/* Return:
- - 1 if SI is known to start with more than OFF nonzero characters.
+ * +1 if SI is known to start with more than OFF nonzero characters.
- - 0 if SI is known to start with OFF nonzero characters,
- but is not known to start with more.
+ * 0 if SI is known to start with OFF nonzero characters,
+ but is not known to start with more.
- - -1 if SI might not start with OFF nonzero characters. */
+ * -1 if SI might not start with OFF nonzero characters. */
static inline int
compare_nonzero_chars (strinfo *si, unsigned HOST_WIDE_INT off)
return -1;
}
+/* Same as above but suitable also for strings with non-constant lengths.
+ Uses RVALS to determine length range. */
+
+static int
+compare_nonzero_chars (strinfo *si, unsigned HOST_WIDE_INT off,
+ const vr_values *rvals)
+{
+ if (!si->nonzero_chars)
+ return -1;
+
+ if (TREE_CODE (si->nonzero_chars) == INTEGER_CST)
+ return compare_tree_int (si->nonzero_chars, off);
+
+ if (TREE_CODE (si->nonzero_chars) != SSA_NAME)
+ return -1;
+
+ const value_range *vr
+ = (CONST_CAST (class vr_values *, rvals)
+ ->get_value_range (si->nonzero_chars));
+
+ value_range_kind rng = vr->kind ();
+ if (rng != VR_RANGE || !range_int_cst_p (vr))
+ return -1;
+
+ return compare_tree_int (vr->min (), off);
+}
+
/* Return true if SI is known to be a zero-length string. */
static inline bool
if (!argdata.minlen
|| (integer_zerop (argdata.minlen)
- && integer_all_onesp (argdata.maxbound)
+ && (!argdata.maxbound
+ || integer_all_onesp (argdata.maxbound))
&& integer_all_onesp (argdata.maxlen)))
{
/* Set the upper bound of the length to unbounded. */
|| tree_int_cst_lt (argdata.minlen, pdata->minlen))
pdata->minlen = argdata.minlen;
if (!pdata->maxlen
- || tree_int_cst_lt (pdata->maxlen, argdata.maxlen))
+ || (argdata.maxlen
+ && tree_int_cst_lt (pdata->maxlen, argdata.maxlen)))
pdata->maxlen = argdata.maxlen;
if (!pdata->maxbound
- || (tree_int_cst_lt (pdata->maxbound,
- argdata.maxbound)
+ || TREE_CODE (pdata->maxbound) != INTEGER_CST
+ || (argdata.maxbound
+ && tree_int_cst_lt (pdata->maxbound,
+ argdata.maxbound)
&& !integer_all_onesp (argdata.maxbound)))
pdata->maxbound = argdata.maxbound;
}
if (strinfo *si = get_strinfo (idx))
{
pdata->minlen = get_string_length (si);
- if (!pdata->minlen
- && si->nonzero_chars)
+ if (!pdata->minlen && si->nonzero_chars)
{
if (TREE_CODE (si->nonzero_chars) == INTEGER_CST)
pdata->minlen = si->nonzero_chars;
else
pdata->maxlen = build_all_ones_cst (size_type_node);
}
- else if (TREE_CODE (pdata->minlen) == SSA_NAME)
+ else if (pdata->minlen && TREE_CODE (pdata->minlen) == SSA_NAME)
{
const value_range *vr
= CONST_CAST (class vr_values *, rvals)
pdata->maxlen = build_all_ones_cst (size_type_node);
}
}
- else
+ else if (pdata->minlen && TREE_CODE (pdata->minlen) == INTEGER_CST)
{
pdata->maxlen = pdata->minlen;
pdata->maxbound = pdata->minlen;
}
+ else
+ {
+ /* For PDATA->MINLEN that's a non-constant expression such
+ as PLUS_EXPR whose value range is unknown, set the bounds
+ to zero and SIZE_MAX. */
+ pdata->minlen = build_zero_cst (size_type_node);
+ pdata->maxlen = build_all_ones_cst (size_type_node);
+ }
return true;
}
const vr_values *rvals)
{
bitmap visited = NULL;
+ tree maxbound = pdata->maxbound;
unsigned limit = PARAM_VALUE (PARAM_SSA_NAME_DEF_CHAIN_LIMIT);
if (!get_range_strlen_dynamic (src, pdata, &visited, rvals, &limit))
else if (!pdata->minlen)
pdata->minlen = ssize_int (0);
+ /* If it's unchanged from it initial non-null value, set the conservative
+ MAXBOUND to SIZE_MAX. Otherwise leave it null (if it is null). */
+ if (maxbound && pdata->maxbound == maxbound)
+ pdata->maxbound = build_all_ones_cst (size_type_node);
+
if (visited)
BITMAP_FREE (visited);
}
/* Invalidate string length information for strings whose length
- might change due to stores in stmt. */
+ might change due to stores in stmt, except those marked DON'T
+ INVALIDATE. For string-modifying statements, ZERO_WRITE is
+ set when the statement wrote only zeros. */
static bool
-maybe_invalidate (gimple *stmt)
+maybe_invalidate (gimple *stmt, bool zero_write = false)
{
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, " %s()\n", __func__);
+
strinfo *si;
unsigned int i;
bool nonempty = false;
if (!si->dont_invalidate)
{
ao_ref r;
- /* Do not use si->nonzero_chars. */
- ao_ref_init_from_ptr_and_size (&r, si->ptr, NULL_TREE);
+ tree size = NULL_TREE;
+ if (si->nonzero_chars)
+ {
+ /* Include the terminating nul in the size of the string
+ to consider when determining possible clobber. */
+ tree type = TREE_TYPE (si->nonzero_chars);
+ size = fold_build2 (PLUS_EXPR, type, si->nonzero_chars,
+ build_int_cst (type, 1));
+ }
+ ao_ref_init_from_ptr_and_size (&r, si->ptr, size);
if (stmt_may_clobber_ref_p_1 (stmt, &r))
{
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ if (size && tree_fits_uhwi_p (size))
+ fprintf (dump_file,
