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C++: remove some side-effect instructions

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This leverages the existing alias analysis to identify functions which
have no reads or writes of the AllAliasedMemory virtual variable, and
therefore have no global side effects. A recursion over the call graph
identifies functions which have no indirect global side effects, and
calls to those functions have their global side effect instructions
removed.
This commit is contained in:
Robert Marsh
2022-07-29 10:38:13 -04:00
parent 4ae218729a
commit d324969d68
6 changed files with 325 additions and 508 deletions
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657
cpp/ql/test/library-tests/ir/ir/operand_locations.expected
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File diff suppressed because it is too large Load Diff

78
cpp/ql/test/library-tests/ir/ssa/aliased_ssa_ir.expected
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@@ -1050,46 +1050,36 @@ ssa.cpp:
# 240| r240_3(glval<unknown>) = FunctionAddress[Constructible] :
# 240| r240_4(int) = Constant[1] :
# 240| v240_5(void) = Call[Constructible] : func:r240_3, this:r240_1, 0:r240_4
# 240| m240_6(unknown) = ^CallSideEffect : ~m239_4
# 240| m240_7(unknown) = Chi : total:m239_4, partial:m240_6
# 240| m240_8(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r240_1
# 240| m240_9(Constructible) = Chi : total:m240_2, partial:m240_8
# 240| m240_6(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r240_1
# 240| m240_7(Constructible) = Chi : total:m240_2, partial:m240_6
# 241| r241_1(glval<Constructible>) = VariableAddress[c] :
# 241| r241_2(glval<unknown>) = FunctionAddress[g] :
# 241| v241_3(void) = Call[g] : func:r241_2, this:r241_1
# 241| m241_4(unknown) = ^CallSideEffect : ~m240_7
# 241| m241_5(unknown) = Chi : total:m240_7, partial:m241_4
# 241| v241_6(void) = ^IndirectReadSideEffect[-1] : &:r241_1, m240_9
# 241| m241_7(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r241_1
# 241| m241_8(Constructible) = Chi : total:m240_9, partial:m241_7
# 241| v241_4(void) = ^IndirectReadSideEffect[-1] : &:r241_1, m240_7
# 241| m241_5(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r241_1
# 241| m241_6(Constructible) = Chi : total:m240_7, partial:m241_5
# 242| r242_1(glval<Constructible>) = VariableAddress[c] :
# 242| r242_2(glval<unknown>) = FunctionAddress[g] :
# 242| v242_3(void) = Call[g] : func:r242_2, this:r242_1
# 242| m242_4(unknown) = ^CallSideEffect : ~m241_5
# 242| m242_5(unknown) = Chi : total:m241_5, partial:m242_4
# 242| v242_6(void) = ^IndirectReadSideEffect[-1] : &:r242_1, m241_8
# 242| m242_7(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r242_1
# 242| m242_8(Constructible) = Chi : total:m241_8, partial:m242_7
# 242| v242_4(void) = ^IndirectReadSideEffect[-1] : &:r242_1, m241_6
# 242| m242_5(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r242_1
# 242| m242_6(Constructible) = Chi : total:m241_6, partial:m242_5
# 243| r243_1(glval<Constructible>) = VariableAddress[c2] :
