sccvn: Handle non-byte aligned offset or size for memset (, 123, ) [PR93945]

The following is the last spot in vn_reference_lookup_3 that didn't allow
non-byte aligned offsets or sizes.  To be precise, it did allow size that
wasn't multiple of byte size and that caused a wrong-code issue on
big-endian, as the pr93945.c testcase shows, so for GCC 9 we should add
&& multiple_p (ref->size, BITS_PER_UNIT) check instead.
For the memset with SSA_NAME middle-argument, it still requires byte-aligned
offset, as we'd otherwise need to rotate the value at runtime.

2020-02-27  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/93582
	PR tree-optimization/93945
	* tree-ssa-sccvn.c (vn_reference_lookup_3): Handle memset with
	non-zero INTEGER_CST second argument and ref->offset or ref->size
	not a multiple of BITS_PER_UNIT.

	* gcc.dg/tree-ssa/pr93582-9.c: New test.
	* gcc.c-torture/execute/pr93945.c: New test.

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9665bd11dc7a8c83cd4f2e89170cbe4f28251af3..38bfbb954742044b6862b5c96f5bd14b38621594 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2020-02-27  Jakub Jelinek  <jakub@redhat.com>
+
+       PR tree-optimization/93582
+       PR tree-optimization/93945
+       * tree-ssa-sccvn.c (vn_reference_lookup_3): Handle memset with
+       non-zero INTEGER_CST second argument and ref->offset or ref->size
+       not a multiple of BITS_PER_UNIT.
+
 2020-02-27  Jonathan Wakely  <jwakely@redhat.com>
 
        * doc/install.texi (Binaries): Update description of BullFreeware.

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 085537d977b3a75c4526d5e9694e0e36ff53a0c4..70897c5f94c58077dde50d15623a8f979dd6d1a8 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2020-02-27  Jakub Jelinek  <jakub@redhat.com>
+
+       PR tree-optimization/93582
+       PR tree-optimization/93945
+       * gcc.dg/tree-ssa/pr93582-9.c: New test.
+       * gcc.c-torture/execute/pr93945.c: New test.
+
 2020-02-26  Marek Polacek  <polacek@redhat.com>
 
        PR c++/93789 - ICE with invalid array bounds.

diff --git a/gcc/testsuite/gcc.c-torture/execute/pr93945.c b/gcc/testsuite/gcc.c-torture/execute/pr93945.c
new file mode 100644 (file)
index 0000000..99e455c
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr93945.c
@@ -0,0 +1,45 @@
+/* PR tree-optimization/93945 */
+
+union U { char a[8]; struct S { unsigned int b : 8, c : 13, d : 11; } e; } u;
+
+__attribute__((noipa)) int
+foo (void)
+{
+  __builtin_memset (&u.a, 0xf4, sizeof (u.a));
+  return u.e.c;
+}
+
+__attribute__((noipa)) int
+bar (void)
+{
+  asm volatile ("" : : "g" (&u) : "memory");
+  return u.e.c;
+}
+
+__attribute__((noipa)) int
+baz (void)
+{
+  __builtin_memset (&u.a, 0xf4, sizeof (u.a));
+  return u.e.d;
+}
+
+__attribute__((noipa)) int
+qux (void)
+{
+  asm volatile ("" : : "g" (&u) : "memory");
+  return u.e.d;
+}
+
+int
+main ()
+{
+  int a = foo ();
+  int b = bar ();
+  if (a != b)
+    __builtin_abort ();
+  a = baz ();
+  b = qux ();
+  if (a != b)
+    __builtin_abort ();
+  return 0;
+}

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr93582-9.c b/gcc/testsuite/gcc.dg/tree-ssa/pr93582-9.c
new file mode 100644 (file)
index 0000000..b6ad465
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr93582-9.c
@@ -0,0 +1,23 @@
+/* PR tree-optimization/93582 */
+/* { dg-do compile { target int32 } } */
+/* { dg-options "-O2 -fdump-tree-fre1" } */
+/* { dg-final { scan-tree-dump "return 5364;" "fre1" { target le } } } */
+/* { dg-final { scan-tree-dump "return 7838;" "fre1" { target be } } } */
+/* { dg-final { scan-tree-dump "return 1959;" "fre1" { target le } } } */
+/* { dg-final { scan-tree-dump "return 1268;" "fre1" { target be } } } */
+
+union U { char a[8]; struct S { unsigned int b : 8, c : 13, d : 11; } e; } u;
+
+__attribute__((noipa)) int
+foo (void)
+{
+  __builtin_memset (&u.a, 0xf4, sizeof (u.a));
+  return u.e.c;
+}
+
+__attribute__((noipa)) int
+baz (void)
+{
+  __builtin_memset (&u.a, 0xf4, sizeof (u.a));
+  return u.e.d;
+}

diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index a3fba2878f86a8f4dd7afe2391cc09ae97def368..0487f59f13f7768414e82274f0af3bbae4c76535 100644 (file)
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -2386,7 +2386,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
   vn_reference_t vr = data->vr;
   gimple *def_stmt = SSA_NAME_DEF_STMT (vuse);
   tree base = ao_ref_base (ref);
-  HOST_WIDE_INT offseti, maxsizei;
+  HOST_WIDE_INT offseti = 0, maxsizei, sizei = 0;
   static vec<vn_reference_op_s> lhs_ops;
   ao_ref lhs_ref;
   bool lhs_ref_ok = false;
@@ -2541,9 +2541,13 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
       && (integer_zerop (gimple_call_arg (def_stmt, 1))
          || ((TREE_CODE (gimple_call_arg (def_stmt, 1)) == INTEGER_CST
               || (INTEGRAL_TYPE_P (vr->type) && known_eq (ref->size, 8)))
-             && CHAR_BIT == 8 && BITS_PER_UNIT == 8
+             && CHAR_BIT == 8
+             && BITS_PER_UNIT == 8
+             && BYTES_BIG_ENDIAN == WORDS_BIG_ENDIAN
              && offset.is_constant (&offseti)
-             && offseti % BITS_PER_UNIT == 0))
+             && ref->size.is_constant (&sizei)
+             && (offseti % BITS_PER_UNIT == 0
+                 || TREE_CODE (gimple_call_arg (def_stmt, 1)) == INTEGER_CST)))
       && poly_int_tree_p (gimple_call_arg (def_stmt, 2))
       && (TREE_CODE (gimple_call_arg (def_stmt, 0)) == ADDR_EXPR
          || TREE_CODE (gimple_call_arg (def_stmt, 0)) == SSA_NAME))
@@ -2604,7 +2608,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
       else
        return (void *)-1;
       tree len = gimple_call_arg (def_stmt, 2);
-      HOST_WIDE_INT leni, offset2i, offseti;
+      HOST_WIDE_INT leni, offset2i;
       /* Sometimes the above trickery is smarter than alias analysis.  Take
          advantage of that.  */
       if (!ranges_maybe_overlap_p (offset, maxsize, offset2,
@@ -2618,7 +2622,9 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
          tree val;
          if (integer_zerop (gimple_call_arg (def_stmt, 1)))
            val = build_zero_cst (vr->type);
-         else if (INTEGRAL_TYPE_P (vr->type) && known_eq (ref->size, 8))
+         else if (INTEGRAL_TYPE_P (vr->type)
+                  && known_eq (ref->size, 8)
+                  && offseti % BITS_PER_UNIT == 0)
            {
              gimple_match_op res_op (gimple_match_cond::UNCOND, NOP_EXPR,
                                      vr->type, gimple_call_arg (def_stmt, 1));
@@ -2630,10 +2636,34 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
            }
          else
            {
-             unsigned buflen = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (vr->type));
+             unsigned buflen = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (vr->type)) + 1;
+             if (INTEGRAL_TYPE_P (vr->type))
+               buflen = GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (vr->type)) + 1;
              unsigned char *buf = XALLOCAVEC (unsigned char, buflen);
              memset (buf, TREE_INT_CST_LOW (gimple_call_arg (def_stmt, 1)),
                      buflen);
+             if (BYTES_BIG_ENDIAN)
+               {
+                 unsigned int amnt
+                   = (((unsigned HOST_WIDE_INT) offseti + sizei)
+                      % BITS_PER_UNIT);
+                 if (amnt)
+                   {
+                     shift_bytes_in_array_right (buf, buflen,
+                                                 BITS_PER_UNIT - amnt);
+                     buf++;
+                     buflen--;
+                   }
+               }
+             else if (offseti % BITS_PER_UNIT != 0)
+               {
+                 unsigned int amnt
+                   = BITS_PER_UNIT - ((unsigned HOST_WIDE_INT) offseti
+                                      % BITS_PER_UNIT);
+                 shift_bytes_in_array_left (buf, buflen, amnt);
+                 buf++;
+                 buflen--;
+               }
              val = native_interpret_expr (vr->type, buf, buflen);
              if (!val)
                return (void *)-1;