+ " statement may clobber string "
+ HOST_WIDE_INT_PRINT_UNSIGNED " long\n",
+ tree_to_uhwi (size));
+ else
+ fprintf (dump_file,
+ " statement may clobber string\n");
+ }
+
set_strinfo (i, NULL);
free_strinfo (si);
continue;
}
+
+ if (size
+ && !zero_write
+ && si->stmt
+ && is_gimple_call (si->stmt)
+ && (DECL_FUNCTION_CODE (gimple_call_fndecl (si->stmt))
+ == BUILT_IN_CALLOC))
+ {
+ /* If the clobber test above considered the length of
+ the string (including the nul), then for (potentially)
+ non-zero writes that might modify storage allocated by
+ calloc consider the whole object and if it might be
+ clobbered by the statement reset the allocation
+ statement. */
+ ao_ref_init_from_ptr_and_size (&r, si->ptr, NULL_TREE);
+ if (stmt_may_clobber_ref_p_1 (stmt, &r))
+ si->stmt = NULL;
+ }
}
si->dont_invalidate = false;
nonempty = true;
}
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, " %s() ==> %i\n", __func__, nonempty);
+
return nonempty;
}
else
{
c_strlen_data lendata = { };
+ /* Set MAXBOUND to an arbitrary non-null non-integer node as a request
+ to have it set to the length of the longest string in a PHI. */
+ lendata.maxbound = src;
get_range_strlen (src, &lendata, /* eltsize = */1);
if (TREE_CODE (lendata.minlen) == INTEGER_CST
&& TREE_CODE (lendata.maxbound) == INTEGER_CST)
/* Compute the size of the source sequence, including the nul. */
tree srcsize = srclen ? srclen : size_zero_node;
- srcsize = fold_build2 (PLUS_EXPR, type, srcsize, build_int_cst (type, 1));
-
+ tree one = build_int_cst (type, 1);
+ srcsize = fold_build2 (PLUS_EXPR, type, srcsize, one);
+ tree dstsize = fold_build2 (PLUS_EXPR, type, dstlen, one);
tree sptr = si && si->ptr ? si->ptr : src;
- if (check_bounds_or_overlap (stmt, dst, sptr, dstlen, srcsize))
+ if (check_bounds_or_overlap (stmt, dst, sptr, dstsize, srcsize))
{
gimple_set_no_warning (stmt, true);
set_no_warning = true;
return true when the call is transfomred, false otherwise. */
static bool
-handle_builtin_memset (gimple_stmt_iterator *gsi)
+handle_builtin_memset (gimple_stmt_iterator *gsi, bool *zero_write)
{
gimple *stmt2 = gsi_stmt (*gsi);
if (!integer_zerop (gimple_call_arg (stmt2, 1)))
return false;
+
+ /* Let the caller know the memset call cleared the destination. */
+ *zero_write = true;
+
tree ptr = gimple_call_arg (stmt2, 0);
int idx1 = get_stridx (ptr);
if (idx1 <= 0)
return true;
}
-/* Handle a call to memcmp. We try to handle small comparisons by
- converting them to load and compare, and replacing the call to memcmp
- with a __builtin_memcmp_eq call where possible.
- return true when call is transformed, return false otherwise. */
+/* Return a pointer to the first such equality expression if RES is used
+ only in expressions testing its equality to zero, and null otherwise. */
-static bool
-handle_builtin_memcmp (gimple_stmt_iterator *gsi)
+static gimple *
+used_only_for_zero_equality (tree res)
{
- gcall *stmt2 = as_a <gcall *> (gsi_stmt (*gsi));
- tree res = gimple_call_lhs (stmt2);
- tree arg1 = gimple_call_arg (stmt2, 0);
- tree arg2 = gimple_call_arg (stmt2, 1);
- tree len = gimple_call_arg (stmt2, 2);
- unsigned HOST_WIDE_INT leni;
+ gimple *first_use = NULL;
+
use_operand_p use_p;
imm_use_iterator iter;
- if (!res)
- return false;
-
FOR_EACH_IMM_USE_FAST (use_p, iter, res)
{
- gimple *ustmt = USE_STMT (use_p);
+ gimple *use_stmt = USE_STMT (use_p);
- if (is_gimple_debug (ustmt))
- continue;
- if (gimple_code (ustmt) == GIMPLE_ASSIGN)
+ if (is_gimple_debug (use_stmt))
+ continue;
+ if (gimple_code (use_stmt) == GIMPLE_ASSIGN)
{
- gassign *asgn = as_a <gassign *> (ustmt);
- tree_code code = gimple_assign_rhs_code (asgn);
- if ((code != EQ_EXPR && code != NE_EXPR)
- || !integer_zerop (gimple_assign_rhs2 (asgn)))
- return false;
+ tree_code code = gimple_assign_rhs_code (use_stmt);
+ if (code == COND_EXPR)
+ {
+ tree cond_expr = gimple_assign_rhs1 (use_stmt);
+ if ((TREE_CODE (cond_expr) != EQ_EXPR
+ && (TREE_CODE (cond_expr) != NE_EXPR))
+ || !integer_zerop (TREE_OPERAND (cond_expr, 1)))
+ return NULL;
+ }
+ else if (code == EQ_EXPR || code == NE_EXPR)
+ {
+ if (!integer_zerop (gimple_assign_rhs2 (use_stmt)))
+ return NULL;
+ }
+ else
+ return NULL;
}
- else if (gimple_code (ustmt) == GIMPLE_COND)
+ else if (gimple_code (use_stmt) == GIMPLE_COND)
{
- tree_code code = gimple_cond_code (ustmt);
+ tree_code code = gimple_cond_code (use_stmt);
if ((code != EQ_EXPR && code != NE_EXPR)
- || !integer_zerop (gimple_cond_rhs (ustmt)))
- return false;
+ || !integer_zerop (gimple_cond_rhs (use_stmt)))
+ return NULL;
}
else
- return false;
+ return NULL;
+
+ if (!first_use)
+ first_use = use_stmt;
}
+ return first_use;
+}
+
+/* Handle a call to memcmp. We try to handle small comparisons by
+ converting them to load and compare, and replacing the call to memcmp
+ with a __builtin_memcmp_eq call where possible.
