| File: | var/lib/jenkins/workspace/firefox-scan-build/dom/xslt/xpath/txXPathOptimizer.cpp |
| Warning: | line 164, column 12 Although the value stored to 'typeTest' is used in the enclosing expression, the value is never actually read from 'typeTest' |
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| 1 | /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
| 2 | /* This Source Code Form is subject to the terms of the Mozilla Public |
| 3 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| 4 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| 5 | |
| 6 | #include "mozilla/Assertions.h" |
| 7 | #include "txXPathOptimizer.h" |
| 8 | #include "txExprResult.h" |
| 9 | #include "nsAtom.h" |
| 10 | #include "nsGkAtoms.h" |
| 11 | #include "txXPathNode.h" |
| 12 | #include "txExpr.h" |
| 13 | #include "txIXPathContext.h" |
| 14 | |
| 15 | class txEarlyEvalContext : public txIEvalContext { |
| 16 | public: |
| 17 | explicit txEarlyEvalContext(txResultRecycler* aRecycler) |
| 18 | : mRecycler(aRecycler) {} |
| 19 | |
| 20 | // txIEvalContext |
| 21 | nsresult getVariable(int32_t aNamespace, nsAtom* aLName, |
| 22 | txAExprResult*& aResult) override { |
| 23 | MOZ_CRASH("shouldn't depend on this context")do { MOZ_ReportCrash("" "shouldn't depend on this context", "/var/lib/jenkins/workspace/firefox-scan-build/dom/xslt/xpath/txXPathOptimizer.cpp" , 23); AnnotateMozCrashReason("MOZ_CRASH(" "shouldn't depend on this context" ")"); do { *((volatile int*)__null) = 23; ::abort(); } while (false); } while (false); |
| 24 | } |
| 25 | nsresult isStripSpaceAllowed(const txXPathNode& aNode, |
| 26 | bool& aAllowed) override { |
| 27 | MOZ_CRASH("shouldn't depend on this context")do { MOZ_ReportCrash("" "shouldn't depend on this context", "/var/lib/jenkins/workspace/firefox-scan-build/dom/xslt/xpath/txXPathOptimizer.cpp" , 27); AnnotateMozCrashReason("MOZ_CRASH(" "shouldn't depend on this context" ")"); do { *((volatile int*)__null) = 27; ::abort(); } while (false); } while (false); |
| 28 | } |
| 29 | void* getPrivateContext() override { |
| 30 | MOZ_CRASH("shouldn't depend on this context")do { MOZ_ReportCrash("" "shouldn't depend on this context", "/var/lib/jenkins/workspace/firefox-scan-build/dom/xslt/xpath/txXPathOptimizer.cpp" , 30); AnnotateMozCrashReason("MOZ_CRASH(" "shouldn't depend on this context" ")"); do { *((volatile int*)__null) = 30; ::abort(); } while (false); } while (false); |
| 31 | } |
| 32 | txResultRecycler* recycler() override { return mRecycler; } |
| 33 | void receiveError(const nsAString& aMsg, nsresult aRes) override {} |
| 34 | const txXPathNode& getContextNode() override { |
| 35 | MOZ_CRASH("shouldn't depend on this context")do { MOZ_ReportCrash("" "shouldn't depend on this context", "/var/lib/jenkins/workspace/firefox-scan-build/dom/xslt/xpath/txXPathOptimizer.cpp" , 35); AnnotateMozCrashReason("MOZ_CRASH(" "shouldn't depend on this context" ")"); do { *((volatile int*)__null) = 35; ::abort(); } while (false); } while (false); |
| 36 | } |
| 37 | uint32_t size() override { MOZ_CRASH("shouldn't depend on this context")do { MOZ_ReportCrash("" "shouldn't depend on this context", "/var/lib/jenkins/workspace/firefox-scan-build/dom/xslt/xpath/txXPathOptimizer.cpp" , 37); AnnotateMozCrashReason("MOZ_CRASH(" "shouldn't depend on this context" ")"); do { *((volatile int*)__null) = 37; ::abort(); } while (false); } while (false); } |
