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fold-const: Fix up fold_truth_andor_1 shift handling [PR103813]

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Some time ago I've changed const_binop -> wide_int_binop, so that it punts
on shifts by negative count.  fold_truth_andor_1 doesn't check the results
of const_binop (?SHIFT_EXPR, ) though and assumes they will be always
non-NULL, which is no longer the case.

2021-12-28  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/103813
	* fold-const.c (fold_truth_andor_1): Punt of const_binop LSHIFT_EXPR
	or RSHIFT_EXPR returns NULL.  Formatting fix.

	* gcc.c-torture/compile/pr103813.c: New test.
This commit is contained in:
Jakub Jelinek 2021-12-28 17:41:24 +01:00
parent 3c5fd3616f
commit 9258ac53cf
2 changed files with 22 additions and 2 deletions
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14
gcc/fold-const.c
View file

@ -6454,15 +6454,19 @@ fold_truth_andor_1 (location_t loc, enum tree_code code, tree truth_type,
size_int (xll_bitpos));
rl_mask = const_binop (LSHIFT_EXPR, fold_convert_loc (loc, lntype, rl_mask),
size_int (xrl_bitpos));
if (ll_mask == NULL_TREE || rl_mask == NULL_TREE)
return 0;
if (l_const)
{
l_const = fold_convert_loc (loc, lntype, l_const);
l_const = unextend (l_const, ll_bitsize, ll_unsignedp, ll_and_mask);
l_const = const_binop (LSHIFT_EXPR, l_const, size_int (xll_bitpos));
if (l_const == NULL_TREE)
return 0;
if (! integer_zerop (const_binop (BIT_AND_EXPR, l_const,
fold_build1_loc (loc, BIT_NOT_EXPR,
lntype, ll_mask))))
lntype, ll_mask))))
{
warning (0, "comparison is always %d", wanted_code == NE_EXPR);
@ -6474,9 +6478,11 @@ fold_truth_andor_1 (location_t loc, enum tree_code code, tree truth_type,
r_const = fold_convert_loc (loc, lntype, r_const);
r_const = unextend (r_const, rl_bitsize, rl_unsignedp, rl_and_mask);
r_const = const_binop (LSHIFT_EXPR, r_const, size_int (xrl_bitpos));
if (r_const == NULL_TREE)
return 0;
if (! integer_zerop (const_binop (BIT_AND_EXPR, r_const,
fold_build1_loc (loc, BIT_NOT_EXPR,
lntype, rl_mask))))
lntype, rl_mask))))
{
warning (0, "comparison is always %d", wanted_code == NE_EXPR);
@ -6521,6 +6527,8 @@ fold_truth_andor_1 (location_t loc, enum tree_code code, tree truth_type,
rr_mask = const_binop (LSHIFT_EXPR, fold_convert_loc (loc,
rntype, rr_mask),
size_int (xrr_bitpos));
if (lr_mask == NULL_TREE || rr_mask == NULL_TREE)
return 0;
/* Make a mask that corresponds to both fields being compared.
Do this for both items being compared. If the operands are the
@ -6580,6 +6588,8 @@ fold_truth_andor_1 (location_t loc, enum tree_code code, tree truth_type,
size_int (MIN (xll_bitpos, xrl_bitpos)));
lr_mask = const_binop (RSHIFT_EXPR, lr_mask,
size_int (MIN (xlr_bitpos, xrr_bitpos)));
if (ll_mask == NULL_TREE || lr_mask == NULL_TREE)
return 0;
/* Convert to the smaller type before masking out unwanted bits. */
type = lntype;

10
gcc/testsuite/gcc.c-torture/compile/pr103813.c Normal file
View file

@ -0,0 +1,10 @@
/* PR middle-end/103813 */
struct A { char b; char c[0x21000000]; };
struct A d;
int
foo ()
{
return d.c[0x20000000] || d.c[1];
}