From 89672e111d2c46ab0532a80ab03b2fe32f2eee6b Mon Sep 17 00:00:00 2001
From: Ben Vanik <ben.vanik@gmail.com>
Date: Thu, 23 May 2013 11:46:26 -0700
Subject: [PATCH] Optimizing memory accesses a bit by letting libjit use
 relative addressing.

---
 src/xenia/cpu/libjit/libjit_emitter.cc | 25 ++++++++++++++-----------
 src/xenia/cpu/libjit/libjit_emitter.h  |  2 +-
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/src/xenia/cpu/libjit/libjit_emitter.cc b/src/xenia/cpu/libjit/libjit_emitter.cc
index 4932dc1ad..a209f09ee 100644
--- a/src/xenia/cpu/libjit/libjit_emitter.cc
+++ b/src/xenia/cpu/libjit/libjit_emitter.cc
@@ -1275,7 +1275,7 @@ void LibjitEmitter::update_fpr_value(uint32_t n, jit_value_t value) {
   jit_insn_store(fn_, locals_.fpr[n], value);
 }
 
-jit_value_t LibjitEmitter::GetMemoryAddress(uint32_t cia, jit_value_t addr) {
+jit_value_t LibjitEmitter::TouchMemoryAddress(uint32_t cia, jit_value_t addr) {
   // Input address is always in 32-bit space.
   // TODO(benvanik): is this required? It's one extra instruction on every
   //     access...
@@ -1303,11 +1303,7 @@ jit_value_t LibjitEmitter::GetMemoryAddress(uint32_t cia, jit_value_t addr) {
   //   b.SetInsertPoint(valid_bb);
   // }
 
-  // Rebase off of memory base pointer.
-  // We could store the memory base as a global value (or indirection off of
-  // state) if we wanted to avoid embedding runtime values into the code.
-  jit_value_t membase = get_uint64((uint64_t)xe_memory_addr(memory_, 0));
-  return jit_insn_add(fn_, addr, membase);
+  return addr;
 }
 
 jit_value_t LibjitEmitter::ReadMemory(
@@ -1335,8 +1331,12 @@ jit_value_t LibjitEmitter::ReadMemory(
       return NULL;
   }
 
-  jit_value_t address = GetMemoryAddress(cia, addr);
-  jit_value_t value = jit_insn_load_relative(fn_, address, 0, data_type);
+  // Rebase off of memory base pointer.
+  // We could store the memory base as a global value (or indirection off of
+  // state) if we wanted to avoid embedding runtime values into the code.
+  jit_value_t address = TouchMemoryAddress(cia, addr);
+  jit_nint membase = (jit_nint)xe_memory_addr(memory_, 0);
+  jit_value_t value = jit_insn_load_relative(fn_, address, membase, data_type);
   if (acquire) {
     // TODO(benvanik): acquire semantics.
     // load_value->setAlignment(size);
@@ -1380,8 +1380,6 @@ void LibjitEmitter::WriteMemory(
       return;
   }
 
-  jit_value_t address = GetMemoryAddress(cia, addr);
-
   // Truncate, if required.
   if (jit_value_get_type(value) != data_type) {
     value = jit_insn_convert(fn_, value, data_type, 0);
@@ -1400,5 +1398,10 @@ void LibjitEmitter::WriteMemory(
   //   store_value->setAtomic(Release);
   // }
 
-  jit_insn_store_relative(fn_, address, 0, value);
+  // Rebase off of memory base pointer.
+  // We could store the memory base as a global value (or indirection off of
+  // state) if we wanted to avoid embedding runtime values into the code.
+  jit_value_t address = TouchMemoryAddress(cia, addr);
+  jit_nint membase = (jit_nint)xe_memory_addr(memory_, 0);
+  jit_insn_store_relative(fn_, address, membase, value);
 }
diff --git a/src/xenia/cpu/libjit/libjit_emitter.h b/src/xenia/cpu/libjit/libjit_emitter.h
index 61a60578d..5378eb4fd 100644
--- a/src/xenia/cpu/libjit/libjit_emitter.h
+++ b/src/xenia/cpu/libjit/libjit_emitter.h
@@ -92,7 +92,7 @@ public:
   jit_value_t fpr_value(uint32_t n);
   void update_fpr_value(uint32_t n, jit_value_t value);
 
-  jit_value_t GetMemoryAddress(uint32_t cia, jit_value_t addr);
+  jit_value_t TouchMemoryAddress(uint32_t cia, jit_value_t addr);
   jit_value_t ReadMemory(
       uint32_t cia, jit_value_t addr, uint32_t size, bool acquire = false);
   void WriteMemory(