[all-commits] [llvm/llvm-project] aeccfe: Add option to generate additional debug info for e...

[William Junda Huang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: aeccfee348c717165541d8d895b9b0cdfe31415c
      https://github.com/llvm/llvm-project/commit/aeccfee348c717165541d8d895b9b0cdfe31415c
  Author: William Junda Huang <williamjhuang at google.com>
  Date:   2024-05-29 (Wed, 29 May 2024)

  Changed paths:
    M clang/lib/CodeGen/CGDebugInfo.cpp
    M clang/lib/CodeGen/CGDebugInfo.h
    M clang/lib/CodeGen/CGExprScalar.cpp
    A clang/test/CodeGenCXX/debug-info-ptr-to-ptr.cpp

  Log Message:
  -----------
  Add option to generate additional debug info for expression dereferencing pointer to pointers. (#81545)

Such expression does not correspond to a variable in the source code
thus does not have a debug location. When the user collects perf data on
the program, if the intermediate memory load instruction is sampled, it
could not be attributed to any variable/class member, which causes the
sampling results to be under-counted.
This patch adds an option `-fdebug_info_for_pointer_type` to generate a
psuedo variable and its debug info for intermediate expression with
pointer dereferencing, so that perf data collected on the instruction of
that expression can be attributed to the correct class member.

This is a prototype so comments are needed.



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