[JDK-8354925] AArch64: Assertion fails isImmediateEncodable(ImmediateOp.ORR, imm64)

[graalvmbot]

Hi,

This is due to me misunderstanding what can orr v, imm do. It turns out that a vector of long and imm = 1L << 32 is not a valid combination. The solution is to change the computation from:

tmp1 = src * 2;
tmp2 = tmp1 << 32;
tmp2 = tmp2 | (1L << 32);
dst = tmp1 | tmp2

into:

tmp1 = src * 2;
tmp2 = tmp1 | ((1L << 32) | 1); // This means that we reinterpret tmp1 as a vector of int, the bit in the upper half will be shifted away
tmp2 = tmp2 << 32;
dst = tmp1 | tmp2;

Please review, thanks a lot.