[DebugInfo][LICM] Debug value info loss caused by removing dead instructions without salvaging

[Apochens]

1. Removing the dead instruction without salvaging the debug value info in hoistGEP:

llvm-project/llvm/lib/Transforms/Scalar/LICM.cpp

Line 2543 in 393c783

eraseInstruction(*Src, SafetyInfo, MSSAU);

Code example: https://godbolt.org/z/b3331YxE8

2. Removing the dead instruction without salvaging the debug value info in hoistAdd:

llvm-project/llvm/lib/Transforms/Scalar/LICM.cpp

Line 2597 in 393c783

eraseInstruction(cast<Instruction>(*VariantLHS), SafetyInfo, MSSAU);

Code example: https://godbolt.org/z/TbjdP5Y1d

3. Removing the dead instruction without salvaging the debug value info in hoistSub:

llvm-project/llvm/lib/Transforms/Scalar/LICM.cpp

Line 2675 in 393c783

eraseInstruction(cast<Instruction>(*VariantLHS), SafetyInfo, MSSAU);

Code example: https://godbolt.org/z/h3veE8fj9

4. Removing the dead instruction without salvaging the debug value info in hoistBOAssociation:

llvm-project/llvm/lib/Transforms/Scalar/LICM.cpp

Lines 2882 to 2883 in 393c783

	if (BO0->use_empty())
	eraseInstruction(*BO0, SafetyInfo, MSSAU);

Code example: https://godbolt.org/z/9nE7Tob6E

[llvmbot]

@llvm/issue-subscribers-debuginfo

Author: Shan Huang (Apochens)

1. Removing the dead instruction without salvaging the debug value info in `hoistAdd`:

llvm-project/llvm/lib/Transforms/Scalar/LICM.cpp

Line 2597 in 393c783

eraseInstruction(cast<Instruction>(*VariantLHS), SafetyInfo, MSSAU);

Code example: https://godbolt.org/z/TbjdP5Y1d

2. Removing the dead instruction without salvaging the debug value info in hoistSub:

llvm-project/llvm/lib/Transforms/Scalar/LICM.cpp

Line 2675 in 393c783

eraseInstruction(cast<Instruction>(*VariantLHS), SafetyInfo, MSSAU);

Code example: https://godbolt.org/z/h3veE8fj9

3. Removing the dead instruction without salvaging the debug value info in hoistBOAssociation:

llvm-project/llvm/lib/Transforms/Scalar/LICM.cpp

Lines 2882 to 2883 in 393c783

	if (BO0->use_empty())
	eraseInstruction(*BO0, SafetyInfo, MSSAU);

Code example: https://godbolt.org/z/9nE7Tob6E