+ return true when call is transformed, return false otherwise. */
+
+static bool
+handle_builtin_memcmp (gimple_stmt_iterator *gsi)
+{
+ gcall *stmt = as_a <gcall *> (gsi_stmt (*gsi));
+ tree res = gimple_call_lhs (stmt);
+
+ if (!res || !used_only_for_zero_equality (res))
+ return false;
+
+ tree arg1 = gimple_call_arg (stmt, 0);
+ tree arg2 = gimple_call_arg (stmt, 1);
+ tree len = gimple_call_arg (stmt, 2);
+ unsigned HOST_WIDE_INT leni;
+
if (tree_fits_uhwi_p (len)
&& (leni = tree_to_uhwi (len)) <= GET_MODE_SIZE (word_mode)
&& pow2p_hwi (leni))
if (int_mode_for_size (leni, 1).exists (&mode)
&& (align >= leni || !targetm.slow_unaligned_access (mode, align)))
{
- location_t loc = gimple_location (stmt2);
+ location_t loc = gimple_location (stmt);
tree type, off;
type = build_nonstandard_integer_type (leni, 1);
gcc_assert (known_eq (GET_MODE_BITSIZE (TYPE_MODE (type)), leni));
}
}
- gimple_call_set_fndecl (stmt2, builtin_decl_explicit (BUILT_IN_MEMCMP_EQ));
+ gimple_call_set_fndecl (stmt, builtin_decl_explicit (BUILT_IN_MEMCMP_EQ));
return true;
}
-/* If IDX1 and IDX2 refer to strings A and B of unequal lengths, return
- the result of 0 == strncmp (A, B, N) (which is the same as strcmp for
- sufficiently large N). Otherwise return false. */
-
-static bool
-strxcmp_unequal (int idx1, int idx2, unsigned HOST_WIDE_INT n)
-{
- unsigned HOST_WIDE_INT len1;
- unsigned HOST_WIDE_INT len2;
-
- bool nulterm1;
- bool nulterm2;
-
- if (idx1 < 0)
- {
- len1 = ~idx1;
- nulterm1 = true;
- }
- else if (strinfo *si = get_strinfo (idx1))
- {
- if (tree_fits_uhwi_p (si->nonzero_chars))
- {
- len1 = tree_to_uhwi (si->nonzero_chars);
- nulterm1 = si->full_string_p;
- }
- else
- return false;
- }
- else
- return false;
-
- if (idx2 < 0)
- {
- len2 = ~idx2;
- nulterm2 = true;
- }
- else if (strinfo *si = get_strinfo (idx2))
- {
- if (tree_fits_uhwi_p (si->nonzero_chars))
- {
- len2 = tree_to_uhwi (si->nonzero_chars);
- nulterm2 = si->full_string_p;
- }
- else
- return false;
- }
- else
- return false;
-
- /* N is set to UHWI_MAX for strcmp and less to strncmp. Adjust
- the length of each string to consider to be no more than N. */
- if (len1 > n)
- len1 = n;
- if (len2 > n)
- len2 = n;
-
- if ((len1 < len2 && nulterm1)
- || (len2 < len1 && nulterm2))
- /* The string lengths are definitely unequal and the result can
- be folded to one (since it's used for comparison with zero). */
- return true;
-
- /* The string lengths may be equal or unequal. Even when equal and
- both strings nul-terminated, without the string contents there's
- no way to determine whether they are equal. */
- return false;
-}
-
/* Given an index to the strinfo vector, compute the string length
for the corresponding string. Return -1 when unknown. */
/* Determine the minimum size of the object referenced by DEST expression
which must have a pointer type.
- Return the minimum size of the object if successful or NULL when the size
- cannot be determined. */
-static tree
+ Return the minimum size of the object if successful or HWI_M1U when
+ the size cannot be determined. */
+
+static unsigned HOST_WIDE_INT
determine_min_objsize (tree dest)
{
unsigned HOST_WIDE_INT size = 0;
+ init_object_sizes ();
+
if (compute_builtin_object_size (dest, 2, &size))
- return build_int_cst (sizetype, size);
+ return size;
/* Try to determine the size of the object through the RHS
of the assign statement. */
{
gimple *stmt = SSA_NAME_DEF_STMT (dest);
if (!is_gimple_assign (stmt))
- return NULL_TREE;
+ return HOST_WIDE_INT_M1U;
if (!gimple_assign_single_p (stmt)
&& !gimple_assign_unary_nop_p (stmt))
- return NULL_TREE;
+ return HOST_WIDE_INT_M1U;
dest = gimple_assign_rhs1 (stmt);
return determine_min_objsize (dest);
/* Try to determine the size of the object from its type. */
if (TREE_CODE (dest) != ADDR_EXPR)
- return NULL_TREE;
+ return HOST_WIDE_INT_M1U;
tree type = TREE_TYPE (dest);
if (TREE_CODE (type) == POINTER_TYPE)
type = TYPE_MAIN_VARIANT (type);
- /* We cannot determine the size of the array if it's a flexible array,
- which is declared at the end of a structure. */
- if (TREE_CODE (type) == ARRAY_TYPE
- && !array_at_struct_end_p (dest))
+ /* The size of a flexible array cannot be determined. Otherwise,
+ for arrays with more than one element, return the size of its
+ type. GCC itself misuses arrays of both zero and one elements
+ as flexible array members so they are excluded as well. */
+ if (TREE_CODE (type) != ARRAY_TYPE
+ || !array_at_struct_end_p (dest))
{
- tree size_t = TYPE_SIZE_UNIT (type);
- if (size_t && TREE_CODE (size_t) == INTEGER_CST
- && !integer_zerop (size_t))
- return size_t;
+ tree type_size = TYPE_SIZE_UNIT (type);
+ if (type_size && TREE_CODE (type_size) == INTEGER_CST
+ && !integer_onep (type_size)
+ && !integer_zerop (type_size))
+ return tree_to_uhwi (type_size);
}
- return NULL_TREE;
+ return HOST_WIDE_INT_M1U;
}
-/* Handle a call to strcmp or strncmp. When the result is ONLY used to do
- equality test against zero:
-
- A. When the lengths of both arguments are constant and it's a strcmp:
- * if the lengths are NOT equal, we can safely fold the call
- to a non-zero value.
- * otherwise, do nothing now.
-
- B. When the length of one argument is constant, try to replace the call
- with a __builtin_str(n)cmp_eq call where possible, i.e:
-
- strncmp (s, STR, C) (!)= 0 in which, s is a pointer to a string, STR
- is a string with constant length , C is a constant.
- if (C <= strlen(STR) && sizeof_array(s) > C)
- {
- replace this call with
- strncmp_eq (s, STR, C) (!)= 0
- }
- if (C > strlen(STR)
- {
- it can be safely treated as a call to strcmp (s, STR) (!)= 0
- can handled by the following strcmp.
- }
-
- strcmp (s, STR) (!)= 0 in which, s is a pointer to a string, STR
- is a string with constant length.
- if (sizeof_array(s) > strlen(STR))
- {
- replace this call with
- strcmp_eq (s, STR, strlen(STR)+1) (!)= 0
- }
-
- Return true when the call is transformed, return false otherwise.
- */
+/* Given strinfo IDX for ARG, set LENRNG[] to the range of lengths
+ of the string(s) referenced by ARG if it can be determined.
