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gcc/gcc10-pr94015.patch

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2020-03-03 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/94015
* tree-ssa-strlen.c (count_nonzero_bytes): Split portions of the
function where EXP is address of the bytes being stored rather than
the bytes themselves into count_nonzero_bytes_addr. Punt on zero
sized MEM_REF. Use VAR_P macro and handle CONST_DECL like VAR_DECLs.
Use ctor_for_folding instead of looking at DECL_INITIAL. Punt before
calling native_encode_expr if host or target doesn't have 8-bit
chars. Formatting fixes.
(count_nonzero_bytes_addr): New function.
* gcc.dg/pr94015.c: New test.
--- gcc/tree-ssa-strlen.c.jj 2020-03-03 07:57:22.324124042 +0100
+++ gcc/tree-ssa-strlen.c 2020-03-03 18:37:29.382722923 +0100
@@ -4585,6 +4585,11 @@ int ssa_name_limit_t::next_ssa_name (tre
return 0;
}
+static bool
+count_nonzero_bytes_addr (tree, unsigned HOST_WIDE_INT, unsigned HOST_WIDE_INT,
+ unsigned [3], bool *, bool *, bool *,
+ const vr_values *, ssa_name_limit_t &);
+
/* 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.
@@ -4607,102 +4612,6 @@ count_nonzero_bytes (tree exp, unsigned
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);
- if (!si)
- 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_equiv *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;
-
- minlen = tree_to_uhwi (vr->min ());
- maxlen = tree_to_uhwi (vr->max ());
- }
- else
- return false;
-
- if (maxlen < offset)
- return false;
-
- minlen = minlen < offset ? 0 : minlen - offset;
- maxlen -= offset;
- if (maxlen + 1 < nbytes)
- return false;
-
- if (!nbytes
- && TREE_CODE (si->ptr) == SSA_NAME
- && !POINTER_TYPE_P (TREE_TYPE (si->ptr)))
- {
- /* SI->PTR is an SSA_NAME with a DEF_STMT like
- _1 = MEM <unsigned int> [(char * {ref-all})s_4(D)]; */
- gimple *stmt = SSA_NAME_DEF_STMT (exp);
- if (gimple_assign_single_p (stmt)
- && gimple_assign_rhs_code (stmt) == MEM_REF)
- {
- tree rhs = gimple_assign_rhs1 (stmt);
- if (tree refsize = TYPE_SIZE_UNIT (TREE_TYPE (rhs)))
- if (tree_fits_uhwi_p (refsize))
- {
- nbytes = tree_to_uhwi (refsize);
- maxlen = nbytes;
- }
- }
-
- if (!nbytes)
- return false;
- }
-
- if (nbytes <= minlen)
- *nulterm = false;
-
- 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) == ADDR_EXPR)
- {
- /* If the size of the access hasn't been determined yet it's that
- of a pointer. */
- if (!nbytes)
- nbytes = tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (exp)));
- exp = TREE_OPERAND (exp, 0);
- }
-
if (TREE_CODE (exp) == SSA_NAME)
{
/* Handle non-zero single-character stores specially. */
@@ -4758,8 +4667,7 @@ count_nonzero_bytes (tree exp, unsigned
tree arg = TREE_OPERAND (exp, 0);
tree off = TREE_OPERAND (exp, 1);
- if (TREE_CODE (off) != INTEGER_CST
- || !tree_fits_uhwi_p (off))
+ if (TREE_CODE (off) != INTEGER_CST || !tree_fits_uhwi_p (off))
return false;
unsigned HOST_WIDE_INT wioff = tree_to_uhwi (off);
@@ -4776,15 +4684,17 @@ count_nonzero_bytes (tree exp, unsigned
if (!typesize || !tree_fits_uhwi_p (typesize))
return false;
nbytes = tree_to_uhwi (typesize);
+ if (!nbytes)
+ return false;
/* Handle MEM_REF = SSA_NAME types of assignments. */
- return count_nonzero_bytes (arg, offset, nbytes, lenrange, nulterm,
- allnul, allnonnul, rvals, snlim);
+ return count_nonzero_bytes_addr (arg, offset, nbytes, lenrange, nulterm,
+ allnul, allnonnul, rvals, snlim);
}
- if (TREE_CODE (exp) == VAR_DECL && TREE_READONLY (exp))
+ if (VAR_P (exp) || TREE_CODE (exp) == CONST_DECL)
{
- exp = DECL_INITIAL (exp);
+ exp = ctor_for_folding (exp);
if (!exp)
return false;
}
@@ -4809,6 +4719,8 @@ count_nonzero_bytes (tree exp, unsigned
unsigned char buf[256];
if (!prep)
{
+ if (CHAR_BIT != 8 || BITS_PER_UNIT != 8)
+ return false;
/* If the pointer to representation hasn't been set above
for STRING_CST point it at the buffer. */
prep = reinterpret_cast <char *>(buf);
