[wasm] Remove --trace-wasm-decode-time flag

This seems like a very specific flag which is rarely used. It not only
adds local overhead, but also requires an additional parameter at
{BuildGraphForWasmFunction}.
Thus this CL removes it completely. Interested parties can still measure
timing locally.

R=titzer@chromium.org

Bug: v8:9183
Change-Id: I5f152cdb9456d1001ed38722d44c71cf5ae44ae3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1631420Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61858}

src/compiler/wasm-compiler.cc

@@ -6389,14 +6389,9 @@ bool BuildGraphForWasmFunction(AccountingAllocator* allocator,
                                wasm::CompilationEnv* env,
                                const wasm::FunctionBody& func_body,
                                int func_index, wasm::WasmFeatures* detected,
-                               double* decode_ms, MachineGraph* mcgraph,
+                               MachineGraph* mcgraph,
                                NodeOriginTable* node_origins,
                                SourcePositionTable* source_positions) {
-  base::ElapsedTimer decode_timer;
-  if (FLAG_trace_wasm_decode_time) {
-    decode_timer.Start();
-  }
-
   // Create a TF graph during decoding.
   WasmGraphBuilder builder(env, mcgraph->zone(), mcgraph, func_body.sig,
                            source_positions);
@@ -6425,9 +6420,6 @@ bool BuildGraphForWasmFunction(AccountingAllocator* allocator,
       func_index < FLAG_trace_wasm_ast_end) {
     PrintRawWasmCode(allocator, func_body, env->module, wasm::kPrintLocals);
   }
-  if (FLAG_trace_wasm_decode_time) {
-    *decode_ms = decode_timer.Elapsed().InMillisecondsF();
-  }
   return true;
 }
 
@@ -6454,9 +6446,6 @@ wasm::WasmCompilationResult ExecuteTurbofanWasmCompilation(
                "ExecuteTurbofanCompilation", "func_index", func_index,
                "body_size",
                static_cast<uint32_t>(func_body.end - func_body.start));
-  double decode_ms = 0;
-  size_t node_count = 0;
-
   Zone zone(wasm_engine->allocator(), ZONE_NAME);
   MachineGraph* mcgraph = new (&zone) MachineGraph(
       new (&zone) Graph(&zone), new (&zone) CommonOperatorBuilder(&zone),
@@ -6483,8 +6472,8 @@ wasm::WasmCompilationResult ExecuteTurbofanWasmCompilation(
   SourcePositionTable* source_positions =
       new (mcgraph->zone()) SourcePositionTable(mcgraph->graph());
   if (!BuildGraphForWasmFunction(wasm_engine->allocator(), env, func_body,
-                                 func_index, detected, &decode_ms, mcgraph,
-                                 node_origins, source_positions)) {
+                                 func_index, detected, mcgraph, node_origins,
+                                 source_positions)) {
     return wasm::WasmCompilationResult{};
   }
 
@@ -6492,12 +6481,6 @@ wasm::WasmCompilationResult ExecuteTurbofanWasmCompilation(
     node_origins->AddDecorator();
   }
 
-  base::ElapsedTimer pipeline_timer;
-  if (FLAG_trace_wasm_decode_time) {
-    node_count = mcgraph->graph()->NodeCount();
-    pipeline_timer.Start();
-  }
-
   // Run the compiler pipeline to generate machine code.
   auto call_descriptor = GetWasmCallDescriptor(&zone, func_body.sig);
   if (mcgraph->machine()->Is32()) {
@@ -6508,14 +6491,6 @@ wasm::WasmCompilationResult ExecuteTurbofanWasmCompilation(
       &info, wasm_engine, mcgraph, call_descriptor, source_positions,
       node_origins, func_body, env->module, func_index);
 
-  if (FLAG_trace_wasm_decode_time) {
-    double pipeline_ms = pipeline_timer.Elapsed().InMillisecondsF();
-    PrintF(
-        "wasm-compilation phase 1 ok: %u bytes, %0.3f ms decode, %zu nodes, "
-        "%0.3f ms pipeline\n",
-        static_cast<unsigned>(func_body.end - func_body.start), decode_ms,
-        node_count, pipeline_ms);
-  }
   // TODO(bradnelson): Improve histogram handling of size_t.
   counters->wasm_compile_function_peak_memory_bytes()->AddSample(
       static_cast<int>(mcgraph->graph()->zone()->allocation_size()));

