hohn/codeql
1
0
Fork 0
mirror of https://github.com/github/codeql.git synced 2026-05-05 13:45:19 +02:00
Code Issues Packages Projects Releases Wiki Activity

C++: handle degenerate phi nodes

Browse Source
This commit is contained in:
Robert Marsh
2021-04-19 17:21:34 -07:00
parent 7930c4ab19
commit 6600436dd9
5 changed files with 23 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/internal/SSAConstruction.qll
View File

@@ -43,11 +43,25 @@ private module Cached {
class TStageInstruction =
TRawInstruction or TPhiInstruction or TChiInstruction or TUnreachedInstruction;
/**
* If `oldInstruction` is a `Phi` instruction that has exactly one reachable predecessor block,
* this predicate returns the `PhiInputOperand` corresponding to that predecessor block.
* Otherwise, this predicate does not hold.
*/
private OldIR::PhiInputOperand getDegeneratePhiOperand(OldInstruction oldInstruction) {
result =
unique(OldIR::PhiInputOperand operand |
operand = oldInstruction.(OldIR::PhiInstruction).getAnInputOperand() and
operand.getPredecessorBlock() instanceof OldBlock
)
}
cached
predicate hasInstruction(TStageInstruction instr) {
instr instanceof TRawInstruction and instr instanceof OldInstruction
or
instr instanceof TPhiInstruction
instr instanceof TPhiInstruction and
not exists(getDegeneratePhiOperand(instr))
or
instr instanceof TChiInstruction
or
@@ -150,16 +164,13 @@ private module Cached {
(
result = getNewInstruction(oldOperand.getAnyDef()) and
overlap = originalOverlap
/*
* or
* exists(OldIR::PhiInputOperand phiOperand, Overlap phiOperandOverlap |
* phiOperand = getDegeneratePhiOperand(oldOperand.getAnyDef()) and
* result = getNewDefinitionFromOldSSA(phiOperand, phiOperandOverlap) and
* overlap = combineOverlap(phiOperandOverlap, originalOverlap)
* )
*/
or
exists(OldIR::PhiInputOperand phiOperand, Overlap phiOperandOverlap |
phiOperand = getDegeneratePhiOperand(oldOperand.getAnyDef()) and
result = getNewDefinitionFromOldSSA(phiOperand, phiOperandOverlap) and
overlap = combineOverlap(phiOperandOverlap, originalOverlap)
)
)
)
}

4
cpp/ql/test/library-tests/ir/ssa/aliased_ssa_consistency.expected
View File

@@ -10,13 +10,9 @@ instructionWithoutSuccessor
ambiguousSuccessors
unexplainedLoop
unnecessaryPhiInstruction
| ssa.cpp:345:3:345:13 | Phi: return ... | Instruction 'Phi: return ...' is in a block with only 0 predecessors in function '$@'. | ssa.cpp:335:5:335:25 | int UnreachablePhiOperand(int, int) | int UnreachablePhiOperand(int, int) |
| ssa.cpp:395:5:395:5 | Phi: ; | Instruction 'Phi: ;' is in a block with only 0 predecessors in function '$@'. | ssa.cpp:383:5:383:24 | int FusedBlockPhiOperand(int, int, int, bool) | int FusedBlockPhiOperand(int, int, int, bool) |
memoryOperandDefinitionIsUnmodeled
operandAcrossFunctions
instructionWithoutUniqueBlock
| ssa.cpp:345:3:345:13 | Phi: return ... | Instruction 'Phi: return ...' is a member of 0 blocks in function '$@'. | ssa.cpp:335:5:335:25 | int UnreachablePhiOperand(int, int) | int UnreachablePhiOperand(int, int) |
| ssa.cpp:395:5:395:5 | Phi: ; | Instruction 'Phi: ;' is a member of 0 blocks in function '$@'. | ssa.cpp:383:5:383:24 | int FusedBlockPhiOperand(int, int, int, bool) | int FusedBlockPhiOperand(int, int, int, bool) |
containsLoopOfForwardEdges
lostReachability
backEdgeCountMismatch

4
cpp/ql/test/library-tests/ir/ssa/aliased_ssa_consistency_unsound.expected
View File

@@ -10,13 +10,9 @@ instructionWithoutSuccessor
ambiguousSuccessors
unexplainedLoop
unnecessaryPhiInstruction
| ssa.cpp:345:3:345:13 | Phi: return ... | Instruction 'Phi: return ...' is in a block with only 0 predecessors in function '$@'. | ssa.cpp:335:5:335:25 | int UnreachablePhiOperand(int, int) | int UnreachablePhiOperand(int, int) |
| ssa.cpp:395:5:395:5 | Phi: ; | Instruction 'Phi: ;' is in a block with only 0 predecessors in function '$@'. | ssa.cpp:383:5:383:24 | int FusedBlockPhiOperand(int, int, int, bool) | int FusedBlockPhiOperand(int, int, int, bool) |
memoryOperandDefinitionIsUnmodeled
operandAcrossFunctions
instructionWithoutUniqueBlock
| ssa.cpp:345:3:345:13 | Phi: return ... | Instruction 'Phi: return ...' is a member of 0 blocks in function '$@'. | ssa.cpp:335:5:335:25 | int UnreachablePhiOperand(int, int) | int UnreachablePhiOperand(int, int) |
| ssa.cpp:395:5:395:5 | Phi: ; | Instruction 'Phi: ;' is a member of 0 blocks in function '$@'. | ssa.cpp:383:5:383:24 | int FusedBlockPhiOperand(int, int, int, bool) | int FusedBlockPhiOperand(int, int, int, bool) |
containsLoopOfForwardEdges
lostReachability
backEdgeCountMismatch

2
cpp/ql/test/library-tests/ir/ssa/aliased_ssa_ir.expected
View File

@@ -1618,7 +1618,7 @@ ssa.cpp:
# 340| m340_4(int) = Store[ret] : &:r340_3, r340_2
# 345| r345_1(glval<int>) = VariableAddress[#return] :
# 345| r345_2(glval<int>) = VariableAddress[ret] :
# 345| r345_3(int) = Load[ret] : &:r345_2
# 345| r345_3(int) = Load[ret] : &:r345_2, m340_4
# 345| m345_4(int) = Store[#return] : &:r345_1, r345_3
# 335| r335_9(glval<int>) = VariableAddress[#return] :
# 335| v335_10(void) = ReturnValue : &:r335_9, m345_4

2
cpp/ql/test/library-tests/ir/ssa/aliased_ssa_ir_unsound.expected
View File

@@ -1608,7 +1608,7 @@ ssa.cpp:
# 340| m340_4(int) = Store[ret] : &:r340_3, r340_2
# 345| r345_1(glval<int>) = VariableAddress[#return] :
# 345| r345_2(glval<int>) = VariableAddress[ret] :
# 345| r345_3(int) = Load[ret] : &:r345_2
# 345| r345_3(int) = Load[ret] : &:r345_2, m340_4
# 345| m345_4(int) = Store[#return] : &:r345_1, r345_3
# 335| r335_9(glval<int>) = VariableAddress[#return] :
# 335| v335_10(void) = ReturnValue : &:r335_9, m345_4