[clang] [llvm] Add option to generate additional debug info for expression dereferencing pointer to pointers. (PR #94100)

[William Junda Huang via cfe-commits]

huangjd wrote:

By just specifying `-g` Even without `-fdebug-info-for-profiling` it is going to introduce debug variables as a sequence of alloca-store-load too, so is it a requirement to guarantee `-O0` output stays identical with or without debug info? 

Emitting a dbg.value was what I originally though of, but there is a IR validation pass after frontend codegen that does not permit it, not sure if there's other design reason for this check 



https://github.com/llvm/llvm-project/pull/94100