On October 16, 2017 8:46:12 PM GMT+02:00, Jakub Jelinek <ja...@redhat.com>
wrote:
>Hi!
>
>The tree-cfg.c verification requires that BIT_FIELD_REF bitpos fits
>into
>uhwi, but fold-const.c happily creates BIT_FIELD_REFs with negative
>bitpos
>(on invalid source).
>
>The following patch just punts optimization instead of creating
>BIT_FIELD_REF with negative bitpos and also adds some formatting fixes.
>
>Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Richard.
>2017-10-16 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/82549
> * fold-const.c (optimize_bit_field_compare, fold_truth_andor_1):
> Formatting fixes. Instead of calling make_bit_field_ref with negative
> bitpos return 0.
>
> * gcc.c-torture/compile/pr82549.c: New test.
>
>--- gcc/fold-const.c.jj 2017-10-13 09:17:44.000000000 +0200
>+++ gcc/fold-const.c 2017-10-14 13:46:35.939329846 +0200
>@@ -4013,21 +4013,20 @@ optimize_bit_field_compare (location_t l
> size_int (nbitsize - lbitsize - lbitpos));
>
> if (! const_p)
>- /* If not comparing with constant, just rework the comparison
>- and return. */
>- return fold_build2_loc (loc, code, compare_type,
>- fold_build2_loc (loc, BIT_AND_EXPR, unsigned_type,
>- make_bit_field_ref (loc, linner, lhs,
>- unsigned_type,
>- nbitsize, nbitpos,
>- 1, lreversep),
>- mask),
>- fold_build2_loc (loc, BIT_AND_EXPR, unsigned_type,
>- make_bit_field_ref (loc, rinner, rhs,
>- unsigned_type,
>- nbitsize, nbitpos,
>- 1, rreversep),
>- mask));
>+ {
>+ if (nbitpos < 0)
>+ return 0;
>+
>+ /* If not comparing with constant, just rework the comparison
>+ and return. */
>+ tree t1 = make_bit_field_ref (loc, linner, lhs, unsigned_type,
>+ nbitsize, nbitpos, 1, lreversep);
>+ t1 = fold_build2_loc (loc, BIT_AND_EXPR, unsigned_type, t1,
>mask);
>+ tree t2 = make_bit_field_ref (loc, rinner, rhs, unsigned_type,
>+ nbitsize, nbitpos, 1, rreversep);
>+ t2 = fold_build2_loc (loc, BIT_AND_EXPR, unsigned_type, t2,
>mask);
>+ return fold_build2_loc (loc, code, compare_type, t1, t2);
>+ }
>
>/* Otherwise, we are handling the constant case. See if the constant
>is too
> big for the field. Warn and return a tree for 0 (false) if so. We do
>@@ -4058,6 +4057,9 @@ optimize_bit_field_compare (location_t l
> }
> }
>
>+ if (nbitpos < 0)
>+ return 0;
>+
> /* Single-bit compares should always be against zero. */
> if (lbitsize == 1 && ! integer_zerop (rhs))
> {
>@@ -5874,7 +5876,10 @@ fold_truth_andor_1 (location_t loc, enum
> results. */
> ll_mask = const_binop (BIT_IOR_EXPR, ll_mask, rl_mask);
> lr_mask = const_binop (BIT_IOR_EXPR, lr_mask, rr_mask);
>- if (lnbitsize == rnbitsize && xll_bitpos == xlr_bitpos)
>+ if (lnbitsize == rnbitsize
>+ && xll_bitpos == xlr_bitpos
>+ && lnbitpos >= 0
>+ && rnbitpos >= 0)
> {
> lhs = make_bit_field_ref (loc, ll_inner, ll_arg,
> lntype, lnbitsize, lnbitpos,
>@@ -5898,10 +5903,14 @@ fold_truth_andor_1 (location_t loc, enum
> Note that we still must mask the lhs/rhs expressions. Furthermore,
> the mask must be shifted to account for the shift done by
> make_bit_field_ref. */
>- if ((ll_bitsize + ll_bitpos == rl_bitpos
>- && lr_bitsize + lr_bitpos == rr_bitpos)
>- || (ll_bitpos == rl_bitpos + rl_bitsize
>- && lr_bitpos == rr_bitpos + rr_bitsize))
>+ if (((ll_bitsize + ll_bitpos == rl_bitpos
>+ && lr_bitsize + lr_bitpos == rr_bitpos)
>+ || (ll_bitpos == rl_bitpos + rl_bitsize
>+ && lr_bitpos == rr_bitpos + rr_bitsize))
>+ && ll_bitpos >= 0
>+ && rl_bitpos >= 0
>+ && lr_bitpos >= 0
>+ && rr_bitpos >= 0)
> {
> tree type;
>
>@@ -5970,6 +5979,9 @@ fold_truth_andor_1 (location_t loc, enum
> }
> }
>
>+ if (lnbitpos < 0)
>+ return 0;
>+
> /* Construct the expression we will return. First get the component
> reference we will make. Unless the mask is all ones the width of
> that field, perform the mask operation. Then compare with the
>--- gcc/testsuite/gcc.c-torture/compile/pr82549.c.jj 2017-10-14
>13:49:27.831214544 +0200
>+++ gcc/testsuite/gcc.c-torture/compile/pr82549.c 2017-10-14
>13:49:23.561267090 +0200
>@@ -0,0 +1,9 @@
>+/* PR tree-optimization/82549 */
>+
>+int a, b[1];
>+
>+int
>+main ()
>+{
>+ return !a || b[-2] || b[-2];
>+}
>
> Jakub
