From ebc5326ed5268e69bc7b3fda4843e97c6d0cf102 Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Tue, 7 Sep 2021 20:10:45 +0200
Subject: [PATCH] [dxso] Correctly handle multiplication by zero

---
 src/dxso/dxso_compiler.cpp | 70 +++++++++++++++++++++++++++++++-------
 src/dxso/dxso_compiler.h   | 13 +++++++
 2 files changed, 71 insertions(+), 12 deletions(-)

diff --git a/src/dxso/dxso_compiler.cpp b/src/dxso/dxso_compiler.cpp
index cf7ed2d9..128c42d8 100644
--- a/src/dxso/dxso_compiler.cpp
+++ b/src/dxso/dxso_compiler.cpp
@@ -1436,15 +1436,61 @@ namespace dxvk {
   }
 
 
+  DxsoRegisterValue DxsoCompiler::emitMulOperand(
+          DxsoRegisterValue       operand,
+          DxsoRegisterValue       other) {
+    if (!m_moduleInfo.options.d3d9FloatEmulation)
+      return operand;
+
+    uint32_t boolId = getVectorTypeId({ DxsoScalarType::Bool, other.type.ccount });
+    uint32_t zeroId = m_module.constfReplicant(0.0f, other.type.ccount);
+
+    DxsoRegisterValue result;
+    result.type = operand.type;
+    result.id = m_module.opSelect(getVectorTypeId(result.type),
+      m_module.opFOrdEqual(boolId, other.id, zeroId), zeroId, operand.id);
+    return result;
+  }
+
+
+  DxsoRegisterValue DxsoCompiler::emitMul(
+          DxsoRegisterValue       a,
+          DxsoRegisterValue       b) {
+    auto az = emitMulOperand(a, b);
+    auto bz = emitMulOperand(b, a);
+
+    DxsoRegisterValue result;
+    result.type = a.type;
+    result.id = m_module.opFMul(getVectorTypeId(result.type), az.id, bz.id);
+    return result;
+  }
+
+
+  DxsoRegisterValue DxsoCompiler::emitFma(
+          DxsoRegisterValue       a,
+          DxsoRegisterValue       b,
+          DxsoRegisterValue       c) {
+    auto az = emitMulOperand(a, b);
+    auto bz = emitMulOperand(b, a);
+
+    DxsoRegisterValue result;
+    result.type = a.type;
+    result.id = m_module.opFFma(getVectorTypeId(result.type), az.id, bz.id, c.id);
+    return result;
+  }
+
+
   DxsoRegisterValue DxsoCompiler::emitDot(
             DxsoRegisterValue       a,
             DxsoRegisterValue       b) {
+    auto az = emitMulOperand(a, b);
+    auto bz = emitMulOperand(b, a);
+
     DxsoRegisterValue dot;
     dot.type        = a.type;
     dot.type.ccount = 1;
 
-    dot.id = m_module.opDot(getVectorTypeId(dot.type), a.id, b.id);
-
+    dot.id = m_module.opDot(getVectorTypeId(dot.type), az.id, bz.id);
     return dot;
   }
 
@@ -1865,15 +1911,15 @@ namespace dxvk {
         break;
       case DxsoOpcode::Mad:
         if (!m_moduleInfo.options.longMad) {
-          result.id = m_module.opFFma(typeId,
-            emitRegisterLoad(src[0], mask).id,
-            emitRegisterLoad(src[1], mask).id,
-            emitRegisterLoad(src[2], mask).id);
+          result.id = emitFma(
+            emitRegisterLoad(src[0], mask),
+            emitRegisterLoad(src[1], mask),
+            emitRegisterLoad(src[2], mask)).id;
         }
         else {
-          result.id = m_module.opFMul(typeId,
-            emitRegisterLoad(src[0], mask).id,
-            emitRegisterLoad(src[1], mask).id);
+          result.id = emitMul(
+            emitRegisterLoad(src[0], mask),
+            emitRegisterLoad(src[1], mask)).id;
 
           result.id = m_module.opFAdd(typeId,
             result.id,
@@ -1881,9 +1927,9 @@ namespace dxvk {
         }
         break;
       case DxsoOpcode::Mul:
-        result.id = m_module.opFMul(typeId,
-          emitRegisterLoad(src[0], mask).id,
-          emitRegisterLoad(src[1], mask).id);
+        result.id = emitMul(
+          emitRegisterLoad(src[0], mask),
+          emitRegisterLoad(src[1], mask)).id;
         break;
       case DxsoOpcode::Rcp:
         result.id = m_module.opFDiv(typeId,
diff --git a/src/dxso/dxso_compiler.h b/src/dxso/dxso_compiler.h
index 9cd90485..0a1ce589 100644
--- a/src/dxso/dxso_compiler.h
+++ b/src/dxso/dxso_compiler.h
@@ -545,6 +545,19 @@ namespace dxvk {
     DxsoRegisterValue emitSaturate(
             DxsoRegisterValue       srcValue);
 
+    DxsoRegisterValue emitMulOperand(
+            DxsoRegisterValue       operand,
+            DxsoRegisterValue       other);
+
+    DxsoRegisterValue emitMul(
+            DxsoRegisterValue       a,
+            DxsoRegisterValue       b);
+
+    DxsoRegisterValue emitFma(
+            DxsoRegisterValue       a,
+            DxsoRegisterValue       b,
+            DxsoRegisterValue       c);
+
     DxsoRegisterValue emitDot(
             DxsoRegisterValue       a,
             DxsoRegisterValue       b);