[PATCH] D113465: [llvm-dwarfdump][Statistics] Handle LTO cases with cross CU referencing

[Orlando Cazalet-Hyams via Phabricator via llvm-commits]

Orlando added a comment.

Hi,

> Note that each entry within the concrete inlined instance tree in the main.c CU has a DW_AT_abstract_origin attribute which refers to a corresponding entry within the abstract instance tree in the sum.c CU.
> llvm-dwarfdump (its --statistics option, to be precise) did not properly report DW_TAG_formal_parameters/DW_TAG_variables which had 0% location coverage, mainly because information about abstract instance trees and their parameters/variables was stored locally - just for the currently processed CU, rather than globally - for all CUs.

You state that the variables should have "0% location coverage", but the variables in your example each have a location that covers the entirety of its inlined scope (100% coverage):

  0x0000006d:     DW_TAG_inlined_subroutine
                    DW_AT_abstract_origin	(0x00000000000000b0 "sum")
                    DW_AT_low_pc	(0x00000000002016ef)
                    DW_AT_high_pc	(0x00000000002016f1)
                    DW_AT_call_file	("main.c")
                    DW_AT_call_line	(5)
                    DW_AT_call_column	(0x19)
  
  0x00000081:       DW_TAG_formal_parameter
                      DW_AT_location	(DW_OP_reg0 RAX)
                      DW_AT_abstract_origin	(0x00000000000000bc "a")

Am I missing something?

I added just one inline nit/question but I haven't fully reviewed this - please don't let my questions block the review process.



================
Comment at: llvm/tools/llvm-dwarfdump/Statistics.cpp:48
+using CrossCUReferencingDIELocationTy =
+    llvm::SmallVector<std::unique_ptr<DIELocation>>;
+
----------------
Is there a reason that this cannot be just `llvm::SmallVector<DIELocation>` (i.e. drop the unique_ptr wrapper)?


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