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Merge pull request #17225 from geoffw0/aliasperf2
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C++: Improve AliasedSSA performance
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@jketema
jketema authored Oct 21, 2024
2 parents 490f814 + e36a1c7 commit 9ef1a9c
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Showing 8 changed files with 782 additions and 4 deletions.
9 changes: 7 additions & 2 deletions cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/internal/AliasedSSA.qll
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Expand Up @@ -683,8 +683,13 @@ private Overlap getExtentOverlap(MemoryLocation0 def, MemoryLocation0 use) {
def.getVirtualVariable() = use.getVirtualVariable() and
def instanceof EntireAllocationMemoryLocation and
(
// EntireAllocationMemoryLocation exactly overlaps itself.
use instanceof EntireAllocationMemoryLocation and
// EntireAllocationMemoryLocation exactly overlaps any EntireAllocationMemoryLocation for the
// same allocation. Checking the allocation, rather than the memory location itself, ensures
// that we get the right relationship between the "must" and "may" memory locations for that
// allocation.
// Note that if one of the locations is a "may" access, the overlap will be downgraded to
// `MustTotallyOverlap` or `MayPartialOverlap` in `getOverlap()`.
use.(EntireAllocationMemoryLocation).getAnAllocation() = def.getAnAllocation() and
result instanceof MustExactlyOverlap
or
not use instanceof EntireAllocationMemoryLocation and
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62 changes: 62 additions & 0 deletions cpp/ql/test/library-tests/ir/ssa/aliased_ssa_ir.expected
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Expand Up @@ -2200,3 +2200,65 @@ ssa.cpp:
# 439| r439_15(glval<int>) = VariableAddress[#temp439:13] :
# 439| m439_16(int) = Store[#temp439:13] : &:r439_15, r439_14
#-----| Goto -> Block 1

# 442| void NonEscapingParams(void*, void*)
# 442| Block 0
# 442| v442_1(void) = EnterFunction :
# 442| m442_2(unknown) = AliasedDefinition :
# 442| m442_3(unknown) = InitializeNonLocal :
# 442| m442_4(unknown) = Chi : total:m442_2, partial:m442_3
# 442| r442_5(glval<void *>) = VariableAddress[a] :
# 442| m442_6(void *) = InitializeParameter[a] : &:r442_5
# 442| r442_7(void *) = Load[a] : &:r442_5, m442_6
# 442| m442_8(unknown) = InitializeIndirection[a] : &:r442_7
# 442| r442_9(glval<void *>) = VariableAddress[b] :
# 442| m442_10(void *) = InitializeParameter[b] : &:r442_9
# 442| r442_11(void *) = Load[b] : &:r442_9, m442_10
# 442| m442_12(unknown) = InitializeIndirection[b] : &:r442_11
# 444| v444_1(void) = NoOp :
# 442| v442_13(void) = ReturnIndirection[a] : &:r442_7, m442_8
# 442| v442_14(void) = ReturnIndirection[b] : &:r442_11, m442_12
# 442| v442_15(void) = ReturnVoid :
# 442| v442_16(void) = AliasedUse : m442_3
# 442| v442_17(void) = ExitFunction :

# 446| void EscapingParams(void*, void*)
# 446| Block 0
# 446| v446_1(void) = EnterFunction :
# 446| m446_2(unknown) = AliasedDefinition :
# 446| m446_3(unknown) = InitializeNonLocal :
# 446| m446_4(unknown) = Chi : total:m446_2, partial:m446_3
# 446| r446_5(glval<void *>) = VariableAddress[a] :
# 446| m446_6(void *) = InitializeParameter[a] : &:r446_5
# 446| r446_7(void *) = Load[a] : &:r446_5, m446_6
# 446| m446_8(unknown) = InitializeIndirection[a] : &:r446_7
# 446| m446_9(unknown) = Chi : total:m446_4, partial:m446_8
# 446| r446_10(glval<void *>) = VariableAddress[b] :
# 446| m446_11(void *) = InitializeParameter[b] : &:r446_10
# 446| r446_12(void *) = Load[b] : &:r446_10, m446_11
# 446| m446_13(unknown) = InitializeIndirection[b] : &:r446_12
# 446| m446_14(unknown) = Chi : total:m446_9, partial:m446_13
# 448| r448_1(glval<unknown>) = FunctionAddress[Escape] :
# 448| r448_2(glval<void *>) = VariableAddress[a] :
# 448| r448_3(void *) = Load[a] : &:r448_2, m446_6
# 448| v448_4(void) = Call[Escape] : func:r448_1, 0:r448_3
# 448| m448_5(unknown) = ^CallSideEffect : ~m446_14
# 448| m448_6(unknown) = Chi : total:m446_14, partial:m448_5
# 448| v448_7(void) = ^BufferReadSideEffect[0] : &:r448_3, ~m448_6
# 448| m448_8(unknown) = ^BufferMayWriteSideEffect[0] : &:r448_3
# 448| m448_9(unknown) = Chi : total:m448_6, partial:m448_8
# 449| r449_1(glval<unknown>) = FunctionAddress[Escape] :
# 449| r449_2(glval<void *>) = VariableAddress[b] :
# 449| r449_3(void *) = Load[b] : &:r449_2, m446_11
# 449| v449_4(void) = Call[Escape] : func:r449_1, 0:r449_3
# 449| m449_5(unknown) = ^CallSideEffect : ~m448_9
# 449| m449_6(unknown) = Chi : total:m448_9, partial:m449_5
# 449| v449_7(void) = ^BufferReadSideEffect[0] : &:r449_3, ~m449_6
# 449| m449_8(unknown) = ^BufferMayWriteSideEffect[0] : &:r449_3
# 449| m449_9(unknown) = Chi : total:m449_6, partial:m449_8
# 450| v450_1(void) = NoOp :
# 446| v446_15(void) = ReturnIndirection[a] : &:r446_7, ~m449_9
# 446| v446_16(void) = ReturnIndirection[b] : &:r446_12, ~m449_9
# 446| v446_17(void) = ReturnVoid :
# 446| v446_18(void) = AliasedUse : ~m449_9
# 446| v446_19(void) = ExitFunction :
62 changes: 62 additions & 0 deletions cpp/ql/test/library-tests/ir/ssa/aliased_ssa_ir_unsound.expected
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Original file line number Diff line number Diff line change
Expand Up @@ -2200,3 +2200,65 @@ ssa.cpp:
# 439| r439_15(glval<int>) = VariableAddress[#temp439:13] :
# 439| m439_16(int) = Store[#temp439:13] : &:r439_15, r439_14
#-----| Goto -> Block 1

