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C++: Fix joins in cpp/use-after-free #15136

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merged 1 commit into from Dec 18, 2023

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MathiasVP
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@MathiasVP MathiasVP commented Dec 18, 2023

This was highlighted by the nightly C/C++ DCA.

Before:

Pipeline base for UseAfterFree::ParameterSinks::getAnAlwaysDereferencedParameter/0#bfd578a4@7c3b71t2 was evaluated in 1 iterations totaling 1ms (delta sizes total: 4868).
  4868  ~0%    {1} r1 = JOIN `UseAfterFree::ParameterSinks::getAnAlwaysDereferencedParameter0/0#2ee9f822` WITH project#Instruction::InitializeParameterInstruction#d726fcda ON FIRST 1 OUTPUT Lhs.0
               return r1

Pipeline standard for UseAfterFree::ParameterSinks::getAnAlwaysDereferencedParameter/0#bfd578a4@7c3b71t2 was evaluated in 5 iterations totaling 676ms (delta sizes total: 927).
                  {2} r1 = `_ValueNumberingInternal::tvalueNumber/1#f03b58f9_project#Instruction::InitializeParameterInstruction__#loop_invariant_prefix` AND NOT `UseAfterFree::ParameterSinks::getAnAlwaysDereferencedParameter/0#bfd578a4#prev`(FIRST 1)
  1541170   ~0%   {2} r2 = SCAN r1 OUTPUT In.1, In.0
  5825857   ~1%   {2} r3 = JOIN r2 WITH `ValueNumberingInternal::tvalueNumber/1#f03b58f9_10#join_rhs` ON FIRST 1 OUTPUT Rhs.1, Lhs.1
   881300   ~0%   {4} r4 = JOIN r3 WITH `UseAfterFree::ParameterSinks::callHasTargetAndArgument/4#2549c98d_3012#join_rhs` ON FIRST 1 OUTPUT Rhs.3, Lhs.1, Rhs.1, Rhs.2
   642364   ~1%   {3} r5 = JOIN r4 WITH `project#UseAfterFree::ParameterSinks::getAnAlwaysReachedCallInstruction/1#30c9505a` ON FIRST 1 OUTPUT Lhs.2, Lhs.3, Lhs.1
   586991   ~0%   {2} r6 = JOIN r5 WITH `UseAfterFree::ParameterSinks::initializeParameterInFunction/3#0f75893b` ON FIRST 2 OUTPUT Rhs.2, Lhs.2
      948   ~3%   {1} r7 = JOIN r6 WITH `UseAfterFree::ParameterSinks::getAnAlwaysDereferencedParameter/0#bfd578a4#prev_delta` ON FIRST 1 OUTPUT Lhs.1
                  return r7

After:

Pipeline base for UseAfterFree::ParameterSinks::initializeParameterInFunction/2#29dff0d6@8b351y1h was evaluated in 1 iterations totaling 0ms (delta sizes total: 0).
  0  ~0%    {2} r1 = EMPTY(entity, int)
            return r1

Pipeline standard for UseAfterFree::ParameterSinks::initializeParameterInFunction/2#29dff0d6@8b351y1h was evaluated in 6 iterations totaling 3ms (delta sizes total: 5782).
  5782  ~0%    {2} r1 = JOIN `UseAfterFree::ParameterSinks::getAnAlwaysDereferencedParameter/0#bfd578a4#prev_delta` WITH `Instruction::InitializeParameterInstruction.hasIndex/1#0f90b0b3` ON FIRST 1 OUTPUT Lhs.0, Rhs.1
  5782  ~1%    {2} r2 = JOIN r1 WITH `Instruction::Instruction.getEnclosingFunction/0#dispred#cb8ccc56` ON FIRST 1 OUTPUT Rhs.1, Lhs.1
  5782  ~1%    {2} r3 = JOIN r2 WITH functions ON FIRST 1 OUTPUT Lhs.0, Lhs.1
  5782  ~1%    {2} r4 = r3 AND NOT `UseAfterFree::ParameterSinks::initializeParameterInFunction/2#29dff0d6#prev`(FIRST 2)
               return r4

Pipeline base for UseAfterFree::ParameterSinks::alwaysDereferencedArgumentHasValueNumber/1#500ae075@8b351x1h was evaluated in 1 iterations totaling 0ms (delta sizes total: 0).
  0  ~0%    {1} r1 = EMPTY(unique numbered_tuple)
                return r1

Pipeline standard for UseAfterFree::ParameterSinks::alwaysDereferencedArgumentHasValueNumber/1#500ae075@8b351x1h was evaluated in 5 iterations totaling 5ms (delta sizes total: 4109).
  4370   ~5%    {1} r1 = JOIN `UseAfterFree::ParameterSinks::initializeParameterInFunction/2#29dff0d6#prev_delta` WITH `UseAfterFree::ParameterSinks::callHasTargetAndArgument/3#f5b63eb0` ON FIRST 2 OUTPUT Rhs.2
  4355  ~10%    {1} r2 = JOIN r1 WITH `ValueNumberingInternal::tvalueNumber/1#f03b58f9` ON FIRST 1 OUTPUT Rhs.1
  4109   ~3%    {1} r3 = r2 AND NOT `UseAfterFree::ParameterSinks::alwaysDereferencedArgumentHasValueNumber/1#500ae075#prev`(FIRST 1)
                    return r3

Pipeline base for UseAfterFree::ParameterSinks::getAnAlwaysDereferencedParameter/0#bfd578a4@8b351w1h was evaluated in 1 iterations totaling 1ms (delta sizes total: 4868).
  4868  ~0%    {1} r1 = JOIN `UseAfterFree::ParameterSinks::getAnAlwaysDereferencedParameter0/0#2ee9f822` WITH project#Instruction::InitializeParameterInstruction#d726fcda ON FIRST 1 OUTPUT Lhs.0
                return r1

Pipeline standard for UseAfterFree::ParameterSinks::getAnAlwaysDereferencedParameter/0#bfd578a4@8b351w1h was evaluated in 5 iterations totaling 6ms (delta sizes total: 914).
  10174  ~0%    {1} r1 = JOIN `UseAfterFree::ParameterSinks::alwaysDereferencedArgumentHasValueNumber/1#500ae075#prev_delta` WITH `ValueNumberingInternal::tvalueNumber/1#f03b58f9_10#join_rhs` ON FIRST 1 OUTPUT Rhs.1
    973  ~0%    {1} r2 = JOIN r1 WITH project#Instruction::InitializeParameterInstruction#d726fcda ON FIRST 1 OUTPUT Lhs.0
    914  ~0%    {1} r3 = r2 AND NOT `UseAfterFree::ParameterSinks::getAnAlwaysDereferencedParameter/0#bfd578a4#prev`(FIRST 1)
                return r3

@MathiasVP MathiasVP requested a review from a team as a code owner December 18, 2023 13:53
@github-actions github-actions bot added the C++ label Dec 18, 2023
@MathiasVP MathiasVP added the no-change-note-required This PR does not need a change note label Dec 18, 2023
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LGTM if DCA is happy.

@MathiasVP MathiasVP merged commit 41c49ae into github:main Dec 18, 2023
14 of 15 checks passed
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