+ If the length cannot be determined, set *SIZE to the size of
+ the array the string is stored in, if any. If no such array is
+ known, set *SIZE to -1. When the strings are nul-terminated set
+ *NULTERM to true, otherwise to false. Return true on success. */
static bool
-handle_builtin_string_cmp (gimple_stmt_iterator *gsi)
+get_len_or_size (tree arg, int idx, unsigned HOST_WIDE_INT lenrng[2],
+ unsigned HOST_WIDE_INT *size, bool *nulterm)
{
- gcall *stmt = as_a <gcall *> (gsi_stmt (*gsi));
- tree res = gimple_call_lhs (stmt);
- use_operand_p use_p;
- imm_use_iterator iter;
- tree arg1 = gimple_call_arg (stmt, 0);
- tree arg2 = gimple_call_arg (stmt, 1);
- int idx1 = get_stridx (arg1);
- int idx2 = get_stridx (arg2);
- HOST_WIDE_INT length = -1;
- bool is_ncmp = false;
+ /* Set so that both LEN and ~LEN are invalid lengths, i.e.,
+ maximum possible length + 1. */
+ lenrng[0] = lenrng[1] = HOST_WIDE_INT_MAX;
- if (!res)
- return false;
-
- /* When both arguments are unknown, do nothing. */
- if (idx1 == 0 && idx2 == 0)
- return false;
+ *size = HOST_WIDE_INT_M1U;
- /* Handle strncmp function. */
- if (gimple_call_num_args (stmt) == 3)
+ if (idx < 0)
{
- tree len = gimple_call_arg (stmt, 2);
- if (tree_fits_shwi_p (len))
- length = tree_to_shwi (len);
-
- is_ncmp = true;
+ /* IDX is the inverted constant string length. */
+ lenrng[0] = ~idx;
+ lenrng[1] = lenrng[0];
+ *nulterm = true;
}
-
- /* For strncmp, if the length argument is NOT known, do nothing. */
- if (is_ncmp && length < 0)
- return false;
-
- /* When the result is ONLY used to do equality test against zero. */
- FOR_EACH_IMM_USE_FAST (use_p, iter, res)
+ else if (idx == 0)
+ ; /* Handled below. */
+ else if (strinfo *si = get_strinfo (idx))
{
- gimple *use_stmt = USE_STMT (use_p);
+ if (!si->nonzero_chars)
+ arg = si->ptr;
+ else if (tree_fits_uhwi_p (si->nonzero_chars))
+ {
+ lenrng[0] = tree_to_uhwi (si->nonzero_chars);
+ *nulterm = si->full_string_p;
+ /* Set the upper bound only if the string is known to be
+ nul-terminated, otherwise leave it at maximum + 1. */
+ if (*nulterm)
+ lenrng[1] = lenrng[0];
+ }
+ else if (TREE_CODE (si->nonzero_chars) == SSA_NAME)
+ {
+ wide_int min, max;
+ value_range_kind rng = get_range_info (si->nonzero_chars, &min, &max);
+ if (rng == VR_RANGE)
+ {
+ lenrng[0] = min.to_uhwi ();
+ lenrng[1] = max.to_uhwi ();
+ *nulterm = si->full_string_p;
+ }
+ }
+ else if (si->ptr)
+ arg = si->ptr;
+ }
- if (is_gimple_debug (use_stmt))
- continue;
- if (gimple_code (use_stmt) == GIMPLE_ASSIGN)
+ if (lenrng[0] == HOST_WIDE_INT_MAX)
+ {
+ /* Compute the minimum and maximum real or possible lengths. */
+ c_strlen_data lendata = { };
+ if (get_range_strlen (arg, &lendata, /* eltsize = */1))
{
- tree_code code = gimple_assign_rhs_code (use_stmt);
- if (code == COND_EXPR)
+ if (tree_fits_shwi_p (lendata.maxlen) && !lendata.maxbound)
{
- tree cond_expr = gimple_assign_rhs1 (use_stmt);
- if ((TREE_CODE (cond_expr) != EQ_EXPR
- && (TREE_CODE (cond_expr) != NE_EXPR))
- || !integer_zerop (TREE_OPERAND (cond_expr, 1)))
- return false;
+ lenrng[0] = tree_to_shwi (lendata.minlen);
+ lenrng[1] = tree_to_shwi (lendata.maxlen);
+ *nulterm = true;
}
- else if (code == EQ_EXPR || code == NE_EXPR)
+ else if (lendata.maxbound && tree_fits_shwi_p (lendata.maxbound))
{
- if (!integer_zerop (gimple_assign_rhs2 (use_stmt)))
- return false;
- }
- else
- return false;
+ /* Set *SIZE to the conservative LENDATA.MAXBOUND which
+ is a conservative estimate of the longest string based
+ on the sizes of the arrays referenced by ARG. */
+ *size = tree_to_uhwi (lendata.maxbound) + 1;
+ *nulterm = false;
+ }
}
- else if (gimple_code (use_stmt) == GIMPLE_COND)
+ else
{
- tree_code code = gimple_cond_code (use_stmt);
- if ((code != EQ_EXPR && code != NE_EXPR)
- || !integer_zerop (gimple_cond_rhs (use_stmt)))
- return false;
+ /* Set *SIZE to the size of the smallest object referenced
+ by ARG if ARG denotes a single object, or to HWI_M1U
+ otherwise. */
+ *size = determine_min_objsize (arg);
+ *nulterm = false;
}
+ }
+
+ return lenrng[0] != HOST_WIDE_INT_MAX || *size != HOST_WIDE_INT_M1U;
+}
+
+/* If IDX1 and IDX2 refer to strings A and B of unequal lengths, return
+ the result of 0 == strncmp (A, B, BOUND) (which is the same as strcmp
+ for a sufficiently large BOUND). If the result is based on the length
+ of one string being greater than the longest string that would fit in
+ the array pointer to by the argument, set *PLEN and *PSIZE to
+ the corresponding length (or its complement when the string is known
+ to be at least as long and need not be nul-terminated) and size.
