Adds branch instructions and labels to the MIPS simulator, assembler, disassembler.

runtime/vm/simulator_mips.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_MIPS)
 
 // Only build the simulator if not compiling for real MIPS hardware.
 #if !defined(HOST_ARCH_MIPS)
 
@@ skipping 972 matching lines @@
     }
     default: {
       OS::PrintErr("DecodeSpecial2: 0x%x\n", instr->InstructionBits());
       UnimplementedInstruction(instr);
       break;
     }
   }
 }
 
 
+void Simulator::DoBranch(Instr* instr, bool taken, bool likely) {
+  ASSERT(!delay_slot_);
+  int32_t imm_val = instr->SImmField() << 2;
+
+  uword next_pc;
+  if (taken) {
+    next_pc = pc_ + imm_val;
+    if (likely) {
+      ExecuteDelaySlot();
+    }
+  } else {
+    next_pc = pc_ + (2 * Instr::kInstrSize);  // Next after delay slot.
+  }
+  if (!likely) {
+    ExecuteDelaySlot();
+  }
+  pc_ = next_pc - Instr::kInstrSize;
+
+  return;
+}
+
+
+void Simulator::DecodeRegImm(Instr* instr) {
+  ASSERT(instr->OpcodeField() == REGIMM);
+  switch (instr->RegImmFnField()) {
+    case BGEZ: {
+      // Format(instr, "bgez 'rs, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      DoBranch(instr, rs_val >= 0, false);
+      break;
+    }
+    case BGEZL: {
+      // Format(instr, "bgezl 'rs, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      DoBranch(instr, rs_val >= 0, true);
+      break;
+    }
+    case BLTZ: {
+      // Format(instr, "bltz 'rs, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      DoBranch(instr, rs_val < 0, false);
+      break;
+    }
+    case BLTZL: {
+      // Format(instr, "bltzl 'rs, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      DoBranch(instr, rs_val < 0, true);
+      break;
+    }
+    default: {
+      OS::PrintErr("DecodeRegImm: 0x%x\n", instr->InstructionBits());
+      UNIMPLEMENTED();

[regis, 2013/03/22 19:51:16]

Why not UnimplementedInstruction(instr)?

[zra, 2013/03/22 20:16:01]

Ah right. Thanks. I missed this one.

+      break;
+    }
+  }
+}
+
+
 void Simulator::InstructionDecode(Instr* instr) {
   switch (instr->OpcodeField()) {
     case SPECIAL: {
       DecodeSpecial(instr);
       break;
     }
     case SPECIAL2: {
       DecodeSpecial2(instr);
       break;
     }
+    case REGIMM: {
+      DecodeRegImm(instr);
+      break;
+    }
     case ADDIU: {
       // Format(instr, "addiu 'rt, 'rs, 'imms");
       int32_t rs_val = get_register(instr->RsField());
       int32_t imm_val = instr->SImmField();
       int32_t res = rs_val + imm_val;
       // Rt is set even on overflow.
       set_register(instr->RtField(), res);
       break;
     }
     case ANDI: {
       // Format(instr, "andi 'rt, 'rs, 'immu");
       int32_t rs_val = get_register(instr->RsField());
       set_register(instr->RtField(), rs_val & instr->UImmField());
       break;
     }
+    case BEQ: {
+      // Format(instr, "beq 'rs, 'rt, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      int32_t rt_val = get_register(instr->RtField());
+      DoBranch(instr, rs_val == rt_val, false);
+      break;
+    }
+    case BEQL: {
+      // Format(instr, "beql 'rs, 'rt, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      int32_t rt_val = get_register(instr->RtField());
+      DoBranch(instr, rs_val == rt_val, true);
+      break;
+    }
+    case BGTZ: {
+      ASSERT(instr->RtField() == R0);
+      // Format(instr, "bgtz 'rs, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      DoBranch(instr, rs_val > 0, false);
+      break;
+    }
+    case BGTZL: {
+      ASSERT(instr->RtField() == R0);
+      // Format(instr, "bgtzl 'rs, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      DoBranch(instr, rs_val > 0, true);
+      break;
+    }
+    case BLEZ: {
+      ASSERT(instr->RtField() == R0);
+      // Format(instr, "blez 'rs, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      DoBranch(instr, rs_val <= 0, false);
+      break;
+    }
+    case BLEZL: {
+      ASSERT(instr->RtField() == R0);
+      // Format(instr, "blezl 'rs, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      DoBranch(instr, rs_val <= 0, true);
+      break;
+    }
+    case BNE: {
+      // Format(instr, "bne 'rs, 'rt, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      int32_t rt_val = get_register(instr->RtField());
+      DoBranch(instr, rs_val != rt_val, false);
+      break;
+    }
+    case BNEL: {
+      // Format(instr, "bnel 'rs, 'rt, 'dest");
+      int32_t rs_val = get_register(instr->RsField());
+      int32_t rt_val = get_register(instr->RtField());
+      DoBranch(instr, rs_val != rt_val, true);
+      break;
+    }
     case LB: {
       // Format(instr, "lb 'rt, 'imms('rs)");
       int32_t base_val = get_register(instr->RsField());
       int32_t imm_val = instr->SImmField();
       uword addr = base_val + imm_val;
       if (Simulator::IsIllegalAddress(addr)) {
         HandleIllegalAccess(addr, instr);
       } else {
         int32_t res = ReadB(addr);
         set_register(instr->RtField(), res);
@@ skipping 240 matching lines @@
   // Restore the SP register and return R1:R0.
   set_register(SP, sp_before_call);
   return Utils::LowHighTo64Bits(get_register(V0), get_register(V1));
 }
 
 }  // namespace dart
 
 #endif  // !defined(HOST_ARCH_MIPS)
 
 #endif  // defined TARGET_ARCH_MIPS