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C++: allow phi nodes to self-bound

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This commit is contained in:
Robert Marsh
2018-12-13 11:55:55 -08:00
parent b2cd9a29f2
commit 567eee1114
3 changed files with 20 additions and 5 deletions
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9
cpp/ql/src/semmle/code/cpp/rangeanalysis/RangeAnalysis.qll
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@@ -118,7 +118,7 @@ private import RangeAnalysisCache
import RangeAnalysisPublic
/**
* Gets a condition that tests whether `op` equals `bound + delta`.
* Gets a condition that tests whether `vn` equals `bound + delta`.
*
* If the condition evaluates to `testIsTrue`:
* - `isEq = true` : `i == bound + delta`
@@ -151,11 +151,11 @@ private predicate boundFlowStepSsa(
}
/**
* Gets a condition that tests whether `op` is bounded by `bound + delta`.
* Gets a condition that tests whether `vn` is bounded by `bound + delta`.
*
* If the condition evaluates to `testIsTrue`:
* - `upper = true` : `op <= bound + delta`
* - `upper = false` : `op >= bound + delta`
* - `upper = true` : `vn <= bound + delta`
* - `upper = false` : `vn >= bound + delta`
*/
private IRGuardCondition boundFlowCond(ValueNumber vn, NonPhiOperand bound, int delta, boolean upper,
boolean testIsTrue)
@@ -549,7 +549,6 @@ private predicate boundedInstruction(
boundedPhiCandValidForEdge(i, b, delta, upper, fromBackEdge, origdelta, reason, op)
)
or
not i instanceof PhiInstruction and
i = b.getInstruction(delta) and
(upper = true or upper = false) and
fromBackEdge = false and