[wasm][interpreter] Remove breakpoint support

The interpreter is not used for debugging any more. Hence any breakpoint
support and related functionality is dead code.

This CL removes
- the {SetBreakpoint} and {GetBreakpoint} methods,
- the {break_pc_} field which holds the current pause position,
- the {break_flags_} field which is used to break at function entry and
  after calls,
- functions to modify {break_flags_},
- the dead {kInternalBreakpoint} and {kInvalidPc} constants (plus
  respective macros and enums),
- the {orig_start} and {orig_end} fields (code is not being modified any
  more, so we just use {start} and {end} now),
- the {PrepareStepIn} method,
- the unimplemented {SetTracing} method, and
- two tests that test breakpoints in the interpreter.

R=thibaudm@chromium.org

Bug: v8:10389
Change-Id: I52103c37516446e40d3dfa365d6b480a7c623577
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2215163
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67958}

src/wasm/wasm-interpreter.h

@@ -29,8 +29,6 @@ using sp_t = size_t;
 using pcdiff_t = int32_t;
 using spdiff_t = uint32_t;
 
-constexpr pc_t kInvalidPc = 0x80000000;
-
 struct ControlTransferEntry {
   // Distance from the instruction to the label to jump to (forward, but can be
   // negative).
@@ -132,7 +130,6 @@ class V8_EXPORT_PRIVATE WasmInterpreter {
     ExceptionHandlingResult RaiseException(Isolate*, Handle<Object> exception);
 
     // Stack inspection and modification.
-    pc_t GetBreakpointPc();
     int GetFrameCount();
     // The InterpretedFrame is only valid as long as the Thread is paused.
     FramePtr GetFrame(int index);
@@ -147,14 +144,6 @@ class V8_EXPORT_PRIVATE WasmInterpreter {
     // Returns the number of calls / function frames executed on this thread.
     uint64_t NumInterpretedCalls();
 
-    // Thread-specific breakpoints.
-    // TODO(wasm): Implement this once we support multiple threads.
-    // bool SetBreakpoint(const WasmFunction* function, int pc, bool enabled);
-    // bool GetBreakpoint(const WasmFunction* function, int pc);
-
-    void AddBreakFlags(uint8_t flags);
-    void ClearBreakFlags();
-
     // Each thread can have multiple activations, each represented by a portion
     // of the stack frames of this thread. StartActivation returns the id
     // (counting from 0 up) of the started activation.
@@ -180,19 +169,6 @@ class V8_EXPORT_PRIVATE WasmInterpreter {
   void Run();
   void Pause();
 
-  // Prepare {function} for stepping in from Javascript.
-  void PrepareStepIn(const WasmFunction* function);
-
-  // Set a breakpoint at {pc} in {function} to be {enabled}. Returns the
-  // previous state of the breakpoint at {pc}.
-  bool SetBreakpoint(const WasmFunction* function, pc_t pc, bool enabled);
-
-  // Gets the current state of the breakpoint at {function}.
-  bool GetBreakpoint(const WasmFunction* function, pc_t pc);
-
-  // Enable or disable tracing for {function}. Return the previous state.
-  bool SetTracing(const WasmFunction* function, bool enabled);
-
   //==========================================================================
   // Thread iteration and inspection.
   //==========================================================================

test/cctest/wasm/test-run-wasm-interpreter.cc

@@ -273,49 +273,6 @@ std::unique_ptr<int[]> Find(byte* code, size_t code_size, int n, ...) {
   return offsets;
 }
 