+ Otherwise return null. */
+
+static tree
+strxcmp_eqz_result (tree arg1, int idx1, tree arg2, int idx2,
+ unsigned HOST_WIDE_INT bound, unsigned HOST_WIDE_INT len[2],
+ unsigned HOST_WIDE_INT *psize)
+{
+ /* Determine the range the length of each string is in and whether it's
+ known to be nul-terminated, or the size of the array it's stored in. */
+ bool nul1, nul2;
+ unsigned HOST_WIDE_INT siz1, siz2;
+ unsigned HOST_WIDE_INT len1rng[2], len2rng[2];
+ if (!get_len_or_size (arg1, idx1, len1rng, &siz1, &nul1)
+ || !get_len_or_size (arg2, idx2, len2rng, &siz2, &nul2))
+ return NULL_TREE;
+
+ /* BOUND is set to HWI_M1U for strcmp and less to strncmp, and LENiRNG
+ to HWI_MAX when invalid. Adjust the length of each string to consider
+ to be no more than BOUND. */
+ if (len1rng[0] < HOST_WIDE_INT_MAX && len1rng[0] > bound)
+ len1rng[0] = bound;
+ if (len1rng[1] < HOST_WIDE_INT_MAX && len1rng[1] > bound)
+ len1rng[1] = bound;
+ if (len2rng[0] < HOST_WIDE_INT_MAX && len2rng[0] > bound)
+ len2rng[0] = bound;
+ if (len2rng[1] < HOST_WIDE_INT_MAX && len2rng[1] > bound)
+ len2rng[1] = bound;
+
+ /* Two empty strings are equal. */
+ if (len1rng[1] == 0 && len2rng[1] == 0)
+ return integer_one_node;
+
+ /* The strings are definitely unequal when the lower bound of the length
+ of one of them is greater than the length of the longest string that
+ would fit into the other array. */
+ if (len1rng[0] == HOST_WIDE_INT_MAX
+ && len2rng[0] != HOST_WIDE_INT_MAX
+ && ((len2rng[0] < bound && len2rng[0] >= siz1)
+ || len2rng[0] > siz1))
+ {
+ *psize = siz1;
+ len[0] = len1rng[0];
+ /* Set LEN[0] to the lower bound of ARG1's length when it's
+ nul-terminated or to the complement of its minimum length
+ otherwise, */
+ len[1] = nul2 ? len2rng[0] : ~len2rng[0];
+ return integer_zero_node;
+ }
+
+ if (len2rng[0] == HOST_WIDE_INT_MAX
+ && len1rng[0] != HOST_WIDE_INT_MAX
+ && ((len1rng[0] < bound && len1rng[0] >= siz2)
+ || len1rng[0] > siz2))
+ {
+ *psize = siz2;
+ len[0] = nul1 ? len1rng[0] : ~len1rng[0];
+ len[1] = len2rng[0];
+ return integer_zero_node;
+ }
+
+ /* The strings are also definitely unequal when their lengths are unequal
+ and at least one is nul-terminated. */
+ if (len1rng[0] != HOST_WIDE_INT_MAX
+ && len2rng[0] != HOST_WIDE_INT_MAX
+ && ((len1rng[1] < len2rng[0] && nul1)
+ || (len2rng[1] < len1rng[0] && nul2)))
+ {
+ if (bound <= len1rng[0] || bound <= len2rng[0])
+ *psize = bound;
else
- return false;
+ *psize = HOST_WIDE_INT_M1U;
+
+ len[0] = len1rng[0];
+ len[1] = len2rng[0];
+ return integer_zero_node;
}
- /* When the lengths of the arguments are known to be unequal
- we can safely fold the call to a non-zero value for strcmp;
- otherwise, do nothing now. */
- if (idx1 != 0 && idx2 != 0)
+ /* The string lengths may be equal or unequal. Even when equal and
+ both strings nul-terminated, without the string contents there's
+ no way to determine whether they are equal. */
+ return NULL_TREE;
+}
+
+/* Diagnose pointless calls to strcmp or strncmp STMT with string
+ arguments of lengths LEN or size SIZ and (for strncmp) BOUND,
+ whose result is used in equality expressions that evaluate to
+ a constant due to one argument being longer than the size of
+ the other. */
+
+static void
+maybe_warn_pointless_strcmp (gimple *stmt, HOST_WIDE_INT bound,
+ unsigned HOST_WIDE_INT len[2],
+ unsigned HOST_WIDE_INT siz)
+{
+ tree lhs = gimple_call_lhs (stmt);
+ gimple *use = used_only_for_zero_equality (lhs);
+ if (!use)
+ return;
+
+ bool at_least = false;
+
+ /* Excessive LEN[i] indicates a lower bound. */
+ if (len[0] > HOST_WIDE_INT_MAX)
{
- if (strxcmp_unequal (idx1, idx2, length))
- {
- replace_call_with_value (gsi, integer_one_node);
- return true;
- }
- return false;
+ at_least = true;
+ len[0] = ~len[0];
}
- /* When the length of one argument is constant. */
- tree var_string = NULL_TREE;
- HOST_WIDE_INT const_string_leni = -1;
+ if (len[1] > HOST_WIDE_INT_MAX)
+ {
+ at_least = true;
+ len[1] = ~len[1];
+ }
- if (idx1)
+ unsigned HOST_WIDE_INT minlen = MIN (len[0], len[1]);
+
+ /* FIXME: Include a note pointing to the declaration of the smaller
+ array. */
+ location_t stmt_loc = gimple_nonartificial_location (stmt);
+ if (stmt_loc == UNKNOWN_LOCATION && EXPR_HAS_LOCATION (lhs))
+ stmt_loc = tree_nonartificial_location (lhs);
+ stmt_loc = expansion_point_location_if_in_system_header (stmt_loc);
+
+ tree callee = gimple_call_fndecl (stmt);
+ bool warned = false;
+ if (siz <= minlen && bound == -1)
+ warned = warning_at (stmt_loc, OPT_Wstring_compare,
+ (at_least
+ ? G_("%G%qD of a string of length %wu or more and "
+ "an array of size %wu evaluates to nonzero")
+ : G_("%G%qD of a string of length %wu and an array "
+ "of size %wu evaluates to nonzero")),
+ stmt, callee, minlen, siz);
+ else if (!at_least && siz <= HOST_WIDE_INT_MAX)
+ {
+ if (len[0] != HOST_WIDE_INT_MAX && len[1] != HOST_WIDE_INT_MAX)
+ warned = warning_at (stmt_loc, OPT_Wstring_compare,
+ "%G%qD of strings of length %wu and %wu "
+ "and bound of %wu evaluates to nonzero",
+ stmt, callee, len[0], len[1], bound);
+ else
+ warned = warning_at (stmt_loc, OPT_Wstring_compare,
+ "%G%qD of a string of length %wu, an array "
+ "of size %wu and bound of %wu evaluates to "
+ "nonzero",
+ stmt, callee, minlen, siz, bound);
+ }
+
+ if (warned)
{
- const_string_leni = compute_string_length (idx1);
- var_string = arg2;
+ location_t use_loc = gimple_location (use);
+ if (LOCATION_LINE (stmt_loc) != LOCATION_LINE (use_loc))
+ inform (use_loc, "in this expression");
}
- else
+}
+
+
+/* Optimize a call to strcmp or strncmp either by folding it to a constant
+ when possible or by transforming the latter to the former. Warn about
+ calls where the length of one argument is greater than the size of
+ the array to which the other argument points if the latter's length
+ is not known. Return true when the call has been transformed into
+ another and false otherwise. */
+
+static bool
+handle_builtin_string_cmp (gimple_stmt_iterator *gsi)
+{
+ gcall *stmt = as_a <gcall *> (gsi_stmt (*gsi));
+ tree lhs = gimple_call_lhs (stmt);
+
+ if (!lhs)
+ return false;
+
+ tree arg1 = gimple_call_arg (stmt, 0);
+ tree arg2 = gimple_call_arg (stmt, 1);
+ int idx1 = get_stridx (arg1);
+ int idx2 = get_stridx (arg2);
+
+ /* For strncmp set to the the value of the third argument if known. */
+ HOST_WIDE_INT bound = -1;
+
+ /* Extract the strncmp bound. */
+ if (gimple_call_num_args (stmt) == 3)
{
- gcc_checking_assert (idx2);
- const_string_leni = compute_string_length (idx2);
- var_string = arg1;
+ tree len = gimple_call_arg (stmt, 2);
+ if (tree_fits_shwi_p (len))
+ bound = tree_to_shwi (len);
+
+ /* If the bound argument is NOT known, do nothing. */
+ if (bound < 0)
+ return false;
}
- if (const_string_leni < 0)
+ {
+ /* Set to the length of one argument (or its complement if it's
+ the lower bound of a range) and the size of the array storing
+ the other if the result is based on the former being equal to
+ or greater than the latter. */
+ unsigned HOST_WIDE_INT len[2] = { HOST_WIDE_INT_MAX, HOST_WIDE_INT_MAX };
+ unsigned HOST_WIDE_INT siz = HOST_WIDE_INT_M1U;
+
+ /* Try to determine if the two strings are either definitely equal
+ or definitely unequal and if so, either fold the result to zero
+ (when equal) or set the range of the result to ~[0, 0] otherwise. */
+ if (tree eqz = strxcmp_eqz_result (arg1, idx1, arg2, idx2, bound,
+ len, &siz))
+ {
+ if (integer_zerop (eqz))
+ {
+ maybe_warn_pointless_strcmp (stmt, bound, len, siz);
+
+ /* When the lengths of the first two string arguments are
+ known to be unequal set the range of the result to non-zero.