# 243| m243_2(Constructible) = Uninitialized[c2] : &:r243_1
# 243| r243_3(glval<unknown>) = FunctionAddress[Constructible] :
# 243| r243_4(int) = Constant[2] :
# 243| v243_5(void) = Call[Constructible] : func:r243_3, this:r243_1, 0:r243_4
# 243| m243_6(unknown) = ^CallSideEffect : ~m242_5
# 243| m243_7(unknown) = Chi : total:m242_5, partial:m243_6
# 243| m243_8(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r243_1
# 243| m243_9(Constructible) = Chi : total:m243_2, partial:m243_8
# 243| m243_6(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r243_1
# 243| m243_7(Constructible) = Chi : total:m243_2, partial:m243_6
# 244| r244_1(glval<Constructible>) = VariableAddress[c2] :
# 244| r244_2(glval<unknown>) = FunctionAddress[g] :
# 244| v244_3(void) = Call[g] : func:r244_2, this:r244_1
# 244| m244_4(unknown) = ^CallSideEffect : ~m243_7
# 244| m244_5(unknown) = Chi : total:m243_7, partial:m244_4
# 244| v244_6(void) = ^IndirectReadSideEffect[-1] : &:r244_1, m243_9
# 244| m244_7(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r244_1
# 244| m244_8(Constructible) = Chi : total:m243_9, partial:m244_7
# 244| v244_4(void) = ^IndirectReadSideEffect[-1] : &:r244_1, m243_7
# 244| m244_5(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r244_1
# 244| m244_6(Constructible) = Chi : total:m243_7, partial:m244_5
# 245| v245_1(void) = NoOp :
# 239| v239_5(void) = ReturnVoid :
# 239| v239_6(void) = AliasedUse : ~m244_5
# 239| v239_6(void) = AliasedUse : m239_3
# 239| v239_7(void) = ExitFunction :
# 247| char* VoidStarIndirectParameters(char*, int)
@@ -1391,43 +1381,37 @@ ssa.cpp:
# 294| r294_18(glval<int>) = VariableAddress[x] :
# 294| r294_19(int) = Load[x] : &:r294_18, m291_6
# 294| v294_20(void) = Call[A] : func:r294_17, this:r294_16, 0:r294_19
# 294| m294_21(unknown) = ^CallSideEffect : ~m294_14
# 294| m294_22(unknown) = Chi : total:m294_14, partial:m294_21
# 294| m294_23(A) = ^IndirectMayWriteSideEffect[-1] : &:r294_16
# 294| m294_24(unknown) = Chi : total:m294_15, partial:m294_23
# 294| v294_25(void) = Call[A] : func:r294_9, this:r294_8, 0:r294_16
# 294| m294_26(unknown) = ^CallSideEffect : ~m294_22
# 294| m294_27(unknown) = Chi : total:m294_22, partial:m294_26
# 294| v294_28(void) = ^BufferReadSideEffect[0] : &:r294_16, ~m294_24
# 294| m294_29(A) = ^IndirectMayWriteSideEffect[-1] : &:r294_8
# 294| m294_30(unknown) = Chi : total:m294_7, partial:m294_29
# 294| m294_31(unknown) = ^BufferMayWriteSideEffect[0] : &:r294_16
# 294| m294_32(unknown) = Chi : total:m294_24, partial:m294_31
# 294| r294_33(glval<int>) = FieldAddress[i] : r294_8
# 294| r294_34(int) = Load[?] : &:r294_33, ~m294_30
# 294| m294_35(int) = Store[j] : &:r294_1, r294_34
# 294| m294_21(A) = ^IndirectMayWriteSideEffect[-1] : &:r294_16
# 294| m294_22(unknown) = Chi : total:m294_15, partial:m294_21
# 294| v294_23(void) = Call[A] : func:r294_9, this:r294_8, 0:r294_16
# 294| v294_24(void) = ^BufferReadSideEffect[0] : &:r294_16, ~m294_22
# 294| m294_25(A) = ^IndirectMayWriteSideEffect[-1] : &:r294_8
# 