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

[Jakub Jelinek via Gcc-patches]

Hi!

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.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok
for trunk?

2021-12-28  Jakub Jelinek  <ja...@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.

--- gcc/fold-const.c.jj 2021-12-02 19:41:52.606553108 +0100
+++ gcc/fold-const.c    2021-12-27 17:43:38.315971936 +0100
@@ -6454,15 +6454,19 @@ fold_truth_andor_1 (location_t loc, enum
                         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
       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
       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
                                 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;
--- gcc/testsuite/gcc.c-torture/compile/pr103813.c.jj   2021-12-27 
17:45:28.737380460 +0100
+++ gcc/testsuite/gcc.c-torture/compile/pr103813.c      2021-12-27 
17:44:45.388005245 +0100
@@ -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];
+}

        Jakub