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Merge pull request #2983 from jbj/definitionReachesRank-perf

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C++: IR: faster definitionReachesRank
This commit is contained in:
Robert Marsh
2020-03-04 09:57:06 -08:00
committed by GitHub
parent c5d39039bc 6b2fd17f03
commit 80ec5c11b3
3 changed files with 33 additions and 30 deletions
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21
cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/internal/SSAConstruction.qll
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@@ -665,17 +665,18 @@ module DefUse {
private predicate definitionReachesRank(
Alias::MemoryLocation useLocation, OldBlock block, int defRank, int reachesRank
) {
// The def always reaches the next use, even if there is also a def on the
// use instruction.
hasDefinitionAtRank(useLocation, _, block, defRank, _) and
reachesRank <= exitRank(useLocation, block) and // Without this, the predicate would be infinite.
(
// The def always reaches the next use, even if there is also a def on the
// use instruction.
reachesRank = defRank + 1
or
// If the def reached the previous rank, it also reaches the current rank,
// unless there was another def at the previous rank.
definitionReachesRank(useLocation, block, defRank, reachesRank - 1) and
not hasDefinitionAtRank(useLocation, _, block, reachesRank - 1, _)
reachesRank = defRank + 1
or
// If the def reached the previous rank, it also reaches the current rank,
// unless there was another def at the previous rank.
exists(int prevRank |
reachesRank = prevRank + 1 and
definitionReachesRank(useLocation, block, defRank, prevRank) and
not prevRank = exitRank(useLocation, block) and
not hasDefinitionAtRank(useLocation, _, block, prevRank, _)
)
}

21
cpp/ql/src/semmle/code/cpp/ir/implementation/unaliased_ssa/internal/SSAConstruction.qll
View File

@@ -665,17 +665,18 @@ module DefUse {
private predicate definitionReachesRank(
Alias::MemoryLocation useLocation, OldBlock block, int defRank, int reachesRank
) {
// The def always reaches the next use, even if there is also a def on the
// use instruction.
hasDefinitionAtRank(useLocation, _, block, defRank, _) and
reachesRank <= exitRank(useLocation, block) and // Without this, the predicate would be infinite.
(
// The def always reaches the next use, even if there is also a def on the
// use instruction.
reachesRank = defRank + 1
or
// If the def reached the previous rank, it also reaches the current rank,
// unless there was another def at the previous rank.
definitionReachesRank(useLocation, block, defRank, reachesRank - 1) and
not hasDefinitionAtRank(useLocation, _, block, reachesRank - 1, _)
reachesRank = defRank + 1
or
// If the def reached the previous rank, it also reaches the current rank,
// unless there was another def at the previous rank.
exists(int prevRank |
reachesRank = prevRank + 1 and
definitionReachesRank(useLocation, block, defRank, prevRank) and
not prevRank = exitRank(useLocation, block) and
not hasDefinitionAtRank(useLocation, _, block, prevRank, _)
)
}