From c12251607768afa133971f316dcb54b25522e86f Mon Sep 17 00:00:00 2001
From: Ryan Houdek <Sonicadvance1@gmail.com>
Date: Tue, 17 Nov 2020 12:41:59 -0800
Subject: [PATCH] Adds resizable frontend decoded buffer

Allows us to save memory in the frontend decoder by starting out with a
small buffer until we hit larger code blocks.
---
 External/FEXCore/Source/Interface/Core/Frontend.cpp | 12 ++++++++++--
 External/FEXCore/Source/Interface/Core/Frontend.h   |  4 +++-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/External/FEXCore/Source/Interface/Core/Frontend.cpp b/External/FEXCore/Source/Interface/Core/Frontend.cpp
index 2afa80d57..062276db1 100644
--- a/External/FEXCore/Source/Interface/Core/Frontend.cpp
+++ b/External/FEXCore/Source/Interface/Core/Frontend.cpp
@@ -983,11 +983,19 @@ bool Decoder::DecodeInstructionsAtEntry(uint8_t const* _InstStream, uint64_t PC)
         break;
       }
 
-      if (DecodedSize >= CTX->Config.MaxInstPerBlock ||
-          DecodedSize >= DecodedBuffer.size()) {
+      if (DecodedSize >= CTX->Config.MaxInstPerBlock) {
         break;
       }
 
+      if (DecodedSize >= DecodedBuffer.size() &&
+          DecodedBuffer.size() == MaxDecodedBufferSize) {
+        break;
+      }
+      else if (DecodedSize >= DecodedBuffer.size()) {
+        // We can keep going
+        DecodedBuffer.resize(std::min(static_cast<size_t>(DecodedBuffer.size() * 1.5), MaxDecodedBufferSize));
+      }
+
       if (TotalInstructions >= CTX->Config.MaxInstPerBlock) {
         break;
       }
diff --git a/External/FEXCore/Source/Interface/Core/Frontend.h b/External/FEXCore/Source/Interface/Core/Frontend.h
index 86ba0711a..d1c1ca669 100644
--- a/External/FEXCore/Source/Interface/Core/Frontend.h
+++ b/External/FEXCore/Source/Interface/Core/Frontend.h
@@ -45,7 +45,9 @@ private:
   bool NormalOp(FEXCore::X86Tables::X86InstInfo const *Info, uint16_t Op);
   bool NormalOpHeader(FEXCore::X86Tables::X86InstInfo const *Info, uint16_t Op);
 
-  static constexpr size_t DefaultDecodedBufferSize = 0x10000;
+  static constexpr size_t DefaultDecodedBufferSize = 0x200;
+  static constexpr size_t MaxDecodedBufferSize = 0x10000;
+
   std::vector<FEXCore::X86Tables::DecodedInst> DecodedBuffer;
   size_t DecodedSize {};