-TEST(Breakpoint_I32Add) {
-  static const int kLocalsDeclSize = 1;
-  static const int kNumBreakpoints = 3;
-  byte code[] = {WASM_I32_ADD(WASM_GET_LOCAL(0), WASM_GET_LOCAL(1))};
-  std::unique_ptr<int[]> offsets =
-      Find(code, sizeof(code), kNumBreakpoints, kExprLocalGet, kExprLocalGet,
-           kExprI32Add);
-
-  WasmRunner<int32_t, uint32_t, uint32_t> r(ExecutionTier::kInterpreter);
-
-  r.Build(code, code + arraysize(code));
-
-  WasmInterpreter* interpreter = r.interpreter();
-  WasmInterpreter::Thread* thread = interpreter->GetThread(0);
-  for (int i = 0; i < kNumBreakpoints; i++) {
-    interpreter->SetBreakpoint(r.function(), kLocalsDeclSize + offsets[i],
-                               true);
-  }
-
-  FOR_UINT32_INPUTS(a) {
-    for (uint32_t b = 11; b < 3000000000u; b += 1000000000u) {
-      thread->Reset();
-      WasmValue args[] = {WasmValue(a), WasmValue(b)};
-      thread->InitFrame(r.function(), args);
-
-      for (int i = 0; i < kNumBreakpoints; i++) {
-        thread->Run();  // run to next breakpoint
-        // Check the thread stopped at the right pc.
-        CHECK_EQ(WasmInterpreter::PAUSED, thread->state());
-        CHECK_EQ(static_cast<size_t>(kLocalsDeclSize + offsets[i]),
-                 thread->GetBreakpointPc());
-      }
-
-      thread->Run();  // run to completion
-
-      // Check the thread finished with the right value.
-      CHECK_EQ(WasmInterpreter::FINISHED, thread->state());
-      uint32_t expected = (a) + (b);
-      CHECK_EQ(expected, thread->GetReturnValue().to<uint32_t>());
-    }
-  }
-}
-
 TEST(Step_I32Mul) {
   static const int kTraceLength = 4;
   byte code[] = {WASM_I32_MUL(WASM_GET_LOCAL(0), WASM_GET_LOCAL(1))};
@@ -351,49 +308,6 @@ TEST(Step_I32Mul) {
   }
 }
 
-TEST(Breakpoint_I32And_disable) {
-  static const int kLocalsDeclSize = 1;
-  static const int kNumBreakpoints = 1;
-  byte code[] = {WASM_I32_AND(WASM_GET_LOCAL(0), WASM_GET_LOCAL(1))};
-  std::unique_ptr<int[]> offsets =
-      Find(code, sizeof(code), kNumBreakpoints, kExprI32And);
-
-  WasmRunner<int32_t, uint32_t, uint32_t> r(ExecutionTier::kInterpreter);
-
-  r.Build(code, code + arraysize(code));
-
-  WasmInterpreter* interpreter = r.interpreter();
-  WasmInterpreter::Thread* thread = interpreter->GetThread(0);
-
-  FOR_UINT32_INPUTS(a) {
-    for (uint32_t b = 11; b < 3000000000u; b += 1000000000u) {
-      // Run with and without breakpoints.
-      for (int do_break = 0; do_break < 2; do_break++) {
-        interpreter->SetBreakpoint(r.function(), kLocalsDeclSize + offsets[0],
-                                   do_break);
-        thread->Reset();
-        WasmValue args[] = {WasmValue(a), WasmValue(b)};
-        thread->InitFrame(r.function(), args);
-
-        if (do_break) {
-          thread->Run();  // run to next breakpoint
-          // Check the thread stopped at the right pc.
-          CHECK_EQ(WasmInterpreter::PAUSED, thread->state());
-          CHECK_EQ(static_cast<size_t>(kLocalsDeclSize + offsets[0]),
-                   thread->GetBreakpointPc());
-        }
-
-        thread->Run();  // run to completion
-
-        // Check the thread finished with the right value.
-        CHECK_EQ(WasmInterpreter::FINISHED, thread->state());
-        uint32_t expected = (a) & (b);
-        CHECK_EQ(expected, thread->GetReturnValue().to<uint32_t>());
-      }
-    }
-  }
-}
-
 TEST(MemoryGrow) {
   {
     WasmRunner<int32_t, uint32_t> r(ExecutionTier::kInterpreter);