From 3ced6c5cf216f66c8fbd3dbb50056e542f842019 Mon Sep 17 00:00:00 2001
From: gibbed <rick@gibbed.us>
Date: Sun, 18 Nov 2018 08:03:52 -0600
Subject: [PATCH] [CPU] Add constant VectorAverage.

---
 .../passes/constant_propagation_pass.cc       | 11 ++++++++++
 src/xenia/cpu/hir/value.cc                    | 21 +++++++++++++++++++
 src/xenia/cpu/hir/value.h                     |  2 ++
 3 files changed, 34 insertions(+)

diff --git a/src/xenia/cpu/compiler/passes/constant_propagation_pass.cc b/src/xenia/cpu/compiler/passes/constant_propagation_pass.cc
index 8c3e7f196..44e1e37c1 100644
--- a/src/xenia/cpu/compiler/passes/constant_propagation_pass.cc
+++ b/src/xenia/cpu/compiler/passes/constant_propagation_pass.cc
@@ -772,6 +772,17 @@ bool ConstantPropagationPass::Run(HIRBuilder* builder) {
           }
           break;
 
+        case OPCODE_VECTOR_AVERAGE:
+          if (i->src1.value->IsConstant() && i->src2.value->IsConstant()) {
+            v->set_from(i->src1.value);
+            uint32_t arith_flags = i->flags >> 8;
+            v->VectorAverage(i->src2.value, hir::TypeName(i->flags & 0xFF),
+                             !!(arith_flags & ARITHMETIC_UNSIGNED),
+                             !!(arith_flags & ARITHMETIC_SATURATE));
+            i->Remove();
+          }
+          break;
+
         default:
           // Ignored.
           break;
diff --git a/src/xenia/cpu/hir/value.cc b/src/xenia/cpu/hir/value.cc
index 38cd29294..a2613e3e9 100644
--- a/src/xenia/cpu/hir/value.cc
+++ b/src/xenia/cpu/hir/value.cc
@@ -1376,6 +1376,27 @@ void Value::DotProduct4(Value* other) {
   }
 }
 
+void Value::VectorAverage(Value* other, TypeName type, bool is_unsigned,
+                          bool saturate) {
+  assert_true(this->type == VEC128_TYPE && other->type == VEC128_TYPE);
+  switch (type) {
+    case INT16_TYPE:
+      // TODO(gibbed): is this correct?
+      alignas(16) int8_t result[16];
+      __m128i src1 =
+          _mm_load_si128(reinterpret_cast<const __m128i*>(constant.v128.i8));
+      __m128i src2 = _mm_load_si128(
+          reinterpret_cast<const __m128i*>(other->constant.v128.i8));
+      __m128i dest = _mm_avg_epu16(src1, src2);
+      _mm_store_si128(reinterpret_cast<__m128i*>(result), dest);
+      std::memcpy(constant.v128.i8, result, sizeof(result));
+      break;
+    default:
+      assert_unhandled_case(type);
+      break;
+  }
+}
+
 void Value::ByteSwap() {
   switch (type) {
     case INT8_TYPE:
diff --git a/src/xenia/cpu/hir/value.h b/src/xenia/cpu/hir/value.h
index 44e4807c4..ff41edf3b 100644
--- a/src/xenia/cpu/hir/value.h
+++ b/src/xenia/cpu/hir/value.h
@@ -535,6 +535,8 @@ class Value {
   void VectorSub(Value* other, TypeName type, bool is_unsigned, bool saturate);
   void DotProduct3(Value* other);
   void DotProduct4(Value* other);
+  void VectorAverage(Value* other, TypeName type, bool is_unsigned,
+                     bool saturate);
   void ByteSwap();
   void CountLeadingZeros(const Value* other);
   bool Compare(Opcode opcode, Value* other);