From 50a8cabbbb8365b2d907d1bf42f96f39f5b4f48e Mon Sep 17 00:00:00 2001
From: John Kessenich <cepheus@frii.com>
Date: Mon, 10 Jun 2013 07:37:49 +0000
Subject: [PATCH] Add constant folding for length(), normalize(), fwidth(),
 dFdx(), and dFdy().

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@21918 e7fa87d3-cd2b-0410-9028-fcbf551c1848
---
 Test/constFold.frag                     |  4 +++
 glslang/MachineIndependent/Constant.cpp | 48 +++++++++++++++++++------
 2 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/Test/constFold.frag b/Test/constFold.frag
index 3b0d3607..e08dc846 100644
--- a/Test/constFold.frag
+++ b/Test/constFold.frag
@@ -8,8 +8,11 @@ const float e = float(d); // 2.0
 const float f = e * float(c); // 6.0
 const float g = f / float(d); // 3.0
 
+const vec2 pytho = vec2(3.0, 4.0);
+
 in vec4 inv;
 out vec4 FragColor;
+out vec2 out2;
 
 void main()
 {
@@ -26,4 +29,5 @@ void main()
     vec4 arrayMax[int(max(float(array2.length()), float(array3.length())))];
     vec4 arrayMin[int(min(float(array2.length()), float(array3.length())))];
     FragColor = vec4(arrayMax.length(), arrayMin.length(), sin(3.14), cos(3.14));  // 3, 2, .00159, -.999
+    out2 = length(pytho) + normalize(pytho) + dFdx(pytho) + dFdy(pytho) + fwidth(pytho); // 5+3/5, 5+4/5
 }
diff --git a/glslang/MachineIndependent/Constant.cpp b/glslang/MachineIndependent/Constant.cpp
index e8c42a7f..f973cc1a 100644
--- a/glslang/MachineIndependent/Constant.cpp
+++ b/glslang/MachineIndependent/Constant.cpp
@@ -377,12 +377,35 @@ TIntermTyped* TIntermConstantUnion::fold(TOperator op, const TType& returnType,
     case EOpDeterminant:
     case EOpAny:
     case EOpAll:
+    case EOpLength:
         newConstArray = new constUnion[1];
-        break;
+        break;        
+    
     default:
         newConstArray = new constUnion[objectSize];
     }
 
+    // Process non-component-wise operations
+    switch (op) {
+    case EOpLength:
+    case EOpNormalize:
+    {
+        double sum = 0;
+        for (int i = 0; i < objectSize; i++)
+            sum += double(unionArray[i].getFConst()) * unionArray[i].getFConst();
+        double length = sqrt(sum);
+        if (op == EOpLength)
+            newConstArray[0].setFConst(float(length));
+        else {
+            for (int i = 0; i < objectSize; i++)
+                newConstArray[i].setFConst(float(unionArray[i].getFConst() / length));
+        }
+        break;
+    }
+    default:
+        break;
+    }
+
     // TODO: Functionality: constant folding: separate component-wise from non-component-wise
     for (int i = 0; i < objectSize; i++) {
         switch (op) {
@@ -433,6 +456,18 @@ TIntermTyped* TIntermConstantUnion::fold(TOperator op, const TType& returnType,
             newConstArray[i].setFConst(atan(unionArray[i].getFConst()));
             break;
 
+        case EOpLength:
+        case EOpNormalize:
+            // handled above as special case
+            break;
+
+        case EOpDPdx:
+        case EOpDPdy:
+        case EOpFwidth:
+            // The derivatives are all mandated to create a constant 0.
+            newConstArray[i].setFConst(0.0f);
+            break;
+
         // TODO: Functionality: constant folding: the rest of the ops have to be fleshed out
 
         case EOpExp:
@@ -465,13 +500,6 @@ TIntermTyped* TIntermConstantUnion::fold(TOperator op, const TType& returnType,
         case EOpPackHalf2x16:
         case EOpUnpackHalf2x16:
 
-        case EOpLength:
-
-        case EOpDPdx:
-        case EOpDPdy:
-        case EOpFwidth:
-            // The derivatives are all mandated to create a constant 0.
-
         case EOpDeterminant:
         case EOpMatrixInverse:
         case EOpTranspose:
@@ -480,7 +508,7 @@ TIntermTyped* TIntermConstantUnion::fold(TOperator op, const TType& returnType,
         case EOpAll:
 
         default:
-            infoSink.info.message(EPrefixInternalError, "Invalid operator for constant folding", getLine());
+            infoSink.info.message(EPrefixInternalError, "missing operator for unary constant folding", getLine());
             return 0;
         }
     }
@@ -521,7 +549,6 @@ TIntermTyped* TIntermediate::fold(TIntermAggregate* aggrNode)
     case EOpMix:
     case EOpDistance:
     case EOpCross:
-    case EOpNormalize:
         objectSize = children[0]->getAsConstantUnion()->getType().getObjectSize();
         break;
     case EOpDot:
@@ -574,7 +601,6 @@ TIntermTyped* TIntermediate::fold(TIntermAggregate* aggrNode)
     case EOpDistance:
     case EOpDot:
     case EOpCross:
-    case EOpNormalize:
     case EOpFaceForward:
     case EOpReflect:
     case EOpRefract: