bpf: add selftests for lsh, rsh, arsh with reg operand

Current tests cover only shifts with an immediate as the source
operand/shift counts; add a new test case to cover register operand.
Signed-off-by: Jie Meng <jmeng@fb.com>
Link: https://lore.kernel.org/r/20221007202348.1118830-4-jmeng@fb.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/verifier/jit.c

@@ -20,6 +20,30 @@
 	.result = ACCEPT,
 	.retval = 2,
 },
+{
+	"jit: lsh, rsh, arsh by reg",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_0, 1),
+	BPF_MOV64_IMM(BPF_REG_4, 1),
+	BPF_MOV64_IMM(BPF_REG_1, 0xff),
+	BPF_ALU64_REG(BPF_LSH, BPF_REG_1, BPF_REG_0),
+	BPF_ALU32_REG(BPF_LSH, BPF_REG_1, BPF_REG_4),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0x3fc, 1),
+	BPF_EXIT_INSN(),
+	BPF_ALU64_REG(BPF_RSH, BPF_REG_1, BPF_REG_4),
+	BPF_MOV64_REG(BPF_REG_4, BPF_REG_1),
+	BPF_ALU32_REG(BPF_RSH, BPF_REG_4, BPF_REG_0),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_4, 0xff, 1),
+	BPF_EXIT_INSN(),
+	BPF_ALU64_REG(BPF_ARSH, BPF_REG_4, BPF_REG_4),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_4, 0, 1),
+	BPF_EXIT_INSN(),
+	BPF_MOV64_IMM(BPF_REG_0, 2),
+	BPF_EXIT_INSN(),
+	},
+	.result = ACCEPT,
+	.retval = 2,
+},
 {
 	"jit: mov32 for ldimm64, 1",
 	.insns = {