diff mbox series

[v3,2/3,sim/riscv] Add support for compressed integer instruction set simulation

Message ID 20231217065218.3799535-3-jaydeep.patil@imgtec.com
State New
Headers
Series sim: riscv: Compressed instruction simulation and semi-hosting support |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_gdb_build--master-arm success Testing passed
linaro-tcwg-bot/tcwg_gdb_check--master-arm success Testing passed
linaro-tcwg-bot/tcwg_gdb_build--master-aarch64 success Testing passed
linaro-tcwg-bot/tcwg_gdb_check--master-aarch64 success Testing passed

Commit Message

Jaydeep Patil Dec. 17, 2023, 6:52 a.m. UTC 
  From: Jaydeep Patil <jaydeep.patil@imgtec.com>

Added support for compressed integer instruction set ("c"). Added test file
sim/testsuite/riscv/c-ext.s to test compressed instructions.
---
 sim/riscv/sim-main.c        | 336 ++++++++++++++++++++++++++++++++++--
 sim/testsuite/riscv/c-ext.s | 110 ++++++++++++
 2 files changed, 436 insertions(+), 10 deletions(-)
 create mode 100755 sim/testsuite/riscv/c-ext.s

Comments

Mike Frysinger Dec. 18, 2023, 4:29 p.m. UTC | #1 
On 17 Dec 2023 06:52, jaydeep.patil@imgtec.com wrote:
> Added support for compressed integer instruction set ("c").

you haven't responded to feedback in previous patches.  please do that
before posting new ones, or clearly document in the patch the feedback
you've addressed as is standard git behavior.

> --- a/sim/riscv/sim-main.c
> +++ b/sim/riscv/sim-main.c
>  
> +/* Return address register.  */
> +#define REG_RA 1
> +
> +/* Stack pointer register.  */
> +#define REG_SP 2

we already have SIM_RISCV_xxx_REGNUM.  don't invent new ones.
-mike
Jaydeep Patil Dec. 19, 2023, 6:15 a.m. UTC | #2 
Mike Frysinger <vapier@gentoo.org> writes:

>you haven't responded to feedback in previous patches.  please do that before posting new ones, or clearly document in the patch the feedback you've addressed as is standard git behavior.

I have replied to your questions.

>we already have SIM_RISCV_xxx_REGNUM.  don't invent new ones

Will address this in next revision

Regards,
Jaydeep
diff mbox series

Patch

diff --git a/sim/riscv/sim-main.c b/sim/riscv/sim-main.c
index 8a23d2aa1f9..1b374323aa7 100644
--- a/sim/riscv/sim-main.c
+++ b/sim/riscv/sim-main.c
@@ -974,6 +974,327 @@  execute_a (SIM_CPU *cpu, unsigned_word iw, const struct riscv_opcode *op)
   return pc;
 }
 