src/compiler/wasm-compiler.h

@@ -49,7 +49,7 @@ bool BuildGraphForWasmFunction(AccountingAllocator* allocator,
                                wasm::CompilationEnv* env,
                                const wasm::FunctionBody& func_body,
                                int func_index, wasm::WasmFeatures* detected,
-                               double* decode_ms, MachineGraph* mcgraph,
+                               MachineGraph* mcgraph,
                                NodeOriginTable* node_origins,
                                SourcePositionTable* source_positions);
 

src/flags/flag-definitions.h

@@ -624,8 +624,6 @@ DEFINE_IMPLICATION(future, wasm_tier_up)
 #endif
 DEFINE_IMPLICATION(wasm_tier_up, liftoff)
 DEFINE_DEBUG_BOOL(trace_wasm_decoder, false, "trace decoding of wasm code")
-DEFINE_DEBUG_BOOL(trace_wasm_decode_time, false,
-                  "trace decoding time of wasm code")
 DEFINE_DEBUG_BOOL(trace_wasm_compiler, false, "trace compiling of wasm code")
 DEFINE_DEBUG_BOOL(trace_wasm_interpreter, false,
                   "trace interpretation of wasm code")

src/wasm/baseline/liftoff-compiler.cc

@@ -2052,10 +2052,6 @@ WasmCompilationResult ExecuteLiftoffCompilation(AccountingAllocator* allocator,
                "ExecuteLiftoffCompilation", "func_index", func_index,
                "body_size",
                static_cast<uint32_t>(func_body.end - func_body.start));
-  base::ElapsedTimer compile_timer;
-  if (FLAG_trace_wasm_decode_time) {
-    compile_timer.Start();
-  }
 
   Zone zone(allocator, "LiftoffCompilationZone");
   const WasmModule* module = env ? env->module : nullptr;
@@ -2082,14 +2078,6 @@ WasmCompilationResult ExecuteLiftoffCompilation(AccountingAllocator* allocator,
 
   counters->liftoff_compiled_functions()->Increment();
 
-  if (FLAG_trace_wasm_decode_time) {
-    double compile_ms = compile_timer.Elapsed().InMillisecondsF();
-    PrintF(
-        "wasm-compilation liftoff phase 1 ok: %u bytes, %0.3f ms decode and "
-        "compile\n",
-        static_cast<unsigned>(func_body.end - func_body.start), compile_ms);
-  }
-
   WasmCompilationResult result;
   compiler->GetCode(&result.code_desc);
   result.instr_buffer = instruction_buffer->ReleaseBuffer();

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

@@ -1534,11 +1534,6 @@ class WasmFullDecoder : public WasmDecoder<validate> {
     DCHECK(stack_.empty());
     DCHECK(control_.empty());
 
-    base::ElapsedTimer decode_timer;
-    if (FLAG_trace_wasm_decode_time) {
-      decode_timer.Start();
-    }
-
     if (this->end_ < this->pc_) {
       this->error("function body end < start");
       return false;
@@ -1561,13 +1556,7 @@ class WasmFullDecoder : public WasmDecoder<validate> {
 
     if (this->failed()) return this->TraceFailed();
 
-    if (FLAG_trace_wasm_decode_time) {
-      double ms = decode_timer.Elapsed().InMillisecondsF();
-      PrintF("wasm-decode %s (%0.3f ms)\n\n",
-             VALIDATE(this->ok()) ? "ok" : "failed", ms);
-    } else {
-      TRACE("wasm-decode %s\n\n", VALIDATE(this->ok()) ? "ok" : "failed");
-    }
+    TRACE("wasm-decode %s\n\n", VALIDATE(this->ok()) ? "ok" : "failed");
 
     return true;
   }

src/wasm/module-decoder.cc

@@ -1307,9 +1307,8 @@ class ModuleDecoderImpl : public Decoder {
                           const WasmModule* module, WasmFunction* function) {
     WasmFunctionName func_name(function,
                                wire_bytes.GetNameOrNull(function, module));
-    if (FLAG_trace_wasm_decoder || FLAG_trace_wasm_decode_time) {
-      StdoutStream os;
-      os << "Verifying wasm function " << func_name << std::endl;
+    if (FLAG_trace_wasm_decoder) {
+      StdoutStream{} << "Verifying wasm function " << func_name << std::endl;
     }
     FunctionBody body = {
         function->sig, function->code.offset(),