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C++: Fix IRGuards ternary behaviour

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This commit is contained in:
Jeroen Ketema
2023-12-05 12:17:46 +01:00
parent d84961571b
commit 4d702e2eee
2 changed files with 20 additions and 9 deletions
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23
cpp/ql/lib/semmle/code/cpp/controlflow/IRGuards.qll
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@@ -5,6 +5,8 @@
import cpp
import semmle.code.cpp.ir.IR
private import semmle.code.cpp.ir.implementation.raw.internal.TranslatedExpr
private import semmle.code.cpp.ir.implementation.raw.internal.InstructionTag
/**
* Holds if `block` consists of an `UnreachedInstruction`.
@@ -201,10 +203,25 @@ private class GuardConditionFromIR extends GuardCondition {
* `&&` and `||`. See the detailed explanation on predicate `controls`.
*/
private predicate controlsBlock(BasicBlock controlled, boolean testIsTrue) {
exists(IRBlock irb |
exists(IRBlock irb, Instruction instr |
ir.controls(irb, testIsTrue) and
irb.getAnInstruction().getAst().(ControlFlowNode).getBasicBlock() = controlled and
not isUnreachedBlock(irb)
instr = irb.getAnInstruction() and
instr.getAst().(ControlFlowNode).getBasicBlock() = controlled and
not isUnreachedBlock(irb) and
not this.excludeAsControlledInstruction(instr)
)
}
private predicate excludeAsControlledInstruction(Instruction instr) {
// Exclude the temporaries generated by a ternary expression.
exists(TranslatedConditionalExpr tce |
instr = tce.getInstruction(ConditionValueFalseStoreTag())
or
instr = tce.getInstruction(ConditionValueTrueStoreTag())
or
instr = tce.getInstruction(ConditionValueTrueTempAddressTag())
or
instr = tce.getInstruction(ConditionValueFalseTempAddressTag())
)
}
}