| 38 | uint32_t position() override { |
| 39 | MOZ_CRASH("shouldn't depend on this context")do { MOZ_ReportCrash("" "shouldn't depend on this context", "/var/lib/jenkins/workspace/firefox-scan-build/dom/xslt/xpath/txXPathOptimizer.cpp" , 39); AnnotateMozCrashReason("MOZ_CRASH(" "shouldn't depend on this context" ")"); do { *((volatile int*)__null) = 39; ::abort(); } while (false); } while (false); |
| 40 | } |
| 41 | |
| 42 | private: |
| 43 | txResultRecycler* mRecycler; |
| 44 | }; |
| 45 | |
| 46 | nsresult txXPathOptimizer::optimize(Expr* aInExpr, Expr** aOutExpr) { |
| 47 | *aOutExpr = nullptr; |
| 48 | nsresult rv = NS_OK; |
| 49 | |
| 50 | // First check if the expression will produce the same result |
| 51 | // under any context. |
| 52 | Expr::ExprType exprType = aInExpr->getType(); |
| 53 | if (exprType != Expr::LITERAL_EXPR && |
| 54 | !aInExpr->isSensitiveTo(Expr::ANY_CONTEXT)) { |
| 55 | RefPtr<txResultRecycler> recycler = new txResultRecycler; |
| 56 | txEarlyEvalContext context(recycler); |
| 57 | RefPtr<txAExprResult> exprRes; |
| 58 | |
| 59 | // Don't throw if this fails since it could be that the expression |
| 60 | // is or contains an error-expression. |
| 61 | rv = aInExpr->evaluate(&context, getter_AddRefs(exprRes)); |
| 62 | if (NS_SUCCEEDED(rv)((bool)(__builtin_expect(!!(!NS_FAILED_impl(rv)), 1)))) { |
| 63 | *aOutExpr = new txLiteralExpr(exprRes); |
| 64 | } |
| 65 | |
| 66 | return NS_OK; |
| 67 | } |
| 68 | |
| 69 | // Then optimize sub expressions |
| 70 | uint32_t i = 0; |
| 71 | Expr* subExpr; |
| 72 | while ((subExpr = aInExpr->getSubExprAt(i))) { |
| 73 | Expr* newExpr = nullptr; |
| 74 | rv = optimize(subExpr, &newExpr); |
| 75 | NS_ENSURE_SUCCESS(rv, rv)do { nsresult __rv = rv; if (((bool)(__builtin_expect(!!(NS_FAILED_impl (__rv)), 0)))) { mozilla::SmprintfPointer msg = mozilla::Smprintf ( "NS_ENSURE_SUCCESS(%s, %s) failed with " "result 0x%" "X", "rv" , "rv", static_cast<uint32_t>(__rv)); NS_DebugBreak(NS_DEBUG_WARNING , msg.get(), nullptr, "/var/lib/jenkins/workspace/firefox-scan-build/dom/xslt/xpath/txXPathOptimizer.cpp" , 75); return rv; } } while (false); |
| 76 | if (newExpr) { |
| 77 | delete subExpr; |
| 78 | aInExpr->setSubExprAt(i, newExpr); |
| 79 | } |
| 80 | |
| 81 | ++i; |
| 82 | } |
| 83 | |
| 84 | // Finally see if current expression can be optimized |
| 85 | switch (exprType) { |
| 86 | case Expr::LOCATIONSTEP_EXPR: |
| 87 | return optimizeStep(aInExpr, aOutExpr); |
| 88 | |
| 89 | case Expr::PATH_EXPR: |
| 90 | return optimizePath(aInExpr, aOutExpr); |
| 91 | |
| 92 | case Expr::UNION_EXPR: |
| 93 | return optimizeUnion(aInExpr, aOutExpr); |
| 94 | |
| 95 | default: |
| 96 | break; |
| 97 | } |
| 98 | |
| 99 | return NS_OK; |
| 100 | } |
| 101 | |
| 102 | nsresult txXPathOptimizer::optimizeStep(Expr* aInExpr, Expr** aOutExpr) { |
| 103 | LocationStep* step = static_cast<LocationStep*>(aInExpr); |
| 104 | |
| 105 | if (step->getAxisIdentifier() == LocationStep::ATTRIBUTE_AXIS) { |
| 106 | // Test for @foo type steps. |
| 107 | txNameTest* nameTest = nullptr; |
| 108 | if (!step->getSubExprAt(0) && |
| 109 | step->getNodeTest()->getType() == txNameTest::NAME_TEST && |
| 110 | (nameTest = static_cast<txNameTest*>(step->getNodeTest())) |