# 442| void NonEscapingParams(void*, void*)
# 442| Block 0
# 442| v442_1(void) = EnterFunction :
# 442| m442_2(unknown) = AliasedDefinition :
# 442| m442_3(unknown) = InitializeNonLocal :
# 442| m442_4(unknown) = Chi : total:m442_2, partial:m442_3
# 442| r442_5(glval<void *>) = VariableAddress[a] :
# 442| m442_6(void *) = InitializeParameter[a] : &:r442_5
# 442| r442_7(void *) = Load[a] : &:r442_5, m442_6
# 442| m442_8(unknown) = InitializeIndirection[a] : &:r442_7
# 442| r442_9(glval<void *>) = VariableAddress[b] :
# 442| m442_10(void *) = InitializeParameter[b] : &:r442_9
# 442| r442_11(void *) = Load[b] : &:r442_9, m442_10
# 442| m442_12(unknown) = InitializeIndirection[b] : &:r442_11
# 444| v444_1(void) = NoOp :
# 442| v442_13(void) = ReturnIndirection[a] : &:r442_7, m442_8
# 442| v442_14(void) = ReturnIndirection[b] : &:r442_11, m442_12
# 442| v442_15(void) = ReturnVoid :
# 442| v442_16(void) = AliasedUse : m442_3
# 442| v442_17(void) = ExitFunction :

# 446| void EscapingParams(void*, void*)
# 446| Block 0
# 446| v446_1(void) = EnterFunction :
# 446| m446_2(unknown) = AliasedDefinition :
# 446| m446_3(unknown) = InitializeNonLocal :
# 446| m446_4(unknown) = Chi : total:m446_2, partial:m446_3
# 446| r446_5(glval<void *>) = VariableAddress[a] :
# 446| m446_6(void *) = InitializeParameter[a] : &:r446_5
# 446| r446_7(void *) = Load[a] : &:r446_5, m446_6
# 446| m446_8(unknown) = InitializeIndirection[a] : &:r446_7
# 446| m446_9(unknown) = Chi : total:m446_4, partial:m446_8
# 446| r446_10(glval<void *>) = VariableAddress[b] :
# 446| m446_11(void *) = InitializeParameter[b] : &:r446_10
# 446| r446_12(void *) = Load[b] : &:r446_10, m446_11
# 446| m446_13(unknown) = InitializeIndirection[b] : &:r446_12
# 446| m446_14(unknown) = Chi : total:m446_9, partial:m446_13
# 448| r448_1(glval<unknown>) = FunctionAddress[Escape] :
# 448| r448_2(glval<void *>) = VariableAddress[a] :
# 448| r448_3(void *) = Load[a] : &:r448_2, m446_6
# 448| v448_4(void) = Call[Escape] : func:r448_1, 0:r448_3
# 448| m448_5(unknown) = ^CallSideEffect : ~m446_14
# 448| m448_6(unknown) = Chi : total:m446_14, partial:m448_5
# 448| v448_7(void) = ^BufferReadSideEffect[0] : &:r448_3, ~m448_6
# 448| m448_8(unknown) = ^BufferMayWriteSideEffect[0] : &:r448_3
# 448| m448_9(unknown) = Chi : total:m448_6, partial:m448_8
# 449| r449_1(glval<unknown>) = FunctionAddress[Escape] :
# 449| r449_2(glval<void *>) = VariableAddress[b] :
# 449| r449_3(void *) = Load[b] : &:r449_2, m446_11
# 449| v449_4(void) = Call[Escape] : func:r449_1, 0:r449_3
# 449| m449_5(unknown) = ^CallSideEffect : ~m448_9
# 449| m449_6(unknown) = Chi : total:m448_9, partial:m449_5
# 449| v449_7(void) = ^BufferReadSideEffect[0] : &:r449_3, ~m449_6
# 449| m449_8(unknown) = ^BufferMayWriteSideEffect[0] : &:r449_3
# 449| m449_9(unknown) = Chi : total:m449_6, partial:m449_8
# 450| v450_1(void) = NoOp :
# 446| v446_15(void) = ReturnIndirection[a] : &:r446_7, ~m449_9
# 446| v446_16(void) = ReturnIndirection[b] : &:r446_12, ~m449_9
# 446| v446_17(void) = ReturnVoid :
# 446| v446_18(void) = AliasedUse : ~m449_9
# 446| v446_19(void) = ExitFunction :
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