[wasm] Add interface callback before each instruction

In Liftoff, we want to trace the cache state basically before or after
processing each instruction. Instead of duplicating this code
everywhere, introduce a new interface method {NextInstruction}, which
is called before each instruction.

R=titzer@chromium.org

Bug: v8:6600
Change-Id: Iea61738d200076690a8440a75a2fd90018efa43b
Reviewed-on: https://chromium-review.googlesource.com/852457
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50447}

src/wasm/baseline/liftoff-compiler.cc

@@ -347,13 +347,15 @@ class LiftoffCompiler {
     BindUnboundLabels(decoder);
   }
 
-  void Block(Decoder* decoder, Control* block) {
+  void NextInstruction(Decoder* decoder, WasmOpcode) {
     TraceCacheState(decoder);
+  }
+
+  void Block(Decoder* decoder, Control* block) {
     block->label_state.stack_base = __ cache_state()->stack_height();
   }
 
   void Loop(Decoder* decoder, Control* loop) {
-    TraceCacheState(decoder);
     loop->label_state.stack_base = __ cache_state()->stack_height();
 
     // Before entering a loop, spill all locals to the stack, in order to free
@@ -396,7 +398,6 @@ class LiftoffCompiler {
   }
 
   void FallThruTo(Decoder* decoder, Control* c) {
-    TraceCacheState(decoder);
     if (c->end_merge.reached) {
       __ MergeFullStackWith(c->label_state);
     } else if (c->is_onearmed_if()) {
@@ -406,6 +407,7 @@ class LiftoffCompiler {
     } else {
       c->label_state.Split(*__ cache_state());
     }
+    TraceCacheState(decoder);
   }
 
   void PopControl(Decoder* decoder, Control* c) {
@@ -431,7 +433,6 @@ class LiftoffCompiler {
 
   void UnOp(Decoder* decoder, WasmOpcode opcode, FunctionSig*,
             const Value& value, Value* result) {
-    TraceCacheState(decoder);
 #define CASE_UNOP(opcode, type, fn)           \
   case WasmOpcode::kExpr##opcode:             \
     type##UnOp(&LiftoffAssembler::emit_##fn); \
@@ -473,7 +474,6 @@ class LiftoffCompiler {
 
   void BinOp(Decoder* decoder, WasmOpcode opcode, FunctionSig*,
              const Value& lhs, const Value& rhs, Value* result) {
-    TraceCacheState(decoder);
 #define CASE_BINOP(opcode, type, fn) \
   case WasmOpcode::kExpr##opcode:    \
     return type##BinOp(&LiftoffAssembler::emit_##fn);
@@ -494,7 +494,6 @@ class LiftoffCompiler {
   }
 
   void I32Const(Decoder* decoder, Value* result, int32_t value) {
-    TraceCacheState(decoder);
     __ cache_state()->stack_state.emplace_back(kWasmI32, value);
     CheckStackSizeLimit(decoder);
   }
@@ -515,7 +514,6 @@ class LiftoffCompiler {
   }
 
   void Drop(Decoder* decoder, const Value& value) {
-    TraceCacheState(decoder);
     __ DropStackSlot(&__ cache_state()->stack_state.back());
     __ cache_state()->stack_state.pop_back();
   }
@@ -540,7 +538,6 @@ class LiftoffCompiler {
 
   void GetLocal(Decoder* decoder, Value* result,
                 const LocalIndexOperand<validate>& operand) {
-    TraceCacheState(decoder);
     auto& slot = __ cache_state()->stack_state[operand.index];
     DCHECK_EQ(slot.type(), operand.type);
     switch (slot.loc()) {
@@ -665,12 +662,10 @@ class LiftoffCompiler {
   }
 
   void Br(Decoder* decoder, Control* target) {
-    TraceCacheState(decoder);
     Br(target);
   }
 
   void BrIf(Decoder* decoder, const Value& cond, Control* target) {
-    TraceCacheState(decoder);
     Label cont_false;
     Register value = __ PopToRegister(kGpReg).gp();
     __ emit_i32_test(value);
@@ -800,8 +795,6 @@ class LiftoffCompiler {
     if (operand.sig->return_count() > 1)
       return unsupported(decoder, "multi-return");
 
-    TraceCacheState(decoder);
-
     compiler::CallDescriptor* call_desc =
         compiler::GetWasmCallDescriptor(&compilation_zone_, operand.sig);
 

src/wasm/function-body-decoder-impl.h

@@ -551,6 +551,7 @@ struct ControlWithNamedConstructors : public ControlBase<Value> {
   F(StartFunctionBody, Control* block)                                         \
   F(FinishFunction)                                                            \
   F(OnFirstError)                                                              \
+  F(NextInstruction, WasmOpcode)                                               \
   /* Control: */                                                               \
   F(Block, Control* block)                                                     \
   F(Loop, Control* block)                                                      \
@@ -1331,6 +1332,9 @@ class WasmFullDecoder : public WasmDecoder<validate> {
     while (this->pc_ < this->end_) {  // decoding loop.
       unsigned len = 1;
       WasmOpcode opcode = static_cast<WasmOpcode>(*this->pc_);
+
+      CALL_INTERFACE_IF_REACHABLE(NextInstruction, opcode);
+
 #if DEBUG
       TraceLine trace_msg;
 #define TRACE_PART(...) trace_msg.Append(__VA_ARGS__)

src/wasm/function-body-decoder.cc

@@ -142,11 +142,11 @@ class WasmGraphBuildingInterface {
     block->end_env = break_env;
   }
 
-  void FinishFunction(Decoder* decoder) {
-    builder_->PatchInStackCheckIfNeeded();
-  }
+  void FinishFunction(Decoder*) { builder_->PatchInStackCheckIfNeeded(); }
 
-  void OnFirstError(Decoder* decoder) {}
+  void OnFirstError(Decoder*) {}
+
+  void NextInstruction(Decoder*, WasmOpcode) {}
 
   void Block(Decoder* decoder, Control* block) {
     // The break environment is the outer environment.