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GeezerVison is showing github.com — C++: Implement a pruning version of 'getAnUltimateDefinition'. · github/codeql@393512f

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  • cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal
    • DataFlowUtil.qll
    • SsaImpl.qll
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‎cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll‎

Copy file name to clipboardExpand all lines: cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll
+2Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1018,4 +1018,6 @@ module Ssa {
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class IndirectExplicitDefinition = SsaImpl::IndirectExplicitDefinition;
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class PhiNode = SsaImpl::PhiNode;
1021+
1022+
import SsaImpl::Public
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}
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‎cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaImpl.qll‎

Copy file name to clipboardExpand all lines: cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaImpl.qll
+77-7Lines changed: 77 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1405,14 +1405,80 @@ private class PhiCycle extends PhiCycleEquivalence::EquivalenceClass {
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}
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}
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1408-
/** An static single assignment (SSA) definition. */
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class Definition extends SsaImpl::Definition {
1410-
private Definition getAPhiInputOrPriorDefinition() {
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result = this.(PhiNode).getAnInput()
1412-
or
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uncertainWriteDefinitionInput(this, result)
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private Definition getAPhiInputOrPriorDefinition(Definition def) {
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result = def.(PhiNode).getAnInput()
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or
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uncertainWriteDefinitionInput(def, result)
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}
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module Public {
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/**
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* A module signature to define relevant ultimate definitions for an
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* optimized version of `Definition.getAnUltimateDefinition`.
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*/
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signature module GetAnUltimateDefinitionSig {
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/**
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* Holds if `def` is a relevant definition. This defines the set
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* of `Definition`s which may be returned by
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* `GetAnUltimateDefinition::getAnUltimateDefinition`.
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*/
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predicate isRelevantUltimateDefinition(Definition def);
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}
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/**
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* A module which constructs an optimized version of
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* ```
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* Definition.getAnUltimateDefinition
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* ```
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* by restricting the set of possible ultimate definitions.
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*
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* Use this module by defining a module `M` which implements
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* `GetAnUltimateDefinitionSig` and then call:
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* ```
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* GetAnUltimateDefinition<M>::getAnUltimateDefinition
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* ```
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*/
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module GetAnUltimateDefinition<GetAnUltimateDefinitionSig Sig> {
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private import Sig
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private predicate relevantUltimateDefinition(Definition def) {
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isRelevantUltimateDefinition(def) and
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not def instanceof PhiNode
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}
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private predicate fwd(Definition def) {
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relevantUltimateDefinition(def)
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or
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exists(Definition def0 |
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fwd(def0) and
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def0 = getAPhiInputOrPriorDefinition(def)
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)
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}
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private predicate step(Definition def1, Definition def2) {
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fwd(def1) and
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fwd(def2) and
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def1 = getAPhiInputOrPriorDefinition(def2)
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}
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/**
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* Gets a definition that ultimately defines this SSA definition and is
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* not itself a phi node.
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*
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* This predicate is restricted to ultimate definitions which
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* satisfy `isRelevantUltimateDefinition`.
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*/
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Definition getAnUltimateDefinition(Definition def) {
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step*(result, def) and
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relevantUltimateDefinition(result)
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}
14141475
}
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}
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1478+
import Public
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/** An static single assignment (SSA) definition. */
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class Definition extends SsaImpl::Definition {
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/**
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* Holds if this SSA definition is live at the end of basic block `bb`.
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* That is, this definition reaches the end of basic block `bb`, at which
@@ -1424,9 +1490,13 @@ class Definition extends SsaImpl::Definition {
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/**
14251491
* Gets a definition that ultimately defines this SSA definition and is
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* not itself a phi node.
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*
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* Note: A more efficient implementation of this predicate exists. See the
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* `GetAnUltimateDefinition` module for a description of how to access
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* the more efficient implementation.
14271497
*/
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final Definition getAnUltimateDefinition() {
1429-
result = this.getAPhiInputOrPriorDefinition*() and
1499+
result = getAPhiInputOrPriorDefinition*(this) and
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not result instanceof PhiNode
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}
14321502

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