On 11/02/2013 07:14 AM, Richard Sandiford wrote:
The wide-int conversion for the fold_ternary VEC_PERM_EXPR case
converted a mask of valid element numbers to an element count,
which is one greater. The old code set need_mask_canon if an index
was greater than the mask, but the new code sets it if an index
is greater than the element count, giving an off-by-one error.
This patch restores the mainline mask handling and uses that in
the gtu_p call instead.
Tested on powerpc64-linux-gnu and x86_64-linux-gnu. It fixes some
unwanted testsuite differences for one of the ARM targets. OK to install?
Thanks,
Richard
looks ok to me.
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c 2013-11-02 11:07:33.097149207 +0000
+++ gcc/fold-const.c 2013-11-02 11:07:38.107188425 +0000
@@ -14360,7 +14360,7 @@ fold_ternary_loc (location_t loc, enum t
case VEC_PERM_EXPR:
if (TREE_CODE (arg2) == VECTOR_CST)
{
- unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i;
+ unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i, mask;
unsigned char *sel = XALLOCAVEC (unsigned char, nelts);
bool need_mask_canon = false;
bool all_in_vec0 = true;
@@ -14368,23 +14368,22 @@ fold_ternary_loc (location_t loc, enum t
bool maybe_identity = true;
bool single_arg = (op0 == op1);
bool changed = false;
- int nelts_cnt = single_arg ? nelts : nelts * 2;
+ mask = single_arg ? (nelts - 1) : (2 * nelts - 1);
gcc_assert (nelts == VECTOR_CST_NELTS (arg2));
for (i = 0; i < nelts; i++)
{
tree val = VECTOR_CST_ELT (arg2, i);
-
if (TREE_CODE (val) != INTEGER_CST)
return NULL_TREE;
/* Make sure that the perm value is in an acceptable
range. */
wide_int t = val;
- if (wi::gtu_p (t, nelts_cnt))
+ if (wi::gtu_p (t, mask))
{
need_mask_canon = true;
- sel[i] = t.to_uhwi () & (nelts_cnt - 1);
+ sel[i] = t.to_uhwi () & mask;
}
else
sel[i] = t.to_uhwi ();