+/* Register in a compressed instruction.  */
+#define C_REG(X) ((X) + 8)
+
+/* Return address register.  */
+#define REG_RA 1
+
+/* Stack pointer register.  */
+#define REG_SP 2
+
+static sim_cia
+execute_c (SIM_CPU *cpu, unsigned_word iw, const struct riscv_opcode *op)
+{
+  SIM_DESC sd = CPU_STATE (cpu);
+  struct riscv_sim_cpu *riscv_cpu = RISCV_SIM_CPU (cpu);
+  int rd = (iw >> OP_SH_RD) & OP_MASK_RD;
+  int rs1_c = ((iw >> OP_SH_CRS1S) & OP_MASK_CRS1S) + 8;
+  int rs2 = (iw >> OP_SH_CRS2) & OP_MASK_CRS2;
+  int rs2_c = ((iw >> OP_SH_CRS2S) & OP_MASK_CRS2S) + 8;
+  const char *rd_name = riscv_gpr_names_abi[rd];
+  const char *rs1_c_name = riscv_gpr_names_abi[rs1_c];
+  const char *rs2_name = riscv_gpr_names_abi[rs2];
+  const char *rs2_c_name = riscv_gpr_names_abi[rs2_c];
+  signed_word imm;
+  unsigned_word tmp;
+  sim_cia pc = riscv_cpu->pc + 2;
+
+  switch (op->match)
+    {
+    case MATCH_C_JR | MATCH_C_MV:
+      switch (op->mask)
+	{
+	case MASK_C_MV:
+	  TRACE_INSN (cpu, "c.mv %s, %s; // %s = %s",
+		      rd_name, rs2_name, rd_name, rs2_name);
+	  store_rd (cpu, rd, riscv_cpu->regs[rs2]);
+	  break;
+	case MASK_C_JR:
+	  TRACE_INSN (cpu, "c.jr %s;",
+		      rd_name);
+	  pc = riscv_cpu->regs[rd];
+	  TRACE_BRANCH (cpu, "to %#" PRIxTW, pc);
+	  break;
+	}
+      break;
+    case MATCH_C_J:
+      imm = EXTRACT_CJTYPE_IMM (iw);
+      TRACE_INSN (cpu, "c.j %" PRIxTW,
+		  imm);
+      pc = riscv_cpu->pc + imm;
+      TRACE_BRANCH (cpu, "to %#" PRIxTW, pc);
+      break;
+    case MATCH_C_JAL | MATCH_C_ADDIW:
+      /* JAL and ADDIW have the same mask, so switch based on op name.  */
+      switch (op->name[2])
+	{
+	case 'j':
+	  imm = EXTRACT_CJTYPE_IMM (iw);
+	  TRACE_INSN (cpu, "c.jal %" PRIxTW,
+		      imm);
+	  store_rd (cpu, REG_RA, riscv_cpu->pc + 2);
+	  pc = riscv_cpu->pc + imm;
+	  TRACE_BRANCH (cpu, "to %#" PRIxTW, pc);
+	  break;
+	case 'a':
+	  imm = EXTRACT_CITYPE_IMM (iw);
+	  TRACE_INSN (cpu, "c.addiw %s, %s, %#" PRIxTW ";  // %s += %#" PRIxTW,
+		      rd_name, rd_name, imm, rd_name, imm);
+	  RISCV_ASSERT_RV64 (cpu, "insn: %s", op->name);
+	  store_rd (cpu, rd, EXTEND32 (riscv_cpu->regs[rd] + imm));
+	  break;
+	default:
+	  TRACE_INSN (cpu, "UNHANDLED INSN: %s", op->name);
+	  sim_engine_halt (sd, cpu, NULL, riscv_cpu->pc, sim_signalled,
+			   SIM_SIGILL);
+	}
+      break;
+    case MATCH_C_JALR | MATCH_C_ADD | MATCH_C_EBREAK:
+      switch (op->mask)
+	{
+	case MASK_C_ADD:
+	  TRACE_INSN (cpu, "c.add %s, %s; // %s += %s",
+		      rd_name, rs2_name, rd_name, rs2_name);
+	  store_rd (cpu, rd, riscv_cpu->regs[rd] + riscv_cpu->regs[rs2]);
+	  break;
+	case MASK_C_JALR:
+	  TRACE_INSN (cpu, "c.jalr %s, %s;",
+		      riscv_gpr_names_abi[REG_RA], rd_name);
+	  store_rd (cpu, REG_RA, riscv_cpu->pc + 2);
+	  pc = riscv_cpu->regs[rd];
+	  TRACE_BRANCH (cpu, "to %#" PRIxTW, pc);
+	  break;
+	case MASK_C_EBREAK:
+	  TRACE_INSN (cpu, "ebreak");
+	  sim_engine_halt (sd, cpu, NULL, riscv_cpu->pc, sim_stopped,