| 111 | ->mLocalName != nsGkAtoms::_asterisk) { |
| 112 | *aOutExpr = new txNamedAttributeStep( |
| 113 | nameTest->mNamespace, nameTest->mPrefix, nameTest->mLocalName); |
| 114 | return NS_OK; // return since we no longer have a step-object. |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | // Test for predicates that can be combined into the nodetest |
| 119 | Expr* pred; |
| 120 | while ((pred = step->getSubExprAt(0)) && |
| 121 | !pred->canReturnType(Expr::NUMBER_RESULT) && |
| 122 | !pred->isSensitiveTo(Expr::NODESET_CONTEXT)) { |
| 123 | txNodeTest* predTest = new txPredicatedNodeTest(step->getNodeTest(), pred); |
| 124 | step->dropFirst(); |
| 125 | step->setNodeTest(predTest); |
| 126 | } |
| 127 | |
| 128 | return NS_OK; |
| 129 | } |
| 130 | |
| 131 | nsresult txXPathOptimizer::optimizePath(Expr* aInExpr, Expr** aOutExpr) { |
| 132 | PathExpr* path = static_cast<PathExpr*>(aInExpr); |
| 133 | |
| 134 | uint32_t i; |
| 135 | Expr* subExpr; |
| 136 | // look for steps like "//foo" that can be turned into "/descendant::foo" |
| 137 | // and "//." that can be turned into "/descendant-or-self::node()" |
| 138 | for (i = 0; (subExpr = path->getSubExprAt(i)); ++i) { |
| 139 | if (path->getPathOpAt(i) == PathExpr::DESCENDANT_OP && |
| 140 | subExpr->getType() == Expr::LOCATIONSTEP_EXPR && |
| 141 | !subExpr->getSubExprAt(0)) { |
| 142 | LocationStep* step = static_cast<LocationStep*>(subExpr); |
| 143 | if (step->getAxisIdentifier() == LocationStep::CHILD_AXIS) { |
| 144 | step->setAxisIdentifier(LocationStep::DESCENDANT_AXIS); |
| 145 | path->setPathOpAt(i, PathExpr::RELATIVE_OP); |
| 146 | } else if (step->getAxisIdentifier() == LocationStep::SELF_AXIS) { |
| 147 | step->setAxisIdentifier(LocationStep::DESCENDANT_OR_SELF_AXIS); |
| 148 | path->setPathOpAt(i, PathExpr::RELATIVE_OP); |
| 149 | } |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | // look for expressions that start with a "./" |
| 154 | subExpr = path->getSubExprAt(0); |
| 155 | LocationStep* step; |
| 156 | if (subExpr->getType() == Expr::LOCATIONSTEP_EXPR && path->getSubExprAt(1) && |
| 157 | path->getPathOpAt(1) != PathExpr::DESCENDANT_OP) { |
| 158 | step = static_cast<LocationStep*>(subExpr); |
| 159 | if (step->getAxisIdentifier() == LocationStep::SELF_AXIS && |
| 160 | !step->getSubExprAt(0)) { |
| 161 | txNodeTest* test = step->getNodeTest(); |
| 162 | txNodeTypeTest* typeTest; |
| 163 | if (test->getType() == txNodeTest::NODETYPE_TEST && |
| 164 | (typeTest = static_cast<txNodeTypeTest*>(test))->getNodeTestType() == |
Although the value stored to 'typeTest' is used in the enclosing expression, the value is never actually read from 'typeTest' | |
| 165 | txNodeTypeTest::NODE_TYPE) { |
| 166 | // We have a '.' as first step followed by a single '/'. |
| 167 | |
| 168 | // Check if there are only two steps. If so, return the second |
| 169 | // as resulting expression. |
| 170 | if (!path->getSubExprAt(2)) { |
| 171 | *aOutExpr = path->getSubExprAt(1); |
| 172 | path->setSubExprAt(1, nullptr); |
| 173 | |
| 174 | return NS_OK; |
| 175 | } |
| 176 | |
| 177 | // Just delete the '.' step and leave the rest of the PathExpr |
| 178 | path->deleteExprAt(0); |
| 179 | } |
| 180 | } |
| 181 | } |
| 182 | |
| 183 | return NS_OK; |
| 184 | } |
| 185 | |
