michael@0: /*
michael@0:  * Copyright (C) 2012 Apple Inc. All rights reserved.
michael@0:  *
michael@0:  * Redistribution and use in source and binary forms, with or without
michael@0:  * modification, are permitted provided that the following conditions
michael@0:  * are met:
michael@0:  * 1. Redistributions of source code must retain the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer.
michael@0:  * 2. Redistributions in binary form must reproduce the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer in the
michael@0:  *    documentation and/or other materials provided with the distribution.
michael@0:  *
michael@0:  * THIS SOFTWARE IS PROVIDED BY APPLE, INC. ``AS IS'' AND ANY
michael@0:  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
michael@0:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
michael@0:  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE, INC. OR
michael@0:  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
michael@0:  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
michael@0:  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
michael@0:  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
michael@0:  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0:  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
michael@0:  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0:  */
michael@0: 
michael@0: #include "third_party/compiler/ArrayBoundsClamper.h"
michael@0: 
michael@0: // The built-in 'clamp' instruction only accepts floats and returns a float.  I
michael@0: // iterated a few times with our driver team who examined the output from our
michael@0: // compiler - they said the multiple casts generates more code than a single
michael@0: // function call.  An inline ternary operator might have been better, but since
michael@0: // the index value might be an expression itself, we'd have to make temporary
michael@0: // variables to avoid evaluating the expression multiple times.  And making
michael@0: // temporary variables was difficult because ANGLE would then need to make more
michael@0: // brutal changes to the expression tree.
michael@0: 
michael@0: const char* kIntClampBegin = "// BEGIN: Generated code for array bounds clamping\n\n";
michael@0: const char* kIntClampEnd = "// END: Generated code for array bounds clamping\n\n";
michael@0: const char* kIntClampDefinition = "int webgl_int_clamp(int value, int minValue, int maxValue) { return ((value < minValue) ? minValue : ((value > maxValue) ? maxValue : value)); }\n\n";
michael@0: 
michael@0: namespace {
michael@0: 
michael@0: class ArrayBoundsClamperMarker : public TIntermTraverser {
michael@0: public:
michael@0:     ArrayBoundsClamperMarker()
michael@0:         : mNeedsClamp(false)
michael@0:    {
michael@0:    }
michael@0: 
michael@0:    virtual bool visitBinary(Visit visit, TIntermBinary* node)
michael@0:    {
michael@0:        if (node->getOp() == EOpIndexIndirect)
michael@0:        {
michael@0:            TIntermTyped* left = node->getLeft();
michael@0:            if (left->isArray() || left->isVector() || left->isMatrix())
michael@0:            {
michael@0:                node->setAddIndexClamp();
michael@0:                mNeedsClamp = true;
michael@0:            }
michael@0:        }
michael@0:        return true;
michael@0:    }
michael@0: 
michael@0:     bool GetNeedsClamp() { return mNeedsClamp; }
michael@0: 
michael@0: private:
michael@0:     bool mNeedsClamp;
michael@0: };
michael@0: 
michael@0: }  // anonymous namespace
michael@0: 
michael@0: ArrayBoundsClamper::ArrayBoundsClamper()
michael@0:     : mClampingStrategy(SH_CLAMP_WITH_CLAMP_INTRINSIC)
michael@0:     , mArrayBoundsClampDefinitionNeeded(false)
michael@0: {
michael@0: }
michael@0: 
michael@0: void ArrayBoundsClamper::SetClampingStrategy(ShArrayIndexClampingStrategy clampingStrategy)
michael@0: {
michael@0:     ASSERT(clampingStrategy == SH_CLAMP_WITH_CLAMP_INTRINSIC ||
michael@0:            clampingStrategy == SH_CLAMP_WITH_USER_DEFINED_INT_CLAMP_FUNCTION);
michael@0: 
michael@0:     mClampingStrategy = clampingStrategy;
michael@0: }
michael@0: 
michael@0: void ArrayBoundsClamper::MarkIndirectArrayBoundsForClamping(TIntermNode* root)
michael@0: {
michael@0:     ASSERT(root);
michael@0: 
michael@0:     ArrayBoundsClamperMarker clamper;
michael@0:     root->traverse(&clamper);
michael@0:     if (clamper.GetNeedsClamp())
michael@0:     {
michael@0:         SetArrayBoundsClampDefinitionNeeded();
michael@0:     }
michael@0: }
michael@0: 
michael@0: void ArrayBoundsClamper::OutputClampingFunctionDefinition(TInfoSinkBase& out) const
michael@0: {
michael@0:     if (!mArrayBoundsClampDefinitionNeeded)
michael@0:     {
michael@0:         return;
michael@0:     }
michael@0:     if (mClampingStrategy != SH_CLAMP_WITH_USER_DEFINED_INT_CLAMP_FUNCTION)
michael@0:     {
michael@0:         return;
michael@0:     }
michael@0:     out << kIntClampBegin << kIntClampDefinition << kIntClampEnd;
michael@0: }