+ This allows the call to be eliminated if its result is only
+ used in tests for equality to zero. */
+ wide_int zero = wi::zero (TYPE_PRECISION (TREE_TYPE (lhs)));
+ set_range_info (lhs, VR_ANTI_RANGE, zero, zero);
+ return false;
+ }
+ /* When the two strings are definitely equal (such as when they
+ are both empty) fold the call to the constant result. */
+ replace_call_with_value (gsi, integer_zero_node);
+ return true;
+ }
+ }
+
+ /* Return if nothing is known about the strings pointed to by ARG1
+ and ARG2. */
+ if (idx1 == 0 && idx2 == 0)
return false;
- unsigned HOST_WIDE_INT var_sizei = 0;
- /* try to determine the minimum size of the object pointed by var_string. */
- tree size = determine_min_objsize (var_string);
+ /* Determine either the length or the size of each of the strings,
+ whichever is available. */
+ HOST_WIDE_INT cstlen1 = -1, cstlen2 = -1;
+ HOST_WIDE_INT arysiz1 = -1, arysiz2 = -1;
- if (!size)
+ if (idx1)
+ cstlen1 = compute_string_length (idx1);
+ else
+ arysiz1 = determine_min_objsize (arg1);
+
+ /* Bail if neither the string length nor the size of the array
+ it is stored in can be determined. */
+ if (cstlen1 < 0 && arysiz1 < 0)
return false;
- if (tree_fits_uhwi_p (size))
- var_sizei = tree_to_uhwi (size);
+ /* Repeat for the second argument. */
+ if (idx2)
+ cstlen2 = compute_string_length (idx2);
+ else
+ arysiz2 = determine_min_objsize (arg2);
- if (var_sizei == 0)
+ if (cstlen2 < 0 && arysiz2 < 0)
return false;
- /* For strncmp, if length > const_string_leni , this call can be safely
- transformed to a strcmp. */
- if (is_ncmp && length > const_string_leni)
- is_ncmp = false;
+ if (cstlen1 < 0 && cstlen2 < 0)
+ return false;
+
+ if (cstlen1 >= 0)
+ ++cstlen1;
+ if (cstlen2 >= 0)
+ ++cstlen2;
- unsigned HOST_WIDE_INT final_length
- = is_ncmp ? length : const_string_leni + 1;
+ /* The exact number of characters to compare. */
+ HOST_WIDE_INT cmpsiz = bound < 0 ? cstlen1 < 0 ? cstlen2 : cstlen1 : bound;
+ /* The size of the array in which the unknown string is stored. */
+ HOST_WIDE_INT varsiz = arysiz1 < 0 ? arysiz2 : arysiz1;
- /* Replace strcmp or strncmp with the corresponding str(n)cmp_eq. */
- if (var_sizei > final_length)
+ if (cmpsiz < varsiz && used_only_for_zero_equality (lhs))
{
- tree fn
- = (is_ncmp
- ? builtin_decl_implicit (BUILT_IN_STRNCMP_EQ)
- : builtin_decl_implicit (BUILT_IN_STRCMP_EQ));
- if (!fn)
- return false;
- tree const_string_len = build_int_cst (size_type_node, final_length);
- update_gimple_call (gsi, fn, 3, arg1, arg2, const_string_len);
+ /* If the known length is less than the size of the other array
+ and the strcmp result is only used to test equality to zero,
+ transform the call to the equivalent _eq call. */
+ if (tree fn = builtin_decl_implicit (bound < 0 ? BUILT_IN_STRCMP_EQ
+ : BUILT_IN_STRNCMP_EQ))
+ {
+ tree n = build_int_cst (size_type_node, cmpsiz);
+ update_gimple_call (gsi, fn, 3, arg1, arg2, n);
+ return true;
+ }
}
- else
- return false;
- return true;
+ return false;
}
/* Handle a POINTER_PLUS_EXPR statement.
return 0;
}
-/* Determine the minimum and maximum number of leading non-zero bytes
+/* Determines the minimum and maximum number of leading non-zero bytes
in the representation of EXP and set LENRANGE[0] and LENRANGE[1]
- to each. Set LENRANGE[2] to the total number of bytes in
- the representation. Set *NULTREM if the representation contains
- a zero byte, and set *ALLNUL if all the bytes are zero. Avoid
- recursing deeper than the limits in SNLIM allow. Return true
- on success and false otherwise. */
+ to each. Sets LENRANGE[2] to the total number of bytes in
+ the representation. Sets *NULTREM if the representation contains
+ a zero byte, and sets *ALLNUL if all the bytes are zero.
+ OFFSET and NBYTES are the offset into the representation and
+ the size of the access to it determined from a MEM_REF or zero
+ for other expressions.
+ Avoid recursing deeper than the limits in SNLIM allow.
+ Returns true on success and false otherwise. */
static bool
count_nonzero_bytes (tree exp, unsigned HOST_WIDE_INT offset,
unsigned HOST_WIDE_INT nbytes,
unsigned lenrange[3], bool *nulterm,
- bool *allnul, bool *allnonnul, ssa_name_limit_t &snlim)
+ bool *allnul, bool *allnonnul, const vr_values *rvals,
+ ssa_name_limit_t &snlim)
{
int idx = get_stridx (exp);
if (idx > 0)
{
strinfo *si = get_strinfo (idx);
- /* FIXME: Handle non-constant lengths in some range. */
- if (!si || !tree_fits_shwi_p (si->nonzero_chars))
+ if (!si)
return false;
- unsigned len = tree_to_shwi (si->nonzero_chars);
- unsigned size = len + si->full_string_p;
- if (size <= offset)
- return false;
+ /* Handle both constant lengths as well non-constant lengths
+ in some range. */
+ unsigned HOST_WIDE_INT minlen, maxlen;
+ if (tree_fits_shwi_p (si->nonzero_chars))
+ minlen = maxlen = tree_to_shwi (si->nonzero_chars);
+ else if (nbytes
+ && si->nonzero_chars
+ && TREE_CODE (si->nonzero_chars) == SSA_NAME)
+ {
+ const value_range *vr
+ = CONST_CAST (class vr_values *, rvals)
+ ->get_value_range (si->nonzero_chars);
+ if (vr->kind () != VR_RANGE
+ || !range_int_cst_p (vr))
+ return false;
- len -= offset;
- size -= offset;
+ minlen = tree_to_uhwi (vr->min ());
+ maxlen = tree_to_uhwi (vr->max ());
+ }
+ else
+ return false;
- if (size < nbytes)
+ if (maxlen < offset)
return false;
- if (len < lenrange[0])
- lenrange[0] = len;
- if (lenrange[1] < len)
- lenrange[1] = len;
+ minlen = minlen < offset ? 0 : minlen - offset;
+ maxlen -= offset;
+ if (maxlen + 1 < nbytes)
+ return false;
- if (!si->full_string_p)
+ if (nbytes <= minlen)
*nulterm = false;
- /* Since only the length of the string are known and
- its contents, clear ALLNUL and ALLNONNUL purely on
- the basis of the length. */
- if (len)
- *allnul = false;
- else
+ if (nbytes < minlen)
+ {
+ minlen = nbytes;
+ if (nbytes < maxlen)
+ maxlen = nbytes;
+ }
+
+ if (minlen < lenrange[0])
+ lenrange[0] = minlen;
+ if (lenrange[1] < maxlen)
+ lenrange[1] = maxlen;
+
+ if (lenrange[2] < nbytes)
+ (lenrange[2] = nbytes);
+
+ /* Since only the length of the string are known and not its contents,
+ clear ALLNUL and ALLNONNUL purely on the basis of the length. */
+ *allnul = false;
+ if (minlen < nbytes)
*allnonnul = false;
+
return true;
}
if (TREE_CODE (exp) == SSA_NAME)
{
- /* Handle a single-character specially. */
+ /* Handle non-zero single-character stores specially. */
tree type = TREE_TYPE (exp);
if (TREE_CODE (type) == INTEGER_TYPE
&& TYPE_MODE (type) == TYPE_MODE (char_type_node)
- && TYPE_PRECISION (type) == TYPE_PRECISION (char_type_node))
+ && TYPE_PRECISION (type) == TYPE_PRECISION (char_type_node)
+ && tree_expr_nonzero_p (exp))
{
- /* Determine if the character EXP is known to be non-zero
- (even if its exact value is not known) and if so, recurse
- once to set the range, etc. */
- if (tree_expr_nonzero_p (exp))
- return count_nonzero_bytes (build_int_cst (type, 1),
- offset, nbytes, lenrange,
- nulterm, allnul, allnonnul, snlim);
- /* Don't know whether EXP is or isn't nonzero. */
- return false;
+ /* If the character EXP is known to be non-zero (even if its
+ exact value is not known) recurse once to set the range
+ for an arbitrary constant. */
+ exp = build_int_cst (type, 1);
+ return count_nonzero_bytes (exp, offset, 1, lenrange,
+ nulterm, allnul, allnonnul, rvals, snlim);
}
gimple *stmt = SSA_NAME_DEF_STMT (exp);
- if (gimple_code (stmt) != GIMPLE_PHI)
- return false;
-
- /* Avoid processing an SSA_NAME that has already been visited
- or if an SSA_NAME limit has been reached. Indicate success
- if the former and failure if the latter. */
- if (int res = snlim.next_ssa_name (exp))
- return res > 0;
-
- /* Determine the minimum and maximum from the PHI arguments. */
- unsigned int n = gimple_phi_num_args (stmt);
- for (unsigned i = 0; i != n; i++)
+ if (gimple_assign_single_p (stmt))
{
- tree def = gimple_phi_arg_def (stmt, i);
- if (!count_nonzero_bytes (def, offset, nbytes, lenrange, nulterm,
- allnul, allnonnul, snlim))
+ exp = gimple_assign_rhs1 (stmt);
+ if (TREE_CODE (exp) != MEM_REF)
return false;
+ /* Handle MEM_REF below. */
}
+ else if (gimple_code (stmt) == GIMPLE_PHI)
+ {
+ /* Avoid processing an SSA_NAME that has already been visited
+ or if an SSA_NAME limit has been reached. Indicate success
+ if the former and failure if the latter. */
+ if (int res = snlim.next_ssa_name (exp))
+ return res > 0;
+
+ /* Determine the minimum and maximum from the PHI arguments. */
+ unsigned int n = gimple_phi_num_args (stmt);
+ for (unsigned i = 0; i != n; i++)
+ {
+ tree def = gimple_phi_arg_def (stmt, i);
+ if (!count_nonzero_bytes (def, offset, nbytes, lenrange, nulterm,
+ allnul, allnonnul, rvals, snlim))
+ return false;
+ }
- return true;
+ return true;
+ }
}
if (TREE_CODE (exp) == MEM_REF)
{
+ if (nbytes)
+ return false;
+
tree arg = TREE_OPERAND (exp, 0);
tree off = TREE_OPERAND (exp, 1);
/* The size of the MEM_REF access determines the number of bytes. */
tree type = TREE_TYPE (exp);
- if (tree typesize = TYPE_SIZE_UNIT (type))
- nbytes = tree_to_uhwi (typesize);
- else
+ tree typesize = TYPE_SIZE_UNIT (type);
+ if (!typesize || !tree_fits_uhwi_p (typesize))
return false;
+ nbytes = tree_to_uhwi (typesize);
/* Handle MEM_REF = SSA_NAME types of assignments. */
return count_nonzero_bytes (arg, offset, nbytes, lenrange, nulterm,
- allnul, allnonnul, snlim);
+ allnul, allnonnul, rvals, snlim);
}
if (TREE_CODE (exp) == VAR_DECL && TREE_READONLY (exp))
prep = reinterpret_cast <char *>(buf);
/* Try to extract the representation of the constant object
or expression starting from the offset. */
- nbytes = native_encode_expr (exp, buf, sizeof buf, offset);
- if (!nbytes)
+ unsigned repsize = native_encode_expr (exp, buf, sizeof buf, offset);
+ if (repsize < nbytes)
+ {
+ /* This should only happen when REPSIZE is zero because EXP
+ doesn't denote an object with a known initializer, except
+ perhaps when the reference reads past its end. */
+ lenrange[0] = 0;
