match.pd: Avoid other build_nonstandard_integer_type calls [PR111369]

In the light of the PR111668 patch which shows that
build_nonstandard_integer_type is needed (at least for some signed prec > 1
BOOLEAN_TYPEs if we use e.g. negation), I've reworked this patch and handled
the last problematic build_nonstandard_integer_type call in there as well.

In the x == cstN ? cst4 : cst3 optimization it uses
build_nonstandard_integer_type solely for BOOLEAN_TYPEs (I really don't see
why ENUMERAL_TYPEs would be a problem, we treat them in GIMPLE as uselessly
convertible to same precision/sign INTEGER_TYPEs), for INTEGER_TYPEs it is
really a no-op (might return a different type, but always INTEGER_TYPE
with same TYPE_PRECISION same TYPE_UNSIGNED) and for BITINT_TYPE with larger
precisions really harmful (we shouldn't create large precision
INTEGER_TYPEs).

The a?~t:t optimization just omits the negation of a in type for 1-bit
precision types or any BOOLEAN_TYPEs.  I think that is correct, because
for both signed and unsigned 1-bit precision type, cast to type of a bool
value yields already 0, -1 or 0, 1 values and for 1-bit precision negation
of that is still 0, -1 or 0, 1 (except for invoking sometimes UB).
And for signed larger precision BOOLEAN_TYPEs I think it is correct as well,
cast of [0, 1] to type yields 0, -1 and those can be xored with 0 or -1
to yield the proper result, any other values would be UB.

This fixes PR111369, where one of the bitint*.c tests FAILs with
GCC_TEST_RUN_EXPENSIVE=1.

2023-10-04  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/111369
	* match.pd (x == cstN ? cst4 : cst3): Use
	build_nonstandard_integer_type only if type1 is BOOLEAN_TYPE.
	Fix comment typo.  Formatting fix.
	(a?~t:t -> (-(a))^t): Always convert to type rather
	than using build_nonstandard_integer_type.  Perform negation
	only if type has precision > 1 and is not signed BOOLEAN_TYPE.

diff --git a/gcc/match.pd b/gcc/match.pd
index 5cdd3ef58c5c141163868ac8e62828aa52de4f24..4bdd83e6e061b16dbdb2845b9398fcfb8a6c9739 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -5178,7 +5178,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 
 /* Optimize
    # x_5 in range [cst1, cst2] where cst2 = cst1 + 1
-   x_5 ? cstN ? cst4 : cst3
+   x_5 == cstN ? cst4 : cst3
    # op is == or != and N is 1 or 2
    to r_6 = x_5 + (min (cst3, cst4) - cst1) or
    r_6 = (min (cst3, cst4) + cst1) - x_5 depending on op, N and which
@@ -5214,7 +5214,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
         type1 = type;
        auto prec = TYPE_PRECISION (type1);
        auto unsign = TYPE_UNSIGNED (type1);
-       type1 = build_nonstandard_integer_type (prec, unsign);
+       if (TREE_CODE (type1) == BOOLEAN_TYPE)
+       type1 = build_nonstandard_integer_type (prec, unsign);
        min = wide_int::from (min, prec,
                             TYPE_SIGN (TREE_TYPE (@0)));
        wide_int a = wide_int::from (wi::to_wide (arg0), prec,
@@ -5253,14 +5254,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
       }
       (if (code == PLUS_EXPR)
        (convert (plus (convert:type1 @0) { arg; }))
-       (convert (minus { arg; } (convert:type1 @0)))
-      )
-     )
-    )
-   )
-  )
- )
-)
+       (convert (minus { arg; } (convert:type1 @0))))))))))
 #endif
 
 (simplify
@@ -6758,13 +6752,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (with { bool wascmp; }
   (if (INTEGRAL_TYPE_P (type)
        && bitwise_inverted_equal_p (@1, @2, wascmp)
-       && (!wascmp || element_precision (type) == 1))
-   (with {
-     auto prec = TYPE_PRECISION (type);
-     auto unsign = TYPE_UNSIGNED (type);
-     tree inttype = build_nonstandard_integer_type (prec, unsign);
-    }
-    (convert (bit_xor (negate (convert:inttype @0)) (convert:inttype @2)))))))
+       && (!wascmp || TYPE_PRECISION (type) == 1))
+   (if ((!TYPE_UNSIGNED (type) && TREE_CODE (type) == BOOLEAN_TYPE)
+       || TYPE_PRECISION (type) == 1)
+    (bit_xor (convert:type @0) @2)
+    (bit_xor (negate (convert:type @0)) @2)))))
 #endif
 
 /* Simplify pointer equality compares using PTA.  */