[clang] [clang] constexpr built-in reduce and function. (PR #116822)

[Simon Pilgrim via cfe-commits]

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@@ -765,3 +765,11 @@ constexpr long long reduceMulLong2 = __builtin_reduce_mul((vector4long){(1LL <<
 // expected-note at -1 {{outside the range of representable values of type 'long long'}}
 static_assert(__builtin_reduce_mul((vector4uint){~0U, 1, 1, 2}) == ~0U - 1);
 static_assert(__builtin_reduce_mul((vector4ulong){~0ULL, 1, 1, 2}) == ~0ULL - 1);
+
+static_assert(__builtin_reduce_and((vector4char){}) == 0);
+static_assert(__builtin_reduce_and((vector4char){(char)0x11, (char)0x22, (char)0x44, (char)0x88}) == 0);
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RKSimon wrote:

Include some tests that give non-zero results (helps to check for sign-extensions in the comparisons)

https://github.com/llvm/llvm-project/pull/116822