1 /*
2 * Copyright (C) 2012 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE, INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE, INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26 #include "third_party/compiler/ArrayBoundsClamper.h"
27
28 #include "compiler/translator/IntermTraverse.h"
29
30 // The built-in 'clamp' instruction only accepts floats and returns a float. I
31 // iterated a few times with our driver team who examined the output from our
32 // compiler - they said the multiple casts generates more code than a single
33 // function call. An inline ternary operator might have been better, but since
34 // the index value might be an expression itself, we'd have to make temporary
35 // variables to avoid evaluating the expression multiple times. And making
36 // temporary variables was difficult because ANGLE would then need to make more
37 // brutal changes to the expression tree.
38
39 const char* kIntClampBegin = "// BEGIN: Generated code for array bounds clamping\n\n";
40 const char* kIntClampEnd = "// END: Generated code for array bounds clamping\n\n";
41 const char* kIntClampDefinition = "int webgl_int_clamp(int value, int minValue, int maxValue) { return ((value < minValue) ? minValue : ((value > maxValue) ? maxValue : value)); }\n\n";
42
43 namespace sh
44 {
45
46 namespace
47 {
48
49 class ArrayBoundsClamperMarker : public TIntermTraverser {
50 public:
ArrayBoundsClamperMarker()51 ArrayBoundsClamperMarker()
52 : TIntermTraverser(true, false, false),
53 mNeedsClamp(false)
54 {
55 }
56
visitBinary(Visit visit,TIntermBinary * node)57 bool visitBinary(Visit visit, TIntermBinary *node) override
58 {
59 if (node->getOp() == EOpIndexIndirect)
60 {
61 TIntermTyped* left = node->getLeft();
62 if (left->isArray() || left->isVector() || left->isMatrix())
63 {
64 node->setAddIndexClamp();
65 mNeedsClamp = true;
66 }
67 }
68 return true;
69 }
70
GetNeedsClamp()71 bool GetNeedsClamp() { return mNeedsClamp; }
72
73 private:
74 bool mNeedsClamp;
75 };
76
77 } // anonymous namespace
78
ArrayBoundsClamper()79 ArrayBoundsClamper::ArrayBoundsClamper()
80 : mClampingStrategy(SH_CLAMP_WITH_CLAMP_INTRINSIC)
81 , mArrayBoundsClampDefinitionNeeded(false)
82 {
83 }
84
SetClampingStrategy(ShArrayIndexClampingStrategy clampingStrategy)85 void ArrayBoundsClamper::SetClampingStrategy(ShArrayIndexClampingStrategy clampingStrategy)
86 {
87 mClampingStrategy = clampingStrategy;
88 }
89
MarkIndirectArrayBoundsForClamping(TIntermNode * root)90 void ArrayBoundsClamper::MarkIndirectArrayBoundsForClamping(TIntermNode* root)
91 {
92 ASSERT(root);
93
94 ArrayBoundsClamperMarker clamper;
95 root->traverse(&clamper);
96 if (clamper.GetNeedsClamp())
97 {
98 SetArrayBoundsClampDefinitionNeeded();
99 }
100 }
101
OutputClampingFunctionDefinition(TInfoSinkBase & out) const102 void ArrayBoundsClamper::OutputClampingFunctionDefinition(TInfoSinkBase& out) const
103 {
104 if (!mArrayBoundsClampDefinitionNeeded)
105 {
106 return;
107 }
108 if (mClampingStrategy != SH_CLAMP_WITH_USER_DEFINED_INT_CLAMP_FUNCTION)
109 {
110 return;
111 }
112 out << kIntClampBegin << kIntClampDefinition << kIntClampEnd;
113 }
114
115 } // namespace sh
116