+			   SIM_SIGTRAP);
+	}
+      break;
+    case MATCH_C_BEQZ:
+      imm = EXTRACT_CBTYPE_IMM (iw);
+      TRACE_INSN (cpu, "c.beqz %s, %#" PRIxTW ";  "
+		       "// if (%s == 0) goto %#" PRIxTW,
+		  rs1_c_name, imm, rs1_c_name, riscv_cpu->pc + imm);
+      if (riscv_cpu->regs[rs1_c] == riscv_cpu->regs[0])
+	{
+	  pc = riscv_cpu->pc + imm;
+	  TRACE_BRANCH (cpu, "to %#" PRIxTW, pc);
+	}
+      break;
+    case MATCH_C_BNEZ:
+      imm = EXTRACT_CBTYPE_IMM (iw);
+      TRACE_INSN (cpu, "c.bnez %s, %#" PRIxTW ";  "
+		       "// if (%s != 0) goto %#" PRIxTW,
+		  rs1_c_name, imm, rs1_c_name, riscv_cpu->pc + imm);
+      if (riscv_cpu->regs[rs1_c] != riscv_cpu->regs[0])
+	{
+	  pc = riscv_cpu->pc + imm;
+	  TRACE_BRANCH (cpu, "to %#" PRIxTW, pc);
+	}
+      break;
+    case MATCH_C_LWSP:
+      imm = EXTRACT_CITYPE_LWSP_IMM (iw);
+      TRACE_INSN (cpu, "c.lwsp %s, %" PRIiTW "(sp);",
+		  rd_name, imm);
+      store_rd (cpu, rd, EXTEND32 (
+	    sim_core_read_unaligned_4 (cpu, riscv_cpu->pc, read_map,
+				       riscv_cpu->regs[REG_SP] + imm)));
+      break;
+    case MATCH_C_LW:
+      imm = EXTRACT_CLTYPE_LW_IMM (iw);
+      TRACE_INSN (cpu, "c.lw %s, %" PRIiTW "(%s);",
+		  rs2_c_name, imm, rs1_c_name);
+      store_rd (cpu, rs2_c, EXTEND32 (
+	    sim_core_read_unaligned_4 (cpu, riscv_cpu->pc, read_map,
+				       riscv_cpu->regs[rs1_c] + imm)));
+      break;
+    case MATCH_C_SWSP:
+      imm = EXTRACT_CSSTYPE_SWSP_IMM (iw);
+      TRACE_INSN (cpu, "c.swsp %s, %" PRIiTW "(sp);",
+		  rs2_name, imm);
+      sim_core_write_unaligned_4 (cpu, riscv_cpu->pc, write_map,
+				  riscv_cpu->regs[REG_SP] + imm,
+				  riscv_cpu->regs[rs2]);
+      break;
+    case MATCH_C_SW:
+      imm = EXTRACT_CLTYPE_LW_IMM (iw);
+      TRACE_INSN (cpu, "c.sw %s, %" PRIiTW "(%s);",
+		  rs2_c_name, imm, rs1_c_name);
+      sim_core_write_unaligned_4 (cpu, riscv_cpu->pc, write_map,
+				  riscv_cpu->regs[rs1_c] + (imm),
+				  riscv_cpu->regs[rs2_c]);
+      break;
+    case MATCH_C_ADDI:
+      imm = EXTRACT_CITYPE_IMM (iw);
+      TRACE_INSN (cpu, "c.addi %s, %s, %#" PRIxTW ";  // %s += %#" PRIxTW,
+		  rd_name, rd_name, imm, rd_name, imm);
+      store_rd (cpu, rd, riscv_cpu->regs[rd] + imm);
+      break;
+    case MATCH_C_LUI:
+      imm = EXTRACT_CITYPE_LUI_IMM (iw);
+      TRACE_INSN (cpu, "c.lui %s, %#" PRIxTW ";",
+		  rd_name, imm);
+      store_rd (cpu, rd, imm);
+      break;
+    case MATCH_C_LI:
+      imm = EXTRACT_CITYPE_IMM (iw);
+      TRACE_INSN (cpu, "c.li %s, %#" PRIxTW ";  // %s = %#" PRIxTW,
+		  rd_name, imm, rd_name, imm);
+      store_rd (cpu, rd, imm);
+      break;
+    case MATCH_C_ADDI4SPN:
+      imm = EXTRACT_CIWTYPE_ADDI4SPN_IMM (iw);
+      TRACE_INSN (cpu, "c.addi4spn %s, %" PRIiTW "; // %s = sp + %" PRIiTW,
+		  rs2_c_name, imm, rs2_c_name, imm);
+      store_rd (cpu, rs2_c, riscv_cpu->regs[REG_SP] + (imm));
+      break;
+    case MATCH_C_ADDI16SP:
+      imm = EXTRACT_CITYPE_ADDI16SP_IMM (iw);
+      TRACE_INSN (cpu, "c.addi16sp %s, %" PRIiTW "; // %s = sp + %" PRIiTW,
+		  rd_name, imm, rd_name, imm);
+      store_rd (cpu, rd, riscv_cpu->regs[REG_SP] + imm);
+      break;
+    case MATCH_C_SUB:
+      TRACE_INSN (cpu, "c.sub %s, %s;  // %s = %s - %s",
+		  rs1_c_name, rs2_c_name, rs1_c_name, rs1_c_name, rs2_c_name);
+      store_rd (cpu, rs1_c, riscv_cpu->regs[rs1_c] - riscv_cpu->regs[rs2_c]);
+      break;
+    case MATCH_C_AND:
+      TRACE_INSN (cpu, "c.and %s, %s;  // %s = %s & %s",
+		  rs1_c_name, rs2_c_name, rs1_c_name, rs1_c_name, rs2_c_name);
+      store_rd (cpu, rs1_c, riscv_cpu->regs[rs1_c] & riscv_cpu->regs[rs2_c]);
+      break;
+    case MATCH_C_OR:
+      TRACE_INSN (cpu, "c.or %s, %s;  // %s = %s | %s",
+		  rs1_c_name, rs2_c_name, rs1_c_name, rs1_c_name, rs2_c_name);
+      store_rd (cpu, rs1_c, riscv_cpu->regs[rs1_c] | riscv_cpu->regs[rs2_c]);
+      break;
+    case MATCH_C_XOR:
+      TRACE_INSN (cpu, "c.xor %s, %s;  // %s = %s ^ %s",
+		  rs1_c_name, rs2_c_name, rs1_c_name, rs1_c_name, rs2_c_name);
+      store_rd (cpu, rs1_c, riscv_cpu->regs[rs1_c] ^ riscv_cpu->regs[rs2_c]);
+      break;
+    case MATCH_C_SLLI | MATCH_C_SLLI64:
+      if (op->mask == MASK_C_SLLI64)
+	{
+	  /* Reserved for custom use.  */
+	  TRACE_INSN (cpu, "UNHANDLED INSN: %s", op->name);
+	  sim_engine_halt (sd, cpu, NULL, riscv_cpu->pc, sim_signalled,
+			   SIM_SIGILL);
+	  break;
+	}
+      imm = EXTRACT_CITYPE_IMM (iw);
+      TRACE_INSN (cpu, "c.slli %s, %" PRIiTW ";  // %s = %s << %#" PRIxTW,
+		  rd_name, imm, rd_name, rd_name, imm);
+      store_rd (cpu, rd, riscv_cpu->regs[rd] << imm);
+      break;
+    case MATCH_C_SRLI | MATCH_C_SRLI64:
+      if (op->mask == MASK_C_SRLI64)
+	{
+	  /* Reserved for custom use.  */
+	  TRACE_INSN (cpu, "UNHANDLED INSN: %s", op->name);
+	  sim_engine_halt (sd, cpu, NULL, riscv_cpu->pc, sim_signalled,
+			   SIM_SIGILL);
+	  break;
+	}
+      imm = EXTRACT_CITYPE_IMM (iw);
+      TRACE_INSN (cpu, "c.srli %s, %" PRIiTW ";  // %s = %s >> %#" PRIxTW,
+		  rs1_c_name, imm, rs1_c_name, rs1_c_name, imm);
+      if (RISCV_XLEN (cpu) == 32)
+	store_rd (cpu, rs1_c,
+		  EXTEND32 ((uint32_t) riscv_cpu->regs[rs1_c] >> imm));
+      else
+	store_rd (cpu, rs1_c, riscv_cpu->regs[rs1_c] >> imm);
+      break;
+    case MATCH_C_SRAI | MATCH_C_SRAI64:
+      if (op->mask == MASK_C_SRAI64)
+	{
+	  /* Reserved for custom use.  */
+	  TRACE_INSN (cpu, "UNHANDLED INSN: %s", op->name);
+	  sim_engine_halt (sd, cpu, NULL, riscv_cpu->pc, sim_signalled,
+			   SIM_SIGILL);
+	  break;
+	}
+      imm = EXTRACT_CITYPE_IMM (iw);
+      TRACE_INSN (cpu, "c.srai %s, %" PRIiTW ";  // %s = %s >> %#" PRIxTW,
+		  rs1_c_name, imm, rs1_c_name, rs1_c_name, imm);
+      if (RISCV_XLEN (cpu) == 32)
+	{
+	  if (imm > 0x1f)
+	    sim_engine_halt (sd, cpu, NULL, riscv_cpu->pc, sim_signalled,
+			     SIM_SIGILL);
+	  tmp = ashiftrt (riscv_cpu->regs[rs1_c], imm);
+	}
+      else
+	tmp = ashiftrt64 (riscv_cpu->regs[rs1_c], imm);
