, a1, 1);
+ T (0 !=, a112 + 2, a1, 1);
+
+ T (0 ==, a1, a112 + 0, 1);
+ T (0 ==, a1, a112 + 1, 1);
+ T (0 !=, a1, a112 + 2, 1);
+
+ T (0 ==, a112 + 0, a12, 0);
+ T (0 ==, a112 + 0, a12, 1);
+ T (0 !=, a112 + 0, a12, 2);
+
+ T (0 ==, a112 + 1, a12, 2);
+ T (0 !=, a112 + 1, a12 + 1, 1);
+ T (0 ==, a112 + 2, a12 + 1, 1);
+
+ /* Mixed array and string. */
+ T (0 ==, s112 + 0, a12, 0);
+ T (0 ==, s112 + 0, a12, 1);
+ T (0 !=, s112 + 0, a12, 2);
+
+ T (0 ==, s112 + 1, a12, 0);
+ T (0 ==, s112 + 1, a12, 1);
+ T (0 ==, s112 + 1, a12, 2);
+ T (0 !=, s112 + 2, a12, 2);
+
+ T (0 ==, a112 + 0, s1, 1);
+ T (0 ==, a112 + 1, s1, 1);
+ T (0 !=, a112 + 2, s1, 1);
+}
+
+/* { dg-final { scan-tree-dump-not "strcmp" "forwprop1" } }
+ { dg-final { scan-tree-dump-not "strncmp" "forwprop1" } }
+ { dg-final { scan-tree-dump-not "failure_on_line_" "forwprop1" } } */
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