u = (u & m (bits - 0)) * 5

movabsq	$72057594037927935, %rdi ## imm = 0xFFFFFFFFFFFFFF
andq	%rcx, %rdi
leaq	(%rdi,%rdi,4), %r8

u = (u & m (bits - 0)) * 10

movabsq	$72057594037927935, %rdi ## imm = 0xFFFFFFFFFFFFFF
andq	%rcx, %rdi
addq	%rdi, %rdi
leaq	(%rdi,%rdi,4), %rcx