+      store_rd (cpu, rd, tmp);
+      break;
+    case MATCH_C_ANDI:
+      imm = EXTRACT_CITYPE_IMM (iw);
+      TRACE_INSN (cpu, "c.andi %s, %" PRIiTW ";  // %s = %s & %#" PRIxTW,
+		  rs1_c_name, imm, rs1_c_name, rs1_c_name, imm);
+      store_rd (cpu, rs1_c, riscv_cpu->regs[rs1_c] & imm);
+      break;
+    case MATCH_C_ADDW:
+      TRACE_INSN (cpu, "c.addw %s, %s;  // %s = %s + %s",
+		  rs1_c_name, rs2_c_name, rs1_c_name, rs1_c_name, rs2_c_name);
+      RISCV_ASSERT_RV64 (cpu, "insn: %s", op->name);
+      store_rd (cpu, rs1_c,
+		EXTEND32 (riscv_cpu->regs[rs1_c] + riscv_cpu->regs[rs2_c]));
+      break;
+    case MATCH_C_SUBW:
+      TRACE_INSN (cpu, "c.subw %s, %s;  // %s = %s - %s",
+		  rs1_c_name, rs2_c_name, rs1_c_name, rs1_c_name, rs2_c_name);
+      RISCV_ASSERT_RV64 (cpu, "insn: %s", op->name);
+      store_rd (cpu, rs1_c,
+		EXTEND32 (riscv_cpu->regs[rs1_c] - riscv_cpu->regs[rs2_c]));
+      break;
+    case MATCH_C_LDSP:
+      imm = EXTRACT_CITYPE_LDSP_IMM (iw);
+      TRACE_INSN (cpu, "c.ldsp %s, %" PRIiTW "(sp);",
+		  rd_name, imm);
+      RISCV_ASSERT_RV64 (cpu, "insn: %s", op->name);
+      store_rd (cpu, rd,
+	  sim_core_read_unaligned_8 (cpu, riscv_cpu->pc, read_map,
+				     riscv_cpu->regs[REG_SP] + imm));
+      break;
+    case MATCH_C_LD:
+      imm = EXTRACT_CLTYPE_LD_IMM (iw);
+      TRACE_INSN (cpu, "c.ld %s, %" PRIiTW "(%s);",
+		  rs1_c_name, imm, rs2_c_name);
+      RISCV_ASSERT_RV64 (cpu, "insn: %s", op->name);
+      store_rd (cpu, rs2_c,
+	  sim_core_read_unaligned_8 (cpu, riscv_cpu->pc, read_map,
+				     riscv_cpu->regs[rs1_c] + imm));
+      break;
+    case MATCH_C_SDSP:
+      imm = EXTRACT_CSSTYPE_SDSP_IMM (iw);
+      TRACE_INSN (cpu, "c.sdsp %s, %" PRIiTW "(sp);",
+		  rs2_name, imm);
+      RISCV_ASSERT_RV64 (cpu, "insn: %s", op->name);
+      sim_core_write_unaligned_8 (cpu, riscv_cpu->pc, write_map,
+				  riscv_cpu->regs[REG_SP] + imm,
+				  riscv_cpu->regs[rs2]);
+      break;
+    case MATCH_C_SD:
+      imm = EXTRACT_CLTYPE_LD_IMM (iw);
+      TRACE_INSN (cpu, "c.sd %s, %" PRIiTW "(%s);",
+		  rs2_c_name, imm, rs1_c_name);
+      RISCV_ASSERT_RV64 (cpu, "insn: %s", op->name);
+      sim_core_write_unaligned_8 (cpu, riscv_cpu->pc, write_map,
+				  riscv_cpu->regs[rs1_c] + imm,
+				  riscv_cpu->regs[rs2_c]);
+      break;
+    default:
+      TRACE_INSN (cpu, "UNHANDLED INSN: %s", op->name);
+      sim_engine_halt (sd, cpu, NULL, riscv_cpu->pc, sim_signalled,
+		       SIM_SIGILL);
+  }
+
+  return pc;
+}
+
 static sim_cia
 execute_one (SIM_CPU *cpu, unsigned_word iw, const struct riscv_opcode *op)
 {
@@ -989,6 +1310,8 @@  execute_one (SIM_CPU *cpu, unsigned_word iw, const struct riscv_opcode *op)
     {
     case INSN_CLASS_A:
       return execute_a (cpu, iw, op);
+    case INSN_CLASS_C:
+      return execute_c (cpu, iw, op);
     case INSN_CLASS_I:
       return execute_i (cpu, iw, op);
     case INSN_CLASS_M:
@@ -1019,17 +1342,10 @@  void step_once (SIM_CPU *cpu)
 