| 186 | nsresult txXPathOptimizer::optimizeUnion(Expr* aInExpr, Expr** aOutExpr) { |
| 187 | UnionExpr* uni = static_cast<UnionExpr*>(aInExpr); |
| 188 | |
| 189 | // Check for expressions like "foo | bar" and |
| 190 | // "descendant::foo | descendant::bar" |
| 191 | |
| 192 | nsresult rv; |
| 193 | uint32_t current; |
| 194 | Expr* subExpr; |
| 195 | for (current = 0; (subExpr = uni->getSubExprAt(current)); ++current) { |
| 196 | if (subExpr->getType() != Expr::LOCATIONSTEP_EXPR || |
| 197 | subExpr->getSubExprAt(0)) { |
| 198 | continue; |
| 199 | } |
| 200 | |
| 201 | LocationStep* currentStep = static_cast<LocationStep*>(subExpr); |
| 202 | LocationStep::LocationStepType axis = currentStep->getAxisIdentifier(); |
| 203 | |
| 204 | txUnionNodeTest* unionTest = nullptr; |
| 205 | |
| 206 | // Check if there are any other steps with the same axis and merge |
| 207 | // them with currentStep |
| 208 | uint32_t i; |
| 209 | for (i = current + 1; (subExpr = uni->getSubExprAt(i)); ++i) { |
| 210 | if (subExpr->getType() != Expr::LOCATIONSTEP_EXPR || |
| 211 | subExpr->getSubExprAt(0)) { |
| 212 | continue; |
| 213 | } |
| 214 | |
| 215 | LocationStep* step = static_cast<LocationStep*>(subExpr); |
| 216 | if (step->getAxisIdentifier() != axis) { |
| 217 | continue; |
| 218 | } |
| 219 | |
| 220 | // Create a txUnionNodeTest if needed |
| 221 | if (!unionTest) { |
| 222 | nsAutoPtr<txNodeTest> owner(unionTest = new txUnionNodeTest); |
| 223 | rv = unionTest->addNodeTest(currentStep->getNodeTest()); |
| 224 | NS_ENSURE_SUCCESS(rv, rv)do { nsresult __rv = rv; if (((bool)(__builtin_expect(!!(NS_FAILED_impl (__rv)), 0)))) { mozilla::SmprintfPointer msg = mozilla::Smprintf ( "NS_ENSURE_SUCCESS(%s, %s) failed with " "result 0x%" "X", "rv" , "rv", static_cast<uint32_t>(__rv)); NS_DebugBreak(NS_DEBUG_WARNING , msg.get(), nullptr, "/var/lib/jenkins/workspace/firefox-scan-build/dom/xslt/xpath/txXPathOptimizer.cpp" , 224); return rv; } } while (false); |
| 225 | |
| 226 | currentStep->setNodeTest(unionTest); |
| 227 | owner.forget(); |
| 228 | } |
| 229 | |
| 230 | // Merge the nodetest into the union |
| 231 | rv = unionTest->addNodeTest(step->getNodeTest()); |
| 232 | NS_ENSURE_SUCCESS(rv, rv)do { nsresult __rv = rv; if (((bool)(__builtin_expect(!!(NS_FAILED_impl (__rv)), 0)))) { mozilla::SmprintfPointer msg = mozilla::Smprintf ( "NS_ENSURE_SUCCESS(%s, %s) failed with " "result 0x%" "X", "rv" , "rv", static_cast<uint32_t>(__rv)); NS_DebugBreak(NS_DEBUG_WARNING , msg.get(), nullptr, "/var/lib/jenkins/workspace/firefox-scan-build/dom/xslt/xpath/txXPathOptimizer.cpp" , 232); return rv; } } while (false); |
| 233 | |
| 234 | step->setNodeTest(nullptr); |
| 235 | |
| 236 | // Remove the step from the UnionExpr |
| 237 | uni->deleteExprAt(i); |
| 238 | --i; |
| 239 | } |
| 240 | |
| 241 | // Check if all expressions were merged into a single step. If so, |
| 242 | // return the step as the new expression. |
| 243 | if (unionTest && current == 0 && !uni->getSubExprAt(1)) { |
| 244 | // Make sure the step doesn't get deleted when the UnionExpr is |
| 245 | uni->setSubExprAt(0, nullptr); |
| 246 | *aOutExpr = currentStep; |
| 247 | |
| 248 | // Return right away since we no longer have a union |
| 249 | return NS_OK; |
| 250 | } |
| 251 | } |
| 252 | |
| 253 | return NS_OK; |
| 254 | } |