[PATCH] D69027: [llvm-dwarfdump][Statistics] Fix calculation of OffsetToFirstDefinition

[Alexey Lapshin via Phabricator via llvm-commits]

avl added a comment.

I think OffsetToFirstDefinition should not be taken into account at all.
i.e., coverage should be calculated against block scope, not against variable scope(which is unknown).

If we have the following case:

DW_TAG_lexical_block

  DW_AT_ranges  (0x00000000
     [0x000000000000010, 0x0000000000000197))
  
  DW_TAG_variable
    DW_AT_location  (0x0000018e
       [0x0000000000000183,  0x0000000000000197): DW_OP_reg0 RAX)

And then will create a fix which improves debug info in such a way:

DW_TAG_lexical_block

  DW_AT_ranges  (0x00000000
     [0x000000000000010, 0x0000000000000197))
  
  DW_TAG_variable
    DW_AT_location  (0x0000018e
       [0x0000000000000100,  0x0000000000000183): DW_OP_reg1 RBX)
       [0x0000000000000183,  0x0000000000000197): DW_OP_reg0 RAX)

In both cases reported statistic there would be 100%. 
That hides original low coverage for that variable and makes invisible performed improvement.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D69027/new/

https://reviews.llvm.org/D69027