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/tree_util/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 =
42 "int webgl_int_clamp(int value, int minValue, int maxValue) { return ((value < minValue) ? "
43 "minValue : ((value > maxValue) ? maxValue : value)); }\n\n";
44
45 namespace sh
46 {
47
48 namespace
49 {
50
51 class ArrayBoundsClamperMarker : public TIntermTraverser
52 {
53 public:
ArrayBoundsClamperMarker()54 ArrayBoundsClamperMarker() : TIntermTraverser(true, false, false), mNeedsClamp(false) {}
55
visitBinary(Visit visit,TIntermBinary * node)56 bool visitBinary(Visit visit, TIntermBinary *node) override
57 {
58 if (node->getOp() == EOpIndexIndirect)
59 {
60 TIntermTyped *left = node->getLeft();
61 if (left->isArray() || left->isVector() || left->isMatrix())
62 {
63 node->setAddIndexClamp();
64 mNeedsClamp = true;
65 }
66 }
67 return true;
68 }
69
GetNeedsClamp()70 bool GetNeedsClamp() { return mNeedsClamp; }
71
72 private:
73 bool mNeedsClamp;
74 };
75
76 } // anonymous namespace
77
ArrayBoundsClamper()78 ArrayBoundsClamper::ArrayBoundsClamper()
79 : mClampingStrategy(SH_CLAMP_WITH_CLAMP_INTRINSIC), mArrayBoundsClampDefinitionNeeded(false)
80 {}
81
SetClampingStrategy(ShArrayIndexClampingStrategy clampingStrategy)82 void ArrayBoundsClamper::SetClampingStrategy(ShArrayIndexClampingStrategy clampingStrategy)
83 {
84 mClampingStrategy = clampingStrategy;
85 }
86
MarkIndirectArrayBoundsForClamping(TIntermNode * root)87 void ArrayBoundsClamper::MarkIndirectArrayBoundsForClamping(TIntermNode *root)
88 {
89 ASSERT(root);
90
91 ArrayBoundsClamperMarker clamper;
92 root->traverse(&clamper);
93 if (clamper.GetNeedsClamp())
94 {
95 SetArrayBoundsClampDefinitionNeeded();
96 }
97 }
98
OutputClampingFunctionDefinition(TInfoSinkBase & out) const99 void ArrayBoundsClamper::OutputClampingFunctionDefinition(TInfoSinkBase &out) const
100 {
101 if (!mArrayBoundsClampDefinitionNeeded)
102 {
103 return;
104 }
105 if (mClampingStrategy != SH_CLAMP_WITH_USER_DEFINED_INT_CLAMP_FUNCTION)
106 {
107 return;
108 }
109 out << kIntClampBegin << kIntClampDefinition << kIntClampEnd;
110 }
111
112 } // namespace sh
113