294| m294_26(unknown) = Chi : total:m294_7, partial:m294_25
# 294| m294_27(unknown) = ^BufferMayWriteSideEffect[0] : &:r294_16
# 294| m294_28(unknown) = Chi : total:m294_22, partial:m294_27
# 294| r294_29(glval<int>) = FieldAddress[i] : r294_8
# 294| r294_30(int) = Load[?] : &:r294_29, ~m294_26
# 294| m294_31(int) = Store[j] : &:r294_1, r294_30
# 295| r295_1(glval<A *>) = VariableAddress[a] :
# 295| r295_2(glval<unknown>) = FunctionAddress[operator new] :
# 295| r295_3(unsigned long) = Constant[4] :
# 295| r295_4(void *) = Call[operator new] : func:r295_2, 0:r295_3
# 295| m295_5(unknown) = ^CallSideEffect : ~m294_27
# 295| m295_6(unknown) = Chi : total:m294_27, partial:m295_5
# 295| m295_5(unknown) = ^CallSideEffect : ~m294_14
# 295| m295_6(unknown) = Chi : total:m294_14, partial:m295_5
# 295| m295_7(unknown) = ^InitializeDynamicAllocation : &:r295_4
# 295| r295_8(A *) = Convert : r295_4
# 295| r295_9(glval<unknown>) = FunctionAddress[A] :
# 295| v295_10(void) = Call[A] : func:r295_9, this:r295_8
# 295| m295_11(unknown) = ^CallSideEffect : ~m295_6
# 295| m295_12(unknown) = Chi : total:m295_6, partial:m295_11
# 295| m295_13(A) = ^IndirectMayWriteSideEffect[-1] : &:r295_8
# 295| m295_14(unknown) = Chi : total:m295_7, partial:m295_13
# 295| m295_15(A *) = Store[a] : &:r295_1, r295_8
# 295| m295_11(A) = ^IndirectMayWriteSideEffect[-1] : &:r295_8
# 295| m295_12(unknown) = Chi : total:m295_7, partial:m295_11
# 295| m295_13(A *) = Store[a] : &:r295_1, r295_8
# 296| r296_1(glval<Point *>) = VariableAddress[#return] :
# 296| r296_2(glval<Point *>) = VariableAddress[p] :
# 296| r296_3(Point *) = Load[p] : &:r296_2, m292_9
# 296| m296_4(Point *) = Store[#return] : &:r296_1, r296_3
# 291| r291_7(glval<Point *>) = VariableAddress[#return] :
# 291| v291_8(void) = ReturnValue : &:r291_7, m296_4
# 291| v291_9(void) = AliasedUse : ~m295_12
# 291| v291_9(void) = AliasedUse : ~m295_6
# 291| v291_10(void) = ExitFunction :
# 301| int main(int, char**)

78
cpp/ql/test/library-tests/ir/ssa/aliased_ssa_ir_unsound.expected
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@@ -1045,46 +1045,36 @@ ssa.cpp:
# 240| r240_3(glval<unknown>) = FunctionAddress[Constructible] :
# 240| r240_4(int) = Constant[1] :
# 240| v240_5(void) = Call[Constructible] : func:r240_3, this:r240_1, 0:r240_4
# 240| m240_6(unknown) = ^CallSideEffect : ~m239_4
# 240| m240_7(unknown) = Chi : total:m239_4, partial:m240_6
# 240| m240_8(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r240_1
# 240| m240_9(Constructible) = Chi : total:m240_2, partial:m240_8
# 240| m240_6(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r240_1
# 240| m240_7(Constructible) = Chi : total:m240_2, partial:m240_6
# 241| r241_1(glval<Constructible>) = VariableAddress[c] :
# 241| r241_2(glval<unknown>) = FunctionAddress[g] :
# 241| v241_3(void) = Call[g] : func:r241_2, this:r241_1
# 241| m241_4(unknown) = ^CallSideEffect : ~m240_7
# 241| m241_5(unknown) = Chi : total:m240_7, partial:m241_4
# 241| v241_6(void) = ^IndirectReadSideEffect[-1] : &:r241_1, m240_9
# 