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