From a2448308fd90ba0aafd42587a091c0da3c037ba9 Mon Sep 17 00:00:00 2001
From: Diego Frias <styx5242@gmail.com>
Date: Fri, 2 Aug 2024 21:12:20 -0700
Subject: [PATCH] LibWasm: Directly remove from the stack when clearing a label

Theoretically, the previous "pop, then push" method should be faster,
but it's actually faster to just remove from the stack directly.
---
 .../AbstractMachine/BytecodeInterpreter.cpp   | 19 +------------------
 .../AbstractMachine/BytecodeInterpreter.h     |  1 -
 2 files changed, 1 insertion(+), 19 deletions(-)

diff --git a/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp b/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp
index a6941c21baf..50ce2f43dfa 100644
--- a/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp
+++ b/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp
@@ -63,14 +63,8 @@ void BytecodeInterpreter::branch_to_label(Configuration& configuration, LabelInd
         configuration.label_stack().take_last();
     auto label = configuration.label_stack().last();
     dbgln_if(WASM_TRACE_DEBUG, "...which is actually IP {}, and has {} result(s)", label.continuation().value(), label.arity());
-    auto results = pop_values(configuration, label.arity());
-
-    while (configuration.value_stack().size() != label.stack_height())
-        configuration.value_stack().take_last();
-
-    for (auto& result : results.in_reverse())
-        configuration.value_stack().append(result);
 
+    configuration.value_stack().remove(label.stack_height(), configuration.value_stack().size() - label.stack_height() - label.arity());
     configuration.ip() = label.continuation();
 }
 
@@ -409,17 +403,6 @@ double BytecodeInterpreter::read_value<double>(ReadonlyBytes data)
     return bit_cast<double>(static_cast<u64>(raw_value));
 }
 
-Vector<Value> BytecodeInterpreter::pop_values(Configuration& configuration, size_t count)
-{
-    Vector<Value> results;
-    results.resize(count);
-
-    for (size_t i = 0; i < count; ++i)
-        results[i] = configuration.value_stack().take_last();
-
-    return results;
-}
-
 ALWAYS_INLINE void BytecodeInterpreter::interpret_instruction(Configuration& configuration, InstructionPointer& ip, Instruction const& instruction)
 {
     dbgln_if(WASM_TRACE_DEBUG, "Executing instruction {} at ip {}", instruction_name(instruction.opcode()), ip.value());
diff --git a/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.h b/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.h
index 8c39238483d..18234c56ee5 100644
--- a/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.h
+++ b/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.h
@@ -79,7 +79,6 @@ protected:
     template<typename T>
     T read_value(ReadonlyBytes data);
 
-    Vector<Value> pop_values(Configuration& configuration, size_t count);
     ALWAYS_INLINE bool trap_if_not(bool value, StringView reason)
     {
         if (!value)