241| m241_7(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r241_1
# 241| m241_8(Constructible) = Chi : total:m240_9, partial:m241_7
# 241| v241_4(void) = ^IndirectReadSideEffect[-1] : &:r241_1, m240_7
# 241| m241_5(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r241_1
# 241| m241_6(Constructible) = Chi : total:m240_7, partial:m241_5
# 242| r242_1(glval<Constructible>) = VariableAddress[c] :
# 242| r242_2(glval<unknown>) = FunctionAddress[g] :
# 242| v242_3(void) = Call[g] : func:r242_2, this:r242_1
# 242| m242_4(unknown) = ^CallSideEffect : ~m241_5
# 242| m242_5(unknown) = Chi : total:m241_5, partial:m242_4
# 242| v242_6(void) = ^IndirectReadSideEffect[-1] : &:r242_1, m241_8
# 242| m242_7(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r242_1
# 242| m242_8(Constructible) = Chi : total:m241_8, partial:m242_7
# 242| v242_4(void) = ^IndirectReadSideEffect[-1] : &:r242_1, m241_6
# 242| m242_5(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r242_1
# 242| m242_6(Constructible) = Chi : total:m241_6, partial:m242_5
# 243| r243_1(glval<Constructible>) = VariableAddress[c2] :
# 243| m243_2(Constructible) = Uninitialized[c2] : &:r243_1
# 243| r243_3(glval<unknown>) = FunctionAddress[Constructible] :
# 243| r243_4(int) = Constant[2] :
# 243| v243_5(void) = Call[Constructible] : func:r243_3, this:r243_1, 0:r243_4
# 243| m243_6(unknown) = ^CallSideEffect : ~m242_5
# 243| m243_7(unknown) = Chi : total:m242_5, partial:m243_6
# 243| m243_8(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r243_1
# 243| m243_9(Constructible) = Chi : total:m243_2, partial:m243_8
# 243| m243_6(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r243_1
# 243| m243_7(Constructible) = Chi : total:m243_2, partial:m243_6
# 244| r244_1(glval<Constructible>) = VariableAddress[c2] :
# 244| r244_2(glval<unknown>) = FunctionAddress[g] :
# 244| v244_3(void) = Call[g] : func:r244_2, this:r244_1
# 244| m244_4(unknown) = ^CallSideEffect : ~m243_7
# 244| m244_5(unknown) = Chi : total:m243_7, partial:m244_4
# 244| v244_6(void) = ^IndirectReadSideEffect[-1] : &:r244_1, m243_9
# 244| m244_7(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r244_1
# 244| m244_8(Constructible) = Chi : total:m243_9, partial:m244_7
# 244| v244_4(void) = ^IndirectReadSideEffect[-1] : &:r244_1, m243_7
# 244| m244_5(Constructible) = ^IndirectMayWriteSideEffect[-1] : &:r244_1
# 244| m244_6(Constructible) = Chi : total:m243_7, partial:m244_5
# 245| v245_1(void) = NoOp :
# 239| v239_5(void) = ReturnVoid :
# 239| v239_6(void) = AliasedUse : ~m244_5
# 239| v239_6(void) = AliasedUse : m239_3
# 239| v239_7(void) = ExitFunction :
# 247| char* VoidStarIndirectParameters(char*, int)
@@ -1385,43 +1375,37 @@ ssa.cpp:
# 294| r294_18(glval<int>) = VariableAddress[x] :
# 294| r294_19(int) = Load[x] : &:r294_18, m291_6
# 294| v294_20(void) = Call[A] : func:r294_17, this:r294_16, 0:r294_19
# 294| m294_21(unknown) = ^CallSideEffect : ~m294_14
# 294| m294_22(unknown) = Chi : total:m294_14, partial:m294_21
# 294| m294_23(A) = ^IndirectMayWriteSideEffect[-1] : &:r294_16
# 294| m294_24(unknown) = Chi : total:m294_15, partial:m294_23
# 294| v294_25(void) = Call[A] : func:r294_9, this:r294_8, 0:r294_16
# 294| m294_26(unknown) = ^CallSideEffect : ~m294_22
# 294| m294_27(unknown) = Chi : total:m294_22, partial:m294_26
# 294| v294_28(void) = ^BufferReadSideEffect[0] : &:r294_16, ~m294_24
# 294| m294_29(A) = ^IndirectMayWriteSideEffect[-1] : &:r294_8
# 294| m294_30(unknown) = Chi : total:m294_7, partial:m294_29
# 294| m294_31(unknown) = ^BufferMayWriteSideEffect[0] : &:r294_16
# 294| m294_32(unknown) = Chi : total:m294_24, partial:m294_31
# 294| r294_33(glval<int>) = FieldAddress[i] : r294_8
# 294| r294_34(int) = Load[?] : &:r294_33, ~m294_30
# 294| m294_35(int) = Store[j] : &:r294_1, r294_34
# 294| m294_21(A) = ^IndirectMayWriteSideEffect[-1] : &:r294_16
# 294| m294_22(unknown) = Chi : total:m294_15, partial:m294_21
# 294| v294_23(void) = Call[A] : func:r294_9, this:r294_8, 0:r294_16
# 294| v294_24(void) = ^BufferReadSideEffect[0] : &:r294_16, ~m294_22
# 294| m294_25(A) = ^IndirectMayWriteSideEffect[-1] : &:r294_8
# 294| m294_26(unknown) = Chi : total:m294_7, partial:m294_25
# 294| m294_27(unknown) = ^BufferMayWriteSideEffect[0] : &:r294_16
# 294| m294_28(unknown) = Chi : total:m294_22, partial:m294_27
# 294| r294_29(glval<int>) = FieldAddress[i] : r294_8
# 294| r294_30(int) = Load[?] : &:r294_29, ~m294_26
# 294| m294_31(int) = Store[j] : &:r294_1, r294_30
# 295| r295_1(glval<A *>) = VariableAddress[a] :
# 295| r295_2(glval<unknown>) = FunctionAddress[operator new] :
# 295| r295_3(unsigned long) = Constant[4] :
# 295| r295_4(void *) = Call[operator new] : func:r295_2, 0:r295_3
# 295| m295_5(unknown) = ^CallSideEffect : ~m294_27
# 295| m295_6(unknown) = Chi : total:m294_27, partial:m295_5
# 295| m295_5(unknown) = ^CallSideEffect : ~m294_14
# 295| m295_6(unknown) = Chi : total:m294_14, partial:m295_5
# 295| m295_7(unknown) = ^InitializeDynamicAllocation : &:r295_4
# 295| r295_8(A *) = Convert : r295_4
# 295| r295_9(glval<unknown>) = FunctionAddress[A] :
# 295| v295_10(void) = Call[A] : func:r295_9, this:r295_8
# 295| m295_11(unknown) = ^CallSideEffect : ~m295_6
# 295| m295_12(unknown) = Chi : total:m295_6, partial:m295_11
# 295| m295_13(A) = ^IndirectMayWriteSideEffect[-1] : &:r295_8
# 295| m295_14(unknown) = Chi : total:m295_7, partial:m295_13
# 295| m295_15(A *) = Store[a] : &:r295_1, r295_8
# 295| m295_11(A) = ^IndirectMayWriteSideEffect[-1] : &:r295_8
# 295| m295_12(unknown) = Chi : total:m295_7, partial:m295_11
# 295| m295_13(A *) = Store[a] : &:r295_1, r295_8
# 296| r296_1(glval<Point *>) = VariableAddress[#return] :
# 296| r296_2(glval<Point *>) = VariableAddress[p] :
# 296| r296_3(Point *) = Load[p] : &:r296_2, m292_9
# 296| m296_4(Point *) = Store[#return] : &:r296_1, r296_3
# 291| r291_7(glval<Point *>) = VariableAddress[#return] :
# 291| v291_8(void) = ReturnValue : &:r291_7, m296_4
# 291| v291_9(void) = AliasedUse : ~m295_12
# 291| v291_9(void) = AliasedUse : ~m295_6
# 291| v291_10(void) = ExitFunction :
# 301| int main(int, char**)