[v4,2/2,sim/riscv] Add support for compressed integer instructions

Message ID 20231221111337.26415-1-jaydeep.patil@imgtec.com
State New
Headers
Series sim: riscv: Compressed instruction simulation |

Checks

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

Commit Message

Jaydeep Patil Dec. 21, 2023, 11:13 a.m. UTC
  From: Jaydeep Patil <jaydeep.patil@imgtec.com>

Added support for simulation of compressed integer instruction set ("c").
Added test file sim/testsuite/riscv/c-ext.s to test compressed instructions.
The compressed instructions are available for models implementing C extension.
Such as RV32IC, RV64IC, RV32GC, RV64GC etc.
---
 sim/riscv/model_list.def        |   9 +
 sim/riscv/sim-main.c            | 336 +++++++++++++++++++++++++++++++-
 sim/testsuite/riscv/allinsn.exp |  19 ++
 sim/testsuite/riscv/c-ext.s     | 110 +++++++++++
 4 files changed, 464 insertions(+), 10 deletions(-)
 create mode 100644 sim/testsuite/riscv/c-ext.s
  

Comments

Mike Frysinger Dec. 21, 2023, 3:07 p.m. UTC | #1
On 21 Dec 2023 11:13, jaydeep.patil@imgtec.com wrote:
> --- a/sim/riscv/sim-main.c
> +++ b/sim/riscv/sim-main.c
>
> +    case INSN_CLASS_C:
> +      /* Check whether model with C extension is selected.  */
> +      if ((riscv_cpu->csr.misa & 4) != 4)

can simplify to:
	if (riscv_cpu->csr.misa & 4) 

> --- a/sim/testsuite/riscv/allinsn.exp
> +++ b/sim/testsuite/riscv/allinsn.exp
> @@ -5,10 +5,29 @@ sim_init
>  # all machines
>  set all_machs "riscv"
>  
> +# Detect model based on -dumpmachine option of the compiler
> +set result [target_compile $srcdir/lib/compilercheck.c \
> +		$objdir/compilercheck.x "preprocess" \
> +		"additional_flags=-dumpmachine"]
> +if { [string match "riscv32-*" $result] } {
> +  set model "RV32IC"
> +} {
> +  set model "RV64IC"
> +}
> +
>  foreach src [lsort [glob -nocomplain $srcdir/$subdir/*.s]] {
>      # If we're only testing specific files and this isn't one of them, skip it.
>      if ![runtest_file_p $runtests $src] {
>  	continue
>      }
> +
> +    # The c-ext.s needs a model with C extension
> +    global SIMFLAGS_FOR_TARGET
> +    set SIMFLAGS_FOR_TARGET ""
> +    set fname [file tail $src]
> +    if {$fname == "c-ext.s"} {
> +	set SIMFLAGS_FOR_TARGET "--model $model"
> +    }

tests normally declare their requirements, and the exp file processes those
rather than the exp file hardcoding things directly.

try doing:
* change allinsn.exp to do:
  set all_machs "riscv32 riscv64"
* change "mach: riscv" in all testsuite/riscv/*.s files to "mach: all"
* add to c-ext.s:
  # sim(riscv32): --model RV32IC
  # sim(riscv64): --model RV64IC

then i think you can omit the rest of this logic in riscv/allinsn.exp.

this will set us up better for being able to support & test RV32 & RV64 in
the same binary.

> --- /dev/null
> +++ b/sim/testsuite/riscv/c-ext.s
> @@ -0,0 +1,110 @@
> +# Basic load store tests.
> +# 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

instead of pushing gas arguments, use # directives at the top of the file:
# as: <assembler options>
-mike
  

Patch

diff --git a/sim/riscv/model_list.def b/sim/riscv/model_list.def
index 5efd85ab280..b83557e5539 100644
--- a/sim/riscv/model_list.def
+++ b/sim/riscv/model_list.def
@@ -3,7 +3,16 @@  M(I)
 M(IM)
 M(IMA)
 M(IA)
+M(GC)
+M(IC)
+M(IMC)
+M(IMAC)
+M(IAC)
 M(E)
 M(EM)
 M(EMA)
 M(EA)
+M(EC)
+M(EMC)
+M(EMAC)
+M(EAC)
diff --git a/sim/riscv/sim-main.c b/sim/riscv/sim-main.c
index 8a23d2aa1f9..c2eef9bc1d5 100644
--- a/sim/riscv/sim-main.c
+++ b/sim/riscv/sim-main.c
@@ -974,6 +974,320 @@  execute_a (SIM_CPU *cpu, unsigned_word iw, const struct riscv_opcode *op)
   return pc;
 }
 
+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, SIM_RISCV_RA_REGNUM, 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[SIM_RISCV_RA_REGNUM], rd_name);
+	  store_rd (cpu, SIM_RISCV_RA_REGNUM, 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[SIM_RISCV_SP_REGNUM]
+					   + 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[SIM_RISCV_SP_REGNUM] + 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[SIM_RISCV_SP_REGNUM] + (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[SIM_RISCV_SP_REGNUM] + 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[SIM_RISCV_SP_REGNUM]
+				     + 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[SIM_RISCV_SP_REGNUM] + 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 +1303,15 @@  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:
+      /* Check whether model with C extension is selected.  */
+      if ((riscv_cpu->csr.misa & 4) != 4)
+	{
+	  TRACE_INSN (cpu, "UNHANDLED EXTENSION: %d", op->insn_class);
+	  sim_engine_halt (sd, cpu, NULL, riscv_cpu->pc, sim_signalled,
+			   SIM_SIGILL);
+	}
+      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/allinsn.exp b/sim/testsuite/riscv/allinsn.exp
index 972edf4d5ec..b76c45a2366 100644
--- a/sim/testsuite/riscv/allinsn.exp
+++ b/sim/testsuite/riscv/allinsn.exp
@@ -5,10 +5,29 @@  sim_init
 # all machines
 set all_machs "riscv"
 
+# Detect model based on -dumpmachine option of the compiler
+set result [target_compile $srcdir/lib/compilercheck.c \
+		$objdir/compilercheck.x "preprocess" \
+		"additional_flags=-dumpmachine"]
+if { [string match "riscv32-*" $result] } {
+  set model "RV32IC"
+} {
+  set model "RV64IC"
+}
+
 foreach src [lsort [glob -nocomplain $srcdir/$subdir/*.s]] {
     # If we're only testing specific files and this isn't one of them, skip it.
     if ![runtest_file_p $runtests $src] {
 	continue
     }
+
+    # The c-ext.s needs a model with C extension
+    global SIMFLAGS_FOR_TARGET
+    set SIMFLAGS_FOR_TARGET ""
+    set fname [file tail $src]
+    if {$fname == "c-ext.s"} {
+	set SIMFLAGS_FOR_TARGET "--model $model"
+    }
+
     run_sim_test $src $all_machs
 }
diff --git a/sim/testsuite/riscv/c-ext.s b/sim/testsuite/riscv/c-ext.s
new file mode 100644
index 00000000000..049d2b4323e
--- /dev/null
+++ b/sim/testsuite/riscv/c-ext.s
@@ -0,0 +1,110 @@ 
+# Basic load store tests.
+# 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