If fold_truth_andor_for_ifcombine applies a mask to an xor, say
because the result of the xor is compared with a power of two [minus
one], we have to apply the same mask when processing both the left-
and right-hand xor paths for the transformation to be sound. Arrange
for decode_field_reference to propagate the incoming mask along with
the expression to the right-hand operand.
Don't require the right-hand xor operand to be a constant, that was a
cut&pasto.
Regstrapped on x86_64-linux-gnu. Ok to install?
for gcc/ChangeLog
* gimple-fold.cc (decode_field_reference): Add xor_pand_mask.
Propagate pand_mask to the right-hand xor operand. Don't
require the right-hand xor operand to be a constant.
(fold_truth_andor_for_ifcombine): Pass right-hand mask when
appropriate.
---
gcc/gimple-fold.cc | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)
diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index d95f04213ee40..0ad92de3a218f 100644
--- a/gcc/gimple-fold.cc
+++ b/gcc/gimple-fold.cc
@@ -7519,8 +7519,9 @@ gimple_binop_def_p (enum tree_code code, tree t, tree
op[2])
*XOR_P is to be FALSE if EXP might be a XOR used in a compare, in which
case, if XOR_CMP_OP is a zero constant, it will be overridden with *PEXP,
- *XOR_P will be set to TRUE, and the left-hand operand of the XOR will be
- decoded. If *XOR_P is TRUE, XOR_CMP_OP is supposed to be NULL, and then the
+ *XOR_P will be set to TRUE, *XOR_PAND_MASK will be copied from *PAND_MASK,
+ and the left-hand operand of the XOR will be decoded. If *XOR_P is TRUE,
+ XOR_CMP_OP and XOR_PAND_MASK are supposed to be NULL, and then the
right-hand operand of the XOR will be decoded.
*LOAD is set to the load stmt of the innermost reference, if any,
@@ -7537,7 +7538,7 @@ decode_field_reference (tree *pexp, HOST_WIDE_INT
*pbitsize,
HOST_WIDE_INT *pbitpos,
bool *punsignedp, bool *preversep, bool *pvolatilep,
wide_int *pand_mask, bool *psignbit,
- bool *xor_p, tree *xor_cmp_op,
+ bool *xor_p, tree *xor_cmp_op, wide_int *xor_pand_mask,
gimple **load, location_t loc[4])
{
tree exp = *pexp;
@@ -7599,15 +7600,14 @@ decode_field_reference (tree *pexp, HOST_WIDE_INT
*pbitsize,
and_mask = *pand_mask;
/* Turn (a ^ b) [!]= 0 into a [!]= b. */
- if (xor_p && gimple_binop_def_p (BIT_XOR_EXPR, exp, res_ops)
- && uniform_integer_cst_p (res_ops[1]))
+ if (xor_p && gimple_binop_def_p (BIT_XOR_EXPR, exp, res_ops))
{
/* No location recorded for this one, it's entirely subsumed by the
compare. */
if (*xor_p)
{
exp = res_ops[1];
- gcc_checking_assert (!xor_cmp_op);
+ gcc_checking_assert (!xor_cmp_op && !xor_pand_mask);
}
else if (!xor_cmp_op)
/* Not much we can do when xor appears in the right-hand compare
@@ -7618,6 +7618,7 @@ decode_field_reference (tree *pexp, HOST_WIDE_INT
*pbitsize,
*xor_p = true;
exp = res_ops[0];
*xor_cmp_op = *pexp;
+ *xor_pand_mask = *pand_mask;
}
}
@@ -8152,19 +8153,21 @@ fold_truth_andor_for_ifcombine (enum tree_code code,
tree truth_type,
bool l_xor = false, r_xor = false;
ll_inner = decode_field_reference (&ll_arg, &ll_bitsize, &ll_bitpos,
&ll_unsignedp, &ll_reversep, &volatilep,
- &ll_and_mask, &ll_signbit, &l_xor, &lr_arg,
+ &ll_and_mask, &ll_signbit,
+ &l_xor, &lr_arg, &lr_and_mask,
&ll_load, ll_loc);
lr_inner = decode_field_reference (&lr_arg, &lr_bitsize, &lr_bitpos,
&lr_unsignedp, &lr_reversep, &volatilep,
- &lr_and_mask, &lr_signbit, &l_xor, 0,
+ &lr_and_mask, &lr_signbit, &l_xor, 0, 0,
&lr_load, lr_loc);
rl_inner = decode_field_reference (&rl_arg, &rl_bitsize, &rl_bitpos,
&rl_unsignedp, &rl_reversep, &volatilep,
- &rl_and_mask, &rl_signbit, &r_xor, &rr_arg,
+ &rl_and_mask, &rl_signbit,
+ &r_xor, &rr_arg, &rr_and_mask,
&rl_load, rl_loc);
rr_inner = decode_field_reference (&rr_arg, &rr_bitsize, &rr_bitpos,
&rr_unsignedp, &rr_reversep, &volatilep,
- &rr_and_mask, &rr_signbit, &r_xor, 0,
+ &rr_and_mask, &rr_signbit, &r_xor, 0, 0,
&rr_load, rr_loc);
/* It must be true that the inner operation on the lhs of each
--
Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/
Free Software Activist GNU Toolchain Engineer
More tolerance and less prejudice are key for inclusion and diversity
Excluding neuro-others for not behaving ""normal"" is *not* inclusive
