Faster implementation of Math.exp()

src/arm/simulator-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3283 matching lines @@
         dbg.Debug();
       } else {
         InstructionDecode(instr);
       }
       program_counter = get_pc();
     }
   }
 }
 
 
-int32_t Simulator::Call(byte* entry, int argument_count, ...) {
-  va_list parameters;
-  va_start(parameters, argument_count);
-  // Set up arguments
-
-  // First four arguments passed in registers.
-  ASSERT(argument_count >= 4);
-  set_register(r0, va_arg(parameters, int32_t));
-  set_register(r1, va_arg(parameters, int32_t));
-  set_register(r2, va_arg(parameters, int32_t));
-  set_register(r3, va_arg(parameters, int32_t));
-
-  // Remaining arguments passed on stack.
-  int original_stack = get_register(sp);
-  // Compute position of stack on entry to generated code.
-  int entry_stack = (original_stack - (argument_count - 4) * sizeof(int32_t));
-  if (OS::ActivationFrameAlignment() != 0) {
-    entry_stack &= -OS::ActivationFrameAlignment();
-  }
-  // Store remaining arguments on stack, from low to high memory.
-  intptr_t* stack_argument = reinterpret_cast<intptr_t*>(entry_stack);
-  for (int i = 4; i < argument_count; i++) {
-    stack_argument[i - 4] = va_arg(parameters, int32_t);
-  }
-  va_end(parameters);
-  set_register(sp, entry_stack);
-
+void Simulator::CallInternal(byte* entry) {
   // Prepare to execute the code at entry
   set_register(pc, reinterpret_cast<int32_t>(entry));
   // Put down marker for end of simulation. The simulator will stop simulation
   // when the PC reaches this value. By saving the "end simulation" value into
   // the LR the simulation stops when returning to this call point.
   set_register(lr, end_sim_pc);
 
   // Remember the values of callee-saved registers.
   // The code below assumes that r9 is not used as sb (static base) in
   // simulator code and therefore is regarded as a callee-saved register.
@@ skipping 33 matching lines @@
 
   // Restore callee-saved registers with the original value.
   set_register(r4, r4_val);
   set_register(r5, r5_val);
   set_register(r6, r6_val);
   set_register(r7, r7_val);
   set_register(r8, r8_val);
   set_register(r9, r9_val);
   set_register(r10, r10_val);
   set_register(r11, r11_val);
+}
+
+
+int32_t Simulator::Call(byte* entry, int argument_count, ...) {
+  va_list parameters;
+  va_start(parameters, argument_count);
+  // Set up arguments
+
+  // First four arguments passed in registers.
+  ASSERT(argument_count >= 4);
+  set_register(r0, va_arg(parameters, int32_t));
+  set_register(r1, va_arg(parameters, int32_t));
+  set_register(r2, va_arg(parameters, int32_t));
+  set_register(r3, va_arg(parameters, int32_t));
+
+  // Remaining arguments passed on stack.
+  int original_stack = get_register(sp);
+  // Compute position of stack on entry to generated code.
+  int entry_stack = (original_stack - (argument_count - 4) * sizeof(int32_t));
+  if (OS::ActivationFrameAlignment() != 0) {
+    entry_stack &= -OS::ActivationFrameAlignment();
+  }
+  // Store remaining arguments on stack, from low to high memory.
+  intptr_t* stack_argument = reinterpret_cast<intptr_t*>(entry_stack);
+  for (int i = 4; i < argument_count; i++) {
+    stack_argument[i - 4] = va_arg(parameters, int32_t);
+  }
+  va_end(parameters);
+  set_register(sp, entry_stack);
+
+  CallInternal(entry);
 
   // Pop stack passed arguments.
   CHECK_EQ(entry_stack, get_register(sp));
   set_register(sp, original_stack);
 
   int32_t result = get_register(r0);
   return result;
 }
 
 
+double Simulator::CallFP(byte* entry, double d0, double d1) {
+  if (use_eabi_hardfloat()) {
+    set_d_register_from_double(0, d0);
+    set_d_register_from_double(1, d1);
+  } else {
+    int buffer[2];
+    ASSERT(sizeof(buffer[0]) * 2 == sizeof(d0));
+    memcpy(buffer, &d0, sizeof(d0));
+    set_dw_register(0, buffer);
+    memcpy(buffer, &d1, sizeof(d1));
+    set_dw_register(2, buffer);
+  }
+  CallInternal(entry);
+  if (use_eabi_hardfloat()) {
+    return get_double_from_d_register(0);
+  } else {
+    return get_double_from_register_pair(0);
+  }
+}
+
+
 uintptr_t Simulator::PushAddress(uintptr_t address) {
   int new_sp = get_register(sp) - sizeof(uintptr_t);
   uintptr_t* stack_slot = reinterpret_cast<uintptr_t*>(new_sp);
   *stack_slot = address;
   set_register(sp, new_sp);
   return new_sp;
 }
 
 
 uintptr_t Simulator::PopAddress() {
   int current_sp = get_register(sp);
   uintptr_t* stack_slot = reinterpret_cast<uintptr_t*>(current_sp);
   uintptr_t address = *stack_slot;
   set_register(sp, current_sp + sizeof(uintptr_t));
   return address;
 }
 
 } }  // namespace v8::internal
 
 #endif  // USE_SIMULATOR
 
 #endif  // V8_TARGET_ARCH_ARM