   iw = sim_core_read_aligned_2 (cpu, pc, exec_map, pc);
 
-  /* Reject non-32-bit opcodes first.  */
   len = riscv_insn_length (iw);
-  if (len != 4)
-    {
-      sim_io_printf (sd, "sim: bad insn len %#x @ %#" PRIxTA ": %#" PRIxTW "\n",
-		     len, pc, iw);
-      sim_engine_halt (sd, cpu, NULL, pc, sim_signalled, SIM_SIGILL);
-    }
-
-  iw |= ((unsigned_word) sim_core_read_aligned_2 (
-    cpu, pc, exec_map, pc + 2) << 16);
+  if (len == 4)
+    iw |= ((unsigned_word) sim_core_read_aligned_2
+	   (cpu, pc, exec_map, pc + 2) << 16);
 
   TRACE_CORE (cpu, "0x%08" PRIxTW, iw);
 
diff --git a/sim/testsuite/riscv/c-ext.s b/sim/testsuite/riscv/c-ext.s
new file mode 100755
index 00000000000..5bba2058d8e
--- /dev/null
+++ b/sim/testsuite/riscv/c-ext.s
@@ -0,0 +1,110 @@ 
+# Check that the compressed instructions ("c") run without any faults.
+# mach: riscv
+
+.include "testutils.inc"
+
+	.data
+	.align 4
+_data:
+	.word	1234
+	.word	0
+
+	start
+	la	a0, _data
+
+	# Test load-store instructions.
+	.option push
+	.option	arch, +c
+	c.lw	a1,0(a0)
+	c.sw	a1,4(a0)
+	c.lw	a2,4(a0)
+	.option pop
+
+	li	a5,1234
+	bne	a1,a5,test_fail
+	bne	a2,a5,test_fail
+
+	# Test basic arithmetic.
+	.option push
+	.option	arch, +c
+	c.li	a0,0
+	c.li	a1,1
+	c.addi	a0,1
+	c.addi	a0,-1
+	c.addw	a0,a1
+	c.subw	a0,a1
+	.option pop
+
+	li	a5,1
+	bne	a0,x0,test_fail
+	bne	a1,a5,test_fail
+
+	# Test logical operations.
+	.option push
+	.option	arch, +c
+	c.li	a0,7
+	c.li	a1,7
+	c.li	a2,4
+	c.li	a3,3
+	c.li	a4,3
+	c.andi	a0,3
+	c.and	a1,a0
+	c.or	a2,a3
+	c.xor	a4,a4
+	.option pop
+
+	li	a5,3
+	bne	a0,a5,test_fail
+	bne	a1,a5,test_fail
+	bne	a4,x0,test_fail
+	li	a5,7
+	bne	a2,a5,test_fail
+
+	# Test shift operations.
+	.option push
+	.option	arch, +c
+	c.li	a0,4
+	c.li	a1,4
+	c.slli	a0,1
+	c.srli	a1,1
+	.option pop
+
+	li	a5,8
+	bne	a0,a5,test_fail
+	li	a5,2
+	bne	a1,a5,test_fail
+
+	# Test jump instruction.
+	.option push
+	.option	arch, +c
+	c.j	1f
+	.option pop
+
+	j	test_fail
+1:
+	la	a0,2f
+
+	# Test jump register instruction.
+	.option push
+	.option	arch, +c
+	c.jr	a0
+	.option pop
+
+	j	test_fail
+
+2:
+	# Test branch instruction.
+	.option push
+	.option	arch, +c
+	c.li	a0,1
+	c.beqz	a0,test_fail
+	c.li	a0,0
+	c.bnez	a0,test_fail
+	.option pop
+
+test_pass:
+	pass
+	fail
+
+test_fail:
+	fail