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C++: handle phi operands from unreachable blocks

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This commit is contained in:
Robert Marsh
2021-04-20 16:47:20 -07:00
parent 6600436dd9
commit 195b811422
6 changed files with 30 additions and 17 deletions
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20
cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/internal/SSAConstruction.qll
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@@ -68,8 +68,22 @@ private module Cached {
instr instanceof TUnreachedInstruction
}
private IRBlock getNewBlock(OldBlock oldBlock) {
result.getFirstInstruction() = getNewInstruction(oldBlock.getFirstInstruction())
cached IRBlock getNewBlock(OldBlock oldBlock) {
exists(Instruction newEnd, OldIR::Instruction oldEnd |
(
result.getLastInstruction() = newEnd and
not newEnd instanceof ChiInstruction
or
newEnd = result.getLastInstruction().(ChiInstruction).getAPredecessor() // does this work?
) and
(
oldBlock.getLastInstruction() = oldEnd and
not oldEnd instanceof OldIR::ChiInstruction
or
oldEnd = oldBlock.getLastInstruction().(OldIR::ChiInstruction).getAPredecessor() // does this work?
) and
oldEnd = getNewInstruction(newEnd)
)
}
/**
@@ -164,7 +178,7 @@ private module Cached {
(
result = getNewInstruction(oldOperand.getAnyDef()) and
overlap = originalOverlap
or
or
exists(OldIR::PhiInputOperand phiOperand, Overlap phiOperandOverlap |
phiOperand = getDegeneratePhiOperand(oldOperand.getAnyDef()) and
result = getNewDefinitionFromOldSSA(phiOperand, phiOperandOverlap) and

21
cpp/ql/src/semmle/code/cpp/ir/implementation/internal/TOperand.qll
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@@ -36,10 +36,9 @@ private module Internal {
useInstr.getOpcode().hasOperand(tag)
} or
TUnaliasedPhiOperand(
Unaliased::PhiInstruction useInstr, Unaliased::Instruction defInstr,
Unaliased::IRBlock predecessorBlock, Overlap overlap
Unaliased::PhiInstruction useInstr, Unaliased::IRBlock predecessorBlock, Overlap overlap
) {
defInstr = UnaliasedConstruction::getPhiOperandDefinition(useInstr, predecessorBlock, overlap)
exists(UnaliasedConstruction::getPhiOperandDefinition(useInstr, predecessorBlock, overlap))
} or
//// ALIASED
////
@@ -50,10 +49,9 @@ private module Internal {
// important that we use the same definition of "is variable aliased" across
// the phases.
TAliasedPhiOperand(
TAliasedSSAPhiInstruction useInstr, Aliased::Instruction defInstr,
Aliased::IRBlock predecessorBlock, Overlap overlap
TAliasedSSAPhiInstruction useInstr, Aliased::IRBlock predecessorBlock, Overlap overlap
) {
defInstr = AliasedConstruction::getPhiOperandDefinition(useInstr, predecessorBlock, overlap)
exists(AliasedConstruction::getPhiOperandDefinition(useInstr, predecessorBlock, overlap))
} or
TAliasedChiOperand(TAliasedSSAChiInstruction useInstr, ChiOperandTag tag) { any() }
}
@@ -144,7 +142,8 @@ module UnaliasedSSAOperands {
Unaliased::PhiInstruction useInstr, Unaliased::Instruction defInstr,
Unaliased::IRBlock predecessorBlock, Overlap overlap
) {
result = Internal::TUnaliasedPhiOperand(useInstr, defInstr, predecessorBlock, overlap)
defInstr = UnaliasedConstruction::getPhiOperandDefinition(useInstr, predecessorBlock, overlap) and
result = Internal::TUnaliasedPhiOperand(useInstr, predecessorBlock, overlap)
}
TPhiOperand reusedPhiOperand(
@@ -182,7 +181,8 @@ module AliasedSSAOperands {
Aliased::PhiInstruction useInstr, Aliased::Instruction defInstr,
Aliased::IRBlock predecessorBlock, Overlap overlap
) {
result = Internal::TAliasedPhiOperand(useInstr, defInstr, predecessorBlock, overlap)
defInstr = AliasedConstruction::getPhiOperandDefinition(useInstr, predecessorBlock, overlap) and
result = Internal::TAliasedPhiOperand(useInstr, predecessorBlock, overlap)
}
/**
@@ -193,8 +193,9 @@ module AliasedSSAOperands {
Aliased::IRBlock predecessorBlock, Overlap overlap
) {
exists(Unaliased::IRBlock oldBlock |
predecessorBlock.getFirstInstruction() = oldBlock.getFirstInstruction() and
result = Internal::TUnaliasedPhiOperand(useInstr, defInstr, oldBlock, overlap)
predecessorBlock = AliasedConstruction::getNewBlock(oldBlock) and
result = Internal::TUnaliasedPhiOperand(useInstr, oldBlock, _) and
defInstr = AliasedConstruction::getPhiOperandDefinition(useInstr, predecessorBlock, overlap)
)
}

1
cpp/ql/test/library-tests/ir/ssa/aliased_ssa_consistency.expected
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@@ -2,7 +2,6 @@ missingOperand
unexpectedOperand
duplicateOperand
missingPhiOperand
| ssa.cpp:398:3:398:13 | Phi: return ... | Instruction 'Phi: return ...' is missing an operand for predecessor block 'VariableAddress: y' in function '$@'. | ssa.cpp:383:5:383:24 | int FusedBlockPhiOperand(int, int, int, bool) | int FusedBlockPhiOperand(int, int, int, bool) |
missingOperandType
duplicateChiOperand
sideEffectWithoutPrimary

1
cpp/ql/test/library-tests/ir/ssa/aliased_ssa_consistency_unsound.expected
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@@ -2,7 +2,6 @@ missingOperand
unexpectedOperand
duplicateOperand
missingPhiOperand
| ssa.cpp:398:3:398:13 | Phi: return ... | Instruction 'Phi: return ...' is missing an operand for predecessor block 'VariableAddress: y' in function '$@'. | ssa.cpp:383:5:383:24 | int FusedBlockPhiOperand(int, int, int, bool) | int FusedBlockPhiOperand(int, int, int, bool) |
missingOperandType
duplicateChiOperand
sideEffectWithoutPrimary

2
cpp/ql/test/library-tests/ir/ssa/aliased_ssa_ir.expected
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@@ -1802,7 +1802,7 @@ ssa.cpp:
#-----| Goto -> Block 4
# 398| Block 4
# 398| m398_1(int) = Phi : from 1:m388_4
# 398| m398_1(int) = Phi : from 1:m388_4, from 3:m391_4
# 398| r398_2(glval<int>) = VariableAddress[#return] :
# 398| r398_3(glval<int>) = VariableAddress[ret] :
# 398| r398_4(int) = Load[ret] : &:r398_3, m398_1

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

@@ -1792,7 +1792,7 @@ ssa.cpp:
#-----| Goto -> Block 4
# 398| Block 4
# 398| m398_1(int) = Phi : from 1:m388_4
# 398| m398_1(int) = Phi : from 1:m388_4, from 3:m391_4
# 398| r398_2(glval<int>) = VariableAddress[#return] :
# 398| r398_3(glval<int>) = VariableAddress[ret] :
# 398| r398_4(int) = Load[ret] : &:r398_3, m398_1