[PATCH] D78558: [Support] Make DataExtractor error messages more clear

Tue Apr 21 06:59:10 PDT 2020

labath marked an inline comment as done.
labath added inline comments.

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Comment at: llvm/lib/Support/DataExtractor.cpp:27
+        ", 0x%" PRIx64 ")",
+        Data.size(), Offset, Offset + Size);
+  return false;
----------------
jhenderson wrote:
> My instinct says that this needs to be Data.size() + Offset. I'm reading some of the changed messages in the tests and getting confused by how they line up with the range Example: "offset 0x48 while reading [0xbadbeef, 0xbadbef7)" - what is the offset 0x48 referring to? I think "offset 0xbadbef6 while reading..." (or whatever the value actually should be) might be clearer.
Yeah, that one is funny. What happens there is that the very first read starts at a completely bogus offset. In this case that happens because the value of DW_AT_location is (deliberately) corrupted, but it could happen when following other kinds of indirect references (e.g. `DW_FORM_strp`), depending on how exactly is that implemented.

What would you say to checking for `Data.size() < Offset` and emitting a different error message in that case ("reading offset 0xdeadbeef beyond the end of data at 0x48") ?

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D78558/new/

https://reviews.llvm.org/D78558