commit 1c89caef47a27c63a7d0f988e74816692a9b9b39
author Arun Patole <apatole@nvidia.com> Mon Apr 06 17:29:48 2015 +0530
committer Olli Etuaho <oetuaho@nvidia.com> Fri Apr 10 11:04:19 2015 +0000
tree 3fda1b6e18629f531ad5e12d0942a77465b19ff5
parent af930db15010cacfcdc74bee630372b8f6eb3eeb

Support constant folding of exponential built-ins

This change adds constant folding support for unary exponential
built-ins - exp, log, exp2, log2, sqrt and inversesqrt.

BUG=angleproject:913
TEST= dEQP tests
dEQP-GLES3.functional.shaders.constant_expressions.builtin_functions.exponential*
(48 out of 56 tests started passing with this change)

Change-Id: I22af56876d1b7ce305697bf9bf43ad9ec5d8a3a5
Reviewed-on: https://chromium-review.googlesource.com/263708
Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>

src/compiler/translator/IntermNode.cpp

diff --git a/src/compiler/translator/IntermNode.cpp b/src/compiler/translator/IntermNode.cpp
index f9174e8..687ea93 100644
--- a/src/compiler/translator/IntermNode.cpp
+++ b/src/compiler/translator/IntermNode.cpp
@@ -1284,6 +1284,52 @@
                     return nullptr;
                 break;
 
+              case EOpExp:
+                if (!foldFloatTypeUnary(unionArray[i], static_cast<FloatTypeUnaryFunc>(&exp), infoSink, &tempConstArray[i]))
+                  return nullptr;
+                break;
+
+              case EOpLog:
+                // For log(x), results are undefined if x <= 0, we are choosing to set result to 0.
+                if (getType().getBasicType() == EbtFloat && unionArray[i].getFConst() <= 0.0)
+                    tempConstArray[i].setFConst(0.0);
+                else if (!foldFloatTypeUnary(unionArray[i], static_cast<FloatTypeUnaryFunc>(&log), infoSink, &tempConstArray[i]))
+                    return nullptr;
+                break;
+
+              case EOpExp2:
+                if (!foldFloatTypeUnary(unionArray[i], static_cast<FloatTypeUnaryFunc>(&exp2), infoSink, &tempConstArray[i]))
+                    return nullptr;
+                break;
+
+              case EOpLog2:
+                // For log2(x), results are undefined if x <= 0, we are choosing to set result to 0.
+                if (getType().getBasicType() == EbtFloat && unionArray[i].getFConst() <= 0.0)
+                    tempConstArray[i].setFConst(0.0);
+                else if (!foldFloatTypeUnary(unionArray[i], static_cast<FloatTypeUnaryFunc>(&log2), infoSink, &tempConstArray[i]))
+                    return nullptr;
+                break;
+
+              case EOpSqrt:
+                // For sqrt(x), results are undefined if x < 0, we are choosing to set result to 0.
+                if (getType().getBasicType() == EbtFloat && unionArray[i].getFConst() < 0.0)
+                    tempConstArray[i].setFConst(0.0);
+                else if (!foldFloatTypeUnary(unionArray[i], static_cast<FloatTypeUnaryFunc>(&sqrt), infoSink, &tempConstArray[i]))
+                    return nullptr;
+                break;
+
+              case EOpInverseSqrt:
+                // There is no stdlib built-in function equavalent for GLES built-in inversesqrt(),
+                // so getting the square root first using builtin function sqrt() and then taking its inverse.
+                // Also, for inversesqrt(x), results are undefined if x <= 0, we are choosing to set result to 0.
+                if (getType().getBasicType() == EbtFloat && unionArray[i].getFConst() <= 0.0)
+                    tempConstArray[i].setFConst(0.0);
+                else if (!foldFloatTypeUnary(unionArray[i], static_cast<FloatTypeUnaryFunc>(&sqrt), infoSink, &tempConstArray[i]))
+                    return nullptr;
+                else
+                    tempConstArray[i].setFConst(1 / tempConstArray[i].getFConst());
+                break;
+
               default:
                 return NULL;
             }