* Modify simulator and ARM code generator to avoid swi...

src/arm/simulator-arm.cc

-// Copyright 2008 the V8 project authors. All rights reserved.
+// Copyright 2009 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
 //       with the distribution.
@@ skipping 11 matching lines @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <stdlib.h>
 
 #include "v8.h"
 
 #include "disasm.h"
+#include "assembler.h"
 #include "arm/constants-arm.h"
 #include "arm/simulator-arm.h"
 
 #if !defined(__arm__)
 
 // Only build the simulator if not compiling for real ARM hardware.
 namespace assembler {
 namespace arm {
 
 using ::v8::internal::Object;
@@ skipping 330 matching lines @@
   RedoBreakpoints();
 
 #undef COMMAND_SIZE
 #undef ARG_SIZE
 
 #undef STR
 #undef XSTR
 }
 
 
+bool Simulator::initialized_ = false;
+
+
+void Simulator::Initialize() {
+  if (initialized_) return;
+  initialized_ = true;
+  ::v8::internal::ExternalReference::set_redirector(&RedirectExternalReference);
+}
+
+
 Simulator::Simulator() {
+  ASSERT(initialized_);
   // Setup simulator support first. Some of this information is needed to
   // setup the architecture state.
   size_t stack_size = 1 * 1024*1024;  // allocate 1MB for stack
   stack_ = reinterpret_cast<char*>(malloc(stack_size));
   pc_modified_ = false;
   icount_ = 0;
   break_pc_ = NULL;
   break_instr_ = 0;
 
   // Setup architecture state.
@@ skipping 11 matching lines @@
   // some buffer below.
   registers_[sp] = reinterpret_cast<int32_t>(stack_) + stack_size - 64;
   // The lr and pc are initialized to a known bad value that will cause an
   // access violation if the simulator ever tries to execute it.
   registers_[pc] = bad_lr;
   registers_[lr] = bad_lr;
   InitializeCoverage();
 }
 
 
+// When the generated code calls an external reference we need to catch that in
+// the simulator.  The external reference will be a function compiled for the
+// host architecture.  We need to call that function instead of trying to
+// execute it with the simulator.  We do that by redirecting the external
+// reference to a swi (software-interrupt) instruction that is handled by
+// the simulator.  We write the original destination of the jump just after the

[iposva, 2009/06/08 21:48:41]

Please change the comment to say "We write the original destination of the jump
at a known offset from the swi instruction so the simulator knows what to call."
to be somewhat independent of the implementation.

+// swi instruction so the simulator knows what to call.
+class Redirection {
+ public:
+  Redirection(void* external_function, bool fp_return)
+      : external_function_(external_function),
+        swi_instruction_((AL << 28) | (0xf << 24) | call_rt_redirected),
+        fp_return_(fp_return),
+        next_(list_) {
+    list_ = this;
+  }
+
+  void* address_of_swi_instruction() {
+    return reinterpret_cast<void*>(&swi_instruction_);
+  }
+
+  void* external_function() { return external_function_; }
+  bool fp_return() { return fp_return_; }
+
+  static Redirection* Get(void* external_function, bool fp_return) {
+    Redirection* current;
+    for (current = list_; current != NULL; current = current->next_) {
+      if (current->external_function_ == external_function) return current;
+    }
+    return new Redirection(external_function, fp_return);
+  }
+
+  static Redirection* FromSwiInstruction(Instr* swi_instruction) {
+    char* addr_of_swi = reinterpret_cast<char*>(swi_instruction);
+    char* addr_of_redirection =
+        addr_of_swi - OFFSET_OF(Redirection, swi_instruction_);
+    return reinterpret_cast<Redirection*>(addr_of_redirection);
+  }
+
+ private:
+  void* external_function_;
+  uint32_t swi_instruction_;
+  bool fp_return_;
+  Redirection* next_;
+  static Redirection* list_;
+};
+
+
+Redirection* Redirection::list_ = NULL;
+
+
+void* Simulator::RedirectExternalReference(void* external_function,
+                                           bool fp_return) {
+  Redirection* redirection = Redirection::Get(external_function, fp_return);
+  return redirection->address_of_swi_instruction();
+}
+
+
 // Create one simulator per thread and keep it in thread local storage.
 static v8::internal::Thread::LocalStorageKey simulator_key =
     v8::internal::Thread::CreateThreadLocalKey();

[iposva, 2009/06/08 21:48:41]

Please move this static initializer into the Initialize() method while we are
adding the new initializing functionality.

 
+
 // Get the active Simulator for the current thread.
 Simulator* Simulator::current() {
   Simulator* sim = reinterpret_cast<Simulator*>(
       v8::internal::Thread::GetThreadLocal(simulator_key));
   if (sim == NULL) {
     // TODO(146): delete the simulator object when a thread goes away.
     sim = new Simulator();
     v8::internal::Thread::SetThreadLocal(simulator_key, sim);
   }
   return sim;
@@ skipping 485 matching lines @@
   ASSERT(end_address == ((intptr_t)address) - 4);
 }
 
 
 // Calls into the V8 runtime are based on this very simple interface.
 // Note: To be able to return two values from some calls the code in runtime.cc
 // uses the ObjectPair which is essentially two 32-bit values stuffed into a
 // 64-bit value. With the code below we assume that all runtime calls return
 // 64 bits of result. If they don't, the r1 result register contains a bogus
 // value, which is fine because it is caller-saved.
-typedef int64_t (*SimulatorRuntimeCall)(intptr_t arg0, intptr_t arg1);
+typedef int64_t (*SimulatorRuntimeCall)(int32_t arg0,
+                                        int32_t arg1,
+                                        int32_t arg2,
+                                        int32_t arg3);
+typedef double (*SimulatorRuntimeFPCall)(int32_t arg0,
+                                         int32_t arg1,
+                                         int32_t arg2,
+                                         int32_t arg3);
 
 
 // Software interrupt instructions are used by the simulator to call into the
 // C-based V8 runtime.
 void Simulator::SoftwareInterrupt(Instr* instr) {
   int swi = instr->SwiField();
   switch (swi) {
-    case call_rt_r5: {
-      SimulatorRuntimeCall target =
-          reinterpret_cast<SimulatorRuntimeCall>(get_register(r5));
-      intptr_t arg0 = get_register(r0);
-      intptr_t arg1 = get_register(r1);
-      int64_t result = target(arg0, arg1);
-      int32_t lo_res = static_cast<int32_t>(result);
-      int32_t hi_res = static_cast<int32_t>(result >> 32);
-      set_register(r0, lo_res);
-      set_register(r1, hi_res);
-      set_pc(reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
-      break;
-    }
-    case call_rt_r2: {
-      SimulatorRuntimeCall target =
-          reinterpret_cast<SimulatorRuntimeCall>(get_register(r2));
-      intptr_t arg0 = get_register(r0);
-      intptr_t arg1 = get_register(r1);
-      int64_t result = target(arg0, arg1);
-      int32_t lo_res = static_cast<int32_t>(result);
-      int32_t hi_res = static_cast<int32_t>(result >> 32);
-      set_register(r0, lo_res);
-      set_register(r1, hi_res);
-      set_pc(reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
+    case call_rt_redirected: {
+      Redirection* redirection = Redirection::FromSwiInstruction(instr);
+      int32_t arg0 = get_register(r0);
+      int32_t arg1 = get_register(r1);
+      int32_t arg2 = get_register(r2);
+      int32_t arg3 = get_register(r3);
+      // This is dodgy but it works because the C entry stubs are never moved.
+      // See comment in codegen-arm.cc and bug 1242173.
+      int32_t saved_lr = get_register(lr);
+      if (redirection->fp_return()) {
+        intptr_t external =
+            reinterpret_cast<intptr_t>(redirection->external_function());
+        SimulatorRuntimeFPCall target =
+            reinterpret_cast<SimulatorRuntimeFPCall>(external);
+        if (::v8::internal::FLAG_trace_sim) {
+          double x, y;
+          GetFpArgs(&x, &y);
+          PrintF("Call to host function at %p with args %f, %f\n",
+                 FUNCTION_ADDR(target), x, y);
+        }
+        double result = target(arg0, arg1, arg2, arg3);
+        SetFpResult(result);
+      } else {
+        intptr_t external =
+            reinterpret_cast<int32_t>(redirection->external_function());
+        SimulatorRuntimeCall target =
+            reinterpret_cast<SimulatorRuntimeCall>(external);
+        if (::v8::internal::FLAG_trace_sim) {
+          PrintF(
+              "Call to host function at %p with args %08x, %08x, %08x, %08x\n",
+              FUNCTION_ADDR(target),
+              arg0,
+              arg1,
+              arg2,
+              arg3);
+        }
+        int64_t result = target(arg0, arg1, arg2, arg3);
+        int32_t lo_res = static_cast<int32_t>(result);
+        int32_t hi_res = static_cast<int32_t>(result >> 32);
+        set_register(r0, lo_res);
+        set_register(r1, hi_res);
+        set_register(r0, result);

[iposva, 2009/06/08 21:48:41]

Isn't the second write to r0 redundant here? Strangely the compiler does not
complain that you are passing an int64_t into an int32_t parameter.

[Erik Corry, 2009/06/09 09:27:00]

Fixed.

+      }
+      set_register(lr, saved_lr);
+      set_pc(get_register(lr));
       break;
     }
     case break_point: {
       Debugger dbg(this);
       dbg.Debug();
       break;
     }
-    {
-      double x, y, z;
-    case simulator_fp_add:
-      GetFpArgs(&x, &y);
-      z = x + y;
-      SetFpResult(z);
-      TrashCallerSaveRegisters();
-      set_pc(reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
-      break;
-    case simulator_fp_sub:
-      GetFpArgs(&x, &y);
-      z = x - y;
-      SetFpResult(z);
-      TrashCallerSaveRegisters();
-      set_pc(reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
-      break;
-    case simulator_fp_mul:
-      GetFpArgs(&x, &y);
-      z = x * y;
-      SetFpResult(z);
-      TrashCallerSaveRegisters();
-      set_pc(reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
-      break;
-    }
     default: {
       UNREACHABLE();
       break;
     }
   }
 }
 
 
 // Handle execution based on instruction types.
 
@@ skipping 682 matching lines @@
   set_register(r10, r10_val);
   set_register(r11, r11_val);
 
   int result = get_register(r0);
   return reinterpret_cast<Object*>(result);
 }
 
 } }  // namespace assembler::arm
 
 #endif  // !defined(__arm__)