The following patch fixes an old (but now manifesting in a testsuite
fail) issue with value-numbering on big-endian machines. I've
checked the VN results after the patch on aarch64 with -mbig-endian.
Bootstrap and regtest running on x86_64-unknown-linux-gnu.
I'll commit after this succeeded.
Richard.
2019-07-10 Richard Biener <rguent...@suse.de>
PR tree-optimization/91126
* tree-ssa-sccvn.c (n_walk_cb_data::push_partial_def): Adjust
native encoding offset for BYTES_BIG_ENDIAN.
(vn_reference_lookup_3): Likewise.
* gcc.dg/torture/pr91126.c: New testcase.
Index: gcc/tree-ssa-sccvn.c
===================================================================
--- gcc/tree-ssa-sccvn.c (revision 273353)
+++ gcc/tree-ssa-sccvn.c (working copy)
@@ -1832,10 +1832,19 @@ vn_walk_cb_data::push_partial_def (const
0, MIN ((HOST_WIDE_INT)sizeof (buffer), pd.size));
else
{
+ unsigned pad = 0;
+ if (BYTES_BIG_ENDIAN)
+ {
+ /* On big-endian the padding is at the 'front' so
+ just skip the initial bytes. */
+ fixed_size_mode mode = as_a <fixed_size_mode>
+ (TYPE_MODE (TREE_TYPE (pd.rhs)));
+ pad = GET_MODE_SIZE (mode) - pd.size;
+ }
len = native_encode_expr (pd.rhs,
buffer + MAX (0, pd.offset),
sizeof (buffer - MAX (0,
pd.offset)),
- MAX (0, -pd.offset));
+ MAX (0, -pd.offset) + pad);
if (len <= 0
|| len < (pd.size - MAX (0, -pd.offset)))
{
@@ -2568,9 +2577,19 @@ vn_reference_lookup_3 (ao_ref *ref, tree
tree rhs = gimple_assign_rhs1 (def_stmt);
if (TREE_CODE (rhs) == SSA_NAME)
rhs = SSA_VAL (rhs);
+ unsigned pad = 0;
+ if (BYTES_BIG_ENDIAN)
+ {
+ /* On big-endian the padding is at the 'front' so
+ just skip the initial bytes. */
+ fixed_size_mode mode
+ = as_a <fixed_size_mode> (TYPE_MODE (TREE_TYPE (rhs)));
+ pad = GET_MODE_SIZE (mode) - size2i / BITS_PER_UNIT;
+ }
len = native_encode_expr (rhs,
buffer, sizeof (buffer),
- (offseti - offset2i) / BITS_PER_UNIT);
+ ((offseti - offset2i) / BITS_PER_UNIT
+ + pad));
if (len > 0 && len * BITS_PER_UNIT >= maxsizei)
{
tree type = vr->type;
Index: gcc/testsuite/gcc.dg/torture/pr91126.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr91126.c (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr91126.c (working copy)
@@ -0,0 +1,28 @@
+/* { dg-do run } */
+
+struct S
+{
+ __INT32_TYPE__ a : 24;
+ __INT32_TYPE__ b : 8;
+} s;
+
+int
+main()
+{
+ s.a = 0xfefefe;
+ s.b = 0xfe;
+ unsigned char c;
+ c = ((unsigned char *)&s)[0];
+ if (c != 0xfe)
+ __builtin_abort ();
+ c = ((unsigned char *)&s)[1];
+ if (c != 0xfe)
+ __builtin_abort ();
+ c = ((unsigned char *)&s)[2];
+ if (c != 0xfe)
+ __builtin_abort ();
+ c = ((unsigned char *)&s)[3];
+ if (c != 0xfe)
+ __builtin_abort ();
+ return 0;
+}