+ prep = NULL;
+ }
+ else if (!nbytes)
+ nbytes = repsize;
+ else if (nbytes < repsize)
return false;
}
+ if (!nbytes)
+ return false;
+
/* Compute the number of leading nonzero bytes in the representation
and update the minimum and maximum. */
- unsigned n = strnlen (prep, nbytes);
+ unsigned n = prep ? strnlen (prep, nbytes) : nbytes;
if (n < lenrange[0])
lenrange[0] = n;
return true;
}
-/* Same as above except with an implicit SSA_NAME limit. */
+/* Same as above except with an implicit SSA_NAME limit. RVALS is used
+ to determine ranges of dynamically computed string lengths (the results
+ of strlen). */
static bool
count_nonzero_bytes (tree exp, unsigned lenrange[3], bool *nulterm,
- bool *allnul, bool *allnonnul)
+ bool *allnul, bool *allnonnul, const vr_values *rvals)
{
/* Set to optimistic values so the caller doesn't have to worry about
initializing these and to what. On success, the function will clear
ssa_name_limit_t snlim;
return count_nonzero_bytes (exp, 0, 0, lenrange, nulterm, allnul, allnonnul,
- snlim);
+ rvals, snlim);
}
/* Handle a single or multibyte store other than by a built-in function,
'*(int*)a = 12345'). Return true when handled. */
static bool
-handle_store (gimple_stmt_iterator *gsi)
+handle_store (gimple_stmt_iterator *gsi, bool *zero_write, const vr_values *rvals)
{
int idx = -1;
strinfo *si = NULL;
si = get_strinfo (idx);
if (offset == 0)
ssaname = TREE_OPERAND (lhs, 0);
- else if (si == NULL || compare_nonzero_chars (si, offset) < 0)
- return true;
+ else if (si == NULL || compare_nonzero_chars (si, offset, rvals) < 0)
+ {
+ *zero_write = initializer_zerop (rhs);
+ return true;
+ }
}
}
else
const bool ranges_valid
= count_nonzero_bytes (rhs, lenrange, &full_string_p,
- &storing_all_zeros_p, &storing_all_nonzero_p);
+ &storing_all_zeros_p, &storing_all_nonzero_p,
+ rvals);
if (ranges_valid)
{
rhs_minlen = lenrange[0];
storing_nonzero_p = lenrange[1] > 0;
+ *zero_write = storing_all_zeros_p;
- if (tree dstsize = compute_objsize (lhs, 1))
- if (compare_tree_int (dstsize, lenrange[2]) < 0)
- {
- location_t loc = gimple_nonartificial_location (stmt);
- warning_n (loc, OPT_Wstringop_overflow_,
- lenrange[2],
- "%Gwriting %u byte into a region of size %E",
- "%Gwriting %u bytes into a region of size %E",
- stmt, lenrange[2], dstsize);
- }
+ /* Avoid issuing multiple warnings for the same LHS or statement.
+ For example, -Warray-bounds may have already been issued for
+ an out-of-bounds subscript. */
+ if (!TREE_NO_WARNING (lhs) && !gimple_no_warning_p (stmt))
+ {
+ /* Set to the declaration referenced by LHS (if known). */
+ tree decl = NULL_TREE;
+ if (tree dstsize = compute_objsize (lhs, 1, &decl))
+ if (compare_tree_int (dstsize, lenrange[2]) < 0)
+ {
+ /* Fall back on the LHS location if the statement
+ doesn't have one. */
+ location_t loc = gimple_nonartificial_location (stmt);
+ if (loc == UNKNOWN_LOCATION && EXPR_HAS_LOCATION (lhs))
+ loc = tree_nonartificial_location (lhs);
+ loc = expansion_point_location_if_in_system_header (loc);
+ if (warning_n (loc, OPT_Wstringop_overflow_,
+ lenrange[2],
+ "%Gwriting %u byte into a region of size %E",
+ "%Gwriting %u bytes into a region of size %E",
+ stmt, lenrange[2], dstsize))
+ {
+ if (decl)
+ inform (DECL_SOURCE_LOCATION (decl),
+ "destination object declared here");
+ gimple_set_no_warning (stmt, true);
+ }
+ }
+ }
}
else
{
{
/* The offset of the last stored byte. */
unsigned HOST_WIDE_INT endoff = offset + lenrange[2] - 1;
- store_before_nul[0] = compare_nonzero_chars (si, offset);
+ store_before_nul[0] = compare_nonzero_chars (si, offset, rvals);
if (endoff == offset)
store_before_nul[1] = store_before_nul[0];
else
- store_before_nul[1] = compare_nonzero_chars (si, endoff);
+ store_before_nul[1] = compare_nonzero_chars (si, endoff, rvals);
}
else
{
- store_before_nul[0] = compare_nonzero_chars (si, offset);
+ store_before_nul[0] = compare_nonzero_chars (si, offset, rvals);
store_before_nul[1] = store_before_nul[0];
gcc_assert (offset == 0 || store_before_nul[0] >= 0);
}
static bool
strlen_check_and_optimize_call (gimple_stmt_iterator *gsi,
+ bool *zero_write,
const vr_values *rvals)
{
gimple *stmt = gsi_stmt (*gsi);
handle_builtin_malloc (DECL_FUNCTION_CODE (callee), gsi);
break;
case BUILT_IN_MEMSET:
- if (handle_builtin_memset (gsi))
+ if (handle_builtin_memset (gsi, zero_write))
return false;
break;
case BUILT_IN_MEMCMP:
{
gimple *stmt = gsi_stmt (*gsi);
+ /* For statements that modify a string, set to true if the write
+ is only zeros. */
+ bool zero_write = false;
+
if (is_gimple_call (stmt))
{
- if (!strlen_check_and_optimize_call (gsi, rvals))
+ if (!strlen_check_and_optimize_call (gsi, &zero_write, rvals))
return false;
}
else if (!flag_optimize_strlen || !strlen_optimize)
}
/* Handle a single or multibyte assignment. */
- if (is_char_store && !handle_store (gsi))
+ if (is_char_store && !handle_store (gsi, &zero_write, rvals))
return false;
}
}
}
if (gimple_vdef (stmt))
- maybe_invalidate (stmt);
+ maybe_invalidate (stmt, zero_write);
return true;
}
{
strlen_optimize = !warn_only;
- gcc_assert (!strlen_to_stridx);
- if (warn_stringop_overflow || warn_stringop_truncation)
- strlen_to_stridx = new hash_map<tree, stridx_strlenloc> ();
-
- ssa_ver_to_stridx.safe_grow_cleared (num_ssa_names);
- max_stridx = 1;
-
calculate_dominance_info (CDI_DOMINATORS);
bool use_scev = optimize > 0 && flag_printf_return_value;
scev_initialize ();
}
+ gcc_assert (!strlen_to_stridx);
+ if (warn_stringop_overflow || warn_stringop_truncation)
+ strlen_to_stridx = new hash_map<tree, stridx_strlenloc> ();
+
+ /* This has to happen after initializing the loop optimizer
+ and initializing SCEV as they create new SSA_NAMEs. */
+ ssa_ver_to_stridx.safe_grow_cleared (num_ssa_names);
+ max_stridx = 1;
+
/* String length optimization is implemented as a walk of the dominator
tree and a forward walk of statements within each block. */
strlen_dom_walker walker (CDI_DOMINATORS);
projects / thirdparty / gcc.git / blobdiff