@@ -4852,8 +4764,8 @@ count_nonzero_bytes (tree exp, unsigned
if (n)
{
/* When the initial number of non-zero bytes N is non-zero, reset
- *ALLNUL; if N is less than that the size of the representation
- also clear *ALLNONNUL. */
+ *ALLNUL; if N is less than that the size of the representation
+ also clear *ALLNONNUL. */
*allnul = false;
if (n < nbytes)
*allnonnul = false;
@@ -4879,6 +4791,120 @@ count_nonzero_bytes (tree exp, unsigned
return true;
}
+/* Like count_nonzero_bytes, but instead of counting bytes in EXP, count
+ bytes that are pointed to by EXP, which should be a pointer. */
+
+static bool
+count_nonzero_bytes_addr (tree exp, unsigned HOST_WIDE_INT offset,
+ unsigned HOST_WIDE_INT nbytes,
+ unsigned lenrange[3], bool *nulterm,
+ 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);
+ if (!si)
+ 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 (si->nonzero_chars
+ && TREE_CODE (si->nonzero_chars) == SSA_NAME)
+ {
+ vr_values *v = CONST_CAST (vr_values *, rvals);
+ const value_range_equiv *vr = v->get_value_range (si->nonzero_chars);
+ if (vr->kind () != VR_RANGE || !range_int_cst_p (vr))
+ return false;
+
+ minlen = tree_to_uhwi (vr->min ());
+ maxlen = tree_to_uhwi (vr->max ());
+ }
+ else
+ return false;
+
+ if (maxlen < offset)
+ return false;
+
+ minlen = minlen < offset ? 0 : minlen - offset;
+ maxlen -= offset;
+ if (maxlen + 1 < nbytes)
+ return false;
+
+ if (nbytes <= minlen)
+ *nulterm = false;
+
+ 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) == ADDR_EXPR)
+ return count_nonzero_bytes (TREE_OPERAND (exp, 0), offset, nbytes,
+ lenrange, nulterm, allnul, allnonnul, rvals,
+ snlim);
+
+ if (TREE_CODE (exp) == SSA_NAME)
+ {
+ gimple *stmt = SSA_NAME_DEF_STMT (exp);
+ 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_addr (def, offset, nbytes, lenrange,
+ nulterm, allnul, allnonnul, rvals,
+ snlim))
+ return false;
+ }
+
+ return true;
+ }
+ }
+
+ /* Otherwise we don't know anything. */
+ lenrange[0] = 0;
+ if (lenrange[1] < nbytes)
+ lenrange[1] = nbytes;
+ if (lenrange[2] < nbytes)
+ lenrange[2] = nbytes;
+ *nulterm = false;
+ *allnul = false;
+ *allnonnul = false;
+ return true;
+}
+
/* 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). */
--- gcc/testsuite/gcc.dg/pr94015.c.jj 2020-03-03 18:04:47.928594261 +0100
+++ gcc/testsuite/gcc.dg/pr94015.c 2020-03-03 18:04:34.345794259 +0100
@@ -0,0 +1,107 @@
+/* PR tree-optimization/94015 */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+char buf[10] = "AAAAAAAAA";
+
+__attribute__((noipa)) char *
+alloc (void)
+{
+ return buf;
+}
+
+__attribute__((noipa)) void
+f1 (void)
+{
+ char *s = alloc ();
+ *(char **)s = "1234567";
+ s[7] = '\0';
+}
+
+__attribute__((noipa)) void
+f2 (void)
+{
+ char *s = alloc ();
+ *(char **)s = "123456";
+ s[6] = '\0';
+}
+
+__attribute__((noipa)) void
+f3 (void)
+{
+ char *s = alloc ();
+ *(char **)s = "12345";
+ s[5] = '\0';
+}
+
+__attribute__((noipa)) void
+f4 (void)
+{
+ char *s = alloc ();
+ *(char **)s = "1234";
+ s[4] = '\0';
+}
+
+__attribute__((noipa)) void
+f5 (void)
+{
+ char *s = alloc ();
+ *(char **)s = "123";
+ s[3] = '\0';
+}
+
+__attribute__((noipa)) void
+f6 (void)
+{
+ char *s = alloc ();
+ *(char **)s = "12";
+ s[2] = '\0';
+}
+
+__attribute__((noipa)) void
+f7 (void)
+{
+ char *s = alloc ();
+ *(char **)s = "1";
+ s[1] = '\0';
+}
+
+__attribute__((noipa)) void
+f8 (void)
+{
+ char *s = alloc ();
+ *(char **)s = "";
+ s[0] = '\0';
+}
+
+int
+main ()
+{
+ if (sizeof (char *) > 8)
+ return 0;
+ f1 ();
+ if (buf[7] != 0)
+ __builtin_abort ();
+ f2 ();
+ if (buf[6] != 0)
+ __builtin_abort ();
+ f3 ();
+ if (buf[5] != 0)
+ __builtin_abort ();
+ f4 ();
+ if (buf[4] != 0)
+ __builtin_abort ();
+ f5 ();
+ if (buf[3] != 0)
+ __builtin_abort ();
+ f6 ();
+ if (buf[2] != 0)
+ __builtin_abort ();
+ f7 ();
+ if (buf[1] != 0)
+ __builtin_abort ();
+ f8 ();
+ if (buf[0] != 0)
+ __builtin_abort ();
+ return 0;
+}
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